Ophthalmologic apparatus and ophthalmologic apparatus control method

Abstract

To provide an ophthalmologic apparatus capable of simply generating satisfactory three-dimensional data of an observed portion of a subject eye, and an ophthalmologic apparatus control method.SOLUTION: A pre-scan control part 216 executes pre-scanning for an observed portion (fundus Ef). A fault shape acquisition part 218 detects or predicts a fault shape of the observed portion. A main scanning control part 220 executes main scanning for the observed portion by controlling an optical scanner. An optical path length acquisition part 214 acquires an optimum optical path length at a specific scan position of the main scanning at least before the main scanning. An optical path length adjustment control part 224 adjusts an optical path length to an optimum optical path length by controlling an optical path length changing part. A three-dimensional data generation part 226 generates three-dimensional data 404 of the observed portion.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an ophthalmic apparatus that obtains a tomographic image of a subject's eye using optical coherence tomography and a method for controlling the ophthalmic apparatus. [Background technology]

[0002] There is known an ophthalmic apparatus that performs tomographic imaging of a test eye using optical coherence tomography (OCT). For example, the ophthalmic apparatus described in Patent Document 1 includes an interference optical system that splits light from a light source into measurement light and reference light, irradiates the test eye with the measurement light, and detects interference light between the return light from the test eye and the reference light. This interference optical system includes an optical scanner that scans the measurement light, and an optical path length changer such as a corner cube or a reflector that changes the optical path length of the reference light or the measurement light.

[0003] The ophthalmic apparatus described in the above Patent Document 1 irradiates the fundus (site to be observed) of the subject eye with measurement light to obtain a one-dimensional signal in the depth direction of the fundus (A scan), and one-dimensionally scans (line scans) the subject eye with this measurement light to obtain a B-scan image including a fundus tomographic image (B scan).The ophthalmic apparatus described in Patent Document 1 also has a function of adjusting the optical path length of the reference light, etc. to display a predetermined area of ​​the fundus tomographic image at a reference position (designated Z position) in the B-scan image (Auto Z), a function of maintaining the fundus tomographic image at this reference position (Z lock), and a function of changing the reference position (Z lock position change process).

[0004] The ophthalmologic apparatus described in Patent Document 2 performs 3D OCT photography in which B-scans are repeatedly performed while changing the scanning position of the B-scan in a direction perpendicular to both the A-scan direction and the B-scan direction, and generates 3D data of the fundus by acquiring B-scan images for each scanning position (C-scan).

[0005] When performing such 3D OCT imaging, the display position of the fundus tomographic image in the B-scan image (within the frame) acquired at the "scan start position," "scan center position," and "scan end position" of the B-scan changes due to the curvature of the eyeball. In this case, if the scanning range of the measurement light is narrow, almost the entire fundus tomographic image will fit within each B-scan image.

[0006] On the other hand, depending on the conditions of 3D OCT photography (scanning range, curvature of the eyeball, etc.), a back image may occur in which the entire fundus tomographic image is not displayed in the B-scan image, or a part of the fundus tomographic image may be folded back, resulting in an incorrect display of the fundus tomographic image. In such a case, it is possible to adjust the display position of the fundus tomographic image in the B-scan image as in the ophthalmic apparatus described in the above Patent Document 1. However, particularly when the scanning range of the measurement light is set to a wide angle, the reference position is set low so that the entire fundus tomographic image fits within the B-scan image, and therefore the position of the fundus tomographic image in the B-scan image moves downward due to the movement of the eyeball of the subject's eye, and a back image is likely to occur. In this case, the height position (average value) of the tomographic image in the B-scan image remains low, so there is a risk that the reference position will not be changed. In addition, when the scanning range of the measurement light is set to a wide angle, a clear fundus tomographic image cannot be obtained, and the accuracy of position detection of the fundus tomographic image required for the above-mentioned auto-Z, Z-lock, and Z-lock position change processing may decrease.

[0007] Therefore, in the ophthalmic apparatus described in Patent Document 2, A-scan images are acquired in advance at multiple positions in the scanning direction of the B-scan, and the optical path length of the reference light is adjusted based on the A-scan images at multiple positions so that the entire tomographic image of the observed area is positioned at the optimal position within the B-scan image.

