Optical coherence tomography device, control method therefor, and program

Abstract

This optical coherence tomography device includes an optical system and a control unit. The optical system is configured so as to allow an optical condition to be changed and includes an optical scanner, and is configured to scan an object under measurement with measurement light using an optical scanner and thereby acquire optical coherence tomography data for an object under measurement. The control unit controls the optical scanner so as to scan the object under measurement with the measurement light along a high-speed scan axis with reference to a reference position moving along a low-speed scan axis. The control unit changes an optical condition in synchronization with the period of a low-speed scan along the low-speed scan axis.

Description

Optical coherence tomography device, its control method, and program

[0001] The present invention relates to an optical coherence tomography device, a control method for an optical coherence tomography device, and a program.

[0002] Optical coherence tomography (OCT) devices are known that use a light beam from a laser light source or the like to form images representing the surface or internal morphology of an object under test. Because OCT performed by OCT devices is non-invasive to living organisms, it is expected to find widespread application, particularly in the medical and biological fields. For example, in the field of ophthalmology, devices that form images of the fundus, cornea, and the like have been put to practical use. Such devices using OCT techniques (OCT devices) can be used to observe various parts of the subject's eye. Furthermore, because they can acquire high-resolution images, they are used to diagnose various ophthalmic diseases.

[0003] When capturing wide-angle images of an object, the optimal optical conditions for each imaging region (scan region) vary depending on the cross-sectional shape of the object. As a result, the image quality around the region of interest may be insufficient, making it necessary to re-image the object.

[0004] To address this issue, it is conceivable to widen the imaging range (measurement range, depth range) of OCT in the depth direction. However, there is a limit to the imaging range of OCT in the depth direction. Widening the imaging range in the depth direction leads to increased costs for the detection system and an increase in the size of the optical system.

[0005] For example, Patent Document 1 discloses a method of performing a pre-scan and adjusting the optical path length of the reference light so that the entire tomographic image of the observed area is positioned at an optimal position within the B-scan image based on A-scan images at multiple positions in the scanning direction of the B-scan that have been acquired in advance.

[0006] JP 2015-16151 A

[0007] However, in Patent Document 1, a pre-scan must be performed before the actual scan, which increases the imaging time (measurement time).When the object to be measured is a living eye, this increases the burden on the subject.

[0008] The present invention has been made in consideration of the above circumstances, and one of its purposes is to provide a new technology for acquiring an image of a measured object with good image quality when photographing the measured object at a wide angle.

[0009] One aspect of some embodiments is an optical coherence tomography device that includes an optical system configured to change optical conditions, including an optical scanner, and configured to acquire optical coherence tomography data of the object to be measured by scanning the object to be measured with measurement light using the optical scanner; and a controller that controls the optical scanner to scan the object to be measured with the measurement light along a fast scan axis based on a reference position that moves along a slow scan axis, and the controller changes the optical conditions in synchronization with the period of the slow scan along the slow scan axis.

[0010] Another aspect of some embodiments is a method for controlling an optical coherence tomography apparatus including an optical system configured to change optical conditions, the optical system including an optical scanner, and the optical scanner configured to acquire optical coherence tomography data of an object to be measured by scanning the object to be measured with measurement light using the optical scanner. The method for controlling an optical coherence tomography apparatus includes a control step of controlling the optical scanner to scan the object to be measured with the measurement light along a fast scan axis based on a reference position moving along a slow scan axis, and an optical condition changing step of changing the optical conditions in synchronization with a period of the slow scan along the slow scan axis.

[0011] Yet another aspect of some embodiments is a program that causes a computer to execute each step of the above-described method for controlling an optical coherence tomography apparatus.

[0012] Yet another aspect of the embodiment is a computer program product including a computer program / instructions that, when executed by a processor, implements the steps of the above-described method for controlling an optical coherence tomography apparatus.

[0013] Yet another aspect of the embodiment is a computer-readable storage medium (recording medium) having stored thereon a computer program / instruction, which, when executed by a processor, implements each step of the above-described method for controlling an optical coherence tomography apparatus.

[0014] According to the embodiment of the present invention, it is possible to provide a new technique for acquiring an image of an object to be measured with good image quality when photographing the object to be measured at a wide angle.

[0015] FIG. 1 is a schematic diagram showing an example of the configuration of an optical system of an ophthalmic apparatus according to a first embodiment. FIG. 2 is a schematic diagram showing an example of the configuration of an optical system of an ophthalmic apparatus according to a first embodiment. FIG. 3 is a schematic diagram showing an example of the configuration of an optical system of an ophthalmic apparatus according to a first embodiment. FIG. 4 is a schematic diagram showing an example of the configuration of a processing system of an ophthalmic apparatus according to a first embodiment. FIG. 5 is a schematic diagram showing an example of the configuration of a processing system of an ophthalmic apparatus according to a first embodiment. FIG. 6 is a diagram explaining the operation of an ophthalmic apparatus according to a first embodiment. FIG. 7 is a diagram explaining the operation of an ophthalmic apparatus according to a first embodiment. FIG. 8 is a diagram explaining the operation of an ophthalmic apparatus according to a first embodiment. FIG. 9 is a diagram explaining the operation of an ophthalmic apparatus according to a first embodiment. FIG. 10 is a diagram explaining the operation of an ophthalmic apparatus according to a first embodiment. FIG. 11 is a diagram explaining the operation of an ophthalmic apparatus according to a first embodiment. FIG. 12 is a diagram explaining the operation of an ophthalmic apparatus according to a first embodiment. 10A and 10B are explanatory diagrams illustrating the operation of the ophthalmologic apparatus according to the third modified example of the first or second embodiment.

[0016] The present invention relates to an optical coherence tomography device, a method for controlling the optical coherence tomography device, and a program for controlling the optical coherence tomography device. The following describes exemplary embodiments with reference to the accompanying drawings. The contents of documents cited in this specification and any publicly known techniques may be incorporated into the following embodiments.

[0017] An optical coherence tomography (OCT) apparatus according to an embodiment includes an optical system configured to change optical conditions. The optical system includes an optical scanner and is configured to acquire OCT data of an object by scanning the object with measurement light used in OCT using the optical scanner. The OCT apparatus further includes a controller that controls the optical scanner to scan the object with the measurement light using a single scan that combines a slow scan along a slow scan axis and a fast scan along a fast scan axis. Specifically, the controller controls the optical scanner to scan the object with the measurement light along the fast scan axis based on a reference position of the fast scan moving along the slow scan axis. Furthermore, the controller changes the optical conditions of the optical system during scanning (photography, measurement) in synchronization with the period of the slow scan along the slow scan axis.

[0018] In such an OCT device, when a first high-speed scan is performed during a single scan that combines a slow scan and a high-speed scan, the optical conditions of the optical system can be changed in synchronization with the period of the slow scan, based on OCT data obtained by a second high-speed scan that was performed earlier than the first high-speed scan. In some embodiments, the optical conditions of the optical system are fixed during the high-speed scan.

[0019] In some embodiments, the control unit changes the optical conditions based on OCT data obtained by a high-speed scan (or A-scan) performed before the high-speed scan (or A-scan) in which the optical conditions of the optical system are changed during the scan, or an OCT image formed based on the OCT data. Examples of high-speed scans performed before the high-speed scan in which the optical conditions of the optical system are changed include the high-speed scan performed immediately before the first high-speed scan in which the optical conditions of the optical system are changed, and the high-speed scan performed two or more times before the first high-speed scan. That is, the OCT device substantially estimates the cross-sectional structure of the object to be measured based on the OCT data or OCT image obtained by the high-speed scan performed in the past at the first high-speed scan position (area), and changes the optical conditions of the optical system in synchronization with the period of the slow scan based on the estimated cross-sectional structure. The OCT device performs a high-speed scan at a second high-speed scan position different from the first high-speed scan position, which is moved along the slow scan axis.

[0020] In some embodiments, a single scan is a combination of one slow scan (there may be one or more slow scans) and two or more fast scans performed between a predetermined scan start timing and a predetermined scan end timing. In some embodiments, a single scan is a single scan performed between a preset scan start position and a preset scan end position.

[0021] In some embodiments, the OCT apparatus changes the optical conditions of the optical system for each of a plurality of scan regions set on the object to be measured in synchronization with the period of the slow scan along the slow scan axis during scanning. For example, the OCT apparatus substantially estimates the cross-sectional structure of the object to be measured for each scan region based on OCT data or OCT images obtained by a high-speed scan executed in the past, and changes the optical conditions of the optical system based on the estimated cross-sectional structure in synchronization with the period of the slow scan.

[0022] Examples of optical conditions of the optical system include the amount of light of the measurement light used in OCT, the beam diameter, the focal position, the polarization component of the measurement light, the aberration correction component, the optical path length difference between the measurement light and the reference light, and the position of the optical system relative to the object to be measured.

[0023] The slow scan may be a scan defined by any one-dimensional or two-dimensional scan mode. The fast scan may be a scan defined by any one-dimensional or two-dimensional scan mode. Examples of such slow or fast scans include a line scan, a cross scan, a circle scan, a radial scan, a concentric circle scan, a multi-line cross scan, a spiral scan, and a Lissajous scan. An example of a combination of a slow scan and a fast scan is a three-dimensional scan such as an ammonite scan. An ammonite scan is performed by combining a slow scan in which the slow scan axis is a spiral scan axis and a fast scan in which the fast scan axis is a circular scan axis.

[0024] This makes it possible to acquire an image of the object to be measured with good image quality when photographing the object at a wide angle without performing a pre-scan.

[0025] In some embodiments, the optical system includes one or more optical elements, and is configured to be able to change at least one of the focal position of the measurement light used in OCT, the polarization component of the measurement light, the aberration correction component, and the optical path length difference between the measurement light and the reference light by controlling the one or more optical elements.

[0026] In some embodiments, the optical system includes a mechanism for moving the optical system or one or more optical elements, and is configured to be able to change any of the focal position of the measurement light used in OCT, the polarization component of the measurement light, the aberration correction component, and the optical path length difference between the measurement light and the reference light by controlling the mechanism.

[0027] In some embodiments, the OCT apparatus includes a movement mechanism that moves the optical system relative to the object to be measured, and is configured to be able to change the position of the optical system relative to the object to be measured by controlling the movement mechanism.

[0028] The focal position is changed by a focal position changing member as an optical element, examples of which include a lens that can move along the optical axis, a liquid crystal lens, an Alvarez lens, and the like.

[0029] The polarization components are changed by a polarization component changing member as an optical element. An example of the polarization component is a polarization controller. When light from a light source is split into measurement light and reference light used in OCT, the polarization controller may change the polarization components of the light from the light source or the polarization components of the measurement light.

[0030] The aberration correction component is changed by an aberration correction device as an optical element, examples of which include a variable cross cylinder (hereinafter referred to as VCC) lens, a liquid crystal lens, a wavefront aberration correction optical system including a deformable mirror, and an Alvarez lens.

[0031] The optical path length difference is changed by an optical path length changing member as an optical element or mechanism. Examples of the optical path length changing member include a member that changes at least one of the optical path lengths of the measurement light and the reference light.

[0032] The position of the optical system relative to the object under test is changed by a mechanism that changes at least one of the object under test and the optical system, such as a movement mechanism that changes the relative position between the object under test and a holding member that holds the optical system.

[0033] In some embodiments, the optical system includes an interference optical system and an optical path length difference changing member. The interference optical system is configured to split light from a light source into measurement light and reference light, project the measurement light that has passed through a measurement optical path in which one or more optical elements are arranged onto the object under test, and detect interference light between return light from the object under test and the reference light that has passed through the reference optical path. The optical path length difference changing member changes the difference between the optical path length of the measurement light and the optical path length of the reference light. The control unit changes the optical conditions of the optical system by controlling at least one of the one or more optical elements and the optical path length difference changing member.

[0034] In some embodiments, the OCT apparatus includes an image forming unit that forms an image of the object to be measured based on the OCT data, and an image quality evaluation value calculation unit that calculates an evaluation value of the image quality of the image of the object to be measured. The control unit controls the one or more optical elements based on the calculated evaluation value.

[0035] For example, the control unit controls the one or more optical elements based on the calculated evaluation value so that the image of the object to be measured has a quality equal to or higher than a predetermined image quality level. Examples of image quality equal to or higher than the predetermined image quality level include image quality for which the evaluation value of the image quality of the entire image is maximized, image quality for which the evaluation value of the image quality of the entire image is equal to or higher than a predetermined threshold level, image quality for which the statistical value of the evaluation values ​​of the image quality of multiple images calculated for each scan area is maximized, and image quality for which the statistical value of the evaluation values ​​of the image quality of multiple images calculated for each scan area is equal to or higher than a predetermined threshold level. Examples of statistical values ​​include maximum, minimum, median, mean, mode, range, variance, standard deviation, a weighted average value in which the weighting coefficient increases the closer the value is to the target area (the optical axis of the optical system), or a value of a predetermined evaluation formula using any of the above statistical values.

