Ophthalmic apparatus, method for controlling ophthalmic apparatus, and storage medium

Abstract

To provide a new technique for simply and inexpensively expanding an imaging range in the depth direction of OCT.SOLUTION: The ophthalmic apparatus includes an optical system, an optical member, an optical member drive unit, and an image forming unit. The optical system includes an optical scanner, splits light from a light source into measurement light and reference light, projects the measurement light deflected by the optical scanner onto a subject's eye, and detects interference light between return light of the measurement light from the subject's eye and the reference light. The optical member is disposed at a position optically non-conjugate to a position of an exit pupil of the optical system in an optical path of the measurement light, and provides the measurement light with an optical path length difference with respect to a reference position of A-scan for each A-scan position by providing the measurement light with an optical path length different from a reference optical path length provided to the measurement light passing through the reference position according to the A-scan position. The image forming unit is configured to form an OCT image of the subject's eye based on a detection result of the interference light. The optical member has two or more regions that give different optical path lengths to the measurement light passing therethrough.SELECTED DRAWING: Figure 6B

Description

[Technical Field]

[0001] The present invention relates to an ophthalmic apparatus, a control method for an ophthalmic apparatus, and a program. [Background technology]

[0002] In recent years, optical coherence tomography (OCT), which uses a light beam from a laser or other source to form images that represent the surface or internal morphology of an object under measurement, has been attracting attention. Unlike X-ray computed tomography (CT), OCT is non-invasive, and is therefore expected to be particularly useful in the medical and biological fields. For example, in the field of ophthalmology, devices that form images of the fundus and cornea have been put to practical use.

[0003] If such an ophthalmic device using OCT could easily observe and photograph the imaging region of the subject's eye over a wide field of view, it would be useful for screening and treating eye diseases. However, when performing an OCT scan on a wide imaging region, the scan length in the B-scan direction becomes long. Because the cross-sectional shape of imaging regions such as the fundus and anterior segment is curved, if the scan length in the B-scan direction becomes long, the acquired scan data will no longer fit within the OCT's imaging range in the depth direction, resulting in image flipping (aliasing).

[0004] Known methods for expanding the imaging range in the depth direction of OCT include, for example, a method of increasing the sampling speed of OCT measurement results and a method using full-range OCT (e.g., Patent Document 1). However, increasing the sampling speed of OCT measurement results requires a high-speed digitizer. High-speed digitizers are extremely expensive. Furthermore, the method using full-range OCT requires additional hardware such as a phase modulator and complex signal processing.

[0005] As described above, it is difficult to obtain wide-angle OCT data easily and at low cost using conventional methods for expanding the imaging range.

[0006] For example, Patent Documents 2 and 3 disclose a method of providing two reference light paths and acquiring OCT data using reference light that passes through different reference light paths at the center and peripheral parts of the fundus.

[0007] Also, for example, Non-Patent Document 1 discloses a method of changing the optical path length of the reference arm in synchronization with the scan on the measurement arm side. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2015-506772 [Patent Document 2] Japanese Patent Application Publication No. 2018-171168 [Patent Document 3] Japanese Patent Application Publication No. 2019-080804 [Non-patent literature]

[0009] [Non-Patent Document 1] JG Fujimoto et al., “High-Speed, Ultrahigh-Resolution Spectral-Domain OCT with Extended Imaging Range Using Reference Arm Length Matching”, Translational vision science & technology, June 2020, Vol. 9, No. 7, Article 12, p.1-14 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the methods disclosed in Patent Documents 2 and 3 require the provision of two reference optical paths, which increases the size of the optical system and complicates control.

[0011] Furthermore, the method disclosed in Non-Patent Document 1 requires the addition of a mechanism that changes the optical path length of the reference arm in synchronization with the scan on the measurement arm side. This not only increases costs associated with the addition of a mechanism, but also makes synchronous control difficult, potentially affecting the quality of the OCT data.

[0012] The present invention has been made in view of the above circumstances, and one of its objectives is to provide a new technology for expanding the imaging range in the depth direction of OCT simply and at low cost. [Means for solving the problem]

[0013] One aspect of the embodiment is an ophthalmic device including: an optical system that includes an optical scanner, splits light from a light source into measurement light and reference light, projects the measurement light deflected by the optical scanner onto a test eye, and detects interference light between return light of the measurement light from the test eye and the reference light; an optical element that is arranged at a position optically non-conjugate with a position of an exit pupil of the optical system in the optical path of the measurement light, and imparts an optical path length different from a reference optical path length imparted to the measurement light passing through a reference position of an A-scan to the measurement light according to the A-scan position, thereby imparting an optical path length difference from the reference position to the measurement light for each A-scan position; an optical element driving unit that changes the relative position of the optical element with respect to the optical path of the measurement light within a luminous flux cross section of the measurement light; and an image forming unit that forms an OCT image of the test eye based on a detection result of the interference light, wherein the optical element has two or more regions that impart different optical path lengths to the passing measurement light. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a new technique for expanding the imaging range in the depth direction of OCT simply and at low cost. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to an embodiment. [Figure 2] 1A and 1B are schematic diagrams illustrating an example of the configuration of an optical member according to an embodiment. [Figure 3] 1 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to an embodiment. [Figure 4] FIG. 2 is a schematic diagram illustrating an example of the configuration of a processing system of an ophthalmologic apparatus according to an embodiment. [Figure 5] FIG. 2 is a schematic diagram illustrating an example of the configuration of a processing system of an ophthalmologic apparatus according to an embodiment. [Figure 6A] 10A and 10B are diagrams illustrating the operation of an ophthalmologic apparatus according to a comparative example of the embodiment. [Figure 6B] 3A to 3C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. [Figure 7A] 4 is a schematic diagram illustrating an example of the configuration of an optical member according to a first modified example of the embodiment. FIG. [Figure 7B] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical member according to a second modified example of the embodiment. [Figure 7C] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical member according to a third modified example of the embodiment. [Figure 7D] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical member according to a fourth modified example of the embodiment. [Figure 7E] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical member according to a fifth modified example of the embodiment. [Figure 7F] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical member according to a sixth modified example of the embodiment. [Figure 7G] FIG. 13 is a schematic diagram illustrating an example of the configuration of an optical member according to a seventh modified example of the embodiment. [Figure 8] FIG. 4 is a flowchart of an example of the operation of the ophthalmologic apparatus according to the embodiment. [Figure 9] FIG. 4 is a flowchart of an example of the operation of the ophthalmologic apparatus according to the embodiment. [Figure 10] FIG. 4 is a flowchart of an example of the operation of the ophthalmologic apparatus according to the embodiment. [Figure 11] 3A to 3C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. [Figure 12] 3A to 3C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. [Figure 13] 3A to 3C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. [Figure 14] FIG. 13 is a schematic diagram illustrating an example of the configuration of an optical member according to an eighth modified example of the embodiment. [Figure 15] 10A and 10B are explanatory diagrams illustrating the operation of an ophthalmologic apparatus according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] An ophthalmic apparatus, a control method for an ophthalmic apparatus, and a program according to the present invention will be described in detail with reference to the accompanying drawings. Note that the contents of documents cited in this specification and any publicly known techniques may be incorporated into the following embodiments.

[0017] An ophthalmic apparatus according to an embodiment includes an optical system having an optical scanner and an optical element that can be arranged in the optical path of measurement light from the optical system. The optical system includes an interference optical system that splits light from a light source into measurement light and reference light, projects the measurement light deflected by the optical scanner onto a subject's eye, and detects interference light between the measurement light returned from the subject's eye and the reference light. The optical element is an optical path length correction element that imparts an optical path length corresponding to the angle of view to the passing measurement light. Specifically, the optical element imparts an optical path length difference relative to the reference position of the A-scan to the measurement light (light beam) for each A-scan position where the passing measurement light is incident on a measurement site (image capture site) of the subject's eye. This allows the measurement light to be imparted with an optical path length difference for each angle of view (A-scan position) based on the optical path length of the measurement light at the reference angle of view (reference position of the A-scan).

[0018] The optical element is disposed at a position optically non-conjugate with the position of the exit pupil of the optical system in the optical path of the passing measurement light. In some embodiments, the optical element is disposed at a position optically approximately conjugate with the measurement site of the subject's eye. This allows the measurement light to be given an optical path length (optical path length difference) for each field angle at a position where the beam separation of the measurement light is best, so that a desired optical path length (optical path length difference) can be accurately given for a desired field angle range.

[0019] In some embodiments, the ophthalmologic apparatus forms an OCT image based on scan data (OCT data) obtained by an OCT scan using measurement light to which an optical path length difference is applied for each field angle. In this case, in a region where an optical path length difference is applied by an optical member relative to a reference field angle, the OCT image is shifted so that, for example, the position in the depth direction becomes deeper.

[0020] For example, the optical element imparts an optical path length difference to the measurement light so that the optical path length becomes longer at positions away from the reference position of the A-scan (for example, the imaging center, the position equivalent to the optical axis of the optical system). In this case, for a measurement site with a concave cross-sectional shape such as the fundus, the z position of an OCT image obtained by an A-scan performed on a site far from the reference angle of view (reference position of the A-scan) can be shifted deeper in the depth direction.

[0021] For example, the optical element imparts an optical path length difference to the measurement light so that the optical path length becomes shorter at a position where the A-scan position is farther from the reference position of the A-scan. In this case, at a measurement site with a convex cross-sectional shape, such as the anterior segment or edema in the fundus, the z position of the OCT image obtained by an A-scan performed on a site close to the reference angle of view can be shifted to become shallower in the depth direction.

[0022] As described above, it is possible to easily and inexpensively expand the imaging range in the depth direction of OCT, and prevent image flipping.

[0023] The optical path length difference assigned for each angle of view is known information based on the material and structure of the optical component. In some embodiments, the ophthalmologic apparatus identifies an area to which a known optical path length difference is assigned and causes a display unit to distinctively display an image of the identified area. In some embodiments, the ophthalmologic apparatus cancels a shift in the depth direction corresponding to the known optical path length difference to generate a composite image of an area to which an optical path length difference is assigned and an area to which no optical path length difference is assigned, or a composite image of two or more areas to which different optical path length differences are assigned.

[0024] A control method for an ophthalmic device according to an embodiment includes one or more steps for controlling the above-described ophthalmic device. A program according to an embodiment causes a computer (processor) to execute each step of the control method for an ophthalmic device according to an embodiment. A recording medium according to an embodiment is a non-transitory recording medium (storage medium) that can be read by a computer and that stores a program according to an embodiment.

[0025] In this specification, a processor includes circuits such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). The processor realizes the functions of the embodiments by, for example, reading and executing a program stored in a memory circuit or a storage device. The memory circuit or storage device may be included in the processor. Alternatively, the memory circuit or storage device may be provided external to the processor.

[0026] In the following embodiments, an ophthalmic apparatus will be described for photographing a fundus having a concave cross-sectional shape. However, the configuration according to the embodiment can be applied to an ophthalmic apparatus for photographing a part having a convex cross-sectional shape, such as edema in the cornea or fundus. In this case, the direction in which the optical path length difference is applied in the optical element is opposite to that in the following embodiments, and the direction in which the shift amount corresponding to the applied optical path length difference is canceled is also opposite to that in the following embodiments.

[0027] An ophthalmic apparatus according to some embodiments includes one or more of an ophthalmic imaging device, an ophthalmic measurement device, and an ophthalmic treatment device. The ophthalmic imaging device included in the ophthalmic apparatus according to some embodiments is, for example, one or more of a fundus camera, a scanning laser ophthalmoscope, a slit lamp ophthalmoscope, a surgical microscope, etc. The ophthalmic measurement device included in the ophthalmic apparatus according to some embodiments is, for example, one or more of an eye refraction examination device, a tonometer, a specular microscope, a wavefront analyzer, a perimeter, a microperimeter, etc. The ophthalmic treatment device included in the ophthalmic apparatus according to some embodiments is, for example, one or more of a laser treatment device, a surgical device, a surgical microscope, etc.

[0028] An ophthalmologic apparatus according to the following embodiment includes an OCT apparatus capable of OCT measurement and a fundus camera.

[0029] The following description will be given taking an ophthalmic apparatus capable of performing OCT measurement of the fundus of a test eye as an example, but the ophthalmic apparatus according to the embodiment may also be capable of OCT measurement of the anterior segment of the test eye. In some embodiments, the range and measurement site of the OCT measurement are changed by moving a lens that changes the focal position of the measurement light. In some embodiments, by adding one or more attachments (objective lens, front lens, etc.), a configuration is possible in which OCT measurement of the fundus, OCT measurement of the anterior segment, and OCT measurement of the entire eye including the fundus and the anterior segment are possible. In some embodiments, in an ophthalmic apparatus for fundus measurement, a front lens is placed between the objective lens and the test eye, and measurement light converted into a parallel beam is incident on the test eye, thereby performing OCT measurement of the anterior segment.

[0030] In this specification, images acquired by OCT may be collectively referred to as OCT images. Furthermore, the measurement operation for forming an OCT image may be referred to as OCT measurement. Furthermore, in this specification, the optical path length difference may be simply referred to as "optical path length difference," assuming that the optical path length of the measurement light incident on the reference position of the A-scan is used as the reference.

[0031] In the following embodiments, a case where a swept-source OCT technique is used in measurement or imaging using OCT will be described in detail. However, the configuration according to the embodiment can also be applied to an ophthalmic apparatus that uses other types of OCT (for example, spectral domain type or time domain type).

[0032] Hereinafter, the x direction is the direction perpendicular to the optical axis direction of the objective lens (left-right direction, horizontal direction), the y direction is the direction perpendicular to the optical axis direction of the objective lens (up-down direction, vertical direction), and the z direction is the direction of the optical axis of the objective lens.

[0033] [composition] <Optical system configuration> As shown in Figures 1, 2, and 3, the ophthalmologic apparatus 1 includes a fundus camera unit 2, an OCT unit 100, and an arithmetic and control unit 200. The fundus camera unit 2 has an optical system substantially similar to that of a conventional fundus camera. The OCT unit 100 is provided with an optical system for acquiring an OCT image of the fundus (or anterior segment). The arithmetic and control unit 200 includes a computer that executes various arithmetic processes, control processes, etc.

[0034] [Fundus camera unit 2] The fundus camera unit 2 shown in FIG. 1 is provided with an optical system for acquiring a two-dimensional image (fundus image) representing the surface morphology of the fundus Ef of the subject's eye E. Fundus images include observed images and photographed images. The observed image is, for example, a monochrome moving image formed at a predetermined frame rate using near-infrared light. The photographed image may be, for example, a color image obtained by flashing visible light, or a monochrome still image using near-infrared light or visible light as illumination light. The fundus camera unit 2 may be configured to acquire images other than these, such as a fluorescein fluorescent image, an indocyanine green fluorescent image, or an autofluorescent image.

[0035] The fundus camera unit 2 is provided with a chin rest and a forehead rest for supporting the face of the subject. The fundus camera unit 2 is further provided with an illumination optical system 10 and a photographing optical system 30. The illumination optical system 10 irradiates the fundus Ef with illumination light. The photographing optical system 30 guides the fundus reflection light of this illumination light to an imaging device (CCD image sensors (sometimes simply referred to as CCDs) 35, 38). The photographing optical system 30 also guides measurement light from the OCT unit 100 to the fundus Ef, and also guides measurement light that has passed through the fundus Ef to the OCT unit 100.

[0036] The observation light source 11 of the illumination optical system 10 includes, for example, a halogen lamp. Light output from the observation light source 11 (observation illumination light) is reflected by a reflecting mirror 12 having a curved reflecting surface, passes through a condenser lens 13, and passes through a visible light cut filter 14 to become near-infrared light. The observation illumination light is then focused near the imaging light source 15, reflected by a mirror 16, and passes through relay lenses 17 and 18, an aperture 19, and a relay lens 20. The observation illumination light is then reflected by the peripheral portion (the area surrounding the hole) of the apertured mirror 21, passes through a dichroic mirror 48, and is refracted by the objective lens 22 to illuminate the fundus Ef. Note that an LED (Light Emitting Diode) can also be used as the observation light source.

[0037] The fundus reflected light of the observation illumination light is refracted by the objective lens 22, transmitted through the dichroic mirror 48, passes through the hole formed in the central region of the aperture mirror 21, transmitted through the dichroic mirror 55, passes through the focusing lens 31, and is reflected by the mirror 32. This fundus reflected light then transmits through the half mirror 33A, is reflected by the dichroic mirror 33, and is focused by the condenser lens 34 onto the light receiving surface of the CCD image sensor 35. The CCD image sensor 35 detects the fundus reflected light at, for example, a predetermined frame rate. An image (observation image) based on the fundus reflected light detected by the CCD image sensor 35 is displayed on the display device 3. When the focus of the photographing optical system 30 is adjusted to the anterior segment, an observation image of the anterior segment of the subject's eye E is displayed.