[0008] In addition, in the ophthalmologic apparatus described in Patent Document 3, the optical path length of at least one of the measurement light and the reference light is adjusted according to the scanning range of the measurement light during the B scan so that the entire tomographic image of the observed area is positioned at the optimal position within the B scan image. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2016-41221 A [Patent Document 2] JP 2015-16151 A [Patent Document 3] JP 2020-110256 A Summary of the Invention [Problem to be solved by the invention]

[0010] When performing 3D OCT imaging of the fundus of a test eye, the wider the scanning range of the measurement light, the greater the curvature of the fundus tomographic image in the B-scan image. For this reason, depending on the scanning position of the B-scan, the methods described in the above patent documents may not be applicable, that is, the fundus tomographic image in the B-scan image may be displaced from the reference position, and a part of the fundus tomographic image may not be displayed normally. As a result, good 3D data of the fundus may not be generated.

[0011] The present invention has been made in view of the above circumstances, and has an object to provide an ophthalmic apparatus and a control method for an ophthalmic apparatus that can easily generate good three-dimensional data of a site to be observed in a subject's eye. [Means for solving the problem]

[0012] An ophthalmologic apparatus for achieving the object of the present invention includes an interference optical system that splits light emitted from a light source into measurement light and reference light, irradiates an observation site of a subject's eye with the measurement light, and detects interference light between the reference light and return light from the observation site irradiated with the measurement light, an optical path length changer provided in the interference optical system that changes the optical path length of at least one of the measurement light and the reference light, an optical scanner that scans the observation site with the measurement light, a prescan control unit that controls the optical scanner to perform a prescan that is a B-scan of the observation site, a tomographic shape acquisition unit that forms a B-scan image of the observation site based on a detection signal of the interference light detected by the interference optical system during the prescan, and detects or predicts a tomographic shape of the observation site based on the B-scan image, and a tomographic shape acquisition unit that controls the optical scanner to scan the observation site. an optical path length acquisition unit that acquires the optimal optical path length at least at a specific scan position of the main scan before execution of the main scan, where the optimal optical path length is an optical path length that can adjust the position of a tomographic image of the observed area in the B-scan image to a predetermined reference position; an optical path length adjustment control unit that controls the optical path length changing unit to adjust the optical path length to the optimal optical path length during execution of the main scan, based on the tomographic shape detected or predicted by the tomographic shape acquisition unit and the optimal optical path length acquired by the optical path length acquisition unit; and a 3D data generation unit that generates 3D data of the observed area based on a detection signal of the interference light detected by the interference optical system during execution of the main scan.

[0013] According to this ophthalmic apparatus, the image of the observed area in the B-scan image formed at each scan position of the main scan can be adjusted to a reference position by adjusting the optical path length to an optimal optical path length while the main scan is being performed.

[0014] In an ophthalmologic apparatus according to another aspect of the present invention, when a B scan is performed on an observed area, a direction perpendicular to both the A scan direction and the B scan direction is defined as the vertical direction, and a main scan control unit controls the optical scanner to repeatedly perform a B scan as the main scan while changing the scan position along the vertical direction.

[0015] In an ophthalmologic apparatus according to another aspect of the present invention, a prescan control unit controls an optical scanner to perform a B-scan in a vertical direction to the observed region as a prescan, and a tomographic shape acquisition unit detects a specific layer of the observed region from the B-scan image and detects the tomographic shape based on the shape of the specific layer. This makes it possible to detect the tomographic shape of the observed region with high accuracy.

[0016] In an ophthalmologic apparatus according to another aspect of the present invention, a prescan control unit controls an optical scanner to perform B-scans at a plurality of different scan positions as prescans, and a tomographic shape acquisition unit forms a B-scan image for each prescan position and predicts a tomographic shape based on the results of detecting the position of a tomographic image in the B-scan image for each scan position. This allows the tomographic shape of the observed area to be obtained in a short time, making it possible to perform 3D OCT imaging in a short time.

[0017] In an ophthalmologic apparatus according to another aspect of the present invention, the operation mode of the main scan by the main scan control unit can be selectively switched between a normal mode in which the scanning range of the measurement light is set to a first range and a wide-angle mode in which the scanning range is set to a second range wider than the first range, and the pre-scan control unit, the tomographic shape acquisition unit, the optical path length acquisition unit, and the optical path length adjustment control unit operate only when the operation mode is the wide-angle mode. As a result, when the operation mode of the main scan is the normal mode, the pre-scan can be omitted to perform 3D OCT imaging in a short time.