[0036] In some embodiments, the OCT apparatus includes a movement mechanism that moves the optical system relative to the object to be measured, and the control unit controls the movement mechanism to change the optical conditions of the optical system.

[0037] In some embodiments, the OCT apparatus includes the image forming unit, and the control unit controls the optical path length difference changing member based on the position of the object to be measured in the image.

[0038] In some embodiments, the scan region includes a central region including an optical axis of an optical system in the object to be measured, and one or more peripheral regions around the central region. For example, the one or more peripheral regions include one or more intermediate regions disposed outside the central region and surrounding the central region, and a peripheral region disposed outside an outermost intermediate region of the one or more intermediate regions and surrounding the outermost intermediate region.

[0039] This makes it possible to acquire an image of the object to be measured with good image quality even if the inclination of the cross section differs between the central region and one or more peripheral regions of the object to be measured.

[0040] A control method for an OCT apparatus according to an embodiment is a method for controlling an OCT apparatus according to an embodiment. The control method for an OCT apparatus according to an embodiment includes one or more steps executed by the OCT apparatus. A program (computer program) / instructions according to an embodiment cause a computer to execute each step of the control method for an OCT apparatus according to an embodiment. A computer program product according to an embodiment includes a computer program / instructions. When the computer program / instructions are executed by a processor, the computer program product realizes each step of the control method for an OCT apparatus according to an embodiment. A recording medium (storage medium) according to an embodiment is any non-transitory recording medium readable by a computer on which a program according to an embodiment is recorded (stored). A computer-readable storage medium according to an embodiment stores a computer program / instructions. When the computer program / instructions are executed by a processor, the computer-readable storage medium realizes each step of the control method for an OCT apparatus according to an embodiment. The recording medium may be an electronic medium using a magnetic, optical, magneto-optical, semiconductor, or the like. 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. It is also possible to transmit and receive this program via a network such as the Internet or a LAN.

[0041] Hereinafter, an OCT apparatus according to an embodiment will be described taking an ophthalmic apparatus in which a measurement object is a living eye as an example. However, the embodiment can also be applied to an OCT apparatus in which a measurement object is other than a living eye.

[0042] The ophthalmologic apparatus according to the embodiment can perform OCT on any part of the subject's eye, such as the fundus or the anterior segment. 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 (main measurement, provisional measurement).

[0043] 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, but 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).

[0044] In addition, in the following, we will explain the case where the evaluation value of image quality increases as the image quality improves and decreases as the image quality deteriorates, but the embodiment can also be applied to cases where the evaluation value decreases as the image quality improves and increases as the image quality deteriorates.

[0045] 1 to 3, an ophthalmologic apparatus 1 according to the first embodiment 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 similar to that of a conventional fundus camera. The OCT unit 100 is provided with an optical system for acquiring OCT images (e.g., tomographic images) of the fundus (or anterior segment). The arithmetic and control unit 200 includes a computer that executes various types of arithmetic processing, control processing, and the like.

[0046] [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. The fundus image includes an observed image, a photographed image, and the like. 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 also be configured to acquire other images, such as a fluorescein fluorescent image, an indocyanine green fluorescent image, or an autofluorescent image.

[0047] The fundus camera unit 2 is provided with a chin rest and a forehead rest for supporting the subject's face. Furthermore, the fundus camera unit 2 is provided with an illumination optical system 10 and an imaging optical system 30. The illumination optical system 10 irradiates the fundus Ef with illumination light. The imaging 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). Furthermore, the imaging optical system 30 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.

[0048] 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 reflective 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 aperture 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.

[0049] 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 passes 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 imaging optical system 30 is focused on the anterior segment, an observation image of the anterior segment of the subject's eye E is displayed.

[0050] 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 via the same path as the observation illumination light. Fundus reflection light of the imaging illumination light is guided to the dichroic mirror 33 via the same path as the observation illumination light, transmitted through the dichroic mirror 33, reflected by a mirror 36, and 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. Note that the display device 3 displaying the observation image and the display device 3 displaying the photographed image may be the same or different. Furthermore, when a similar photograph 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.

[0051] The LCD (Liquid Crystal Display) 39 displays a fixation target and a visual target for measuring visual acuity. The fixation target is a visual target for causing the subject's eye E to fixate on, and is used during fundus photography, OCT measurement, and the like.

[0052] 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.

[0053] 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. Examples of fixation positions of the subject's eye E include 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, and 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.

[0054] 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 a target (alignment target) for aligning the device optical system with the subject's eye E. The focus optical system 60 generates a target (split target) for focusing on the fundus Ef.

[0055] Light (alignment light) output from an LED 51 of the alignment optical system 50 passes through apertures 52 and 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.

[0056] The corneal reflection of the alignment light passes through the objective lens 22, the dichroic mirror 48, and the hole, with a portion of it passing through the dichroic mirror 55, passing through the focusing lens 31, being reflected by the mirror 32, and then passing through the half mirror 33A. The corneal reflection light that passes through the half mirror 33A is reflected by the dichroic mirror 33 and projected onto the light-receiving surface of the CCD image sensor 35 by the condenser lens 34. The light-receiving image (alignment target) 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 target and moving the optical system (auto-alignment function).

[0057] When performing focus adjustment, the reflective surface of a reflecting rod 67 is obliquely disposed on the optical path of the illumination optical system 10. Light (focusing light) output from the LED 61 of the focusing optical system 60 passes through a relay lens 62, is split into two beams by a split target 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 reflective surface of the reflecting rod 67 by a condenser lens 66 and is then reflected. Furthermore, the focusing light passes through the relay lens 20, is reflected by the aperture mirror 21, passes through the dichroic mirror 48, is refracted by the objective lens 22, and is projected onto the fundus Ef.

[0058] 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 target) 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 target and moves the focusing lens 31 and the focus optical system 60 to adjust the focus (autofocus function). Alternatively, manual focusing may be performed while viewing the split target.

[0059] 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, a field lens 46, and a VCC lens 47.

[0060] 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 includes, for example, a corner cube and a mechanism for moving it.

[0061] The optical scanner 42 is disposed at a position optically conjugate with the pupil of the subject's eye (pupil conjugate position) or in the vicinity thereof. 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.

[0062] 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. 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. This allows the imaging site to be scanned with the measurement light LS in any direction on the xy plane.

[0063] For example, by simultaneously controlling the orientations of the first and second galvanometer mirrors included in the optical scanner 42, it is possible to move the irradiation position of the measurement light along any trajectory on the xy plane, thereby enabling scanning of the imaging region according to a desired scan pattern.

[0064] The OCT focusing lens 45 is movable along the optical path of the measurement light LS (the optical axis of the interference optical system). 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.

[0065] 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 in the same manner as the OCT focusing lens 45.

[0066] The VCC lens 47 is disposed in the optical path of the measurement light and changes at least one of the cylindrical power (cylindrical power) and the cylindrical axis angle (cylindrical axis angle). The VCC lens 47 has two cylindrical lenses (optical elements) disposed opposite each other and is configured to change at least one of the cylindrical power and the cylindrical axis angle by changing at least one of the axial directions of the two cylindrical lenses. In the first embodiment, each of the two cylindrical lenses is configured to be independently rotatable so that the two axial directions can be changed relative to each other. Furthermore, the two cylindrical lenses are configured to be rotatable together while maintaining the angle formed by the two axial directions.

[0067] The VCC lens 47 is disposed at a position optically conjugate with the pupil of the subject's eye (pupil conjugate position) or in the vicinity thereof. In the first embodiment, since the optical scanner 42 is disposed at a position optically conjugate with the pupil of the subject's eye, the VCC lens 47 is disposed in the vicinity of the position optically conjugate with the pupil of the subject's eye.

[0068] When the purpose is to correct the astigmatism power of the test eye E, even if the VCC lens 47 is positioned near the pupil conjugate position, it can be considered that the deviation of the position of the VCC lens 47 from the pupil conjugate position has little effect on the cylindrical power and cylindrical axis angle changed by the VCC lens 47.

[0069] When the VCC lens 47 is controlled based on optometry data (objective measurement values ​​or subjective test values) of the subject's eye E, the optometry data is mainly measurement values ​​at the fovea of ​​the subject's eye E. However, it can be considered that deviation of the placement position of the VCC lens 47 from the pupil conjugate position has little effect on the cylindrical power and cylindrical axis angle changed by the VCC lens 47. Therefore, even when the imaging site is a site different from the fovea, the VCC lens 47 may be placed near the pupil conjugate position.

[0070] As shown in FIG. 2 , the VCC lens 47 includes cylindrical lenses 471 and 472 (focal lengths f0 and −f0) with equal power but opposite signs. The cylindrical lens 471 (VCC1) has a convex surface (positive power) and is rotatable in a rotation direction dr1 around the optical path of the measurement light LS (the optical axis SO of the interference optical system). The cylindrical lens 472 (VCC2) has a concave surface (negative power) and is rotatable in a rotation direction dr2 around the optical axis SO. The cylindrical lenses 471 and 472 are driven by a driving device such as a pulse motor and are rotated independently around the optical axis SO. When the cylindrical lenses 471 and 472 are rotated in opposite directions, the cylindrical power changes. When the cylindrical lenses 471 and 472 are rotated together in the same direction, the cylindrical axis angle changes.

[0071] For example, any cylindrical power can be generated by rotating the cylindrical lenses 471 and 472 in opposite directions from a state in which the cylindrical axes of the cylindrical lenses 471 and 472 are tilted at a predetermined angle (for example, 45 degrees) relative to the optical axis SO. Also, any cylindrical axis angle can be generated by rotating the cylindrical lenses 471 and 472 integrally in the same direction.

[0072] [OCT Unit 100] An example of the configuration of the OCT unit 100 will be described with reference to Figure 3. The OCT unit 100 is provided with an optical system for acquiring OCT images 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 to generate 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.

[0073] The light source unit 101 includes a wavelength scanning (wavelength sweeping) light source capable of scanning (sweeping) 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.

[0074] 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 external stress to the looped optical fiber 102.

[0075] 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.

[0076] The reference light LR is guided by an optical fiber 110 to a collimator 111 to be 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.

[0077] 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 also 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.

[0078] 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 is then incident on 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.

[0079] 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.

[0080] 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 field lens 46, and the VCC lens 47 and reaches 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.

[0081] The fiber coupler 122 generates interference light by combining (causing interference between) the measurement light LS incident via the optical fiber 128 and the reference light LR incident via the optical fiber 121. The fiber coupler 122 splits the interference light of the measurement light LS and the reference light LR at a predetermined splitting ratio (e.g., 50:50) to generate a pair of interference light LC. The pair of interference light LC emitted from the fiber coupler 122 is guided to a detector 125 by optical fibers 123 and 124, respectively.

[0082] 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 results (detection signals) to the arithmetic and control unit 200. The arithmetic and control unit 200 forms a tomographic image as an OCT image by performing a Fourier transform or the like on the spectral distribution based on the detection results obtained by the detector 125, for example, for each series of wavelength scans (each A-line). The arithmetic and control unit 200 displays the formed image on the display device 3.

[0083] Although the first embodiment employs a Michelson-type interferometer, any type of interferometer, such as a Mach-Zehnder-type, may be appropriately employed. In this 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, field lens 46, and VCC lens 47 shown in FIG. 1 in addition to the configuration shown in FIG. 3 . This interference optical system is an example of an "interference optical system" according to the embodiment. The VCC lens 47 (and the VCC driver 47A described below) is an example of an "aberration correction device (aberration correction member, astigmatism correction optical member)" according to the embodiment. The OCT focusing lens 45 (and the OCT focusing driver 45A described below) is an example of a "focusing position changing member" according to the embodiment. At least one of the optical path length changing unit 41 and the corner cube 114 (and the reference driver 114A described below) is an example of an "optical path length changing member" according to the embodiment. At least one of the polarization controllers 103 and 118 is an example of the "polarization state changing member" according to the embodiment.

[0084] [Arithmetic and Control Unit 200] The configuration of the arithmetic and control unit 200 will be described.

[0085] 4 and 5 show block diagrams of an example configuration of the processing system (control system) of the ophthalmologic apparatus 1 according to the first embodiment. Fig. 5 is a functional block diagram of an example configuration of the analysis unit 232 in Fig. 4. In Fig. 4, parts that are the same as those in Figs. 1 to 3 are given the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0086] The arithmetic and control unit 200 analyzes the detection signal input from the detector 125 to form an OCT image of the fundus oculi Ef (or the anterior segment of the eye). The arithmetic and control process for this is the same as that of a conventional swept-source type OCT device.