[0038] The imaging light source 15 includes, for example, a xenon lamp. Light (imaging illumination light) output from the imaging light source 15 is irradiated onto the fundus Ef along the same path as the observation illumination light. Fundus reflection light of the imaging illumination light is guided to the dichroic mirror 33 along the same path as the observation illumination light, passes through the dichroic mirror 33, is reflected by a mirror 36, and is focused on the light receiving surface of a CCD image sensor 38 by a condenser lens 37. An image (photographed image) based on the fundus reflection light detected by the CCD image sensor 38 is displayed on the display device 3. The display device 3 that displays the observation image and the display device 3 that displays the photographed image may be the same or different. When similar photography is performed by illuminating the subject's eye E with infrared light, an infrared photographed image is displayed. An LED may also be used as the imaging light source.

[0039] The LCD (Liquid Crystal Display) 39 displays a fixation target and a visual target for visual acuity measurement. The fixation target is a visual target for causing the subject's eye E to fixate, and is used during fundus photography, OCT measurement, and the like.

[0040] A portion of the light output from the LCD 39 is reflected by the half mirror 33A, reflected by the mirror 32, passes through the focusing lens 31 and the dichroic mirror 55, and passes through the hole in the aperture mirror 21. The light that has passed through the hole is transmitted through the dichroic mirror 48, refracted by the objective lens 22, and projected onto the fundus Ef.

[0041] The fixation position of the subject's eye E can be changed by changing the display position of the fixation target on the screen of the LCD 39. As with conventional fundus cameras, the fixation position of the subject's eye E can be, for example, a position for acquiring an image centered on the macular region of the fundus Ef, a position for acquiring an image centered on the optic disc, or a position for acquiring an image centered on the center of the fundus between the macular region and the optic disc. It is also possible to arbitrarily change the display position of the fixation target.

[0042] Furthermore, the fundus camera unit 2 is provided with an alignment optical system 50 and a focus optical system 60, similar to conventional fundus cameras. The alignment optical system 50 generates an index (alignment index) for aligning the device optical system with the subject's eye E. The focus optical system 60 generates an index (split index) for focusing on the fundus Ef.

[0043] Light (alignment light) output from an LED 51 of the alignment optical system 50 passes through apertures 52, 53 and a relay lens 54, is reflected by a dichroic mirror 55, and passes through the hole in the aperture mirror 21. The light that has passed through the hole is transmitted through a dichroic mirror 48 and is projected onto the cornea of ​​the subject's eye E by the objective lens 22.

[0044] The corneal reflection light of the alignment light passes through the objective lens 22, dichroic mirror 48, and the hole, and a portion of it passes through the dichroic mirror 55, passes through the focusing lens 31, is reflected by the mirror 32, and passes through the half mirror 33A. The corneal reflection light that passes through the half mirror 33A is reflected by the dichroic mirror 33 and is projected onto the light-receiving surface of the CCD image sensor 35 by the condenser lens 34. The light-receiving image (alignment index) by the CCD image sensor 35 is displayed on the display device 3 together with the observation image. The user performs alignment by performing operations similar to those of a conventional fundus camera. Alternatively, alignment may be performed by the arithmetic and control unit 200 analyzing the position of the alignment index and moving the optical system (auto-alignment function).

[0045] When performing focus adjustment, the reflecting surface of a reflecting rod 67 is obliquely disposed on the optical path of the illumination optical system 10. Light (focusing light) output from an LED 61 of the focusing optical system 60 passes through a relay lens 62, is split into two beams by a split indicator plate 63, passes through a two-hole diaphragm 64, and is reflected by a mirror 65. The light reflected by the mirror 65 is once imaged on the reflecting surface of the reflecting rod 67 by a condenser lens 66 and is then reflected. The focusing light further passes through a relay lens 20, is reflected by an apertured mirror 21, passes through a dichroic mirror 48, is refracted by an objective lens 22, and is projected onto the fundus Ef.

[0046] The fundus reflection light of the focusing light travels the same path as the cornea reflection light of the alignment light and is detected by the CCD image sensor 35. The light image (split index) received by the CCD image sensor 35 is displayed on the display device 3 together with the observation image. As in the conventional method, the arithmetic and control unit 200 analyzes the position of the split index and moves the focusing lens 31 and the focus optical system 60 to adjust the focus (autofocus function). Alternatively, the focus may be adjusted manually while visually checking the split index.

[0047] The dichroic mirror 48 branches the optical path for OCT measurement from the optical path for fundus imaging. The dichroic mirror 48 reflects light in the wavelength band used for OCT measurement and transmits light for fundus imaging. The optical path for OCT measurement is provided with, in order from the OCT unit 100 side, a collimating lens unit 40, an optical path length changing unit 41, an optical scanner 42, a collimating lens 43, a mirror 44, an OCT focusing lens 45, an optical member 80, and a field lens (relay lens) 46.

[0048] The optical element 80 is an optical path length correction element that imparts an optical path length corresponding to the angle of view to the passing measurement light. Specifically, the optical element 80 imparts an optical path length corresponding to the A-scan position by imparting an optical path length difference with respect to the reference position of the A-scan to the measurement light for each A-scan position where the passing measurement light is incident on the imaging site of the subject's eye. For example, the optical element 80 is configured to impart an optical path length to the measurement light according to the angle of view that is different from the reference optical path length imparted to the measurement light passing through the reference position of the A-scan.

[0049] When the imaging area has a concave cross-sectional shape like the fundus, the optical element 80 is configured so that the optical path length difference of a first region through which the measurement light beam incident on the reference position of the A-scan passes is shorter than the optical path length difference of the surrounding region of the first region.

[0050] Fig. 2 schematically shows an example of the configuration of an optical member 80 according to an embodiment. Fig. 2 schematically shows a top view and a cross-sectional view of the optical member 80. In Fig. 2, the optical member 80 is shown in a state where its center substantially coincides with the optical axis O of the optical system (objective lens 22).

[0051] For example, the optical member 80 is a light-transmitting member having an opening formed therein so that the light beam passes through the first region. The optical member 80 is a ring-shaped low-dispersion member having a substantially uniform refractive index in the medium (for example, an Abbe number ν dThe optical member 80 may be a glass member having a refractive index of 64 or more. That is, an opening is formed in the optical member 80 corresponding to an area including the reference position of the A-scan. In this case, the reference optical path length is zero. The reference position of the A-scan may be a position corresponding to the optical axis of the objective lens 22 (interference optical system) (position of the center of imaging). The optical member 80 has a thickness that varies depending on the angle of view, thereby providing the measurement light passing through it with an optical path length that corresponds to the angle of view.

[0052] Such an optical member 80 is disposed at a position that is optically approximately conjugate with the fundus Ef of the eye E to be examined.

[0053] In some embodiments, the optical member 80 is disposed at a predetermined position. In some embodiments, the optical member 80 is configured to be insertable into and removable from the optical path of the measurement light. In some embodiments, the optical member 80 is movable in a direction perpendicular to (intersecting with) the optical path of the measurement light so as to change the position of a boundary region (or a predetermined region including the boundary region) between two regions that impart different optical path lengths to the measurement light.

[0054] In addition, an optical element 80 (specifically, a boundary region between two regions that impart different optical path lengths to the measurement light) may be positioned in the optical path of the measurement light based on a position specified using the operation unit 240B described below for the live image of the imaging area.

[0055] The optical member 80 may be disposed between the objective lens 22 and the dichroic mirror 48, or between the objective lens 22 and the eye E to be examined.

[0056] The optical path length changing unit 41 is configured to be movable in the direction of the arrow shown in Fig. 1 and changes the optical path length of the optical path for OCT measurement. This change in the optical path length is used to correct the optical path length according to the axial length of the subject's eye E, adjust the interference state, etc. The optical path length changing unit 41 is configured to include, for example, a corner cube and a mechanism for moving it.

[0057] When photographing the fundus, the optical scanner 42 is placed at a position optically conjugate with the pupil of the subject's eye (pupil conjugate position) or in the vicinity thereof. When photographing the anterior segment, the optical scanner 42 is placed at a position optically non-conjugate with the pupil of the subject's eye. The optical scanner 42 changes the traveling direction of light (measurement light) passing through the optical path for OCT measurement. The optical scanner 42 is controlled by the arithmetic and control unit 200 (described later) and can deflect the measurement light one-dimensionally or two-dimensionally.

[0058] The optical scanner 42 includes, for example, a first galvanometer mirror, a second galvanometer mirror, and a mechanism for independently driving them. The first galvanometer mirror deflects the measurement light LS so as to scan the imaging site (fundus oculi Ef or anterior segment) in a horizontal direction (x direction) perpendicular to the optical axis of the interference optical system included in the OCT unit 100. The x direction is the horizontal direction in a plane perpendicular to the optical axis of the interference optical system. The second galvanometer mirror deflects the measurement light LS deflected by the first galvanometer mirror so as to scan the imaging site in a vertical direction (y direction) perpendicular to the optical axis of the interference optical system. The y direction is the vertical direction in a plane perpendicular to the optical axis of the interference optical system. This allows the imaging site to be scanned with the measurement light LS in any direction on the xy plane.

[0059] For example, it is possible to move the irradiation position of the measurement light along any trajectory on the xy plane by simultaneously controlling the orientations of the first galvanometer mirror and the second galvanometer mirror included in the optical scanner 42. This makes it possible to scan the imaging region according to a desired scan pattern.

[0060] The OCT focusing lens 45 is movable along the optical path (optical axis of the interference optical system) of the measurement light LS. The OCT focusing lens 45 is controlled by an arithmetic and control unit 200 (described later) and moves along the optical path of the measurement light LS.

[0061] In some embodiments, a liquid crystal lens or an Alvarez lens is provided instead of the OCT focusing lens 45. The liquid crystal lens or the Alvarez lens is controlled by the arithmetic and control unit 200, similar to the OCT focusing lens 45.

[0062] [OCT Unit 100] An example of the configuration of the OCT unit 100 will be described with reference to FIG. 3. The OCT unit 100 is provided with an optical system for acquiring an OCT image of the fundus Ef. This optical system has a configuration similar to that of a conventional swept-source type OCT device. That is, this optical system is an interference optical system that splits light from a wavelength scanning (wavelength swept) light source into measurement light and reference light, causes the measurement light that has passed through the fundus Ef to interfere with the reference light that has passed through a reference light path, thereby generating interference light, and detects this interference light. The detection result (detection signal) of the interference light in the interference optical system is a signal indicating the spectrum of the interference light, and is sent to the arithmetic and control unit 200.

[0063] The light source unit 101 includes a wavelength scanning (wavelength sweeping) light source that can scan (sweep) the wavelength of emitted light, similar to a general swept-source type OCT device. The light source unit 101 changes the output wavelength over time in the near-infrared wavelength band that is invisible to the human eye.

[0064] Light L0 output from the light source unit 101 is guided by an optical fiber 102 to a polarization controller 103, where its polarization state is adjusted. The polarization controller 103 adjusts the polarization state of the light L0 guided through the optical fiber 102, for example, by applying stress from the outside to the looped optical fiber 102.

[0065] The light L0, whose polarization state has been adjusted by the polarization controller 103, is guided by an optical fiber 104 to a fiber coupler 105, where it is split into a measurement light LS and a reference light LR.

[0066] The reference light LR is guided by an optical fiber 110 to a collimator 111 and converted into a parallel beam. The parallel beam of reference light LR passes through an optical path length correction member 112 and a dispersion compensation member 113 and is guided to a corner cube 114. The optical path length correction member 112 acts as a delay means for matching the optical path lengths (optical distances) of the reference light LR and the measurement light LS. The dispersion compensation member 113 acts as a dispersion compensation means for matching the dispersion characteristics of the reference light LR and the measurement light LS.

[0067] The corner cube 114 reverses the traveling direction of the reference light LR, which has been converted into a parallel beam by the collimator 111. The optical path of the reference light LR incident on the corner cube 114 is parallel to the optical path of the reference light LR emerging from the corner cube 114. The corner cube 114 is movable in directions along the incident and emerging optical paths of the reference light LR. This movement changes the length of the optical path (reference optical path) of the reference light LR.

[0068] The reference light LR that has passed through the corner cube 114 passes through a dispersion compensation member 113 and an optical path length correction member 112, is converted from a parallel beam into a convergent beam by a collimator 116, and enters an optical fiber 117. The reference light LR that has entered the optical fiber 117 is guided to a polarization controller 118, where the polarization state of the reference light LR is adjusted.

[0069] The polarization controller 118 has, for example, the same configuration as the polarization controller 103. The reference light LR whose polarization state has been adjusted by the polarization controller 118 is guided to an attenuator 120 by an optical fiber 119, and the light intensity is adjusted under the control of the arithmetic and control unit 200. The reference light LR whose light intensity has been adjusted by the attenuator 120 is guided to a fiber coupler 122 by an optical fiber 121.

[0070] The measurement light LS generated by the fiber coupler 105 is guided by the optical fiber 127 and collimated by the collimating lens unit 40. The collimated measurement light LS passes through the optical path length changing unit 41, the optical scanner 42, the collimating lens 43, the mirror 44, the OCT focusing lens 45, the optical member 80, and the field lens 46 to reach the dichroic mirror 48. The measurement light LS is then reflected by the dichroic mirror 48, refracted by the objective lens 22, and irradiated onto the fundus Ef. The measurement light LS is scattered (including reflected) at various depth positions in the fundus Ef. The backscattered light of the measurement light LS by the fundus Ef travels in the opposite direction along the same path as the outward path and is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

[0071] Fiber coupler 122 generates interference light by combining (causing interference between) measurement light LS incident via optical fiber 128 and reference light LR incident via optical fiber 121. Fiber coupler 122 splits the interference light between measurement light LS and reference light LR at a predetermined splitting ratio (for example, 1:1) to generate a pair of interference light LC. The pair of interference light LC emitted from fiber coupler 122 is guided to detector 125 by optical fibers 123 and 124, respectively.

[0072] The detector 125 is, for example, a balanced photodiode that has a pair of photodetectors that respectively detect a pair of interference light beams LC and outputs the difference between the detection results. The detector 125 sends the detection result (interference signal) to a DAQ (Data Acquisition System) 130. A clock KC is supplied to the DAQ 130 from the light source unit 101. The clock KC is generated in synchronization with the output timing of each wavelength swept (scanned) within a predetermined wavelength range by the wavelength swept light source in the light source unit 101. For example, the light source unit 101 optically delays one of two branched beams obtained by branching light beam L0 of each output wavelength, and then generates the clock KC based on the result of detecting the combined light. The DAQ 130 samples the detection result of the detector 125 based on the clock KC. The DAQ 130 sends the sampled detection result of the detector 125 to the arithmetic and control unit 200. For example, for each series of wavelength scans (each A-line), the arithmetic and control unit 200 forms a reflection intensity profile for each A-line by performing a Fourier transform or the like on the spectral distribution based on the detection results obtained by the detector 125. Furthermore, the arithmetic and control unit 200 forms image data by imaging the reflection intensity profile of each A-line.

[0073] In the embodiment, a Michelson interferometer is used, but any type of interferometer, such as a Mach-Zehnder interferometer, can be appropriately used. In the embodiment, the interference optical system may include the collimating lens unit 40, optical path length changing unit 41, optical scanner 42, collimating lens 43, mirror 44, OCT focusing lens 45, optical member 80, and field lens 46 shown in FIG. 1 in addition to the configuration shown in FIG.

[0074] [Arithmetic and control unit 200] The configuration of the arithmetic and control unit 200 will be described.

[0075] 4 and 5 show block diagrams of a configuration example of a processing system of the ophthalmologic apparatus 1 according to the embodiment. Fig. 5 is a functional block diagram of a configuration example of the correction processing unit 232 in Fig. 4. In Fig. 4, the same parts as those in Fig. 1 or 3 are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0076] The arithmetic and control unit 200 forms an OCT image of the fundus oculi Ef by analyzing the detection signal input from the detector 125. The arithmetic and control process for this purpose is the same as that of a conventional swept source type OCT device.

[0077] 4, the arithmetic and control unit 200 includes a control unit 210, and controls the fundus camera unit 2, a user interface 240 having the function of a display device 3, and each part of the OCT unit 100. For example, the arithmetic and control unit 200 forms an OCT image (tomographic image, three-dimensional image) of the fundus Ef, and causes the formed OCT image to be displayed on the display device 3.