[0087] 4 , the arithmetic and control unit 200 includes a control unit 210, and controls each part of the fundus camera unit 2, the display device 3, and the OCT unit 100. For example, the arithmetic and control unit 200 forms an OCT image of the fundus oculi Ef and displays the formed OCT image on the display device 3.

[0088] 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, operation control of the alignment optical system 50, movement control of the focus optical system 60, movement control of the optical path length changing unit 41, drive control of the VCC lens 47, and operation control of the optical scanner 42.

[0089] The OCT unit 100 is controlled by controlling the operation of the light source unit 101 , the movement of the corner cube 114 , the detector 125 , the attenuator 120 , and the polarization controllers 103 and 118 .

[0090] 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.

[0091] The processor includes circuits such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), and a programmable logic device (e.g., an SPLD (Simple Programmable Logic Device), a CPLD (Complex Programmable Logic Device), or an FPGA (Field Programmable Gate Array)). The processor realizes the functions of the embodiment 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 externally to the processor. In some embodiments, the functionality of the arithmetic and control unit 200 is implemented by one or more processors.

[0092] 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.

[0093] The control unit 210 includes a main control unit 211 and a storage unit 212 .

[0094] (Main Controller 211) The main controller 211 performs various controls by outputting control signals to the respective components of the above-described ophthalmologic apparatus 1. In particular, the main controller 211 controls the CCD image sensors 35, 38, LCD 39, focusing driver 31A, optical path length changer 41, optical scanner 42, OCT focusing driver 45A, and VCC driver 47A for the fundus camera unit 2. Furthermore, the main controller 211 controls the light source unit 101, reference driver 114A, polarization controllers 103, 118, attenuator 120, and detector 125 for the OCT unit 100.

[0095] 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.

[0096] The main control unit 211 controls the display of the fixation target and the visual acuity measurement target on the LCD 39. This allows the visual target presented to the subject's eye E to be switched or the type of visual target to be changed. Furthermore, 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.

[0097] 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.

[0098] 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).

[0099] 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.

[0100] 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.

[0101] The main control unit 211 controls the optical scanner 42. The main control unit 211 controls the optical scanner 42 so as to deflect the measurement light LS in accordance with a deflection pattern corresponding to a preset scan mode.

[0102] 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 (including a combination of slow and fast scans).

[0103] Line scanning is a scanning mode in which the measurement light LS is deflected so that the movement locus of the irradiation position of the measurement light LS at the imaging site (measurement site) is linear. The line direction of the movement locus can be changed (rotated) around the optical axis on the xy plane.

[0104] For example, line scanning includes horizontal scanning and vertical scanning. Horizontal scanning is a scanning mode in which the measurement light LS is deflected so that the movement trajectory of the irradiation position of the measurement light LS is in the horizontal direction (x direction). Horizontal scanning also includes a mode in which the measurement light LS is scanned along multiple horizontally extending scan lines arranged in the vertical direction (y direction). In this mode, the spacing between the scan lines can be set arbitrarily. Furthermore, by sufficiently narrowing the spacing between adjacent scan lines, a three-dimensional image can be formed (three-dimensional scanning). The same applies to vertical scanning.

[0105] The cross scan is a scan mode in which the measurement light LS is deflected so that the movement trajectory of the irradiation position of the measurement light LS at the imaging site (measurement site) is cross-shaped. For example, the cross scan can be performed by performing two line scans whose line directions intersect with each other. The angle at which the two line scans intersect can be changed. In some embodiments, the scan lengths in the B-scan direction of the two line scans are the same. In some embodiments, the scan lengths in the B-scan direction of the two line scans are different.

[0106] The circle scan is a scan mode in which the measurement light LS is deflected so that the movement locus of the irradiation position of the measurement light LS in the imaging region (measurement region) is, for example, circular around the optical axis SO. For example, in the circle scan, the measurement light LS is deflected so that the movement locus is a perfect circle, an ellipse, or an arc (part of a circumference).

[0107] Radial scanning is a scanning mode in which the measurement light LS is deflected so that the movement locus of the irradiation position of the measurement light LS at the imaging site (measurement site) is radial, for example, around the optical axis SO. In radial scanning, the irradiation position of the measurement light LS is moved along a radial locus consisting of multiple straight loci arranged at a predetermined angle. The above-mentioned cross scanning is one form of radial scanning.

[0108] For example, in a radial scan, two or more line scans are performed with different B-scan directions. In some embodiments, the scan lengths in the B-scan direction of the two or more line scans are the same. In some embodiments, the scan length in the B-scan direction of at least one of the two or more line scans is different from the scan lengths of the other line scans.

[0109] Concentric circular scanning is a scanning mode in which the measurement light LS is deflected so that the movement trajectory of the irradiation position of the measurement light LS in the imaging region (measurement region) is, for example, concentric around the optical axis SO. For example, in concentric circular scanning, the measurement light LS is deflected so that the movement trajectory of each circle is a perfect circle, an ellipse, or an arc (part of a circumference). In some embodiments, concentric circular scanning is performed by combining multiple circle scans with different diameters. Circle scanning is one aspect of concentric circular scanning.

[0110] A multi-line cross scan is a scan pattern in which a group of parallel horizontal scan lines (e.g., five lines) and a group of parallel vertical scan lines (e.g., five lines) are arranged so that they intersect at right angles near the center of both scan line groups.

[0111] For example, in each scan line group in the multi-line cross scan, two or more line scans are performed. In some embodiments, the scan lengths in the B-scan direction of the two or more line scans are the same. In some embodiments, the scan length in the B-scan direction of at least one of the two or more line scans is different from the scan lengths of the other line scans.

[0112] Spiral scanning is a scanning mode in which the measurement light LS is deflected so that the movement locus of the irradiation position of the measurement light LS at the imaging site (measurement site) is spiral, for example, around the optical axis SO. In spiral scanning, the irradiation position of the measurement light LS is moved along a spiral locus while gradually decreasing (or increasing) the radius of rotation.

[0113] Lissajous scanning is a scanning mode in which the measurement light LS is deflected so that the movement locus of the irradiation position of the measurement light LS at the imaging region (measurement region) follows a Lissajous curve. Lissajous scanning is disclosed in, for example, Japanese Patent Application Laid-Open No. 2018-68578.

[0114] An example of a scan that combines slow and fast scans is ammonite scan (3D scan). Ammonite scan is a scan mode in which the scan reference position (scan center position) of a circle scan as a fast scan is moved along the scan pattern of a spiral scan as a slow scan. That is, while the scan center position is moved along the spiral scan pattern, circle scans are sequentially performed around each scan center position. As described above, the slow scan may be a scan defined by any one-dimensional or two-dimensional scan mode, and the fast scan may be a scan defined by any one-dimensional or two-dimensional scan mode. Examples of slow or fast scans include line scan, cross scan, circle scan, radial scan, concentric circle scan, multi-line cross scan, spiral scan, and Lissajous scan.

[0115] By scanning the imaging area with the measurement light LS according to a deflection pattern corresponding to the above-mentioned scan mode, a tomographic image as an OCT image can be obtained in a plane defined by the direction along the scan line (scan trajectory) and the fundus depth direction (z direction).

[0116] The OCT focusing driver 45A moves the OCT focusing lens 45 along the optical axis 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.

[0117] 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.

[0118] 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 drive unit 45A.

[0119] The VCC driver 47A rotates the cylindrical lenses 471 and 472 independently of each other around the optical axis of the measurement light LS, thereby changing at least one of the cylindrical power and the cylindrical axis angle.

[0120] For example, the main controller 211 controls the VCC driver 47A 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. In some embodiments, the main controller 211 controls the VCC driver 47A based on the signal-to-noise ratio of the detection result of the interference light LC obtained by deflecting the measurement light LS according to a deflection pattern corresponding to a circle scan, 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.

[0121] If a liquid crystal lens, a deformable mirror, or an Alvarez lens is provided instead of the VCC lens 47, the main control unit 211 can control the liquid crystal lens, the deformable mirror, or the Alvarez lens in the same way as the VCC driving unit 47A.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] The main control unit 211 controls the attenuator 120. For example, the main control unit 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.

[0127] 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.

[0128] 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.

[0129] In some embodiments, the main controller 211 corrects the position of the 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.

[0130] In some embodiments, the main controller 211 changes the optical conditions (imaging conditions, measurement conditions) of the optical system by controlling the optical system constituting the ophthalmic apparatus 1 based on setting information previously stored in the storage unit 212. In this case, the main controller 211 can generate the setting information in advance based on the detection result of the interference light LC acquired in a provisional measurement (provisional imaging) performed before the actual measurement (actual imaging) or an OCT image formed from the detection result. Furthermore, the main controller 211 may generate the setting information in advance based on eyeball shape information (or eyeball aberration information) statistically obtained from multiple pieces of eyeball information that are different from each other.

[0131] The main controller 211 functions as a display controller and causes the display device 3 (or a display unit 240A described later) to display various types of information. The information displayed on the display device 3 includes imaging results (observation images, OCT images (images of the subject's eye formed based on the detection results of interference light LC obtained by scanning with the measurement light LS), measurement results (measurements), evaluation values ​​of the image quality described later, statistical values ​​calculated based on the evaluation values, evaluation index information corresponding to the evaluation values, and the like. The main controller 211 can cause the display device 3 to display the evaluation values, statistical values, or evaluation index information of the image quality of the OCT image in association with the OCT image.

[0132] The main control unit 211 also performs processing to write data to the storage unit 212 and processing to read data from the storage unit 212 .

[0133] (Memory Unit 212) The memory unit 212 stores various types of data. Examples of data stored in the memory 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 or right eye. The memory unit 212 also stores optometry data acquired in advance by an external device (e.g., a refractometer or a subjective optometry device), as well as various programs and data for operating the ophthalmologic apparatus 1. The optometry data includes the astigmatic power and astigmatic axis angle of the subject's eye. The optometry data may further include the spherical power of the subject's eye. The optometry data may include at least one of the spherical power, astigmatic power, and astigmatic axis angle of the subject's eye.

[0134] The storage unit 212 can also store the above-mentioned setting information. The setting information is information for setting the optical conditions of the optical system that constitutes the ophthalmic apparatus 1. More specifically, the setting information is information for setting the optical conditions of the optical system so that the quality of an image formed based on OCT data acquired using the optical system that constitutes the ophthalmic apparatus 1 is at or above a predetermined image quality level. Examples of the optical conditions of the optical system that constitutes the ophthalmic apparatus 1 include the focal position of the measurement light LS used in OCT, the polarization component of the measurement light LS, the aberration correction component, the optical path length difference between the measurement light LS and the reference light LR, and the position of the optical system with respect to the subject's eye E.

[0135] 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.

[0136] (Image Forming Unit 220) The image forming unit 220 forms image data of an OCT image of the fundus oculi Ef or the anterior segment based on the detection signal (interference signal, OCT data) from the detector 125. 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 in multiple A-lines (paths of each measurement light LS in the subject's eye E).

[0137] When an OCT scan is performed for each scan region, the image forming unit 220 can form an image (OCT image) of the subject's eye E for each scan region. In this embodiment, the image forming unit 220 can form an OCT image of the subject's eye E for each scan region based on OCT data acquired under different optical conditions for each scan region.

[0138] To improve image quality, multiple data sets collected by repeating the same pattern scan multiple times can be superimposed (averaged).

[0139] 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.

[0140] (Data Processing Unit 230) The data processing unit 230 performs various types of data processing (image processing) and analysis processing on the detection results of the interference light LC or the image formed by the image forming unit 220. For example, the data processing unit 230 performs various types of correction processing such as analysis of the signal-to-noise ratio of the interference signal, brightness correction of the image, dispersion correction, etc.

[0141] The data processing unit 230 also performs various image processing and analysis processes on the images (fundus images, anterior segment images, etc.) obtained by the fundus camera unit 2 .

[0142] The data processing unit 230 performs known image processing, such as interpolation processing that interpolates pixels between two-dimensional tomographic images, to form image data of a three-dimensional image of the fundus oculi Ef or the subject's eye E. Note that image data of a three-dimensional image refers to 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. When displaying an image based on the volume data, the data processing unit 230 performs rendering processing (such as volume rendering or MIP (Maximum Intensity Projection)) 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.

[0143] 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 originally defined by individual two-dimensional coordinate systems using a single three-dimensional coordinate system (i.e., embedding them in a single three-dimensional space).

[0144] The data processing unit 230 can construct an OCTA image (a vessel-enhanced image, an angiogram) in which retinal blood vessels and choroidal blood vessels are emphasized based on data (e.g., B-scan data, OCT data) collected in time series by OCT scanning. The OCTA image may be an image representing a cross-sectional structure or a front image.

[0145] In some embodiments, the data processing unit 230 compares two OCT images obtained by repeatedly performing B-scans on approximately the same part of the subject's eye E, and constructs an enhanced image (motion contrast image) in which the changed part is emphasized by converting pixel values ​​of the changed part of the signal intensity into pixel values ​​corresponding to the changed part. Furthermore, the data processing unit 230 can form an OCTA (angiography) image by extracting information of a predetermined thickness in a desired part from the constructed multiple enhanced images and constructing it as an en-face image.

[0146] The data processing unit 230 can align the fundus image and the OCT image. When the fundus image and the OCT image are acquired in parallel, the two optical systems are coaxial, so the fundus image and the OCT image, which are acquired (almost) simultaneously, 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 two 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.

[0147] The data processing unit 230 includes an image synthesis unit 231 and an analysis unit 232 .

[0148] (Image Combining Unit 231) The image combining unit 231 generates a composite image by combining multiple images formed by the image forming unit 220. Specifically, the image combining unit 231 aligns multiple OCT images formed for each scan region by the image forming unit 220 to generate a composite image.

[0149] In some embodiments, the image synthesis unit 231 aligns multiple OCT images formed for each scan area based on optical conditions that differ from each other for each scan area, or on setting information of the optical system corresponding to the optical conditions, to generate a synthetic image.

[0150] In some embodiments, the image synthesis unit 231 aligns multiple OCT images to generate a synthesized image so that the correlation value of the overlapping area where the peripheral areas of each of the multiple OCT images formed for each scan area overlap is maximized.

[0151] In some embodiments, the image synthesis unit 231 aligns multiple OCT images based on characteristic regions such as layer regions, vascular regions, or diseased areas depicted in the peripheral regions of each of the multiple OCT images formed for each scan region to generate a synthesized image.

[0152] (Analysis unit 232) In addition to the above analysis processing, the analysis unit 232 performs analysis processing to estimate the substantial cross-sectional structure of the subject's eye E based on OCT data obtained by a previously performed OCT scan (high-speed scan) or an OCT image formed based on the OCT data. For example, the analysis unit 232 performs analysis processing to estimate the substantial cross-sectional structure of the subject's eye E for each scan region based on OCT data or OCT images obtained by a previously performed OCT scan for each scan region.

[0153] The analyzing section 232 includes an image position specifying section 232A and an image quality evaluation value calculating section 232B.

[0154] (Image position specifying unit 232A) The image position specifying unit 232A specifies the substantial cross-sectional structure of the subject's eye E based on the depth position of a site of interest in the image (broadly speaking, the object to be measured (the subject's eye)). An example of the site of interest is the fundus Ef (retina, retinal pigment epithelium layer) whose cross-sectional shape is curved.

[0155] In some embodiments, the image position identifying unit 232A identifies the centroid position in the depth direction (depth range) in a B-scan image (tomographic image) as an OCT image, and identifies the depth direction position of the region of interest in the B-scan image based on the identified centroid position in the depth direction. In this case, for example, the image position identifying unit 232A integrates (or averages) the pixel values ​​of the B-scan image in a direction (B-scan direction) perpendicular to the A-scan direction (depth direction). Then, the image position identifying unit 232A identifies the centroid position in the depth direction based on the obtained integration profile in the A-scan direction.

[0156] In some embodiments, the image position identification unit 232A identifies an area having a predetermined shape from the OCT image as an area in which the area of ​​interest is depicted, and identifies the depth-wise position of the identified area in the OCT image.

[0157] (Image Quality Evaluation Value Calculation Unit 232B) The image quality evaluation value calculation unit 232B identifies the actual cross-sectional structure of the subject's eye E including the site of interest based on an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality (e.g., signal-to-noise ratio). The evaluation value calculation process is performed by analyzing the detection result of the interference light LC, the OCT image formed by the image forming unit 220, or segmented images obtained by segmenting the OCT image. The segmented images may be images obtained by segmenting the OCT image corresponding to each of a plurality of scan areas obtained by segmenting the scan area. Alternatively, the segmented images may be images obtained by segmenting the OCT image corresponding to each of a plurality of preset scan areas.

[0158] The image quality evaluation value calculation unit 232B calculates an arbitrary evaluation value that quantitatively expresses image quality. Typically, the evaluation value is calculated so that the higher the image quality (image quality), the larger the value. The calculation process of the evaluation value executed by the image quality evaluation value calculation unit 232B may be any process. For example, the image quality evaluation value calculation unit 232B can execute processing using any known technology, such as a signal-to-noise ratio (SNR), a contrast-to-noise ratio (CNR), root-mean-square (RMS) granularity, a Wiener spectrum, a modulation transfer function (MTF), or a quality index (QI).

[0159] In a first example of the evaluation value calculation process, the image quality evaluation value calculation unit 232B calculates a differential histogram of the image to be calculated, and calculates the image quality evaluation value using the maximum value of the luminance values ​​(differential values) that have a pixel count equal to or greater than a predetermined percentage of the entire image in the calculated differential histogram. Specifically, the image quality evaluation value calculation unit 232B calculates the difference between the maximum and minimum differential values ​​above a predetermined threshold (e.g., 20%) as the image quality evaluation value. In this case, the image quality evaluation value indicates a high value when the image quality is equal to or greater than a predetermined image quality level, and decreases as the image quality deviates from the predetermined image quality level.

[0160] In a second example of the evaluation value calculation process, the data processing unit 230 (or the analysis unit 232) applies a predetermined analysis process (e.g., segmentation process) to an evaluation region set in an image corresponding to a predetermined portion of the subject's eye E. The image quality evaluation value calculation unit 232B then identifies an image region (signal region) corresponding to the desired portion (tissue) and other image regions (non-signal region). The image quality evaluation value calculation unit 232B then generates a histogram of luminance in the signal region and a histogram of luminance in the non-signal region. The image quality evaluation value calculation unit 232B then calculates an evaluation value corresponding to the image quality based on the degree of overlap between these two histograms. For example, the evaluation value is defined in the range of 0 to 100, so that if both histograms completely overlap, the evaluation value is 0, and if both histograms are completely separated, the evaluation value is 100. This evaluation calculation may include, for example, normalizing the two histograms, generating a probability distribution function, and calculating the evaluation value using a predetermined equation.

[0161] Furthermore, the image quality evaluation value calculation unit 232B may calculate known parameters that express image quality, such as signal-to-noise ratio (SNR), spatial resolution, contrast, etc. In this case, the image quality evaluation value indicates a high value when the image quality is equal to or higher than a predetermined image quality level, and decreases as the image quality deviates from the predetermined image quality level.

[0162] The image quality evaluation value calculation unit 232B calculates an evaluation value of the image quality of the entire OCT image, or an evaluation value of the image quality for each of the divided images corresponding to each of the multiple scan regions.

[0163] Furthermore, the image quality evaluation value calculation unit 232B can calculate statistics of multiple evaluation values ​​for multiple divided images. Examples of statistical values ​​include maximum value, minimum value, median value, average value, mode value, range, variance, standard deviation, a weighted average value in which the weighting coefficient increases the closer to the target area (the optical axis of the optical system), or a value of a predetermined evaluation formula using any of the above statistical values.

[0164] An example of the evaluation formula is one in which the value VCCQ of the evaluation formula increases as the total value of the evaluation values ​​of the multiple segmented images increases and the variation in the evaluation values ​​of the multiple segmented images decreases. In this case, for example, the value VCCQ of the evaluation formula is the sum of the evaluation values ​​of the multiple segmented images divided by (the standard deviation of the multiple evaluation values ​​+ 1).

[0165] The main controller 211 estimates the analysis result obtained by the analyzer 232 as the substantial cross-sectional structure of the subject's eye E, and changes the optical conditions of the optical system in synchronization with the period of the slow scan based on the estimated cross-sectional structure. In some embodiments, the main controller 211 estimates the substantial cross-sectional structure of the subject's eye E for each scan region, and changes the optical conditions of the optical system in synchronization with the period of the slow scan based on the estimated cross-sectional structure.

[0166] 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-mentioned functions is stored in advance in a storage device such as a hard disk drive.

[0167] (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.

[0168] 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 that integrates display and operation functions, 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 of 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.

[0169] The subject's eye E (fundus oculi Ef, anterior segment) is an example of an "object to be measured" according to the embodiment. The optical system, optical path length changing unit 41, OCT focusing lens 45, and VCC lens 47 (interference optical system) included in the OCT unit 100 are examples of an "optical system" according to the embodiment. The OCT focusing lens 45, corner cube 114, optical path length changing unit 41, and polarization controller 103 are examples of "one or more optical elements" according to the embodiment. The focal position of the measurement light LS, the polarization component of the measurement light LS, the aberration correction component, the optical path length difference between the measurement light LS and the reference light LR, or the position of the optical system relative to the subject's eye E are examples of "optical conditions of the optical system" according to the embodiment. The ophthalmic apparatus 1 is an example of an "OCT apparatus" according to the embodiment. The optical path length changing unit 41, or the corner cube 114 and reference driver 114A are examples of an "optical path length difference changing member" according to the embodiment. The OCT focusing lens 45 is an example of a "focusing lens" according to the embodiment. The VCC lens 47 is an example of an "aberration correction device" according to the embodiment. The display device 3 or the display unit 240A is an example of a "display means" according to the embodiment.

[0170] Hereinafter, a case will be described in which the ophthalmologic apparatus 1 according to the first embodiment performs an ammonite scan as an OCT scan on the subject's eye E. However, this embodiment can also be applied to a case in which an OCT scan is performed on the subject's eye E in a scan mode other than the ammonite scan.

[0171] FIG. 6 shows an explanatory diagram of an ammonite scan according to the first embodiment.

[0172] The Ammonite scan according to the first embodiment is a scan mode in which the scan center position of a high-speed scan is moved along the scan pattern (scan trajectory) of a low-speed scan, and one or more high-speed scans are sequentially performed using a scan pattern defined based on the moved scan center position. In the Ammonite scan according to this embodiment, the high-speed scan is a circle scan, and the low-speed scan is a spiral scan, and each sequentially performed circle scan is performed so as to intersect with the scan pattern of the previous circle scan. In other words, the circle scans are sequentially performed so that the scan patterns of two adjacent circle scans intersect.

[0173] In FIG. 6, the scan pattern Lsc for slow scanning is shown schematically, and the scan pattern HS for fast scanning is shown. ｎ (n is an integer of 4 or more), HS ｎ－１ , H.S. ｎ－２ , H.S. ｎ－３ is shown schematically.

[0174] As described above, the Ammonite scan combines low-speed scanning and high-speed scanning, making it possible to perform scanning of the subject's eye E from a variety of scanning directions with simple control. In particular, it becomes possible to perform high-density scanning in a short period of time in the area near the center of the Ammonite scan (the scan center position of the low-speed scan), and to perform low-density scanning over a longer period of time as the area moves away from the center, making it possible to scan a wide-angle area including the area of ​​interest with simple control.

[0175] According to this embodiment, by scanning the subject's eye E with an ammonite scan, it becomes possible to measure or photograph the subject's eye E at a wider angle with higher image quality, regardless of the cross-sectional structure of the subject's eye E.

[0176] Fig. 7 shows a schematic diagram of an OCT image formed based on OCT data obtained by ammonite scanning according to the first embodiment. For convenience of explanation, Fig. 7 describes the case where an OCTA image is generated, but the same applies to OCT images.

[0177] First, the main controller 211 sets a scan area for the ammonite scan for the subject's eye E. Setting parameters for setting the scan area for the ammonite scan include the scan start position of the slow scan (scan center position of the slow scan), the scan end position of the slow scan, the scan speed of the slow scan, the rate of change of the scan radius from the scan start position of the slow scan, the scan speed of the high-speed scan, and the scan radius of the high-speed scan.

[0178] The main controller 211 controls the optical scanner 42, the OCT unit 100, etc. to move the scan center position of the high-speed scan along the scan pattern of the low-speed scan and repeatedly perform two or more high-speed scans (circle scans) centered on the moved scan center position. The main controller 211 controls the image forming unit 220 to form an OCT image (tomographic image, B-scan image) based on the acquired OCT data each time a circle scan is performed. Next, the main controller 211 controls the data processing unit 230 to sequentially form OCTA images by comparing two OCT images obtained by repeatedly performing circle scans (B-scans) on approximately the same region of the subject's eye E. As a result, an OCTA image IMG is formed in which OCTA images formed in the high-speed scan direction are arranged in the low-speed scan direction.