[0078] The control of the fundus camera unit 2 includes operation control of the observation light source 11, the imaging light source 15 and the LEDs 51, 61, operation control of the CCD image sensors 35, 38, operation control of the LCD 39, movement control of the focusing lens 31, movement control of the OCT focusing lens 45, movement control of the reflecting rod 67, movement control of the focus optical system 60, movement control of the optical path length changing unit 41, operation control of the optical scanner 42, and drive control of the optical member 80.

[0079] The control of the OCT unit 100 includes operation control of the light source unit 101, movement control of the corner cube 114, operation control of the detector 125, operation control of the DAQ 130, operation control of the attenuator 120, operation control of the polarization controllers 103 and 118, and the like.

[0080] The arithmetic and control unit 200 controls the optical system, as well as performs image formation processing and various data processing.

[0081] The arithmetic and control unit 200 includes, for example, a processor, a random access memory (RAM), a read only memory (ROM), a hard disk drive, a communication interface, and the like, similar to a conventional computer. A computer program for controlling the ophthalmologic apparatus 1 is stored in a storage device such as a hard disk drive. The arithmetic and control unit 200 may include various circuit boards, for example, a circuit board for forming an OCT image. The arithmetic and control unit 200 may also include operation devices (input devices) such as a keyboard and a mouse, and a display device such as an LCD. In some embodiments, the functions of the arithmetic and control unit 200 are realized by one or more processors.

[0082] The fundus camera unit 2, the display device 3, the OCT unit 100 and the arithmetic and control unit 200 may be configured integrally (i.e., within a single housing) or may be configured separately in two or more housings.

[0083] The control unit 210 includes a main control unit 211 and a storage unit 212 .

[0084] (Main control unit 211) The main control unit 211 performs various controls by outputting control signals to each unit of the above-mentioned ophthalmologic apparatus 1. In particular, the main control unit 211 controls the CCD image sensors 35, 38, LCD 39, focus driver 31A, optical path length changer 41, optical scanner 42, OCT focus driver 45A, and optical member driver 80A for the fundus camera unit 2. Furthermore, the main control unit 211 controls the light source unit 101, reference driver 114A, polarization controllers 103, 118, attenuator 120, detector 125, and DAQ 130 for the OCT unit 100.

[0085] The main control unit 211 controls the exposure time (charge accumulation time), sensitivity, frame rate, etc. of the CCD image sensor 35 or the CCD image sensor 38. In some embodiments, the main control unit 211 controls the CCD image sensor 35 or the CCD image sensor 38 so as to acquire an image of desired image quality.

[0086] The main control unit 211 controls the display of fixation targets and visual targets for visual acuity measurement on the LCD 39. This allows the visual targets presented to the subject's eye E to be switched or the type of visual target to be changed. In addition, by changing the display position of the visual target on the LCD 39, it is possible to change the visual target presentation position relative to the subject's eye E.

[0087] The focusing driver 31A moves the focusing lens 31 in the optical axis direction. The main controller 211 controls the focusing driver 31A so that the focusing lens 31 is positioned at a desired focusing position. This changes the focusing position of the photographing optical system 30.

[0088] For example, the main controller 211 analyzes the position of the split target in the received light image (split target) obtained by the CCD image sensor 35, and controls the focusing driver 31A and the focus optical system 60. Alternatively, for example, the main controller 211 controls the focusing driver 31A and the focus optical system 60 in response to an operation performed by a user on an operation unit 240B (described later) while displaying a live image of the subject's eye E on a display unit 240A (described later).

[0089] The main controller 211 changes the optical path length of the measurement light LS by controlling the optical path length changer 41. This changes the difference between the optical path length of the measurement light LS and the optical path length of the reference light LR.

[0090] For example, the main control unit 211 analyzes the detection results of the interference light LC obtained by OCT measurement (or an OCT image formed based on the detection results), and controls the optical path length changing unit 41 so that the measurement site is at the desired depth position.

[0091] The main control unit 211 controls the optical scanner 42. The optical scanner 42 deflects the measurement light LS one-dimensionally or two-dimensionally under the control of the main control unit 211. The main control unit 211 controls the optical scanner 42 to deflect the measurement light LS according to a deflection pattern corresponding to a preset scan mode. Examples of such scan modes include line scan, cross scan, circle scan, radial scan, concentric circle scan, multi-line cross scan, spiral scan, Lissajous scan, and three-dimensional scan.

[0092] By scanning the imaging area with the measurement light LS according to the deflection pattern corresponding to the scan mode described above, an OCT image can be obtained in the plane defined by the direction along the scan line (scan trajectory) and the fundus depth direction (z direction).

[0093] The OCT focusing driver 45A moves the OCT focusing lens 45 along the optical path of the measurement light LS. The main controller 211 controls the OCT focusing driver 45A so that the OCT focusing lens 45 is positioned at a desired focusing position. This changes the focusing position of the measurement light LS. The focusing position of the measurement light LS corresponds to the depth position (z position) of the beam waist of the measurement light LS.

[0094] For example, the main control unit 211 controls the OCT focusing drive unit 45A based on the signal-to-noise ratio of the detection result of the interference light LC obtained by OCT measurement, or an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality of the OCT image formed based on the detection result.

[0095] When a liquid crystal lens or an Alvarez lens is provided instead of the OCT focusing lens 45, the main control unit 211 can control the liquid crystal lens or the Alvarez lens in the same way as it controls the OCT focusing driver 45A.

[0096] The optical element driving unit 80A moves the optical element 80. The main control unit 211 controls the optical element driving unit 80A to insert or remove the optical element 80 into or from the optical path of the measurement light LS. This causes the optical element 80 to be inserted into or removed from the optical path of the measurement light LS.

[0097] In some embodiments, the optical element driving unit 80A moves the optical element 80 in a direction intersecting (e.g., a direction perpendicular to) the optical path of the measurement light LS, thereby changing the relative position of the optical element 80 with respect to the optical path of the measurement light LS in the cross section of the beam of the measurement light LS. For example, when the optical element 80 has two or more regions that impart different optical path lengths to the measurement light LS passing therethrough, the main controller 211 controls the optical element driving unit 80A to move the boundary region between the two or more regions in the cross section of the beam of the measurement light LS. This makes it possible to impart different optical path lengths to the vicinity of any site on the fundus oculi Ef.

[0098] The main control unit 211 controls the light source unit 101. Control of the light source unit 101 includes switching the light source on and off, controlling the intensity of the emitted light, changing the center frequency of the emitted light, changing the sweep speed of the emitted light, changing the sweep frequency, changing the sweep wavelength range, and the like.

[0099] The reference driver 114A moves the corner cube 114 provided in the optical path of the reference light along this optical path, thereby changing the difference between the optical path length of the measurement light LS and the optical path length of the reference light LR.

[0100] For example, the main controller 211 analyzes the detection result of the interference light LC obtained by the OCT measurement (or an OCT image formed based on the detection result), and controls the reference driver 114A so that the measurement site is at a desired depth position. In some embodiments, only one of the optical path length changer 41 and the reference driver 114A is provided.

[0101] The main control unit 211 controls the polarization controllers 103 and 118. For example, the main control unit 211 controls the polarization controllers 103 and 118 based on the signal-to-noise ratio of the detection result of the interference light LC obtained by OCT measurement, or an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality of the OCT image formed based on the detection result.

[0102] The main controller 211 controls the attenuator 120. For example, the main controller 211 controls the attenuator 120 based on the signal-to-noise ratio of the detection result of the interference light LC obtained by OCT measurement, or an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality of the OCT image formed based on the detection result.

[0103] The main control unit 211 controls the detector 125. The control of the detector 125 includes control of the exposure time (charge accumulation time), sensitivity, frame rate, and the like.

[0104] The main control unit 211 controls the DAQ 130. The control of the DAQ 130 includes control of sampling timing and the like.

[0105] The moving mechanism 150 moves the fundus camera unit 2 (OCT unit 100) three-dimensionally relative to the subject's eye E. For example, the main controller 211 can control the moving mechanism 150 to move the optical system provided in the fundus camera unit 2 three-dimensionally. This control is used for alignment and tracking. Tracking is the movement of the device optical system in accordance with the movement of the subject's eye E. When tracking is performed, alignment and focusing are performed in advance. Tracking is a function that maintains an appropriate positional relationship where alignment and focus are achieved by moving the device optical system in real time in accordance with the position and orientation of the subject's eye E based on images obtained by capturing a video of the subject's eye E.

[0106] In the case of manual alignment, the user operates a user interface 240 described below to move the optical system and the eye E relative to each other so that the displacement of the eye E relative to the optical system is canceled. For example, the main controller 211 controls the movement mechanism 150 by outputting a control signal corresponding to the operation content of the user interface 240 to the movement mechanism 150, thereby moving the optical system and the eye E relative to each other.

[0107] In the case of auto-alignment, the main controller 211 controls the moving mechanism 150 to move the optical system relative to the subject's eye E so that displacement of the subject's eye E relative to the optical system is canceled. In some embodiments, the main controller 211 controls the moving mechanism 150 to move the optical system relative to the subject's eye E by outputting a control signal to the moving mechanism 150 so that the optical axis of the optical system approximately coincides with the axis of the subject's eye E and the distance of the optical system from the subject's eye E is a predetermined working distance. Here, the working distance is a predetermined value also called the working distance of the objective lens 22, and corresponds to the distance between the subject's eye E and the optical system during measurement (photography) using the optical system.

[0108] The above alignment causes the position of the exit pupil of the optical system (the interference optical system included in the OCT unit 100, the imaging optical system 30) to coincide with the imaging site or a position that is approximately optically conjugate with the imaging site. When imaging the fundus Ef, the position of the exit pupil of the optical system coincides with the fundus Ef or a position that is approximately optically conjugate with the fundus Ef. When imaging the anterior segment, the position of the exit pupil of the optical system coincides with the anterior segment or a position that is approximately optically conjugate with the anterior segment.

[0109] The main controller 211 controls fundus photography and anterior segment photography by controlling the fundus camera unit 2 and the like. The main controller 211 also controls OCT measurement by controlling the fundus camera unit 2 and the OCT unit 100 and the like. The main controller 211 can perform multiple preliminary operations before performing OCT measurement. The preliminary operations include alignment, coarse focus adjustment, polarization adjustment, and fine focus adjustment. The multiple preliminary operations are performed in a predetermined order. In some embodiments, the multiple preliminary operations are performed in the above order.

[0110] In some embodiments, the main controller 211 corrects the position of the scan range (second scan range) for OCT imaging in real time based on tracking information obtained by tracking control (tracking information obtained by tracking the optical system (interference optical system) with respect to the movement of the subject's eye E). The main controller 211 can control the optical scanner 42 to scan the corrected scan range with the measurement light LS.

[0111] Furthermore, the main control unit 211 (display control unit 211A, which will be described later) causes the display device 3 (or the display unit 240A, which will be described later) to display various information. The information displayed on the display device 3 includes the imaging results (observation image, OCT image), the measurement results (measurement values), and information indicating the results of changing the imaging conditions, which will be described later.

[0112] For example, a provisional imaging (provisional measurement) is performed before the actual imaging (actual measurement). The imaging conditions for the actual imaging are adjusted based on the detection result of the interference light LC acquired in the provisional imaging or the OCT image formed from the detection result.

[0113] As shown in FIG. 4, the main control unit 211 includes a display control unit 211A.

[0114] In addition to the display control of the display device 3 as described above, the display control unit 211A can also perform display control of images formed by the image forming unit 220 described below, and display control of data processing results obtained by the data processing unit 230 described below.

[0115] Furthermore, the main control unit 211 performs processing to write data to the storage unit 212 and processing to read data from the storage unit 212 .

[0116] (Storage unit 212) The storage unit 212 stores various types of data. Examples of data stored in the storage unit 212 include image data of OCT images, image data of fundus images, and information about the subject's eye. The information about the subject's eye includes information about the subject, such as a patient ID and name, and information about the subject's eye, such as identification information for the left eye or right eye.

[0117] At least a part of the data stored in the storage unit 212 may be stored in a storage unit provided outside the ophthalmic apparatus 1. For example, the ophthalmic apparatus 1 is communicably connected to a server device having a function of storing at least a part of the data via a network such as an in-hospital LAN (Local Area Network). Here, the ophthalmic apparatus 1 and the server device may be connected via a WAN (Wide Area Network) such as the Internet. Alternatively, the ophthalmic apparatus 1 and the server device may be connected via a network that combines a LAN and a WAN.

[0118] (Image forming unit 220) The image forming unit 220 forms image data of a tomographic image based on the detection signal (interference signal) detected by the detector 125 and sampled by the DAQ 130. That is, the image forming unit 220 forms an image of the subject's eye E based on the detection result of the interference light LC by the interference optical system. This processing includes processes such as noise removal (noise reduction), filtering, and FFT (Fast Fourier Transform), as in conventional swept-source type optical coherence tomography. The image data acquired in this manner is a data set including a group of image data formed by imaging the reflection intensity profiles of multiple A-lines (paths of each measurement light LS within the subject's eye E).

[0119] To improve image quality, multiple data sets collected by repeating the same scan pattern multiple times can be superimposed (averaged).

[0120] The image forming unit 220 is configured to include, for example, the circuit board described above. In this specification, "image data" and an "image" based on the image data may be considered to be the same thing. Also, a portion of the fundus Ef and an image thereof may be considered to be the same thing.

[0121] (Data processing unit 230) The data processing unit 230 performs various data processing (image processing) and analysis processing on the detection result of the interference light LC or the image formed by the image forming unit 220. For example, the data processing unit 230 performs various correction processing such as analysis of the signal-to-noise ratio of the interference signal, image brightness correction, optical path length correction, optical magnification correction, and dispersion correction.

[0122] Furthermore, the data processing unit 230 performs various image processing and analysis processes on the images (fundus images, anterior eye images, etc.) obtained by the fundus camera unit 2.

[0123] The data processing unit 230 performs known image processing, such as interpolation processing that interpolates pixels between tomographic images, to form image data of a three-dimensional image of the fundus oculi Ef. Note that image data of a three-dimensional image means image data in which pixel positions are defined by a three-dimensional coordinate system. Image data of a three-dimensional image includes image data consisting of three-dimensionally arranged voxels. This image data is called volume data or voxel data, etc. When displaying an image based on the volume data, the data processing unit 230 performs rendering processing (volume rendering, MIP (Maximum Intensity Projection), etc.) on the volume data to form image data of a pseudo three-dimensional image as viewed from a specific line of sight. This pseudo three-dimensional image is displayed on a display device, such as the display unit 240A.

[0124] It is also possible to form stack data of multiple tomographic images as image data of a three-dimensional image. Stack data is image data obtained by arranging multiple tomographic images obtained along multiple scanning lines in a three-dimensional manner based on the positional relationship of the scanning lines. In other words, stack data is image data obtained by expressing multiple tomographic images that were originally defined using separate two-dimensional coordinate systems using a single three-dimensional coordinate system (i.e., embedding them in a single three-dimensional space).

[0125] The data processing unit 230 can perform various rendering operations on the acquired three-dimensional data set (volume data, stack data, etc.) to generate B-mode images (longitudinal and axial cross-sectional images) at any cross-section, C-mode images (transverse and horizontal cross-sectional images) at any cross-section, projection images, shadowgrams, and the like. Images of any cross-section, such as B-mode images and C-mode images, are generated by selecting pixels (voxels) on a specified cross-section from the three-dimensional data set. Projection images are generated by projecting the three-dimensional data set in a predetermined direction (z direction, depth direction, axial direction). Shadowgrams are generated by projecting a portion of the three-dimensional data set (e.g., partial data corresponding to a specific layer) in a predetermined direction. Images viewed from the front side of the subject's eye, such as C-mode images, projection images, and shadowgrams, are called en-face images.

[0126] The data processing unit 230 can construct a B-mode image or a front image (a vessel-enhanced image, angiogram) in which retinal blood vessels and choroidal blood vessels are emphasized based on data collected in time series by OCT (for example, B-scan image data). For example, time-series OCT data can be collected by repeatedly scanning approximately the same region of the subject's eye E.

[0127] In some embodiments, the data processor 230 compares time-series B-scan images obtained by B-scanning approximately the same region and converts pixel values ​​of portions of signal intensity change into pixel values ​​corresponding to the change to construct an enhanced image in which the changed portion is emphasized. Furthermore, the data processor 230 extracts information of a predetermined thickness of a desired region from the constructed multiple enhanced images and constructs the image as an en-face image, thereby forming an OCTA image.

[0128] Images generated by the data processing unit 230 (for example, a three-dimensional image, a B-mode image, a C-mode image, a projection image, a shadowgram, and an OCTA image) are also included in the OCT image.

[0129] As shown in FIG. 5, the data processing unit 230 includes an analysis unit 231 and a correction processing unit 232.