[0179] Next, the main controller 211 controls the data processor 230 to perform coordinate transformation into a Cartesian coordinate system for each of the multiple OCTA images formed in the fast scan direction, thereby generating strip images ST0, ST1, ST2, .... For example, in the case of the scan pattern HS in FIG. ０ A strip image ST0 is obtained by the circle scan of the scan pattern HS ０ Scan pattern HS intersecting with １ A strip image ST1 is obtained by the circle scan of the scan pattern HS １ Scan pattern HS intersecting with ２A strip image ST2 is obtained by the circle scan. At this time, it is possible to thin out OCTA images in which artifacts occur due to the movement of the subject's eye E during the circle scan, blinking, etc., and to obtain a strip image by performing coordinate transformation only on OCTA images in which artifacts do not occur.

[0180] The main controller 211 controls the data processor 230 to sequentially align the strip images ST1, ST2, ... with the strip image ST0 as a reference image, to generate composite images CIMG0, CIMG1, CIMG2, ..., CIMGm (m is an integer equal to or greater than 2). The data processor 230 performs alignment based on images within overlapping scan regions in two adjacent strip images (e.g., blood vessel regions in an OCTA image).

[0181] As a result, the composite image CIMGm in FIG. 7 can be obtained by the ammonite scan in FIG.

[0182] [Operation Example] An operation example of the ophthalmologic apparatus 1 according to the first embodiment will be described.

[0183] 8 to 13B show examples of the operation of the ophthalmologic apparatus 1 according to the first embodiment.

[0184] 8 is a schematic diagram illustrating an example of multiple scan areas obtained by dividing the scan area of ​​the OCT scan performed in the ophthalmologic apparatus 1 according to the first embodiment. In Fig. 8, the same parts as those in Fig. 6 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0185] For example, as shown in Fig. 8 , the main controller 211 sets a central region SAR1 including the optical axis of the optical system in the subject's eye E, an intermediate region SAR2 around the central region SAR1, and a peripheral region SAR3 around the intermediate region SAR2. The intermediate region SAR2 is arranged outside the central region SAR1 and surrounds it. In Fig. 8 , the intermediate region SAR2 may be two or more regions arranged concentrically. The peripheral region SAR3 is arranged outside the outermost intermediate region of one or more intermediate regions including the central region SAR1 and surrounds the outermost intermediate region.

[0186] The main controller 211 can change the optical conditions of the optical system for each region shown in Fig. 8. This makes it possible to obtain an OCT image of the subject's eye E with good image quality without performing a pre-scan, while minimizing changes in the image that accompany changes in the optical conditions during scanning, when capturing an image of the subject at a wide angle.

[0187] 9 is a timing diagram showing an example of timing for changing the optical system during a single scan performed in the ophthalmologic apparatus 1 according to the first embodiment. In FIG. 9, the horizontal axis represents time, and the vertical axis schematically represents the signal level of a control signal for controlling each control timing.

[0188] 9, during a single scan that is executed by combining a high-speed scan (circle scan) controlled at a cycle Tfc and a low-speed scan (spiral scan) controlled at a cycle Tsc (>Tfc), the main controller 211 changes the optical conditions of the optical system in synchronization with the control timing of the low-speed scan (cycle of the low-speed scan). The timing for changing the optical conditions of the optical system may be between the execution timings of two consecutive A-scans.

[0189] That is, the main controller 211 sequentially executes OCT scans shown in Fig. 6 on a preset scan region of the fundus Ef. Each time OCT data is acquired by an OCT scan, the main controller 211 controls the image forming unit 220 to form an OCT image. Furthermore, the main controller 211 controls the analysis unit 232 to analyze the OCT image formed by the image forming unit 220 and calculate the position of the region of interest in the OCT image and the image quality evaluation value of the OCT image. Next, as shown in Fig. 9, the main controller 211 changes the optical conditions of the optical system based on the position of the region of interest in the OCT image and the image quality evaluation value of the OCT image, in synchronization with the start timing of the slow scan of the next OCT scan.

[0190] 10 is a schematic diagram showing the focal positions of the measurement light LS, which differ for each scan area in the B-scan image acquired by the ophthalmologic apparatus 1 according to the first embodiment. In FIG. 10, the focal positions of the measurement light LS in the divided images obtained by dividing the B-scan image IMG10 according to the scan areas are shown as beam waists Bw1 to Bw6.

[0191] The B-scan image IMG10 shown in Figure 10 is a tomographic image obtained when the OCT focusing lens 45 is moved for each scan area so that the focal position of the measurement light LS is located on or near the retinal pigment epithelium layer of the fundus Ef.

[0192] For example, the main controller 211 executes an OCT scan (e.g., a circle scan) in advance at a scan position different from the fundus Ef in the B-scan image IMG10 shown in Fig. 10. Then, the main controller 211 moves the OCT focusing lens 45 in synchronization with the start timing of the slow scan for each scan region based on this OCT data or a B-scan image formed based on the OCT data. This makes it possible to acquire a tomographic image of the fundus Ef with good image quality even when an OCT scan is performed on the fundus Ef at a wide angle.

[0193] 11 is a schematic diagram showing tomographic images obtained when the optical path length difference between the measurement light LS and the reference light LR is changed for each scan region by the ophthalmologic apparatus 1 according to the first embodiment. In FIG. 11, divided images IMG21 to IMG26 obtained by dividing the B-scan image according to the scan region are shown.

[0194] For example, the main controller 211 executes an OCT scan (e.g., a circle scan) in advance. Then, based on this OCT data or a B-scan image formed based on the OCT data, the main controller 211 controls the optical path length changing unit 41 and at least one of the corner cube 114 and the reference driver 114A in synchronization with the start timing of a slow scan for each scan region. In this case, the main controller 211 controls the image synthesis unit 231 to align the divided images IMG21 to IMG26 in the depth direction to generate a synthesized image in which the region of interest (the retinal pigment epithelium layer) of the fundus Ef is smoothly connected. This makes it possible to acquire a tomographic image of the fundus Ef with good image quality, even when an OCT scan of the fundus Ef is performed at a wide angle.

[0195] 12A and 12B are flowcharts illustrating an example of the operation of the ophthalmologic apparatus 1 according to the first embodiment. A computer program for implementing the processes illustrated in Fig. 12A and 12B is stored in the storage unit 212. The main control unit 211 operates in accordance with the computer program to execute the processes illustrated in Fig. 12A and 12B.

[0196] Figures 13A and 13B are flowcharts showing an example of the operation of step S6 in Figure 12A. A computer program for realizing the processing shown in Figures 13A and 13B is stored in the storage unit 212. The main control unit 211 operates in accordance with this computer program to execute the processing shown in Figures 13A and 13B.

[0197] (S1: Setting the optical system to the reference position) As shown in FIG. 12A, first, the main control unit 211 sets the optical conditions of the optical system constituting the ophthalmic device 1 to predetermined initial conditions, and sets the optical system to the reference position based on the set initial conditions.

[0198] (S2: Alignment) Next, with the fixation target presented at a predetermined fixation position, the main controller 211 adjusts the alignment of the optical system with respect to the subject's eye E. Examples of alignment adjustment include manual and automatic adjustments.

[0199] 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.

[0200] When the positional relationship between the subject's eye E and the fundus camera unit 2 (objective lens 22) is appropriate, i.e., when the distance (working distance) between the subject's eye E and the fundus camera unit 2 is appropriate and the optical axis of the optical system of the fundus camera unit 2 and the ocular axis (corneal apex position) of the subject's eye E are (almost) aligned, a pair of alignment bright spots are first imaged at predetermined positions (for example, midpoints between the corneal apex and the center of corneal curvature) and then projected onto the subject's eye E by a known method. 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.

[0201] 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 so as 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 distance in each of the predetermined x, y, and z directions (e.g., the results of prior measurement of how much 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.

[0202] (S3: Setting scan area) The main controller 211 sets the scan area so that the site of interest in the subject's eye E is at the scan center position (the position corresponding to the optical axis of the optical system). For example, as shown in FIG. 6 or FIG. 8, the main controller 211 sets ammonite scan as the scan mode and sets multiple scan areas to be scanned.

[0203] (S4: OCT Scan) Next, the main controller 211 controls the optical scanner 42, the OCT unit 100, etc. to perform an ammonite scan on the scan area set in step S3. In step S4, an ammonite scan is performed across multiple scan areas as shown in FIG.

[0204] (S5: Forming OCT images) Next, the main controller 211 controls the image forming unit 220 to sequentially form OCT images based on the OCT data obtained by the OCT scans of the multiple scan areas performed sequentially in step S4.

[0205] In some embodiments, the main controller 211 controls the image combiner 231 to align the multiple OCT images formed in step S5 to generate a combined image. The combined image is one of the OCT images.

[0206] (S6: Analysis) Next, the main controller 211 controls the analyzer 232 to perform an analysis process on the OCT image (or composite image) formed in step S5. In step S6, the position of the region of interest in the OCT image or composite image formed in step S5 and the image quality evaluation value of the OCT image or composite image are calculated.

[0207] Details of step S6 will be described later.

[0208] (S7: Change optical conditions of the optical system?) Next, the main control unit 211 determines whether or not to change the optical conditions of the optical system based on the processing results obtained by the analysis processing executed in step S6. For example, the main control unit 211 determines whether or not there are any optical conditions of the optical system that should be changed as a result of the analysis processing in step S6, thereby determining whether or not to change the optical conditions of the optical system.

[0209] Specifically, the main controller 211 determines to change the optical conditions of the optical system when at least one of the correction amount for the optical path length difference between the measurement light LS and the reference light LR, the correction amount for the focal position of the measurement light LS, the correction amount for the polarization state of the light L0 from the light source unit 101 or the measurement light LS, the aberration correction amount, and the movement correction amount of the optical system is specified. On the other hand, the main controller 211 determines not to change the optical conditions of the optical system when none of the above correction amounts is specified.

[0210] When it is determined in step S7 that the optical conditions of the optical system are to be changed (S7: Y), the operation of the ophthalmic apparatus 1 proceeds to step S8. When it is determined in step S7 that the optical conditions of the optical system are not to be changed (S7: N), the operation of the ophthalmic apparatus 1 proceeds to step S10.

[0211] (S8: Start timing of slow scan?) When it is determined in step S7 that the optical conditions of the optical system are to be changed (S7: Y), the main controller 211 determines whether it is time to start a slow scan that constitutes an ammonite scan. For example, the main controller 211 determines whether it is time to start a slow scan (spiral scan) based on the control content for the optical scanner 42 to perform an OCT scan on the scan area set in step S3.

[0212] If it is determined in step S8 that it is time to start low-speed scanning (S8: Y), the operation of the ophthalmic apparatus 1 proceeds to step S9. If it is determined in step S8 that it is not time to start low-speed scanning (S8: N), the operation of the ophthalmic apparatus 1 repeats step S8.

[0213] (S9: Change Optical Conditions of Optical System) When it is determined in step S8 that it is time to start the slow scan (S8: Y), the main control unit 211 changes the optical conditions of the optical system.

[0214] For example, the main control unit 211 controls the OCT focusing drive unit 45A to change the optical conditions of the optical system by moving the position on the optical axis of the OCT focusing lens 45 by an amount corresponding to the correction amount of the focusing position identified in step S6.

[0215] For example, the main control unit 211 controls the polarization controller 103 to change the polarization component of the light L0 by an amount corresponding to the correction amount of the polarization state identified in step S6, thereby changing the optical conditions of the optical system.

[0216] For example, the main control unit 211 controls the VCC drive unit 47A to change the cylindrical power or cylindrical axis angle of the VCC lens 47 by an amount corresponding to the amount of aberration correction identified in step S6, thereby changing the optical conditions of the optical system.

[0217] For example, the main control unit 211 controls the optical path length changing unit 41 or the reference driving unit 114A to change the optical conditions of the optical system by moving the position of the optical path length changing unit 41 (corner cube) in the optical path of the measurement light LS or the position of the corner cube 114 in the optical path of the reference light LR by the correction amount of the optical path length difference identified in step S6.

[0218] For example, the main control unit 211 controls the movement mechanism 150 to change the optical conditions of the optical system by moving the position of the optical system in the optical axis direction relative to the test eye E or the position in the direction intersecting the optical axis of the optical system by the movement correction amount of the optical system identified in step S6.

[0219] (S10: End of OCT scan?) Following step S9, the main controller 211 determines whether to end the OCT scan. For example, the main controller 211 determines whether to end the OCT scan based on the control content of the optical scanner 42 to perform the OCT scan on the scan area set in step S3.

[0220] When it is determined in step S10 that the OCT scan is to be ended (S10: Y), the operation of the ophthalmic apparatus 1 proceeds to step S11. When it is determined in step S10 that the OCT scan is not to be ended (S10: N), the operation of the ophthalmic apparatus 1 proceeds to step S4.

[0221] (S11: Combining OCT Images) When it is determined in step S10 that the OCT scan is to be ended (S10: Y), the main controller 211 controls the image composition unit 231 to align the multiple OCT images formed in step S5 and generate a composite image. If a composite image has already been generated, step S11 may be omitted.

[0222] (S12: Display) Following step S11, the main control unit 211, as a display control unit, causes the display unit 240A (or the display device 3) to display the composite image generated in step S11.

[0223] In some embodiments, the main control unit 211 causes the display unit 240A to display the correction amount (adjustment amount) of the optical conditions of the optical system identified in step S6 for each scan area.

[0224] This completes the operation of the ophthalmologic apparatus 1 (END).

[0225] 12A, the processing shown in Fig. 13A and Fig. 13B is performed on the OCT images formed in step S5. Prior to the processing in step S6, the image composition unit 231 generates a composite image from the multiple OCT images formed in step S5.

[0226] (S21: Identifying Image Position) In step S6 of FIG. 12A, the main controller 211 controls the image position identifying part 232A to identify the depth position (imaging position) of the region of interest in the OCT image formed in step S5.

[0227] For example, as described above, the image position identifying unit 232A identifies the depth-direction center of gravity position in the OCT image, and identifies the depth-direction position of the area of ​​interest in the OCT image based on the identified depth-direction center of gravity position.

[0228] (S22: Adjust Image Position?) Next, the main controller 211 determines whether or not to adjust the imaging position in the depth direction of the region of interest in the OCT image identified in step S21. For example, the main controller 211 determines whether or not to adjust the imaging position in the depth direction of the region of interest in the OCT image by determining whether or not the imaging position in the depth direction of the region of interest in the OCT image identified in step S21 is within a predetermined depth range.

[0229] If it is determined in step S22 that the imaging position of the region of interest in the OCT image in the depth direction should be adjusted (S22: Y), the process of step S6 proceeds to step S23. If it is determined in step S22 that the imaging position of the region of interest in the OCT image in the depth direction should not be adjusted (S22: N), the process of step S6 proceeds to step S24.

[0230] (S23: Determine the amount of correction for the optical path length difference) When it is determined in step S22 that the depth-direction depiction position of the area of ​​interest in the OCT image should be adjusted (S22: Y), the main control unit 211 determines the amount of correction for the optical path length difference between the measurement light LS and the reference light LR.

[0231] For example, the main controller 211 specifies a correction amount for the optical path length difference between the measurement light LS and the reference light LR based on a displacement of the imaging position in the depth direction of the region of interest in the OCT image specified in step S21 relative to a reference depth position in a predetermined depth range. That is, the main controller 211 specifies a correction amount for the optical path length difference between the measurement light LS and the reference light LR so that the imaging position in the depth direction of the region of interest in the OCT image specified in step S21 coincides with the reference depth position in the predetermined depth range. Examples of the reference depth position include the center position (or center of gravity position) within the predetermined depth range, the upper limit position within a predetermined reference range within the above depth range, and the lower limit position within a predetermined reference range within the above depth range.

[0232] (S24: Calculating image quality evaluation value) When it is determined in step S22 that the depth-wise depiction position of the area of ​​interest in the OCT image should not be adjusted (S22: N), or following step S23, the main control unit 211 controls the image quality evaluation value calculation unit 232B to calculate the image quality evaluation value of the OCT image (synthetic image) formed in step S5.

[0233] For example, the main controller 211 controls the image quality evaluation value calculator 232B to calculate an image quality evaluation value for each of the multiple OCT images formed for each scan region in step S5.

[0234] (S25: Adjust focus position?) Following step S24, the main controller 211 determines whether or not to adjust the focus position of the measurement light LS based on the image quality evaluation value calculated in step S24. In this embodiment, the main controller 211 determines whether or not to adjust the focus position of the measurement light LS for each of the multiple OCT images based on the image quality evaluation value calculated for each of the multiple OCT images in step S24.

[0235] For example, the main control unit 211 determines whether or not the focus position of the measurement light LS should be adjusted based on the result of comparison between a predetermined reference image quality evaluation value and the image quality evaluation value calculated in step S24.

[0236] If it is determined in step S25 that the focal position of the measurement light LS should be adjusted (S25: Y), the process of step S6 proceeds to step S26. If it is determined in step S25 that the focal position of the measurement light LS should not be adjusted (S25: N), the process of step S6 proceeds to step S27.

[0237] (S26: Specify the amount of correction for the focus position) When it is determined in step S25 that the focus position of the measurement light LS should be adjusted (S25: Y), the main controller 211 specifies the amount of correction for the focus position of the measurement light LS.

[0238] For example, the main controller 211 compares a predetermined standard image quality evaluation value with the image quality evaluation value calculated in step S24, and specifies a correction amount for the focal position of the measurement light LS for each of the multiple OCT images so that the image quality of the OCT image formed in step S5 is higher than the image quality corresponding to the standard image quality evaluation value. In some embodiments, the main controller 211 specifies an adjustment direction for the focal position of the measurement light LS based on the displacement of the scan area relative to the deepest part of the cross-sectional shape of the fundus oculi Ef, and specifies a correction amount for the focal position of the measurement light LS in the specified adjustment direction.

[0239] (S27: Adjust polarization state?) When it is determined in step S25 that the focal position of the measurement light LS should not be adjusted (S25: N), or following step S26, the main controller 211 determines whether or not to adjust the polarization state of the light L0 or the measurement light LS from the light source unit 101 based on the image quality evaluation value calculated in step S24. In this embodiment, the main controller 211 determines whether or not to adjust the polarization state of the light L0 or the measurement light LS for each of the multiple OCT images based on the image quality evaluation value calculated for each of the multiple OCT images in step S24.

[0240] For example, the main control unit 211 determines whether or not to adjust the polarization state of the light L0 or the measurement light LS based on a comparison result between a predetermined reference image quality evaluation value and the image quality evaluation value calculated in step S24. In some embodiments, polarization information that associates the comparison result between the reference image quality evaluation value and the calculated image quality evaluation value with the polarization state is stored in advance in the storage unit 212, and the main control unit 211 determines whether or not to adjust the polarization state of the light L0 or the measurement light LS by referring to the polarization information stored in the storage unit 212.

[0241] When it is determined in step S27 that the polarization state of the light L0 or the measurement light LS should be adjusted (S27: Y), the process of step S6 proceeds to step S28. When it is determined in step S27 that the polarization state of the light L0 or the measurement light LS should not be adjusted (S27: N), the process of step S6 proceeds to step S29.

[0242] (S28: Determine the amount of correction for the polarization state) When it is determined in step S27 that the polarization state of the light L0 or the measurement light LS should be adjusted (S27: Y), the main control unit 211 determines the amount of correction for the polarization state of the light L0 or the measurement light LS.

[0243] For example, the main controller 211 compares a predetermined reference image quality evaluation value with the image quality evaluation value calculated in step S24, and specifies the amount of correction for the polarization state of the light L0 or the measurement light LS for each of the multiple OCT images so that the image quality of the OCT image formed in step S5 is higher than the image quality corresponding to the reference image quality evaluation value. In some embodiments, the main controller 211 refers to the polarization information to specify the adjustment direction for the polarization state of the measurement light LS of the light L0, and specifies the amount of correction for the polarization state of the light L0 or the measurement light LS in the specified adjustment direction.

[0244] (S29: Adjust aberration?) Subsequently, when it is determined in step S27 that the polarization state of the light L0 or the measurement light LS should not be adjusted (S27: N), or following step S28, the main controller 211 determines whether or not to adjust the aberration based on the image quality evaluation value calculated in step S24. In this embodiment, the main controller 211 determines whether or not to adjust the aberration for each of the multiple OCT images based on the image quality evaluation value calculated for each of the multiple OCT images in step S24.

[0245] For example, the main control unit 211 determines whether or not to adjust the aberration based on the comparison result between a predetermined reference image quality evaluation value and the image quality evaluation value calculated in step S24. In some embodiments, aberration information that associates the comparison result between the reference image quality evaluation value and the calculated image quality evaluation value with the aberration is stored in advance in the storage unit 212, and the main control unit 211 determines whether or not to adjust the aberration by referring to the aberration information stored in the storage unit 212.

[0246] When it is determined in step S29 that the polarization state of the light L0 or the measurement light LS should be adjusted (S29: Y), the process of step S6 proceeds to step S30. When it is determined in step S29 that the aberration should not be adjusted (S29: N), the process of step S6 proceeds to step S31.

[0247] (S30: Identify Aberration Correction Amount) When it is determined in step S29 that the aberration should be adjusted (S29: Y), the main controller 211 identifies the aberration correction amount.

[0248] For example, the main controller 211 compares a predetermined reference image quality evaluation value with the image quality evaluation value calculated in step S24, and specifies the amount of aberration correction for each of the multiple OCT images so that the image quality of the OCT image formed in step S5 is higher than the image quality corresponding to the reference image quality evaluation value. In some embodiments, the main controller 211 refers to the aberration information to specify the adjustment direction of the polarization state of the measurement light LS of the light L0, and specifies the amount of aberration correction for the specified adjustment direction.

[0249] (S31: Adjust alignment position?) Following step S30, when it is determined in step S29 that the aberration should not be adjusted (S29: N), or following step S30, the main control unit 211 determines whether or not the alignment position of the optical system relative to the test eye E should be adjusted based on the image quality evaluation value calculated in step S24.

[0250] In some embodiments, the main controller 211 determines whether or not to adjust the alignment position for each of the plurality of OCT images based on the image quality evaluation value calculated for each of the plurality of OCT images in step S24. For example, the main controller 211 determines whether or not to adjust the alignment position based on a comparison result between a predetermined reference image quality evaluation value and the image quality evaluation value calculated in step S24.

[0251] In some embodiments, the main controller 211 determines whether or not to adjust the alignment position based on the depiction position of the region of interest in the OCT image identified by the image position identifying part 232 A. For example, the main controller 211 determines whether or not to adjust the alignment position based on the displacement of the position of the region of interest in the OCT image identified by the image position identifying part 232 A relative to a predetermined reference position.

[0252] If it is determined in step S31 that the alignment position should be adjusted (S31: Y), the process of step S6 proceeds to step S32. If it is determined in step S31 that the alignment position should not be adjusted (S31: N), the process of step S6 ends (END).

[0253] (S32: Identify the amount of movement correction of the optical system) When it is determined in step S31 that the alignment position should be adjusted (S32: Y), the main control unit 211 identifies the amount of movement correction of the optical system.

[0254] For example, the main controller 211 compares a predetermined reference image quality evaluation value with the image quality evaluation value calculated in step S24, and specifies the amount of movement correction of the optical system so that the image quality of the OCT image formed in step S5 is higher than the image quality corresponding to the reference image quality evaluation value. In some embodiments, the main controller 211 specifies the amount of movement correction of the optical system for each scan region. In some embodiments, the main controller 211 specifies a single amount of movement correction of the optical system so that a statistical value (e.g., average value) of the image quality evaluation values ​​is maximized.

[0255] For example, the main controller 211 specifies the amount of correction for movement of the optical system based on the displacement of the position of the region of interest in the OCT image specified by the image position specifying part 232A relative to a predetermined reference position.

[0256] When it is determined in step S31 that the alignment position should not be adjusted (S31: N), or following step S32, the process of step S6 ends (END).

[0257] The order of changing the optical conditions of the optical system according to the embodiment is not limited to the order of changing shown in Figures 13A and 13B. The optical conditions of the optical system that are changed according to the embodiment may include at least one of the optical conditions shown in Figures 13A and 13B.

[0258] As described above, according to the first embodiment, when an OCT scan is performed on the subject's eye E by combining a slow scan and a high-speed scan, the cross-sectional structure of the subject's eye E is substantially estimated based on OCT data or OCT images obtained by a high-speed scan performed in the past, and the optical conditions of the optical system are changed in synchronization with the cycle of the slow scan based on the estimated cross-sectional structure. As a result, when the subject's eye E is photographed at a wide angle without performing a pre-scan, an image of the subject's eye E with good image quality can be obtained.

[0259] Second Embodiment In the first embodiment, the ophthalmic apparatus is described as being provided with a VCC lens 47 as an aberration correction device, but the configuration according to the embodiment is not limited to this. For example, the ophthalmic apparatus according to the embodiment may be configured to include a wavefront aberration correction optical system as an aberration correction device.