[0130] (Analysis Department 231) The analysis unit 231 analyzes at least the detection result of the interference light LC or the OCT image formed by the image formation unit 220. In some embodiments, the analysis unit 231 analyzes the detection result of the interference light LC or the OCT image, and outputs an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality (signal-to-noise ratio) of the OCT image as the analysis result. The main control unit 211 can control at least one of the OCT focusing driver 45A, the optical path length changer 41, and the polarization controllers 103 and 118 based on the analysis result obtained by the analysis unit 231.

[0131] For example, the analysis unit 231 analyzes the detection results of the interference light obtained by OCT measurement to determine the focus state of the measurement light LS in focus fine adjustment control. For example, the main control unit 211 performs repetitive OCT measurement while controlling the OCT focusing driver 45A according to a predetermined algorithm. The analysis unit 231 calculates a predetermined evaluation value related to the image quality of the OCT image by analyzing the detection results of the interference light LC repeatedly obtained by OCT measurement. The analysis unit 231 determines whether the calculated evaluation value is equal to or less than a threshold. In some embodiments, the focus fine adjustment is continued until the calculated evaluation value is equal to or less than the threshold. In other words, when the evaluation value is equal to or less than the threshold, the focus state of the measurement light LS is determined to be appropriate, and the focus fine adjustment is continued until the focus state of the measurement light LS is determined to be appropriate.

[0132] In some embodiments, the main controller 211 performs the above-described repetitive OCT measurements to acquire interference signals, while monitoring the intensity (interference intensity, interference sensitivity) of the successively acquired interference signals. Furthermore, while performing this monitoring process, the main controller 211 moves the OCT focusing lens 45 to search for the position of the OCT focusing lens 45 where the interference intensity is maximized. By performing such fine focus adjustment, the OCT focusing lens 45 can be guided to a position where the interference intensity is optimized.

[0133] Furthermore, the analysis unit 231 analyzes the detection results of the interference light obtained by the OCT measurement to determine the polarization state of at least one of the measurement light LS and the reference light LR. For example, the main control unit 211 performs repetitive OCT measurement while controlling at least one of the polarization controllers 103 and 118 according to a predetermined algorithm. In some embodiments, the main control unit 211 controls the attenuator 120 to change the attenuation amount of the reference light LR. The analysis unit 231 calculates a predetermined evaluation value related to the image quality of the OCT image by analyzing the detection results of the interference light LC repeatedly acquired by the OCT measurement. The analysis unit 231 determines whether the calculated evaluation value is equal to or less than a threshold value. This threshold value is set in advance. The polarization adjustment is continued until the calculated evaluation value is equal to or less than the threshold value. In other words, when the evaluation value is equal to or less than the threshold value, it is determined that the polarization state of the measurement light LS is appropriate, and the polarization adjustment is continued until it is determined that the polarization state of the measurement light LS is appropriate.

[0134] In some embodiments, the main controller 211 can also monitor the interference intensity during polarization adjustment.

[0135] Furthermore, the analysis unit 231 performs predetermined analytical processing on the detection results of the interference light obtained by the OCT measurement or on the OCT image formed based on the detection results. The predetermined analytical processing includes identifying predetermined regions (tissues, lesions) in the subject's eye E; calculating the distance (interlayer distance), area, angle, ratio, and density between specified regions; performing calculations using specified formulas; identifying the shape of the predetermined regions; calculating statistical values ​​of these; calculating the distribution of measurement values ​​and statistical values; and image processing based on the results of these analytical processing. The predetermined tissues include blood vessels, the optic disc, the fovea, the macula, etc. The predetermined lesions include exudates, hemorrhage, etc.

[0136] In some embodiments, the analysis unit 231 serves as a segmentation processing unit and identifies multiple layer regions in the A-scan direction based on the acquired data of the subject's eye. In this case, the analysis unit 231 performs segmentation processing on the three-dimensional OCT data to identify multiple partial data sets corresponding to multiple tissues of the subject's eye. The segmentation processing is image processing for identifying specific tissues or tissue boundaries. For example, the analysis unit 231 calculates the gradient of pixel values ​​(brightness values) in each A-scan image included in the scan data and identifies locations with large gradients as tissue boundaries. Note that the A-scan image is one-dimensional image data extending in the depth direction of the fundus. Note that the depth direction of the fundus is defined as, for example, the z direction, the incident direction of the measurement light LS, the axial direction, the optical axis direction of the interference optical system, etc.

[0137] In a typical example, the analysis unit 231 analyzes three-dimensional OCT data representing the fundus (retina, choroid, etc.) and vitreous body to identify multiple partial datasets corresponding to multiple layer tissues of the fundus. Each partial dataset is defined by the boundary of the layer tissue. Examples of layer tissues identified as partial datasets include layer tissues constituting the retina. Layer tissues constituting the retina include the internal limiting membrane, nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, external limiting membrane, photoreceptor layer, and RPE. The analysis unit 231 can identify partial datasets corresponding to Bruch's membrane, choroid, sclera, vitreous body, etc. In some embodiments, the analysis unit 231 identifies partial datasets corresponding to lesions. Examples of lesions include detachments, edema, hemorrhage, tumors, drusen, etc.

[0138] In some embodiments, the analysis unit 231 identifies a layer of tissue of a predetermined number of pixels on the sclera side of the RPE as Bruch's membrane, and acquires a partial data set corresponding to the layer of tissue as a partial data set of Bruch's membrane.

[0139] (Correction processing unit 232) As described above, the correction processing unit 232 performs correction processing on the scan data acquired using the measurement light LS that has passed through the optical member 80 or the OCT image formed based on the scan data.

[0140] As shown in FIG. 5, the correction processing unit 232 includes an optical path length correction unit 232A, an optical magnification correction unit 232B, and a dispersion correction unit 232C. The correction processing unit 232 can perform at least one of an optical path length correction process, an optical magnification correction process, and a dispersion correction process. For example, each of the optical path length correction process and the optical magnification correction process is performed on scan data obtained by an OCT scan or an OCT image formed based on the scan data. For example, each of the dispersion correction processes is performed on the scan data. Note that at least one of the optical path length correction unit 232A, the optical magnification correction unit 232B, and the dispersion correction unit 232C may be included in the image forming unit 220.

[0141] Here, the correction process according to the embodiment will be described.

[0142] Fig. 6A is a diagram illustrating the operation of OCT scanning according to a comparative example of the embodiment. In Fig. 6A, the same parts as in Fig. 1 are given the same reference numerals, and descriptions thereof will be omitted as appropriate. Fig. 6A is a schematic diagram illustrating a beam of measurement light incident on the subject's eye E via the objective lens 22.

[0143] For example, a tomographic image IMG0 can be obtained by deflecting measurement light with an optical scanner and scanning the fundus Ef of the subject's eye E in the y direction. At this time, since the cross-sectional shape of the fundus Ef is curved, if the scan length in the B scan direction becomes long, areas away from the scan center (photography center) may not fit within the imaging range, and image flipping may occur.

[0144] Therefore, the ophthalmologic apparatus 1 according to the embodiment provides an optical path length to the measurement light that scans a desired measurement site by arranging the optical member 80 in the optical path of the measurement light. As a result, even if the scan length in the B scan direction is long, for example, an optical path length difference is provided with respect to the scan center, so that sites away from the scan center (imaging center) can be included in the imaging range, and image flipping can be prevented.

[0145] Fig. 6B is a diagram illustrating the operation of OCT scanning according to the embodiment. In Fig. 6B, the same parts as those in Fig. 1 or 6A are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. Fig. 6A is a schematic diagram illustrating a beam of measurement light incident on the subject's eye E via the objective lens 22.

[0146] In FIG. 6B , for example, optical path length correction members 81, 82, and 83 are arranged to correct the optical path length according to the angle of view of the measurement light LS. Each of the optical path length correction members 81, 82, and 83 imparts an optical path length to the measurement light LS that is different from the scan center. As in FIG. 6A , when the measurement light is deflected by an optical scanner to scan the fundus Ef of the subject's eye E in the y direction, the A-scan data obtained by the measurement light LS passing through the optical path length correction members 81, 82, and 83 shifts in the depth direction. As a result, in the tomographic image IMG1 formed using these scan data, the imaging position of the fundus Ef shifts in the z direction according to the position of the A-scan. In other words, by arranging the optical path length correction member in the optical path of the measurement light LS at the desired angle of view (the A-scan position of the measurement light LS), it becomes possible to include areas away from the scan center (the imaging center) within the imaging range, even if the scan length in the B-scan direction is long.

[0147] In this embodiment, an optical member 80 is disposed in the path of the ray of the measurement light LS corresponding to the desired angle of view as the optical path length correction member shown in FIG. 6B.

[0148] Here, in the embodiment, when scanning the imaging site (fundus oculi Ef), the path of the measurement light LS differs depending on the angle of view of the optical member 80. Therefore, the correction processing unit 232 can change the signal processing (correction processing) depending on the angle of view of the optical member 80 (the rays of the measurement light LS passing through the optical member 80). The correction processing unit 232 can perform different correction processing on the scan data (detection results of interference light) or OCT image depending on the A-scan position.

[0149] For example, the correction processing unit 232 (optical path length correction unit 232A) performs optical path length correction processing on scan data or OCT images acquired by OCT scanning using measurement light LS that travels different paths depending on the angle of view as shown in Fig. 6B, so as to align the optical path lengths. In the example shown in Fig. 2 or 6B, the correction processing unit 232 performs optical path length correction processing on scan data or OCT images (tomographic images) shifted in the depth direction as shown in Fig. 6B, so as to cancel the optical path length imparted by the optical path length correction member. That is, the correction processing unit 232 can correct the scan data or OCT image so as to cancel the optical path length difference imparted to the measurement light LS for each A-scan position.

[0150] Furthermore, for example, the correction processing unit 232 (optical magnification correction unit 232B) can perform optical magnification correction processing to correct variations in optical magnification on scan data or OCT images acquired by OCT scanning using measurement light LS that travels different paths depending on the angle of view as shown in Fig. 6B. That is, the correction processing unit 232 can correct the OCT image so that the size of one pixel is uniform for each A-scan position.

[0151] Furthermore, for example, the correction processing unit 232 (dispersion correction unit 232C) can perform dispersion correction processing to correct variations in chromatic dispersion on scan data acquired by OCT scanning using measurement light LS that travels different paths depending on the angle of view as shown in Fig. 6B. That is, the correction processing unit 232 can correct the scan data to compensate for chromatic dispersion for each A-scan position.

[0152] As described above, the correction processing unit 232 performs at least one of the following: correction processing for the optical path length imparted by the passage of the measurement light LS through the optical element 80; correction processing for the deviation in optical magnification caused by the passage of the measurement light LS through the optical element 80; and correction processing for the dispersion caused by the passage of the measurement light LS through the optical element 80.

[0153] (Optical path length correction section 232A) The optical path length correction unit 232A performs an optical path length correction process on scan data obtained by OCT scanning or an OCT image formed based on the scan data. The optical path length correction process includes a process of aligning a shift in the depth direction caused by the optical path length assigned to the measurement light LS for each angle of view by the optical member 80. The optical path length correction unit 232A can correct the optical path length by shifting the scan data or OCT image in the depth direction (z direction) by an amount corresponding to the optical path length.

[0154] [First processing example] For example, the thickness distribution of the optical element 80 in the xy plane, the refractive index of the medium of the optical element 80, and the position of the optical element 80 in the optical system are known. Therefore, a ray tracing simulation of the measurement light LS may be performed in advance using the thickness distribution, refractive index, and position of the optical element 80, and the optical path length correction amount to be corrected for each ray of the measurement light LS may be calculated from the simulation results. The calculated optical path length correction amount may be stored as correction information in the storage unit 212 or the data processing unit 230. The correction information may include multiple optical path length correction amounts calculated for each ray (angle of view), multiple optical path length correction amounts calculated for each specified region of the xy plane of the optical element 80, or one or more optical path length correction amounts calculated for each region to which an optical path length is assigned. In this case, the optical path length correction unit 232A performs an optical path length correction process on the scan data or OCT image by referring to the correction information stored in advance.

[0155] [Second processing example] For example, for each ophthalmic apparatus, the optical path length distribution at multiple A-scan positions when the optical element 80 is placed in the optical path of the measurement light LS and the optical path length distribution at multiple A-scan positions when the optical element 80 is retracted from the optical path of the measurement light LS may be measured in advance, and the distribution of optical path length differences at the multiple A-scan positions may be calculated from both measurement results. Optical path length correction amounts corresponding to the calculated distribution of optical path length differences may be stored as correction information (calibration data) in the storage unit 212 or the data processing unit 230. The correction information may include multiple optical path length correction amounts obtained for each light ray (angle of view), multiple optical path length correction amounts obtained for each specified region on the xy plane of the optical element 80, or one or more optical path length correction amounts obtained for each region to which an optical path length is assigned. In this case, the optical path length correction unit 232A performs an optical path length correction process on the scan data or OCT image by referring to the correction information stored in advance.

[0156] [Third processing example] For example, a trained correction model may be generated in advance by performing supervised machine learning using scan data or OCT images before optical path length correction as training data and scan data or OCT images after optical path length correction as teacher data. The generated trained correction model can be stored in the storage unit 212 or the data processing unit 230. In this case, the optical path length correction unit 232A inputs the scan data or OCT image before optical path length correction into the trained correction model stored in advance, and acquires the scan data or OCT image after optical path length correction output from the trained correction model.

[0157] [Fourth processing example] For example, the analysis unit 231 performs segmentation processing on the scan data or the OCT image to identify a predetermined layer region in the fundus oculi Ef. The optical path length correction unit 232A performs optical path length correction processing on the scan data or the OCT image by shifting the layer regions identified by the analysis unit 231 in the depth direction (z direction) at the boundary between two regions to which different optical path lengths are assigned so that the layer regions are smoothly connected.

[0158] (Optical magnification correction section 232B) The optical magnification correction unit 232B performs optical magnification correction processing on the OCT data or OCT image obtained by the OCT scan. The optical magnification correction processing includes processing to even out deviations in optical magnification that occur when the measurement light LS travels along different paths for each angle of view due to the optical member 80 (or when the measurement light LS passes through different media). The optical magnification correction unit 232B can correct the size of one pixel by performing stretching, expansion, rotation, affine transformation, etc. on the scan data or OCT image corresponding to the correction amount of the optical magnification.

[0159] [First processing example] For example, the thickness distribution of the optical element 80 in the xy plane, the refractive index of the medium of the optical element 80, and the position of the optical element 80 in the optical system are known. Therefore, a ray tracing simulation of the measurement light LS may be performed in advance using the thickness distribution, refractive index, and position of the optical element 80, and the optical magnification correction amount to be corrected for each ray of the measurement light LS may be calculated from the simulation results. The calculated optical magnification correction amount may be stored as correction information in the storage unit 212 or the data processing unit 230. The correction information may include multiple optical magnification correction amounts calculated for each ray (angle of view), multiple optical magnification correction amounts calculated for each specified region of the xy plane of the optical element 80, or one or more optical magnification correction amounts calculated for each region to which an optical path length is assigned. In this case, the optical magnification correction unit 232B performs optical magnification correction processing on the scan data or OCT image by referring to the correction information stored in advance.

[0160] [Second processing example] For example, for each ophthalmic apparatus, the distribution of optical magnification deviations at multiple A-scan positions may be determined by comparing an image obtained by photographing a reference member with the optical member 80 disposed in the optical path of the measurement light LS with an image obtained by photographing the reference member with the optical member 80 retracted from the optical path of the measurement light LS. An example of the reference member is a member (e.g., a plate) on which a grid-like pattern is depicted. The optical magnification correction amount corresponding to the determined distribution of optical magnification deviations can be stored as correction information in the storage unit 212 or the data processing unit 230. The correction information may include multiple optical magnification correction amounts obtained for each light ray (angle of view), multiple optical magnification correction amounts obtained for each specified region on the xy plane of the optical member 80, or one or more optical magnification correction amounts obtained for each region to which an optical path length is assigned. In this case, the optical magnification correction unit 232B performs optical magnification correction processing on the scan data or OCT image by referring to the pre-stored correction information.

[0161] [Third processing example] For example, a trained correction model may be generated in advance by performing supervised machine learning using scan data or OCT images before optical magnification correction as training data and scan data or OCT images after optical magnification correction as teacher data. The generated trained correction model can be stored in the storage unit 212 or the data processing unit 230. In this case, the optical magnification correction unit 232B inputs the scan data or OCT image before optical magnification correction into the trained correction model stored in advance, and obtains the scan data or OCT image after optical magnification correction output from the trained correction model.