[0260] The configuration according to the second embodiment will be described below, focusing on the differences from the configuration according to the first embodiment.

[0261] Fig. 14 shows an example of the configuration of the optical system of an ophthalmic apparatus 1a according to the second embodiment. In Fig. 14, the same parts as in Fig. 1 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0262] The configuration of the optical system of the ophthalmic device 1a according to the second embodiment differs from the configuration of the optical system of the ophthalmic device 1 according to the first embodiment in that a fundus camera unit 2a is provided instead of the fundus camera unit 2, and that an arithmetic control unit 200a is provided instead of the arithmetic control unit 200.

[0263] The configuration of the fundus camera unit 2a differs from the configuration of the fundus camera unit 2 in that a wavefront aberration correction optical system 70 is provided instead of the VCC lens 47. The arithmetic and control unit 200a differs from the arithmetic and control unit 200 in that the arithmetic and control unit 200a controls the wavefront aberration correction optical system 70 instead of the VCC lens 47.

[0264] The wavefront aberration correction optical system 70 includes a beam splitter 71 , a transmission type compensation optical element 72 , a relay lens 73 , a lens array 74 , and a wavefront sensor 75 .

[0265] 14, a beam splitter 71 and a compensation optical element 72 are disposed between the collimator lens unit 40 and the optical path length changing section 41. The compensation optical element 72 is disposed between the beam splitter 71 and the optical path length changing section 41.

[0266] The beam splitter 71 splits the returning light of the measurement light LS into light guided toward the collimating lens unit 40 and light guided toward the relay lens 73. The beam splitter 71 may be capable of changing the splitting ratio of these lights. For example, when controlling the compensation optical element 72 (described later) (e.g., during provisional measurement), the returning light of the measurement light LS is split into two lights with a splitting ratio of 50:50. When not controlling the compensation optical element 72 (e.g., during actual measurement), the returning light of the measurement light LS can be split into two lights with a splitting ratio of 90:10 so that the amount of light guided toward the collimating lens unit 40 is increased.

[0267] The adaptive optical element 72 may be, for example, a deformable phase plate (DPP). The adaptive optical element 72 is an optical element that can locally change the phase of the wavefront of light passing through it.

[0268] A relay lens 73, a lens array 74, and a wavefront sensor 75 are arranged in the reflection direction of the beam splitter 71. The compensation optical element 72 and the lens array 74 are each arranged at a position optically conjugate with the pupil of the subject's eye E (pupil conjugate position) or in the vicinity thereof.

[0269] The beam splitter 71 transmits the measuring light LS from the collimator lens unit 40 and guides it to the compensation optical element 72, and also guides the return light of the measuring light LS from the test eye E that has passed through the compensation optical element 72 to a relay lens 73. The compensation optical element 72 corrects at least the wavefront aberration of the return light of the measuring light LS. The return light of the measuring light LS guided to the relay lens 73 passes through the relay lens 73 and is guided to the lens array 74.

[0270] The lens array 74 includes a plurality of lenses arranged in an array, and generates a plurality of focused beams from the light that has passed through the relay lens 73. The plurality of focused beams generated by the lens array 74 are irradiated onto the sensor surface of the wavefront sensor 75. The wavefront sensor 75 may be, for example, a CMOS image sensor or a CCD image sensor.

[0271] It is possible to locally change the wavefront of the light passing through the adaptive optical element 72 according to the detection results of the plurality of focused light beams obtained by the wavefront sensor 75. This allows the adaptive optical element 72 to correct the wavefront aberration of the return light of the measurement light LS from the subject's eye E.

[0272] Fig. 15 is a block diagram showing an example of the configuration of a processing system of an ophthalmologic apparatus 1a according to the second embodiment. In Fig. 15, the same components as those in Fig. 4 are denoted by the same reference numerals, and the description thereof will be omitted where appropriate.

[0273] The configuration of the processing system of the ophthalmic apparatus 1a according to the second embodiment differs from the configuration of the processing system of the ophthalmic apparatus 1 according to the first embodiment in that the wavefront aberration correction optical system 70 is controlled instead of the VCC lens 47, and that a control unit 210a is provided instead of the control unit 210.

[0274] The control unit 210a includes a main control unit 211a and a storage unit 212a. The control unit 210a differs from the control unit 210 in that the control unit 210a controls the wavefront aberration correction optical system 70 instead of the VCC driver 47A.

[0275] That is, according to the second embodiment, by controlling the wavefront aberration correction optical system 70, it is possible to change the aberration correction components and change the optical conditions of the optical system.

[0276] The wavefront aberration correction optical system 70 is an example of an "aberration correction device" according to the embodiment. The optical system included in the OCT unit 100, the optical path length changing unit 41, the OCT focusing lens 45, and the wavefront aberration correction optical system 70 (interference optical system) are an example of an "optical system" according to the embodiment.

[0277] <Modifications> In the first and second embodiments, ammonite scanning has been described as an example of a scan that combines a low-speed scan and a high-speed scan, but the embodiments are not limited to this.

[0278] FIG. 16 is an explanatory diagram of XY scanning according to the first embodiment or the first modified example of the second embodiment.

[0279] The XY scan according to the first modification is also a scan mode in which the scan center position of the high-speed scan is moved along the scan pattern (scan trajectory) of the low-speed scan, and one or more high-speed scans are sequentially performed using a scan pattern defined based on the moved scan center position. In the XY scan according to this modification, the high-speed scan is a circle scan, and the low-speed scan is an elliptical scan, and each sequentially performed circle scan is performed so as to intersect with the scan pattern of the previous circle scan. In other words, the circle scans are sequentially performed so that the scan patterns of two adjacent circle scans intersect.

[0280] In FIG. 16, the scan pattern Lsc1 for slow scanning is shown schematically, and the scan pattern HS1 for fast scanning is shown schematically. ｎ (n is an integer of 4 or more), HS1 ｎ－１ , HS1 ｎ－２ , HS1 ｎ－３ is shown schematically.

[0281] Similar to the ammonite scan, the XY scan combines a slow scan and a fast scan, allowing the subject's eye E to be scanned from a variety of scan directions with simple control. In particular, it becomes possible to perform high-density scanning around the center of the XY scan (the scan center position of the slow scan), and a wide-angle region including the site of interest can be scanned with simple control.

[0282] According to this modified example, by scanning the subject's eye E with an XY scan, it becomes possible to measure or photograph the subject's eye E with higher image quality and at a wider angle, regardless of the cross-sectional structure of the subject's eye E.

[0283] FIG. 17 shows an explanatory diagram of a three-dimensional vertical (3D(V)) scan according to the second modification of the first embodiment or the second embodiment.

[0284] The 3D(V) scan according to the second modification is also a scan mode in which the scan center position of the fast scan is moved along the scan pattern (scan trajectory) of the slow scan, and one or more fast scans are sequentially performed using a scan pattern defined based on the moved scan center position. In the 3D(V) scan according to this modification, the fast scan is a vertical line scan, and the slow scan is a horizontal line scan.

[0285] In FIG. 17, the scan pattern Lsc2 for the slow scan is shown schematically, and the scan pattern HS2 for the fast scan is shown schematically. ｎ (n is an integer of 4 or more), HS2 ｎ－１ , HS2 ｎ－２ , HS2 ｎ－３ is shown schematically.

[0286] Similar to ammonite scanning, 3D (V) scanning combines low-speed scanning and high-speed scanning, allowing scanning of the subject's eye E from a variety of scanning directions with simple control. In particular, it becomes possible to scan the subject's eye E with a uniform density, and a wide-angle region including the site of interest can be scanned with simple control.

[0287] According to this modified example, by scanning the subject's eye E with a 3D (V) scan, it becomes possible to measure or photograph the subject's eye E with higher image quality and at a wider angle, regardless of the cross-sectional structure of the subject's eye E.

[0288] FIG. 18 is an explanatory diagram of a three-dimensional horizontal (3D(H)) scan according to the third modification of the first or second embodiment.

[0289] The 3D(H) scan according to the third modification is also a scan mode in which the center position of the high-speed scan is moved along the scan pattern (scan trajectory) of the low-speed scan, and one or more high-speed scans are sequentially performed using a scan pattern defined based on the moved center position of the scan. In the 3D(H) scan according to this modification, the high-speed scan is a horizontal line scan, and the low-speed scan is a vertical line scan.

[0290] In FIG. 18, the scan pattern Lsc3 for the slow scan is shown schematically, and the scan pattern HS3 for the fast scan is shown schematically. ｎ (n is an integer of 4 or more), HS3 ｎ－１ , HS3 ｎ－２ , HS3 ｎ－３ is shown schematically.

[0291] Similar to ammonite scanning, 3D(H) scanning combines low-speed scanning and high-speed scanning, allowing scanning of the subject's eye E from a variety of scanning directions with simple control. In particular, it becomes possible to scan the subject's eye E with uniform density, and a wide-angle region including the site of interest can be scanned with simple control.

[0292] According to this modified example, by scanning the subject's eye E with a 3D (H) scan, it becomes possible to measure or photograph the subject's eye E with higher image quality and at a wider angle, regardless of the cross-sectional structure of the subject's eye E.

[0293] [Operation] An OCT apparatus, a control method for an OCT apparatus, and a program according to the embodiment will be described.

[0294] A first aspect of the embodiment is an OCT device (ophthalmologic device 1, 1a) including an optical system (an optical system included in an OCT unit 100, an optical path length changing unit 41, an OCT focusing lens 45, a VCC lens 47 (or a wavefront aberration correction optical system 70), an interference optical system) and a control unit (210, 210a, a main control unit 211, a main control unit 211a). The optical system is configured to be able to change optical conditions (a focusing position of the measurement light LS, a polarization component of the measurement light LS, an aberration correction component, an optical path length difference between the measurement light LS and the reference light LR, or a position of the optical system with respect to the subject's eye E). The optical system includes an optical scanner (42) and is configured to acquire OCT data of the subject's eye E by scanning the subject's eye E with the measurement light (LS) using the optical scanner. The control unit controls the optical scanner to scan the subject's eye E with the measurement light along a fast scan axis based on a reference position moving along a slow scan axis. The control unit changes the optical conditions in synchronization with the period of the slow scan along the slow scan axis.

[0295] According to this aspect, the optical conditions of the optical system can be changed in synchronization with the cycle of the slow scan using OCT data obtained during the scan, so that an image of the object to be measured can be acquired with good image quality without incurring deterioration in image quality due to a shift in the scan position during the scan, etc. In particular, when the object to be measured is photographed at a wide angle, an image of the object to be measured can be acquired with good image quality without performing a pre-scan.

[0296] In a second aspect of the embodiment, the optical system in the first aspect includes an interference optical system (an optical system included in the OCT unit 100, an optical path length changing unit 41, an OCT focusing lens 45, and a VCC lens 47 (or a wavefront aberration correction optical system 70)) and an optical path length difference changing member (the optical path length changing unit 41, or a corner cube 114 and a reference drive unit 114A). The interference optical system splits light (L0) from a light source (light source unit 101) into measurement light and reference light (LR), projects the measurement light that has passed through a measurement optical path in which one or more optical elements (the OCT focusing lens 45, the corner cube 114, the optical path length changing unit 41, and the polarization controller 103) are arranged, and detects interference light (LC) between return light from the object and the reference light that has passed through the reference optical path. The optical path length difference changing member changes the difference between the optical path length of the measurement light and the optical path length of the reference light. The control unit changes the optical conditions of the optical system by controlling at least one of the one or more optical elements and the optical path length difference changing member.

[0297] According to this aspect, OCT is performed on the object to be measured by changing the optical conditions of the optical system by controlling at least one of the one or more optical elements and the optical path length difference changing member, thereby making it possible to acquire an image of the object to be measured with good image quality regardless of the cross-sectional shape of the object to be measured.

[0298] In a third aspect of the embodiment, in the second aspect, the one or more optical elements include a focusing lens (OCT focusing lens 45) or an aberration correction device (VCC lens 47 or wavefront aberration correction optical system 70).

[0299] According to this aspect, by controlling at least one of the optical path length difference changing member and one or more optical elements including the focusing lens or the aberration correction device, the optical conditions of the optical system are changed without performing a pre-scan, and OCT is performed on the object to be measured. As a result, an image of the object to be measured can be acquired with good image quality regardless of the cross-sectional shape of the object to be measured, and the measurement time (photographing time) can be shortened.

[0300] A fourth aspect of the embodiment is the second or third aspect, and further includes an image forming unit (220) and an image quality evaluation value calculation unit (232B). The image forming unit forms an image of the object to be measured based on OCT data. The image quality evaluation value calculation unit calculates an evaluation value of the image quality of the image of the object to be measured. The control unit controls one or more optical elements based on the evaluation value.