[0162] [Fourth processing example] Furthermore, for example, the deviation in optical magnification due to the presence or absence of insertion of the optical element 80 may be corrected based on the continuity or size difference of characteristic portions depicted in the en-face image of the fundus oculi Ef. Specifically, the data processing unit 230 creates the en-face image from 3D scan data or a 3D OCT image acquired by a 3D OCT scan. The analysis unit 231 identifies characteristic portions in the 3D scan data or the 3D OCT image, and also identifies the above characteristic portions in the corresponding en-face image. Examples of characteristic portions include blood vessels, the optic disc, the fovea, the macula, and diseased areas. The analysis unit 231 identifies at least one of the continuity of characteristic portions on the en-face image and the difference in size (blood vessel diameter if the characteristic portion is a blood vessel) as portions due to the presence or absence of insertion of the optical element 80. The optical magnification correction unit 232B determines the amount of optical magnification correction for the en-face image based on at least one of the continuity and size difference of the identified characteristic portions, and performs optical magnification correction processing on the en-face image using the determined amount of optical magnification correction. Again, the analysis unit 231 identifies at least one of the connections between the characteristic features and the size differences on the en-face image. The amount of optical magnification correction is determined by repeating the identification of at least one of the connections between the characteristic features and the size differences on the en-face image and the correction of the optical magnification until the characteristic features are connected on the en-face image or the size differences between the characteristic features disappear. The optical magnification correction unit 232B performs an optical magnification correction process on the OCT image based on the determined amount of optical magnification correction.

[0163] In the above processing example, a case has been described in which the variation in optical magnification of the entire B-scan is corrected by performing optical magnification correction processing on the OCT image obtained by the measurement light LS that has passed through the optical member 80, but the configuration according to the embodiment is not limited to this. For example, the variation in optical magnification of the entire B-scan may be corrected by performing optical magnification correction processing on scan data or an OCT image obtained by the measurement light LS that has not passed through the optical member 80.

[0164] (Dispersion correction unit 232C) The dispersion correction unit 232C performs dispersion correction processing on the scan data obtained by the OCT scan. The dispersion correction processing includes processing to cancel out the influence of chromatic dispersion caused by the measurement light LS traveling along different paths for each angle of view (or the measurement light LS passing through different media) due to the optical member 80. The dispersion correction unit 232C can perform dispersion correction processing by multiplying the scan data by a dispersion compensation function using a dispersion coefficient corresponding to the dispersion correction amount.

[0165] [First processing example] For example, the thickness distribution of the optical element 80 in the xy plane, the refractive index of the medium of the optical element 80, and the position of the optical element 80 in the optical system are known. Therefore, a ray tracing simulation of the measurement light LS may be performed in advance using the thickness distribution, refractive index, and position of the optical element 80, and the dispersion correction amount (dispersion correction coefficient) to be corrected for each ray of the measurement light LS may be calculated from the simulation results. The calculated dispersion correction amount may be stored as correction information in the storage unit 212 or the data processing unit 230. The correction information may include multiple dispersion correction amounts calculated for each ray (angle of view), multiple dispersion correction amounts calculated for each specified region of the xy plane of the optical element 80, or one or more dispersion correction amounts calculated for each region to which an optical path length is assigned. In this case, the dispersion correction unit 232C performs dispersion correction processing on the scan data by referring to the correction information stored in advance.

[0166] [Second processing example] For example, a trained correction model may be generated in advance by performing supervised machine learning using the scan data before variance correction as training data and the scan data after variance correction as teacher data. The generated trained correction model can be stored in the storage unit 212 or the data processing unit 230. In this case, the variance correction unit 232C inputs the scan data before variance correction to the trained correction model stored in advance and obtains the variance-corrected scan data output from the trained correction model.

[0167] In some embodiments, the correction processing unit 232 executes one or more correction processes selected from the above correction processes depending on the imaging mode, the display mode described below, the measurement area, and the angle of view (A-scan position) of the measurement light LS.

[0168] The data processing unit 230 can align the fundus image and OCT image acquired using the imaging optical system 30. When the fundus image and OCT image are acquired in parallel, the two optical systems are coaxial, so the simultaneously (or substantially simultaneously) acquired fundus image and OCT image can be aligned with each other using the optical axis of the imaging optical system 30 as a reference. Regardless of the timing of acquisition of the fundus image and the OCT image, it is also possible to align the OCT image and the fundus image by aligning the image obtained by projecting the OCT image onto the xy plane with the fundus image. This alignment method can also be applied when the optical system for acquiring the fundus image and the optical system for OCT measurement are not coaxial. Even when the optical systems are not coaxial, if the relative positional relationship between the two optical systems is known, alignment similar to the case of coaxial alignment can be performed by referring to this relative positional relationship.

[0169] The data processing unit 230 that functions as described above is configured to include, for example, the above-mentioned processor, RAM, ROM, hard disk drive, circuit board, etc. A computer program that causes the microprocessor to execute the above functions is stored in advance in a storage device such as a hard disk drive.

[0170] (User Interface 240) The user interface 240 includes a display unit 240A and an operation unit 240B. The display unit 240A includes the display device of the arithmetic and control unit 200 and the display device 3 described above. The operation unit 240B includes the operation device of the arithmetic and control unit 200 described above. The operation unit 240B may include various buttons and keys provided on the housing of the ophthalmologic apparatus 1 or on the outside. For example, if the fundus camera unit 2 has a housing similar to that of a conventional fundus camera, the operation unit 240B may include a joystick, an operation panel, etc. provided on this housing. Furthermore, the display unit 240A may include various display devices such as a touch panel provided on the housing of the fundus camera unit 2.

[0171] It should be noted that the display unit 240A and the operation unit 240B do not need to be configured as separate devices. For example, it is possible to use a device in which the display function and the operation function are integrated, such as a touch panel. In this case, the operation unit 240B is configured to include this touch panel and a computer program. The operation content on the operation unit 240B is input to the control unit 210 as an electrical signal. Furthermore, operations and information input may be performed using a graphical user interface (GUI) displayed on the display unit 240A and the operation unit 240B.

[0172] The display device 3 or the display unit 240A is an example of a "display means" according to this embodiment. The optical system through which the measurement light LS passes from the OCT unit 100 to the objective lens 22 is an example of an "optical system" according to this embodiment.

[0173] <Configuration Example of Optical Member 80> The configuration of the optical member 80 is not limited to the configuration shown in FIG.

[0174] Fig. 7A schematically shows a first modified example of an optical member 80 according to an embodiment. Fig. 7A is a schematic top view and cross-sectional view of the optical member 80. In Fig. 7A, the same parts as in Fig. 2 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0175] The optical element 80 according to the embodiment may be configured to impart an optical path length difference to the measurement light LS so that the amount of change increases continuously or stepwise as the A-scan position moves away from the reference position of the A-scan (e.g., a position corresponding to the optical axis of the objective lens 22). The optical element 80 according to the first configuration example is a light-transmitting element having an opening formed therein so that the light beam passes through the first region, as in FIG. 2 . However, in the first configuration example, the optical element 80 is configured in a multi-stage ring shape. That is, the optical element 80 is configured so that it becomes thicker in the z direction as it moves away from the reference position of the A-scan. According to the first configuration example, while imparting an optical path length stepwise, it is possible to expand the imaging range of the OCT in the depth direction, as in the configuration shown in FIG. 2 .

[0176] In some embodiments, the optical element 80 is arranged so that the surface with a varying thickness (upper surface in FIG. 7A ) faces the OCT unit 100 (interference optical system) and the surface with no varying thickness (lower surface in FIG. 7A ) faces the test eye E. In some embodiments, the optical element 80 is arranged so that the surface with a varying thickness (upper surface in FIG. 7A ) faces the test eye E and the surface with no varying thickness (lower surface in FIG. 7A ) faces the OCT unit 100 (interference optical system).

[0177] Fig. 7B schematically shows a second modified example of the optical member 80 according to the embodiment. Fig. 7B is a schematic top view and cross-sectional view of the optical member 80. In Fig. 7B, the same parts as in Fig. 2 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0178] In the first configuration example, a case where the thickness changes in a two-stage configuration has been described, but in the second configuration example, the thickness changes in a three-stage configuration. According to the second configuration example, it is possible to provide finer optical path lengths than in the first configuration example. This may further reduce degradation in image quality. Note that the optical member 80 may be configured so that the thickness changes in four or more stages.

[0179] Fig. 7C schematically shows a third modified example of the optical member 80 according to the embodiment. Fig. 7C schematically shows a top view and a cross-sectional view of the optical member 80. In Fig. 7C, the same parts as in Fig. 2 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0180] In the first and second configuration examples, the thickness in the z direction changes stepwise, but in the third configuration example, the thickness in the z direction changes continuously. Specifically, in the third configuration example, a gradient is formed so that the thickness gradually changes at the boundary between the region where the optical path length is imparted and the region where the opening is formed. According to the third modification, the change in the optical path length can be changed continuously, which may eliminate the influence of artifacts such as multiple reflections caused by a steep change in the optical path length and reduce degradation of image quality due to optical path length correction.

[0181] Fig. 7D schematically shows a fourth modified example of the optical member 80 according to the embodiment. Fig. 7D is a schematic top view and cross-sectional view of the optical member 80. In Fig. 7D, the same parts as in Fig. 2 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0182] In the first to third configuration examples, the optical member 80 has a circular contour, but the configuration of the optical member 80 according to the embodiment is not limited to this. The contour of the optical member 80 may also be rectangular, as shown in Fig. 7D. According to the fourth modification, the same effect as the first modification can be obtained.

[0183] Fig. 7E schematically shows a fifth modified example of the optical member 80 according to the embodiment. Fig. 7E is a schematic top view and cross-sectional view of the optical member 80. In Fig. 7E, the same parts as in Fig. 2 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0184] In the first to fourth modified examples, the optical member 80 has been described as having a circular opening formed so as to include a position corresponding to the optical axis of the optical system, but the configuration of the optical member 80 according to the embodiment is not limited to this. For example, the optical member 80 may be a member having part of the configuration shown in Fig. 2 and Figs. 7A to 7D above. In Fig. 7E, the optical member 80 is a member obtained by dividing the optical member according to the first configuration example into four equal parts centered on the position corresponding to the optical axis.

[0185] In some embodiments, the optical member 80 according to the fifth modification can be rotated around a position corresponding to the optical axis.

[0186] Fig. 7F schematically shows a sixth modified example of the optical member 80 according to the embodiment. Fig. 7F is a schematic top view and a cross-sectional view of the optical member 80. In Fig. 7F, the same parts as in Fig. 2 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0187] The optical member 80 according to the sixth modification has a rectangular shape. In this case, too, the optical member 80 may be a glass member having a substantially uniform refractive index throughout the medium. In some embodiments, the optical member 80 according to the sixth modification can be moved in a direction intersecting the optical axis (e.g., the x direction or y direction). This allows the optical path length to be adjusted only for the measurement light scanning a desired area.

[0188] Fig. 7G schematically shows a seventh modified example of the optical member 80 according to the embodiment. Fig. 7G is a schematic top view and cross-sectional view of the optical member 80. In Fig. 7G, the same parts as in Fig. 2 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0189] The optical element 80 according to the seventh modification is configured to impart an optical path length difference to the measurement light LS such that the amount of change increases continuously or stepwise as the A-scan position moves away from the reference position of the A-scan. In the seventh modification, the optical element 80 is configured so that the optical path length difference in a first region through which a beam of measurement light incident at a position corresponding to the optical axis (the reference position of the A-scan) passes is longer than the optical path length difference in a peripheral region of the first region. That is, in the seventh configuration example, the optical element 80 is configured so that the thickness increases in the z direction as the beam approaches the reference position of the A-scan. This allows the measurement light incident at an A-scan position near the optical axis to have a longer optical path length than the measurement light incident at an A-scan position in the peripheral region when the imaging site has a convex cross-sectional shape, such as fundus edema or the cornea in the anterior segment. According to the seventh modification, the imaging range in the depth direction of OCT can be expanded even when the degree of curvature of the convex cross-sectional shape increases, as opposed to that of the fundus Ef.

[0190] For example, when the imaging site is edema in the fundus Ef, it is desirable that the optical member 80 is disposed at a position that is approximately optically conjugate with the fundus Ef of the subject's eye E, as described above. On the other hand, when the imaging site is the cornea (anterior segment), it is desirable that the optical member 80 is disposed at a position that is approximately optically conjugate with the cornea of ​​the subject's eye E.

[0191] The optical member 80 according to the embodiment may be a lens element having a refractive power that does not involve movement of the optical conjugate position. When photographing a concave part such as the fundus Ef, the lens element may be a convex lens. When photographing a convex part such as the anterior segment, the lens element may be a concave lens.

[0192] Furthermore, the above-mentioned optical element 80 has been described as being configured using a glass element having a substantially uniform refractive index within the medium, and configured so that the thickness in the optical axis direction varies for each angle of view, but the configuration of the optical element 80 according to the embodiment is not limited to this.

[0193] For example, the optical element 80 according to the embodiment may be configured to have a different refractive index for each angle of view using a member having a constant thickness in the optical axis direction. In some embodiments, the optical element 80 is capable of changing the refractive index for each angle of view. Examples of the optical element 80 that can change the refractive index for each angle of view include a liquid crystal element, a liquid lens, a spatial light modulator, and a gradient index optical element. Furthermore, the optical element 80 may be capable of changing the thickness in the optical axis direction for each angle of view. Examples of gradient index optical elements include a gradient index (GRIN) plane-parallel plate and a gradient index lens.

[0194] Furthermore, although the optical member 80 described above imparts an optical path length by transmitting the measurement light LS, the configuration of the optical member 80 according to the embodiment is not limited to this. For example, the optical member 80 may include a member that imparts an optical path length to the stylus LS for each angle of view by reflecting the measurement light LS using a mirror for each angle of view. For example, the function of the optical member 80 may be realized using a diffractive optical element (DOE) or a deformable element.

[0195] [Example of operation] An example of the operation of the ophthalmologic apparatus 1 according to the embodiment will be described.

[0196] 8, 9, and 10 show flow diagrams of an example of operation of the ophthalmologic apparatus 1 according to the embodiment. FIG. 8 shows a flowchart of an example of operation of the ophthalmologic apparatus 1 according to the embodiment. FIGS. 9 and 10 show flowcharts of an example of operation of step S7 in FIG. 8. The storage unit 212 stores a computer program for realizing the processes shown in FIGS. 8, 9, and 10. The main control unit 211 operates in accordance with this computer program to execute the processes shown in FIGS. 8, 9, and 10.

[0197] (S1: Alignment) First, in a state where a fixation target is presented at a predetermined fixation position, the main controller 211 performs alignment adjustment of the optical system with respect to the subject's eye E. As an example of the alignment adjustment, there are a case where it is performed manually and a case where it is performed automatically.

[0198] When performing alignment adjustment manually, the main controller 211 projects a pair of alignment indicators onto the subject's eye E using the alignment optical system 50. The display unit 240A displays a pair of alignment bright spots as received light images of these alignment indicators. The main controller 211 also causes the display unit 240A to display an alignment scale indicating positions to which the pair of alignment bright spots should be moved. The alignment scale is, for example, a parenthetical image.

[0199] When the positional relationship between the subject's eye E and the fundus camera unit 2 (objective lens 22) is appropriate, a pair of alignment bright spots are first imaged at a predetermined position (for example, a position midway between the corneal apex and the center of corneal curvature) and then projected onto the subject's eye E by a known method. Here, the above-mentioned positional relationship being appropriate means that the distance (working distance) between the subject's eye E and the fundus camera unit 2 is appropriate, and that the optical axis of the optical system of the fundus camera unit 2 and the axis of the subject's eye E (corneal apex position) coincide (or nearly coincide). The examiner (user) can adjust the alignment of the optical system with respect to the subject's eye E by moving the fundus camera unit 2 three-dimensionally so as to guide the pair of alignment bright spots into the alignment scale.

[0200] When performing automatic alignment adjustment, a movement mechanism 150 is used to move the fundus camera unit 2. The data processing unit 230 identifies the position of each alignment bright spot on the screen displayed on the display unit 240A and calculates the displacement between the identified position of each alignment bright spot and the alignment scale. The main control unit 211 moves the fundus camera unit 2 using the movement mechanism 150 to cancel this displacement. The position of each alignment bright spot can be identified, for example, by calculating the luminance distribution of each alignment bright spot and then calculating the center of gravity position based on this luminance distribution. Since the position of the alignment scale is constant, the desired displacement can be obtained, for example, by calculating the displacement between its center position and the center of gravity position. The movement direction and movement distance of the fundus camera unit 2 can be determined by referring to the unit movement distances in the x, y, and z directions that are preset. The unit movement distance is determined, for example, from the results of prior measurement of how far the alignment indicator moves in each direction when the fundus camera unit 2 is moved in each direction. The main control unit 211 generates a signal according to the determined movement direction and movement distance, and transmits this signal to the movement mechanism 150. As a result, the position of the optical system with respect to the eye E is automatically adjusted.

[0201] (S2: Set scan position) Next, the main control unit 211 sets the scan position, which includes a scan range, a scan start position, and a scan end position.

[0202] For example, the main controller 211 sets a scan position specified on an image of the fundus oculi Ef by the user using the operation unit 240B. For example, the main controller 211 sets a position specified on a fundus image of the fundus oculi Ef using the operation unit 240B as a scan position. Examples of fundus images include photographed images acquired using the photographing optical system 30 and live OCT images (projection images, en-face images) obtained by OCT measurement. For example, the main controller 211 sets a scan position to an imaging region previously associated with an imaging mode based on an imaging mode corresponding to an imaging region specified by the user using the operation unit 240B.

[0203] (S3: Optical components are placed) Next, the main control unit 211 places the optical member 80 in the optical path of the measurement light LS. If the optical member 80 has already been placed, step S3 is omitted.

[0204] For example, the main control unit 211 controls the optical member driving unit 80A to position the optical member 80 between the OCT focusing lens 45 and the field lens 46 as shown in FIG.

[0205] In some embodiments, the main controller 211 positions the optical member 80 based on the scan position designated in step S2. For example, the main controller 211 controls the optical member driver 80A to position the optical member 80 at the scan position designated in step S2 so that boundary regions of regions in the optical member 80 that impart different optical path lengths overlap.

[0206] (S4: Adjust the depth position) Next, the main controller 211 adjusts the depth position at which the image region corresponding to the site of interest in the subject's eye E is rendered so that the image region corresponding to the site of interest falls within a predetermined depth range in the tomographic image.

[0207] For example, the main controller 211 displays a fixation target for OCT measurement at a predetermined position on the LCD 39. The main controller 211 can display the fixation target at a display position on the LCD 39 that corresponds to the position of the optical axis of the optical system on the fundus Ef.

[0208] Next, the main controller 211 controls the OCT unit 100 to perform provisional OCT measurement and acquire an adjustment tomographic image for adjusting the reference position of the measurement range in the depth direction. Specifically, the main controller 211 controls the optical scanner 42 to deflect the measurement light LS generated based on the light L0 emitted from the light source unit 101 and scan the fundus Ef of the subject's eye E with the deflected measurement light LS. The detection result of the interference light obtained by scanning with the measurement light LS is sampled in synchronization with a clock KC and then sent to the image forming unit 220. The image forming unit 220 forms a tomographic image (OCT image) of the subject's eye E from the obtained interference signal.

[0209] Next, for example, the main controller 211 causes the analyzer 231 to identify a predetermined region (e.g., the sclera) in the obtained tomographic image, and sets a position a predetermined distance in the depth direction from the position of the identified predetermined region as the reference position of the measurement range. The main controller 211 controls at least one of the optical path length changer 41 and the reference driver 114A in accordance with the reference position. Alternatively, a predetermined position may be set as the reference position of the measurement range so that the optical path lengths of the measurement light LS and the reference light LR are approximately the same.

[0210] (S5: Focus adjustment) Next, the main control unit 211 executes focus adjustment control.

[0211] For example, the main controller 211 controls the OCT focusing driver 45A to move the OCT focusing lens 45 by a predetermined distance, and then controls the OCT unit 100 to perform OCT measurement. As described above, the main controller 211 causes the data processor 230 to determine the focus state of the measurement light LS based on the detection result of the interference light obtained by the OCT measurement. When it is determined that the focus state of the measurement light LS is not appropriate based on the determination result by the data processor 230, the main controller 211 controls the OCT focusing driver 45A again, and repeats this process until it is determined that the focus state is appropriate.

[0212] (S6: Polarization adjustment) Next, the main control unit 211 performs polarization adjustment.

[0213] For example, the main control unit 211 controls at least one of the polarization controllers 103, 118 to change the polarization state of at least one of the light L0 and the measurement light LS by a predetermined amount, and then controls the OCT unit 100 to perform OCT measurement and causes the image forming unit 220 to form an OCT image based on the detection result of the acquired interference light. As described above, the main control unit 211 causes the data processing unit 230 to determine the image quality of the OCT image obtained by the OCT measurement. When it is determined based on the determination result by the data processing unit 230 that the polarization state of the measurement light LS is not appropriate, the main control unit 211 controls the polarization controllers 103, 118 again, and repeats this process until it is determined that the polarization state is appropriate.

[0214] (S7: Acquire scan data) Next, the main controller 211 executes OCT measurement under the measurement environment adjusted in steps S1 to S6 to acquire scan data.

[0215] In step S3, the optical element 80 is disposed in the optical path of the measurement light LS, and therefore, variations in the optical path length, the optical magnification, the focus, and the chromatic dispersion occur in the B-scan data obtained by deflecting the measurement light LS. In step S7, at least one of these variations is corrected. The details of step S7 will be described later.

[0216] (S8:Display) Next, the display control unit 211A causes the display unit 240A to display a tomographic image based on the scan data acquired in step S7.

[0217] For example, in step S7, when scan data in which variations in optical path length, variations in optical magnification, variations in focus, and variations in wavelength dispersion have been corrected is acquired, the display control unit 211A causes the display unit 240A to display a tomographic image formed based on the acquired scan data.

[0218] For example, even if the variation in optical path length is not corrected in step S7, the main controller 211 can control the image forming unit 220 or the data processor 230 to form multiple OCT images based on scan data of a B-scan range to which the same optical path length difference is imparted with respect to the reference position of the A-scan by the optical member 80. The display controller 211A displays the generated multiple OCT images on the display unit 240A.

[0219] This is the end of the operation of the ophthalmologic apparatus 1 (END).

[0220] In step S7 of Fig. 8, for example, the flow shown in Fig. 9 and Fig. 10 is executed. In Fig. 9 and Fig. 10, it is assumed that the angle of view (A scan position) and the optical path length given to the measurement light LS by the optical member 80 arranged in step S3 are known.

[0221] (S11: Deflection control) First, the main controller 211 executes deflection control on the optical scanner 42 so that the measurement light LS is incident on the A scan position determined based on the scan position set in step S2.

[0222] (S12: Optical components in the path of the measurement light?) Next, the main controller 211 determines whether or not the optical member 80 is disposed in the optical path of the measurement light LS deflected in step S11.

[0223] For example, the main control unit 211 can determine, based on the arrangement position of the optical member 80, whether or not the optical member 80 is arranged in the optical path of the measurement light LS incident on the scan position of the A-scan.

[0224] When it is determined that the optical element 80 is disposed in the optical path of the measurement light LS incident on the scan position of the A-scan (S12: Y), the operation of the ophthalmic apparatus 1 proceeds to step S13. When it is determined that the optical element 80 is not disposed in the optical path of the measurement light LS incident on the scan position of the A-scan (S12: N), the operation of the ophthalmic apparatus 1 proceeds to step S14.

[0225] (S13: Move the focusing lens) When it is determined that an optical element 80 is placed in the optical path of the measurement light LS incident on the scan position of the A scan (S12:Y), the main control unit 211 controls the OCT focusing drive unit 45A to move the OCT focusing lens 45 in the optical axis direction by an amount corresponding to the optical path length given to the optical element 80.

[0226] This makes it possible to prevent blurring of the image due to focus shift caused by arranging the optical member 80 that provides the optical path length according to the angle of view.

[0227] (S14: Perform A scan) Following step S13, or when it is determined in step S12 that the optical member 80 is not disposed in the optical path of the measurement light LS incident on the scan position of the A-scan (S12: N), the main controller 211 controls the OCT unit 100 to execute an A-scan. The interference light LC obtained by the A-scan is detected by the detector 125 and input to the DAQ 130 by the clock KC.

[0228] (S15: Rescaling) Next, the main control unit 211 controls the image forming unit 220 to perform a rescaling process on the scan data acquired in step S14. The rescaling process is a process of rearranging the scan data obtained by sampling the detection results of the interference light LC at equal intervals on the time axis using the clock KC so that the wavenumber changes linearly (straight line) on the time axis. By performing the rescaling process, an image can be formed in the same way as when the detection results of the interference light LC are sampled using a wavenumber clock whose wavenumber changes linearly on the time axis.

[0229] (S16: Dispersion correction) Next, the main control unit 211 controls the dispersion correction unit 232C included in the data processing unit 230 or the image forming unit 220 to perform dispersion correction on the scan data that has been rescaled in step S15. Based on the correction information, the dispersion correction unit 232C multiplies the scan data by a dispersion compensation function that uses a dispersion coefficient for compensating for chromatic dispersion caused by the placement of the optical member 80, thereby canceling out the chromatic dispersion.

[0230] (S17: Window function processing) Next, in step S16, the main control unit 211 performs window function processing on the scan data after the variance correction processing. The window function is a function having a predetermined wavelength width corresponding to the imaging range. Examples of window functions include functions representing a rectangular window, a Gaussian window, a Hann window, and a sine window. By performing window function processing, the scan data is weighted for each wavelength position according to the window function, so even if scan data or noise components remain near the boundary of the imaging range, their influence can be further reduced.

[0231] (S18: Fourier transform) Subsequently, in step S17, the main control unit 211 performs a known Fourier transform on the scan data that has been subjected to the window function processing.

[0232] (S19: Next A-scan?) Next, the main controller 211 determines whether or not to execute the next A-scan.

[0233] For example, the main controller 211 can determine whether or not to execute the next A-scan according to the scan range determined by the scan position set in step S2.

[0234] When it is determined that the next A-scan is to be executed (S19: Y), the operation of the ophthalmologic apparatus 1 proceeds to step S11. When it is determined that the next A-scan is not to be executed (S19: N), the operation of the ophthalmologic apparatus 1 proceeds to step S20.

[0235] (S20: Optical path length correction) In step S19, when it is determined that the next A-scan is not to be performed (S19: N), the main control unit 211 controls the optical path length correction unit 232A to perform optical path length correction processing on the scan data of the Fourier transform processing based on the above correction information.

[0236] For example, since the arrangement position of the optical member 80 is known, the A-scan position at which the measurement light LS passing through the optical member 80 is incident is also known. The main control unit 211 determines whether the A-scan is an A-scan using the measurement light LS passing through the optical member 80. When it is determined that the A-scan is an A-scan using the measurement light LS passing through the optical member 80, the main control unit 211 can control the optical path length correction unit 232A to perform the above-mentioned optical path length correction process based on the above correction information. When it is determined that the A-scan is not an A-scan using the measurement light LS passing through the optical member 80, the main control unit 211 does not perform the optical path length correction process on the measurement light. As a result, the optical path length correction process is performed for each A-scan data according to the A-scan position (angle of view).

[0237] (S21: Generate B-scan data) Next, the main control unit 211 generates B-scan data by arranging the A-scan data after the process of step S20 in the B-scan direction.

[0238] For example, the image forming unit 220 can form a B-scan image from B-scan data. The image forming unit 220 can calculate the amplitude component for each pixel of the A-line by using the real part and imaginary part obtained by Fourier transform. For example, when processing for the number of A-lines (1024 lines) that make up the B-scan image is completed, the image forming unit 220 calculates the amplitude components of all pixels, and calculates, for example, 20×log 10 The image forming unit 220 then determines a reference noise level within the tomographic image, and assigns a value within a predetermined brightness value range to each pixel according to the amplitude component logarithmically converted as described above, based on this reference noise level. The image forming unit 220 can form a B-scan image (tomographic image) using the assigned brightness value of each pixel.

[0239] (S22: Optical magnification correction) Next, the main control unit 211 controls the optical magnification correction unit 232B to perform optical magnification correction processing on the B-scan data (tomographic image) generated in step S21 based on the above correction information.

[0240] This is the end of the process in step S7 of FIG. 8 (END).

[0241] As described above, by disposing the optical member 80, OCT scanning is performed using measurement light LS with an optical path length assigned according to the angle of view, and optical path length correction, optical magnification correction, focus error correction, and dispersion correction are performed on the obtained scan data or OCT image. This makes it possible to easily and inexpensively expand the imaging range in the depth direction of OCT even when the scan length in the B scan direction is long.

[0242] 8 to 10, optical path length correction, optical magnification correction, focus correction, and dispersion correction are performed on the scan data. However, embodiments are not limited to this. For example, at least one of optical path length correction, optical magnification correction, focus correction, and dispersion correction may be omitted from the scan data, and the omitted correction may be performed on the OCT image formed based on the scan data. For example, optical path length correction may be performed on the OCT image formed based on the scan data without performing optical path length correction on the scan data.

[0243] FIG. 11 shows an example of an OCT image displayed when optical path length correction is performed on the OCT image.

[0244] For example, even if the variation in optical path length is not corrected in step S7, the main controller 211 forms multiple OCT images IMG11 and IMG12 based on OCT data of a B scan range to which the same optical path length difference is imparted with respect to the reference position of the A scan by the optical member 80. In FIG. 11, the OCT image IMG11 is a tomographic image (first OCT image) of a B scan range (first B scan range) to which no optical path length is imparted by the optical member 80. The OCT image IMG12 is a tomographic image (second OCT image) of a B scan range (second B scan range) to which an optical path length is imparted by the optical member 80.

[0245] The main controller 211 controls the optical path length correction unit 232A to shift each OCT image in the z direction by an amount corresponding to the optical path length difference, thereby canceling the optical path length difference between the OCT images IMG11 and IMG12. In FIG. 11, the OCT image IMG12 is shifted in the z direction. The data processor 230 generates a composite image as shown in FIG. 11 by combining the OCT images IMG11 and IMG12. The display controller 211A causes the display unit 240A to display the generated composite image.

[0246] In some embodiments, multiple OCT images formed based on OCT data of a B-scan range to which the same optical path length difference is imparted by the optical element 80 relative to the reference position of the A-scan are displayed on the display unit 240A in an identifiable manner, without performing optical path length correction processing.

[0247] FIG. 12 shows an example of an OCT image displayed when optical path length correction is not performed on the OCT image.

[0248] For example, the display controller 211A causes the display unit 240A to display, in identifiable frames, OCT images of the B scan range to which the same optical path length difference has been imparted by the optical member 80. In Fig. 12, an OCT image IMG21 of the B scan range to which a first optical path length difference has been imparted with respect to the reference position of the A scan by the optical member 80 is surrounded by a frame G1, and an OCT image IMG22 of the B scan range to which a second optical path length difference has been imparted with respect to the reference position of the A scan by the optical member 80 is surrounded by a frame G2.

[0249] The frames G1 and G2 may be provided so as to cover the boundary region of the regions to which different optical path lengths are imparted by the optical member 80. This makes it possible to avoid the influence of artifacts caused by differences in the imparted optical path lengths and to avoid any influence on a doctor's diagnosis, etc.

[0250] The frames G1 and G2 may be given a predetermined pattern or a predetermined color.

[0251] In some embodiments, the display controller 211A displays a fundus image IMG23 representing the entire fundus together with the OCT images IMG21 and IMG22, and provides auxiliary information for understanding which regions of the fundus correspond to the OCT images IMG21 and IMG22. Examples of the fundus image IMG23 include a composite image of the OCT images IMG21 and IMG22 after optical path length correction, and an image (pre-created image) representing a general cross-sectional structure of the fundus.

[0252] FIG. 13 shows another example of display of an OCT image when optical path length correction is not performed on the OCT image.

[0253] For example, the display controller 211A causes the display unit 240A to display, with gaps, multiple OCT images of the B scan range to which the same optical path length difference has been imparted by the optical member 80. In Fig. 13, an OCT image IMG31 (surrounded by a frame G11) (first OCT image) of the B scan range to which a first optical path length difference has been imparted with respect to the reference position of the A scan by the optical member 80, and an OCT image IMG32 (surrounded by a frame G12) (second OCT image) of the B scan range to which a second optical path length difference has been imparted with respect to the reference position of the A scan by the optical member 80 are displayed separately. Note that each of the OCT images IMG31 and IMG32 does not have to be surrounded by a frame.

[0254] That is, a plurality of OCT images of regions to which different optical path lengths are assigned are displayed at intervals on the display unit 240A, thereby preventing the influence of artifacts caused by differences in assigned optical path lengths and avoiding any influence on a doctor's diagnosis, etc.

[0255] In some embodiments, the display controller 211A displays a fundus image IMG33 representing the entire fundus together with the OCT images IMG31 and IMG32, and provides auxiliary information for understanding which regions of the fundus correspond to the OCT images IMG31 and IMG32. Examples of the fundus image IMG33 include a composite image of the OCT images IMG31 and IMG32 after optical path length correction, an image representing a general cross-sectional structure of the fundus (a pre-created image), and the like.