[0301] According to this aspect, the optical conditions of the optical system are changed based on the evaluation value of the image quality of the image of the object to be measured, so that an image of the object to be measured can be obtained with simple control and high precision, with good image quality, regardless of the cross-sectional shape of the object to be measured.

[0302] A fifth aspect of the embodiment is any of the first to third aspects, further comprising a movement mechanism (150) that moves the optical system relatively to the object to be measured. The control unit controls the movement mechanism to change the optical conditions of the optical system.

[0303] According to this aspect, OCT is performed on the object by changing the optical conditions of the optical system by moving the optical system relative to the object, thereby making it possible to acquire an image of the object with good image quality regardless of the cross-sectional shape of the object, and reducing the measurement time (photographing time).

[0304] A sixth aspect of the embodiment is the second or third aspect, further including an image forming unit (220). The image forming unit forms an image of the object to be measured based on the OCT data. The control unit controls the optical path length difference changing member based on the position of the object to be measured in the image.

[0305] According to this aspect, the optical path length difference between the measurement light and the reference light is changed in synchronization with the period of the slow scan using the OCT data obtained during the scan, so that an image of the object to be measured can be obtained with good image quality.

[0306] In a seventh aspect of the embodiment, in any one of the first to third aspects, the fast scan axis is a circular scan axis, and the slow scan axis is a spiral scan axis.

[0307] According to this aspect, it is possible to scan at high density in a short period of time in the area near the center (the center position of the scan in slow scanning), and to scan at low density over a longer period of time as the area moves away from the center, thereby making it possible to obtain an image of the object to be measured with good image quality in a wide-angle area including the area of ​​interest with simple control.

[0308] An eighth aspect of the embodiment is a control method for an OCT device (ophthalmic device 1, 1a) including an optical system (an optical system included in an OCT unit 100, an optical path length changing unit 41, an OCT focusing lens 45, and a VCC lens 47 (or a wavefront aberration correction optical system 70), and an interference optical system) configured to change optical conditions (the focal position of the measurement light LS, the polarization component of the measurement light LS, the aberration correction component, the optical path length difference between the measurement light LS and the reference light LR, or the position of the optical system with respect to the test eye E), and including an optical scanner (42). The optical scanner is configured to acquire OCT data of the test object (the test eye E) by scanning the test object with the measurement light (LS) using the optical scanner. The control method for the OCT device includes a control step and an optical condition changing step. The control step controls the optical scanner to scan the test object with the measurement light along a fast scan axis based on a reference position that moves along a slow scan axis. The optical condition changing step changes the optical conditions in synchronization with the period of the slow scan along the slow scan axis.

[0309] According to this aspect, the optical conditions of the optical system can be changed in synchronization with the cycle of the slow scan using OCT data obtained during the scan, so that an image of the object to be measured can be acquired with good image quality without incurring deterioration in image quality due to a shift in the scan position during the scan, etc. In particular, when the object to be measured is photographed at a wide angle, an image of the object to be measured can be acquired with good image quality without performing a pre-scan.

[0310] In a ninth aspect of the embodiment, in the eighth aspect, the optical system includes an interference optical system (an optical system included in the OCT unit 100, an optical path length changing unit 41, an OCT focusing lens 45, and a VCC lens 47 (or a wavefront aberration correction optical system 70)) and an optical path length difference changing member (the optical path length changing unit 41, or a corner cube 114 and a reference drive unit 114A). The interference optical system splits light (L0) from a light source (light source unit 101) into measurement light and reference light (LR), projects the measurement light that has passed through a measurement optical path in which one or more optical elements (the OCT focusing lens 45, the corner cube 114, the optical path length changing unit 41, and the polarization controller 103) are arranged, and detects interference light (LC) between return light from the object and the reference light that has passed through the reference optical path. The optical path length difference changing member changes the difference between the optical path length of the measurement light and the optical path length of the reference light. The optical condition changing step changes the optical conditions of the optical system by controlling at least one of one or more optical elements and an optical path length difference changing member.

[0311] According to this aspect, OCT is performed on the object to be measured by changing the optical conditions of the optical system by controlling at least one of the one or more optical elements and the optical path length difference changing member, thereby making it possible to acquire an image of the object to be measured with good image quality regardless of the cross-sectional shape of the object to be measured.

[0312] In a tenth aspect of the embodiment, in the ninth aspect, the one or more optical elements include a focusing lens (OCT focusing lens 45) or an aberration correction device (VCC lens 47 or wavefront aberration correction optical system 70).

[0313] According to this aspect, by controlling at least one of the optical path length difference changing member and one or more optical elements including the focusing lens or the aberration correction device, the optical conditions of the optical system are changed without performing a pre-scan, and OCT is performed on the object to be measured. As a result, an image of the object to be measured can be acquired with good image quality regardless of the cross-sectional shape of the object to be measured, and the measurement time (photographing time) can be shortened.

[0314] An eleventh aspect of the embodiment is the ninth or tenth aspect, and further includes an image forming step and an image quality evaluation value calculation step. The image forming step forms an image of the object to be measured based on OCT data. The image quality evaluation value calculation step calculates an evaluation value of the image quality of the image of the object to be measured. The optical condition changing step controls one or more optical elements based on the evaluation value.

[0315] According to this aspect, the optical conditions of the optical system are changed based on the evaluation value of the image quality of the image of the object to be measured, so that an image of the object to be measured can be obtained with simple control and high precision, with good image quality, regardless of the cross-sectional shape of the object to be measured.

[0316] In a twelfth aspect of the embodiment, in any one of the eighth to tenth aspects, the OCT apparatus includes a moving mechanism (150) that moves the optical system relatively to the object to be measured. The optical condition changing step changes the optical condition of the optical system by controlling the moving mechanism.

[0317] According to this aspect, OCT is performed on the object by changing the optical conditions of the optical system by moving the optical system relative to the object, thereby making it possible to acquire an image of the object with good image quality regardless of the cross-sectional shape of the object, and reducing the measurement time (photographing time).

[0318] A thirteenth aspect of the embodiment is the ninth or tenth aspect, further including an image forming step of forming an image of the object to be measured based on the OCT data, wherein the optical condition changing step controls the optical path length difference changing member based on a position of the object to be measured in the image.

[0319] According to this aspect, the optical path length difference between the measurement light and the reference light is changed in synchronization with the period of the slow scan using the OCT data obtained during the scan, so that an image of the object to be measured can be obtained with good image quality.

[0320] In a fourteenth aspect of the embodiment, in any one of the eighth to tenth aspects, the fast scan axis is a circular scan axis, and the slow scan axis is a spiral scan axis.

[0321] According to this aspect, it is possible to scan at high density in a short period of time in the area near the center (the center position of the scan in slow scanning), and to scan at low density over a longer period of time as the area moves away from the center, thereby making it possible to obtain an image of the object to be measured with good image quality in a wide-angle area including the area of ​​interest with simple control.

[0322] A fifteenth aspect of the embodiment is a program for causing a computer to execute each step of the method for controlling an OCT apparatus according to any one of the eighth to tenth aspects.

[0323] According to this aspect, the optical conditions of the optical system can be changed in synchronization with the cycle of the slow scan using OCT data obtained during the scan, so that an image of the object to be measured can be acquired with good image quality without incurring deterioration in image quality due to a shift in the scan position during the scan, etc. In particular, when the object to be measured is photographed at a wide angle, an image of the object to be measured can be acquired with good image quality without performing a pre-scan.

[0324] 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.

[0325] 1, 1a Ophthalmic apparatus 3 Display device 41 Optical path length changing unit 45 OCT focusing lens 47 VCC lens 47A VCC driving unit 70 Wavefront aberration correction optical system 100 OCT unit 103, 118 Polarization controller 114 Corner cube 114A Reference driving unit 200, 200a Arithmetic control unit 210, 210a Control unit 211, 211a Main control unit 212, 212a Storage unit 220 Image forming unit 230 Data processing unit 231 Image synthesis unit 232 Analysis unit 232A Image position identification unit 232B Image quality evaluation value calculation unit 240A Display unit E Eye to be examined SAR1 Central region SAR2 Intermediate region SAR3 Peripheral region LC Interference light LR Reference light LS measurement light

Claims

1. An optical coherence tomography device comprising: an optical system configured to be able to change optical conditions, including an optical scanner, and configured to acquire optical coherence tomography data of an object to be measured by scanning the object to be measured with measurement light using the optical scanner; and a control unit that controls the optical scanner to scan the object to be measured with the measurement light along a fast scan axis based on a reference position that moves along the slow scan axis, wherein the control unit changes the optical conditions in synchronization with the period of the slow scan along the slow scan axis.

2. The optical system of the optical coherence tomography device described in claim 1, characterized in that it includes an interference optical system that splits light from a light source into the measurement light and reference light, projects the measurement light that has passed through a measurement light path in which one or more optical elements are arranged onto the object to be measured, and detects interference light between the return light from the object to be measured and the reference light that has passed through a reference light path, and an optical path length difference changing member that changes the difference between the optical path length of the measurement light and the optical path length of the reference light, and the control unit changes the optical conditions of the optical system by controlling at least one of the one or more optical elements and the optical path length difference changing member.

3. The optical coherence tomography apparatus according to claim 2, wherein the one or more optical elements include a focusing lens or an aberration correction device.

4. An optical coherence tomography device as described in claim 2 or 3, characterized in that it includes: an image forming unit that forms an image of the object to be measured based on the optical coherence tomography data; and an image quality evaluation value calculation unit that calculates an evaluation value of the image quality of the image of the object to be measured, wherein the control unit controls the one or more optical elements based on the evaluation value.

5. An optical coherence tomography device as described in any one of claims 1 to 3, characterized in that it includes a moving mechanism that moves the optical system relatively to the object to be measured, and the control unit changes the optical conditions of the optical system by controlling the moving mechanism.

6. An optical coherence tomography device as described in claim 2 or claim 3, characterized in that it includes an image forming unit that forms an image of the object to be measured based on the optical coherence tomography data, and the control unit controls the optical path length difference changing member based on the position of the object to be measured in the image.

7. An optical coherence tomography device according to any one of claims 1 to 3, characterized in that the fast scan axis is a circular scan axis, and the slow scan axis is a spiral scan axis.

8. A control method for an optical coherence tomography device including an optical system configured to change optical conditions, including an optical scanner, and configured to acquire optical coherence tomography data of an object to be measured by scanning the object to be measured with measurement light using the optical scanner, the control method including: a control step of controlling the optical scanner to scan the object to be measured with the measurement light along a fast scan axis based on a reference position moving along the slow scan axis; and an optical condition changing step of changing the optical conditions in synchronization with the period of the slow scan along the slow scan axis.

9. The method for controlling an optical coherence tomography device described in claim 8, characterized in that the optical system includes: an interference optical system that splits light from a light source into the measurement light and reference light, projects the measurement light that has passed through a measurement optical path in which one or more optical elements are arranged onto the object to be measured, and detects interference light between return light from the object to be measured and the reference light that has passed through a reference optical path; and an optical path length difference changing member that changes the difference between the optical path length of the measurement light and the optical path length of the reference light, and the optical condition changing step changes the optical conditions of the optical system by controlling at least one of the one or more optical elements and the optical path length difference changing member.

10. The method for controlling an optical coherence tomography apparatus according to claim 9, wherein the one or more optical elements include a focusing lens or an aberration correction device.

11. A method for controlling an optical coherence tomography device as described in claim 9 or 10, characterized in that it includes an image formation step of forming an image of the object to be measured based on the optical coherence tomography data, and an image quality evaluation value calculation step of calculating an evaluation value of the image quality of the image of the object to be measured, wherein the optical condition change step controls the one or more optical elements based on the evaluation value.

12. A method for controlling an optical coherence tomography device as described in any one of claims 8 to 10, characterized in that the optical coherence tomography device includes a moving mechanism for moving the optical system relatively to the object to be measured, and the optical condition changing step changes the optical conditions of the optical system by controlling the moving mechanism.

13. A method for controlling an optical coherence tomography device as described in claim 9 or 10, characterized in that it includes an image formation step of forming an image of the object to be measured based on the optical coherence tomography data, and the optical condition change step controls the optical path length difference change member based on the position of the object to be measured in the image.

14. A method for controlling an optical coherence tomography device described in any one of claims 8 to 10, characterized in that the fast scan axis is a circular scan axis, and the slow scan axis is a spiral scan axis.

15. A program for causing a computer to execute each step of the method for controlling an optical coherence tomography apparatus according to any one of claims 8 to 10.

Images