[0256] <Modification> In the above embodiment, a method has been described in which the imaging range in the depth direction of OCT can be expanded simply and at low cost with only one main OCT measurement, even when the scan length in the B-scan direction is long, by disposing the optical member 80. However, the configuration according to the embodiment is not limited to this.

[0257] Fig. 14 schematically shows an eighth modified example of the optical member 80 according to the embodiment. Fig. 14 is a schematic top view and a cross-sectional view of the optical member 80. In Fig. 14, the same parts as in Fig. 2 are denoted by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0258] The optical member 80 according to the eighth modification is a rectangular parallelepiped low-dispersion optical element (for example, an Abbe number ν d The optical member 80 may be a glass member having a refractive index of 64 or more. The optical member 80 is disposed so as to cover the entire scanning range.

[0259] That is, a first OCT measurement (main measurement) is performed with the optical element 80 disposed in the optical path of the measurement light LS, and a second OCT measurement (main measurement) is performed with the optical element 80 retracted from the optical path of the measurement light LS. A region where image flip has occurred is identified from a first OCT image obtained by the first OCT measurement and a second OCT image obtained by the second OCT measurement, and optical path length correction is performed on the first OCT image of the identified region. A composite image such as that shown in FIG. 11 can be obtained by combining the first OCT image that has undergone optical path length correction with a second OCT image of a region where image flip has not occurred.

[0260] Furthermore, in view of the fact that the display range in the vertical direction on the display unit 240A is limited, the display mode may be switched according to the display magnification of the OCT image displayed on the display unit 240A.

[0261] FIG. 15 is a diagram illustrating the operation of an ophthalmologic apparatus according to a modified example of the embodiment.

[0262] The display controller 211A can cause the display unit 240A to display an OCT image at a display magnification specified by a user's operation using the operation unit 240B. For example, when the display magnification is equal to or less than a predetermined first magnification, the display controller 211A causes the display unit 240A to display a tomographic image IMG41, for which optical path length correction processing has been performed according to the flows of Figures 8 to 10. As described above, the tomographic image IMG41 is obtained by performing an OCT scan with an optical path length assigned using the optical member 80, and optical path length correction has been performed, so that image flip does not occur.

[0263] Here, when the user changes the display magnification using the operation unit 240B and the display magnification exceeds the first magnification, the main control unit 211 controls the data processing unit 230 to separate the image of the region where optical path length correction has been performed from the tomographic image IMG41. As a result, images IMG42 and IMG43 where optical path length correction has been performed are separated from image IMG44 where optical path length correction has not been performed. For example, the display control unit 211A causes the display unit 240A to display images IMG42, IMG44, and IMG43 arranged horizontally. At this time, the display control unit 211A may cause the display unit 240A to display images IMG42, IMG44, and IMG43 as shown in FIG. 12 or 13.

[0264] This makes it possible to observe a tomographic image in detail easily and at low cost, even when the display range in the vertical direction on the display unit 240A is limited and the scan length in the B-scan direction is long.

[0265] In the above embodiment, a method for easily expanding the imaging range in the depth direction of OCT with, for example, a single OCT measurement has been described. However, the configuration of the embodiment is not limited thereto. For example, if the optical element 80 has a transition region in which the optical path length difference imparted to the measurement light changes in a direction intersecting the propagation direction of the measurement light, two or more OCT measurements may be performed to prevent degradation of the image quality of the OCT image due to the transition region. The transition region of the optical element 80 may include, in a plane perpendicular to the propagation direction of the measurement light, a region including a boundary region in which the thickness changes in the propagation direction of the measurement light passing through it, a region including a boundary region in which the refractive index changes, and the like. An example of a region including a boundary region in which the thickness changes in the propagation direction of the measurement light is a region including the outline of an opening, as shown in FIG. 2, etc.

[0266] For example, the main control unit 211 (control unit 210) controls the OCT unit 100 to perform OCT measurement in each of two or more states in which the relative position of the A-scan position at which the measurement light passing through the change area of ​​the optical element 80 is incident is different.

[0267] A first example of the two or more states is a state before and after the A-scan position is moved relative to the change area of ​​the optical member 80 in a direction intersecting the traveling direction of the measurement light. For example, the main control unit 211 can change the relative position of the A-scan position with respect to the change area of ​​the optical member 80 by controlling the optical member driving unit 80A.

[0268] A second example of the two or more states is a state in which the optical member 80 is inserted into the optical path of the measurement light and a state in which the optical member 80 is retracted from the optical path. For example, the main control unit 211 can place the optical member 80 in the optical path of the measurement light or retract the optical member 80 from the optical path of the measurement light by controlling the optical member driving unit 80A.

[0269] A third example of two or more states is a state before and after changing the position of the optical path of the measurement light passing through the change region or the traveling direction of the measurement light.

[0270] When changing the position of the optical path of the measurement light, for example, an optical member that changes the position of the optical axis of the optical path of the measurement light is provided in the ophthalmologic apparatus so as to be insertable into and removable from the optical path of the measurement light. The main control unit 211 controls a moving mechanism (not shown) that can insert and remove this optical member into and from the optical path of the measurement light, thereby changing the relative position of the A-scan position at which the measurement light passing through the change area is incident with respect to the change area of ​​the optical member 80. An example of such an optical member is an optical member (e.g., a plane-parallel plate) that includes a plane-parallel portion that can be arranged so that its thickness direction is oblique to the optical path of the measurement light.

[0271] For example, the ophthalmologic apparatus includes a deflector disposed in the optical path of the measurement light. The main controller 211 controls the deflector to change the traveling direction of the measurement light passing through the change area of ​​the optical member 80, thereby changing the relative position of the A-scan position at which the measurement light passing through the change area is incident with respect to the change area of ​​the optical member 80. An example of such a deflector is an optical scanner provided separately from the optical scanner 42.

[0272] A fourth example of the two or more states is a state in which a fixation target projected onto the fundus Ef of the subject's eye E is projected at a first projection position, and a state in which the fixation target projected onto the fundus Ef is projected at a second projection position different from the first projection position. For example, the main controller 211 can change the projection position of the fixation target on the fundus Ef by controlling the LCD 39. At this time, the main controller 211 controls the LCD 39 to change the projection position of the fixation target on the fundus Ef so that image regions formed based on the measurement light passing through the change region of the optical element 80 do not overlap in the OCT images in each of the two or more states. In some embodiments, correspondence relationship information indicating a correspondence relationship between the region (including the change region) to which an optical path length difference is imparted by the optical element 80 and the projection position of the fixation target on the fundus Ef is stored in advance in the storage unit 212. 1, the fixation projection system including the LCD 39 and the interference optical system are coaxially coupled, and therefore correspondence information indicating the correspondence between the region (including the change region) where an optical path length difference is imparted by the optical member 80 and the incident position of the measurement light on the fundus Ef is stored in advance in the storage unit 212. The main control unit 211 can change the projection position of the fixation target on the fundus Ef by controlling the LCD 39 with reference to the correspondence information.

[0273] Next, the main controller 211 controls the image forming part 220 to form two or more OCT images based on the detection results of the interference light acquired in each of the two or more states described above.

[0274] Then, the main controller 211 controls the data processor 230 to form a composite image by combining two or more OCT images formed by the image forming unit 220. At this time, the data processor 230 can form a composite image by using an image region of the OCT image formed using measurement light that passes through the change region after the A-scan position has been moved relatively with respect to the change region, so as to compensate for deterioration in image quality of an image region of the OCT image formed using measurement light that passes through the change region before the relative movement.

[0275] For example, the data processing unit 230 calculates the correlation function of two OCT images before and after the relative movement, and searches for the relative position of the two OCT images where the correlation value obtained by the correlation function is highest while changing the relative positions of the two images. The data processing unit 230 can identify, among the OCT images before the relative movement at the searched relative position, image regions with large differences in image quality (image regions with low similarity) as image regions formed using measurement light that passed through the change region of the optical element 80. The data processing unit 230 forms a composite image by replacing the identified image region in the OCT image before the relative movement with the corresponding image region in the OCT image after the relative movement. In this case, the data processing unit 230 may form the composite image by superimposing the corresponding image regions. In some embodiments, correspondence information indicating the correspondence between the region (including the change region) where an optical path length difference is imparted by the optical element 80 and the deflection angle of the measurement light by the optical scanner 42 is pre-stored in the storage unit 212. After the relative movement, the main controller 211 controls the optical scanner 42 by referring to the correspondence information to scan only the area including the changed area of ​​the optical member 80, and forms a partial image using the measurement light that has passed through the changed area of ​​the optical member 80. The main controller 211 controls the data processor 230 to replace the image area, in the OCT image before the relative movement, that was formed using the measurement light that has passed through the changed area, with the partial image acquired after the relative movement, to form a composite image.

[0276] Alternatively, the data processing unit 230 uses a correlation function in the same manner as described above to identify an image region formed using measurement light that has passed through the change region of the optical element 80 in each of the two OCT images taken before and after the relative movement, and identifies a specific layer region of the fundus depicted in the image region (e.g., the RPE or the IS / OS line (photoreceptor inner segment / outer segment line)). Next, the data processing unit 230 performs a fitting process on the identified layer region in each of the two OCT images using a known fitting function with variables being the position in the B-scan direction and the position in the A-scan direction, and determines the position and direction of a tangent to the image region in each of the two images using the fitting function determined by the fitting process. The data processing unit 230 forms a composite image by replacing the identified image region in the OCT image taken before the relative movement with the corresponding image region in the OCT image taken after the relative movement so that the positions and directions of the tangents of the two image regions determined are approximately the same. In some embodiments, after the relative movement, the main controller 211 refers to the above-described correspondence information to control the optical scanner 42 to scan only the region including the changed region of the optical element 80, and form a partial image using the measurement light that has passed through the changed region of the optical element 80. The data processor 230 identifies the layer region of the formed partial image, performs fitting, and calculates the position and direction of the tangent, and forms a composite image by replacing the image region in the OCT image before the relative movement with the above-described partial image so that the position and direction of the tangent of the partial image approximately coincide with the position and direction of the tangent of the image region in the OCT image before the relative movement.

[0277] In some embodiments, a program for causing a computer to execute the above-described method for controlling an ophthalmic apparatus is provided. Such a program can be stored on any non-transitory computer-readable recording medium. The recording medium may be an electronic medium using magnetic, optical, magneto-optical, or semiconductor materials. Typically, the recording medium is a magnetic tape, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, a solid-state drive, or the like. The program can also be transmitted and received via a network such as the Internet or a LAN.

[0278] [Effect] An ophthalmic apparatus, a control method for the ophthalmic apparatus, and a program according to an embodiment will be described.

[0279] A first aspect of the embodiment is an ophthalmic apparatus (1) including an optical system (an optical system through which measurement light LS passes from an OCT unit 100 to an objective lens 22), an optical element (80), and an image forming unit (220). The optical system includes an optical scanner (42), splits light (L0) from a light source (light source unit 101) into measurement light (LS) and reference light (LR), projects the measurement light deflected by the optical scanner onto an eye (E), and detects interference light (LC) between the reference light and return light of the measurement light from the eye. The optical element is disposed in a position optically non-conjugate with the exit pupil of the optical system in the optical path of the measurement light, and imparts an optical path length difference to the measurement light relative to a reference position of the A-scan for each A-scan position (angle of view). The image forming unit forms an OCT image (tomographic image) of the eye based on the detection result of the interference light.

[0280] According to this aspect, an optical element is disposed in the optical path of the measurement light, and an optical path length difference is imparted to the measurement light for each A-scan position relative to the A-scan reference position, so that the detection result of the interference light obtained by scanning a desired region can be shifted in the depth direction, thereby enabling the imaging range of OCT in the depth direction to be expanded easily and at low cost.

[0281] In a second aspect of the embodiment, in the first aspect, the optical member imparts an optical path length difference to the measurement light such that the amount of change increases continuously or stepwise as the A-scan position moves away from the reference position.

[0282] According to this aspect, when an OCT scan is performed on a measurement region whose shape changes in the depth direction with respect to the reference position of the A scan, it is possible to easily and inexpensively expand the imaging range of the OCT in the depth direction even if the scan length in the B scan direction becomes longer.

[0283] In a third aspect of the embodiment, in the first or second aspect, the optical element is configured so that the optical path length difference of a first region through which a beam of measurement light incident on a reference position passes is shorter than the optical path length difference of a peripheral region of the first region.

[0284] According to this aspect, when performing an OCT scan on a measurement site with a concave cross-sectional shape, such as the fundus, even if the scan length in the B-scan direction becomes longer, the imaging range in the OCT depth direction can be expanded easily and at low cost.

[0285] In a fourth aspect of the embodiment, in the third aspect, the optical member is a light-transmitting member (glass member) having an opening formed therein so that the light beam passes through the first region.

[0286] According to this aspect, the optical element is positioned so that the measurement light incident on the reference position of the A-scan passes through the opening, thereby making it possible to miniaturize the optical element while avoiding degradation of image quality due to the optical path length correction process.

[0287] In a fifth aspect of the embodiment, in any one of the first to fourth aspects, the optical member is disposed at a position that is optically approximately conjugate with the fundus (Ef) of the subject's eye.

[0288] According to this aspect, the optical path length can be assigned to the measurement light for each A-scan position at the position where the beam separation of the measurement light is best, and therefore, by assigning an optical path length with higher precision, it becomes possible to improve the image quality of the OCT image in which the measurement site having a concave cross-sectional shape is depicted.

[0289] In a sixth aspect of the embodiment, in the first or second aspect, the optical element is configured so that the optical path length difference of a first region through which a beam of measurement light incident on a reference position passes is longer than the optical path length difference of a peripheral region of the first region.

[0290] According to this aspect, when performing an OCT scan on a measurement site with a convex cross-sectional shape, such as edema in the cornea or fundus, even if the scan length in the B-scan direction becomes longer, the imaging range in the OCT depth direction can be expanded easily and at low cost.

[0291] In a seventh aspect of the embodiment, in the sixth aspect, the optical member is placed at a position that is optically approximately conjugate with the cornea of ​​the eye to be examined.

[0292] According to this aspect, the optical path length can be assigned to the measurement light for each A-scan position at the position where the beam separation of the measurement light is best, and therefore, by assigning an optical path length with higher precision, it becomes possible to improve the image quality of the OCT image in which the measurement site having a convex cross-sectional shape is depicted.

[0293] In an eighth aspect of the embodiment, in any one of the first to seventh aspects, the optical member is movable in a direction intersecting the optical path of the measurement light.

[0294] According to this aspect, it is possible to adjust the position of the optical components arranged in the optical path of the measurement light with high precision, and therefore it is possible to provide the measurement light incident on the desired A-scan position with high precision. As a result, it is possible to expand the imaging range in the depth direction of the OCT and achieve high quality OCT images.

[0295] A ninth aspect of the embodiment is any of the first to eighth aspects, and includes a correction processing unit (232) that performs different correction processes on the detection results (scan data) of the interference light or the OCT image depending on the A-scan position.

[0296] According to this aspect, it is possible to perform correction processing on the detection result of interference light or the OCT image obtained by OCT scanning using measurement light that has passed through an optical member, thereby improving the image quality of the OCT image by expanding the imaging range in the depth direction of the OCT.

[0297] In a tenth aspect of the embodiment, in the ninth aspect, the correction processing unit corrects the detection result of the interference light or the OCT image so as to cancel the optical path length difference given to the measurement light for each A-scan position.

[0298] According to this aspect, the optical path length imparted by the optical element to the detection result of interference light or the OCT image obtained by OCT scanning using measurement light that has passed through the optical element is cancelled, and even if the scan length is long in the B scan direction, flipping of the OCT image can be prevented simply and at low cost.

[0299] In an eleventh aspect of the embodiment, in the ninth or tenth aspect, the correction processing unit corrects the OCT image so that the size of one pixel is uniform for each A-scan position.

[0300] According to this aspect, the OCT image obtained by OCT scanning using measurement light that has passed through an optical element can be corrected to reduce variations in optical magnification, thereby enabling the OCT image to have high image quality while expanding the imaging range in the depth direction of the OCT simply and at low cost.

[0301] In a twelfth aspect of the embodiment, in any one of the ninth to eleventh aspects, the correction processing unit corrects the detection result of the interference light so as to compensate for chromatic dispersion for each A-scan position.

[0302] According to this aspect, the detection results of interference light obtained by OCT scanning using measurement light that has passed through an optical element are corrected to suppress variations in wavelength dispersion, making it possible to easily and inexpensively expand the imaging range of OCT in the depth direction while improving the image quality of OCT images.

[0303] A thirteenth aspect of the embodiment is any of the first to twelfth aspects, and includes a display control unit (211A) that causes a display means (display unit 240A, display device 3) to display OCT images. The display control unit causes the display means to display OCT images (IMG21, IMG22) of the B-scan range to which the same optical path length difference has been imparted by the optical member, surrounded by distinguishable frames (G1, G2).

[0304] According to this aspect, the OCT image of the B-scan range, to which the optical element has given the same optical path length difference relative to the reference position of the A-scan, is displayed on the display means by being surrounded by a frame to make it easy to identify, so that the OCT image of the region to which the optical path length has been given can be easily observed without being affected by artifacts that arise from giving different optical path lengths.

[0305] A fourteenth aspect of the embodiment is any of the first to thirteenth aspects, and includes a display control unit (211A) that causes a display means (display unit 240A, display device 3) to display an OCT image. The display control unit causes the display means to display the first OCT image and the second OCT image with a gap between a first OCT image (OCT image IMG32) of a B scan range to which a first optical path length difference has been assigned and a second OCT image (OT image IMG31) of a B scan range to which a second optical path length difference different from the first optical path length difference has been assigned.

[0306] According to this aspect, the OCT images of the B-scan ranges to which different optical path lengths are assigned relative to the reference position of the A-scan by the optical element are separated and displayed on the display means, so that the OCT images of the regions to which optical path lengths are assigned can be easily observed without being affected by artifacts that arise from assigning different optical path lengths.

[0307] A fifteenth aspect of the embodiment is any of the first to thirteenth aspects, and includes a display control unit (211A) that causes the display means (display unit 240A, display device 3) to display an OCT image. The display control unit causes the display means to combine the first OCT image and the second OCT image by moving at least one of a first OCT image (OCT image IMG11) of a first B scan range and a second OCT image (OCT image IMG12) of a second B scan range, which are obtained using measurement light beams having different optical path length differences, in the A scan direction so as to cancel the optical path length differences between the two.

[0308] According to this aspect, even if the scan length in the B-scan direction is long, it is possible to easily and inexpensively display an OCT image while expanding the imaging range in the depth direction of the OCT. This makes it possible to observe OCT images with a long scan length in the B-scan direction in detail without being affected by flipping of the OCT image.

[0309] In a sixteenth aspect of the embodiment, in any one of the first to eighth aspects, the optical member has a change region (for example, a boundary region including a contour portion of an opening) in which the optical path length difference imparted to the measurement light changes. The image forming unit forms two or more OCT images based on detection results of interference light acquired in two or more states in which the relative position of the A-scan position at which the measurement light passing through the change region is incident is different from the relative position of the change region. The ophthalmic apparatus includes an image combining unit (data processing unit 230) that combines the two or more OCT images to form a combined image.

[0310] According to this aspect, it is possible to form two or more OCT images in which the relative positions of the A-scan positions at which the measurement light passing through the change region of the optical element is incident are different relative to the change region of the optical element. As a result, by simply changing the relative positions, it is possible to form a composite image that compensates for portions of the OCT image in which the image quality has deteriorated, which is based on the detection results of the interference light obtained by the measurement light passing through the change region.

[0311] A seventeenth aspect of the embodiment is a method for controlling an ophthalmic apparatus including an optical system (an optical system through which measurement light LS passes from the OCT unit 100 to the objective lens 22) and an optical element (80). The optical system includes an optical scanner (42), splits light (L0) from a light source (light source unit 101) into measurement light (LS) and reference light (LR), projects the measurement light deflected by the optical scanner onto the subject's eye (E), and detects interference light (LC) between return light of the measurement light from the subject's eye and the reference light. The optical element is disposed in a position optically non-conjugate with the position of the exit pupil of the optical system in the optical path of the measurement light, and imparts an optical path length difference to the measurement light relative to a reference position of the A-scan for each A-scan position. The control method for the ophthalmic apparatus includes an image formation step and a correction step. The image formation step forms an OCT image of the subject's eye based on the detection result of the interference light. The correction step performs different correction processes on the detection result of the interference light or the OCT image depending on the A-scan position.

[0312] According to this aspect, an optical element is disposed in the optical path of the measurement light, and an optical path length difference is imparted to the measurement light for each A-scan position relative to the A-scan reference position, so that the detection result of the interference light obtained by scanning a desired region can be shifted in the depth direction, thereby enabling the imaging range of OCT in the depth direction to be expanded easily and at low cost.

[0313] An eighteenth aspect of the embodiment is a method for controlling an ophthalmic apparatus including an optical system (an optical system through which measurement light LS passes from the OCT unit 100 to the objective lens 22) and an optical element (80). The optical system includes an optical scanner (42), splits light (L0) from a light source (light source unit 101) into measurement light (LS) and reference light (LR), projects the measurement light deflected by the optical scanner onto the subject's eye (E), and detects interference light (LC) between return light of the measurement light from the subject's eye and the reference light. The optical element is disposed in a position optically non-conjugate with the position of the exit pupil of the optical system in the optical path of the measurement light, and imparts an optical path length difference from the reference position of the A-scan to the measurement light for each A-scan position. The control method for the ophthalmic apparatus includes an image formation step and a display control step. The image formation step forms an OCT image of the subject's eye based on the detection result of the interference light. The display control step displays the OCT image on a display means (a display unit 240A, a display device 3). The display control step causes the display means to display OCT images (IMG21, IMG22) of the B-scan range to which the same optical path length difference has been imparted by the optical member, surrounded by distinguishable frames (G1, G2).

[0314] According to this aspect, the OCT image of the B-scan range, to which the optical element has given the same optical path length difference relative to the reference position of the A-scan, is displayed on the display means by being surrounded by a frame to make it easy to identify, so that the OCT image of the region to which the optical path length has been given can be easily observed without being affected by artifacts that arise from giving different optical path lengths.

[0315] A nineteenth aspect of the embodiment is a method for controlling an ophthalmic apparatus including an optical system (an optical system through which measurement light LS passes from the OCT unit 100 to the objective lens 22) and an optical element (80). The optical system includes an optical scanner (42), splits light (L0) from a light source (light source unit 101) into measurement light (LS) and reference light (LR), projects the measurement light deflected by the optical scanner onto the subject's eye (E), and detects interference light (LC) between return light of the measurement light from the subject's eye and the reference light. The optical element is disposed in a position optically non-conjugate with the position of the exit pupil of the optical system in the optical path of the measurement light, and imparts an optical path length difference from the reference position of the A-scan to the measurement light for each A-scan position. The control method for the ophthalmic apparatus includes an image formation step and a display control step. The image formation step forms an OCT image of the subject's eye based on the detection result of the interference light. The display control step displays the OCT image on a display means (a display unit 240A, a display device 3). The display control step combines the first OCT image and the second OCT image (OCT image IMG11) of the first B scan range and the second OCT image (OCT image IMG12) of the second B scan range, which are obtained using measurement light beams having different optical path length differences, by moving them in the A scan direction so as to cancel the optical path length differences between the two, and displays the combined image on the display means.

[0316] According to this aspect, even if the scan length in the B-scan direction is long, it is possible to easily and inexpensively display an OCT image while expanding the imaging range in the depth direction of the OCT. This makes it possible to observe OCT images with a long scan length in the B-scan direction in detail without being affected by flipping of the OCT image.

[0317] A twentieth aspect of the embodiment is a method for controlling an ophthalmic apparatus including an optical system (an optical system through which measurement light LS passes from the OCT unit 100 to the objective lens 22) and an optical element (80). The optical system includes an optical scanner (42), splits light (L0) from a light source (light source unit 101) into measurement light (LS) and reference light (LR), projects the measurement light deflected by the optical scanner onto the subject's eye (E), and detects interference light (LC) between the reference light and return light of the measurement light from the subject's eye. The optical element is disposed in a position optically non-conjugate with the position of the exit pupil of the optical system in the optical path of the measurement light, imparts an optical path length difference to the measurement light relative to a reference position of the A-scan for each A-scan position, and has a change region in which the optical path length difference imparted to the measurement light changes. The method for controlling an ophthalmic apparatus includes an image formation step and an image synthesis step. The image forming step forms two or more OCT images of the subject's eye based on detection results of interference light acquired in two or more states where the relative position of the A-scan position at which the measurement light passing through the change region is incident is different with respect to the change region. The image combining step combines the two or more OCT images formed in the image forming step to form a combined image.

[0318] According to this aspect, it is possible to form two or more OCT images in which the relative positions of the A-scan positions at which the measurement light passing through the change region of the optical element is incident are different relative to the change region of the optical element. As a result, by simply changing the relative positions, it is possible to form a composite image that compensates for portions of the OCT image in which the image quality has deteriorated, which is based on the detection results of the interference light obtained by the measurement light passing through the change region.

[0319] A twenty-first aspect of the embodiment is a program for causing a computer to execute each step of the method for controlling an ophthalmologic apparatus according to any one of the seventeenth to twentieth aspects.

[0320] According to this aspect, an optical element is placed in the optical path of the measurement light, and an optical path length difference relative to the reference position of the A-scan is imparted to the measurement light for each A-scan position, making it possible to expand the imaging range of OCT in the depth direction simply and at low cost.

[0321] The configuration described above is merely one example for suitably implementing the present invention. Therefore, any modifications (omissions, substitutions, additions, etc.) can be made as appropriate within the scope of the gist of the present invention. The configuration to be applied is selected, for example, depending on the purpose. Furthermore, depending on the configuration to be applied, effects that are obvious to those skilled in the art or the effects described in this specification can be obtained. [Explanation of symbols]

[0322] 1 Ophthalmology equipment 3 Display device 80 Optical Components 100 OCT units 200 Calculation and Control Unit 210 Control Unit 211 Main control unit 211A Display control unit 212 Storage section 220 Image forming unit 230 Data Processing Unit 231 Analysis Department 232 Correction processing unit 232A Optical path length correction section 232B Optical magnification correction section 232C Dispersion correction section 240A display section 240B Operation section E. Examined eye LC interference light LR reference light LS measurement light

Claims

1. an optical system including an optical scanner that divides light from a light source into measurement light and reference light, projects the measurement light deflected by the optical scanner onto the subject's eye, and detects interference light between return light of the measurement light from the subject's eye and the reference light; an optical member that is arranged at a position optically non-conjugate with a position of an exit pupil of the optical system in the optical path of the measurement light, and that imparts an optical path length different from a reference optical path length imparted to the measurement light passing through a reference position of an A scan to the measurement light according to the A scan position, thereby imparting an optical path length difference with respect to the reference position to the measurement light for each A scan position; an optical member driving unit that changes a relative position of the optical member with respect to the optical path of the measurement light within a beam cross section of the measurement light; an image forming unit that forms an OCT image of the subject's eye based on a detection result of the interference light; Including, The optical member has two or more regions that provide different optical path lengths to the measurement light passing therethrough.

2. The optical member driving unit moves the optical member in a direction intersecting the optical path of the measurement light.

2. An ophthalmic apparatus according to claim 1.

3. The optical member imparts the optical path length difference to the measurement light so that the amount of change increases continuously or stepwise as the A-scan position moves away from the reference position.

3. An ophthalmic apparatus according to claim 1 or 2.

4. The optical member is configured so that an optical path length difference of a first region through which the beam of the measurement light incident on the reference position passes is shorter than an optical path length difference of a region surrounding the first region.

4. The ophthalmic apparatus according to claim 1, wherein the ophthalmic apparatus is a microscope.

5. The optical member is a light-transmitting member having an opening formed therein so that a light beam passes through the first region.

5. An ophthalmic apparatus according to claim 4.

6. The optical member is disposed at a position that is optically conjugate with the fundus of the subject's eye.

6. The ophthalmic apparatus according to claim 1, wherein the ophthalmic apparatus is a microscope.

7. a correction processing unit that performs different correction processes on the detection result of the interference light or the OCT image depending on the A-scan position 7. The ophthalmic apparatus according to claim 1, wherein the ophthalmic apparatus is a microscope.

8. The correction processing unit corrects the detection result of the interference light or the OCT image so as to cancel the optical path length difference imparted to the measurement light for each A-scan position.

8. An ophthalmic apparatus according to claim 7.

9. The correction processing unit corrects the OCT image so that the size of one pixel is uniform for each A-scan position.

9. An ophthalmic apparatus according to claim 7 or 8.

10. The correction processing unit corrects the detection result of the interference light so as to compensate for chromatic dispersion for each A-scan position. The ophthalmic apparatus according to any one of claims 7 to 9.

11. a display control unit that displays the OCT image on a display means; The display control unit causes the display unit to display an OCT image of a B-scan range to which the same optical path length difference has been imparted by the optical member, surrounded by an identifiable frame. The ophthalmic apparatus according to any one of claims 1 to 10.

12. a display control unit that displays the OCT image on a display means; The display control unit causes the display unit to display a first OCT image of a B-scan range to which a first optical path length difference has been applied and a second OCT image of a B-scan range to which a second optical path length difference different from the first optical path length difference has been applied, with a gap provided between the first OCT image and the second OCT image. The ophthalmic apparatus according to any one of claims 1 to 11.

13. a display control unit that displays the OCT image on a display means; The display control unit moves at least one of a first OCT image of a first B scan range and a second OCT image of a second B scan range, which are obtained using measurement light beams having different optical path length differences, in an A scan direction so as to cancel the optical path length differences between the first OCT image and the second OCT image, thereby synthesizing the first OCT image and the second OCT image and displaying the synthesized image on the display unit. The ophthalmic apparatus according to any one of claims 1 to 11.

14. an optical system including an optical scanner that divides light from a light source into measurement light and reference light, projects the measurement light deflected by the optical scanner onto the subject's eye, and detects interference light between return light of the measurement light from the subject's eye and the reference light; an optical element that is arranged at a position optically non-conjugate with a position of an exit pupil of the optical system in an optical path of the measurement light, and that imparts an optical path length different from a reference optical path length imparted to measurement light passing through a reference position of an A scan to the measurement light according to the A scan position, thereby imparting an optical path length difference from the reference position to the measurement light for each A scan position, wherein the optical element has two or more regions that impart different optical path lengths to the measurement light passing therethrough, an optical member driving step of changing a relative position of the optical member with respect to the optical path of the measurement light within a beam cross section of the measurement light; an image forming step of forming an OCT image of the subject's eye based on a detection result of the interference light; a correction step of performing different correction processes on the detection result of the interference light or the OCT image depending on the A-scan position; A method for controlling an ophthalmic device, comprising:

15. an optical system including an optical scanner that divides light from a light source into measurement light and reference light, projects the measurement light deflected by the optical scanner onto the subject's eye, and detects interference light between return light of the measurement light from the subject's eye and the reference light; an optical element that is arranged at a position optically non-conjugate with a position of an exit pupil of the optical system in an optical path of the measurement light, and that imparts an optical path length different from a reference optical path length imparted to measurement light passing through a reference position of an A scan to the measurement light according to the A scan position, thereby imparting an optical path length difference from the reference position to the measurement light for each A scan position, wherein the optical element has two or more regions that impart different optical path lengths to the measurement light passing therethrough, an optical member driving step of changing a relative position of the optical member with respect to the optical path of the measurement light within a beam cross section of the measurement light; an image forming step of forming an OCT image of the subject's eye based on a detection result of the interference light; a display control step of displaying the OCT image on a display means; Including, The display control step causes the display means to display an OCT image of a B-scan range to which the same optical path length difference has been imparted by the optical element, surrounded by a distinguishable frame.

16. an optical system including an optical scanner that divides light from a light source into measurement light and reference light, projects the measurement light deflected by the optical scanner onto the subject's eye, and detects interference light between return light of the measurement light from the subject's eye and the reference light; an optical element that is arranged at a position optically non-conjugate with a position of an exit pupil of the optical system in an optical path of the measurement light, and that imparts an optical path length different from a reference optical path length imparted to measurement light passing through a reference position of an A scan to the measurement light according to the A scan position, thereby imparting an optical path length difference from the reference position to the measurement light for each A scan position, wherein the optical element has two or more regions that impart different optical path lengths to the measurement light passing therethrough, an optical member driving step of changing a relative position of the optical member with respect to the optical path of the measurement light within a beam cross section of the measurement light; an image forming step of forming an OCT image of the subject's eye based on a detection result of the interference light; a display control step of displaying the OCT image on a display means; Including, The display control step is a control method for an ophthalmic device, in which at least one of a first OCT image of a first B scan range and a second OCT image of a second B scan range, which use measurement light beams having different optical path length differences, is moved in the A scan direction so as to cancel the optical path length difference between the first OCT image and the second OCT image, thereby combining the first OCT image and the second OCT image and displaying the result on the display means.

17. A program causing a computer to execute each step of the method for controlling an ophthalmic apparatus according to any one of claims 14 to 16.

Images