[0018] An ophthalmic apparatus according to another aspect of the present invention includes a display device and a live display control unit that executes, before a pre-scan, a B-scan of a specific scan position by an optical scanner, formation of a B-scan image based on a detection signal of interference light detected by the interference optical system, and display of the B-scan image by the display device, wherein the live display control unit adjusts the optical path length to an optimal optical path length based on the detection signal of the interference light detected by the interference optical system, and the optical path length acquisition unit acquires the optimal optical path length adjusted by the live display control unit before the pre-scan.

[0019] In another aspect of the ophthalmic apparatus of the present invention, an image forming unit is provided that forms a B-scan image for each scan position based on a detection signal of interference light detected by the interference optical system for each scan position while the main scan is being performed, and a three-dimensional data generating unit is provided that generates three-dimensional data based on the B-scan image formed by the image forming unit for each scan position.

[0020] To achieve the object of the present invention, there is provided a control method for an ophthalmic apparatus including an interference optical system that divides light emitted from a light source into measurement light and reference light, irradiates an observation site of a subject's eye with the measurement light, and detects interference light between the reference light and return light from the observation site irradiated with the measurement light, an optical path length changer provided in the interference optical system that changes the optical path length of at least one of the measurement light and the reference light, and an optical scanner that scans the observation site with the measurement light, the control method for an ophthalmic apparatus including the steps of: forming a B-scan image of the observation site based on a detection signal of the interference light detected by the interference optical system while the optical scanner is performing a pre-scan, which is a B-scan of the observation site, and detecting or predicting a tomographic shape of the observation site based on the B-scan image; The main scan is a 3D scan in which B-scans are repeatedly performed while changing the scan position of the B-scan relative to the target object, and the optimal optical path length is an optical path length that can adjust the position of a tomographic image of the target object in the B-scan image to a predetermined reference position, the method includes at least an optical path length acquisition step of acquiring the optimal optical path length at a specific scan position of the main scan before execution of the main scan, an optical path length adjustment control step of controlling the optical path length changing unit to adjust the optical path length to the optimal optical path length during execution of the main scan based on the tomographic shape detected or predicted in the tomographic shape acquisition step and the optimal optical path length acquired in the optical path length acquisition step, and a 3D data generation step of generating 3D data of the target object based on a detection signal of the interference light detected by the interference optical system during execution of the main scan. Effect of the Invention

[0021] The present invention can easily generate good three-dimensional data of the observation site of the subject's eye. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic diagram illustrating an example of a configuration of an ophthalmologic apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of the optical system of the OCT unit. [Diagram 3] FIG. 2 is a functional block diagram of an arithmetic control unit according to the first embodiment. [Figure 4] FIG. 1 is an explanatory diagram for explaining three-dimensional OCT imaging. [Diagram 5] FIG. 1 is an explanatory diagram for explaining scanning of the measuring light LS from before imaging to the completion of imaging in three-dimensional OCT imaging [3D(H) scan]. [Figure 6] FIG. 1 is an explanatory diagram for explaining scanning of the measuring light LS from before imaging to the completion of imaging in three-dimensional OCT imaging [3D(V) scan]. [Figure 7] 13 is an explanatory diagram for explaining adjustment of a target optical path length by an optical path length adjustment control unit during execution of a main scan. FIG. [Figure 8] 4 is a flowchart showing a flow of processing for three-dimensional OCT photographing of a fundus by the ophthalmologic apparatus of the first embodiment. [Figure 9] 11 is an explanatory diagram comparing B-scan images at each scanning position of a main scan formed by a conventional method with B-scan images at each scanning position of a main scan formed by the ophthalmologic apparatus 1 of the first embodiment. FIG. [Figure 10] FIG. 11 is an explanatory diagram for explaining a prescan in the second embodiment. [Figure 11] 13 is an explanatory diagram for explaining a prediction process of a tomographic shape of a fundus by a tomographic shape acquisition unit of the second embodiment. FIG. [Figure 12] 13 is a flowchart showing a flow of processing for three-dimensional OCT photographing of a fundus by an ophthalmologic apparatus according to a second embodiment. [Figure 13] FIG. 11 is a functional block diagram of an arithmetic control unit of an ophthalmic apparatus according to a third embodiment. [Figure 14] 13 is a flowchart showing a flow of processing for three-dimensional OCT photographing of a fundus by an ophthalmologic apparatus according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] [Ophthalmic Apparatus of First Embodiment] 1 is a schematic diagram showing an example of the configuration of an ophthalmic apparatus 1 of the first embodiment. The ophthalmic apparatus 1 is a multifunction machine that combines a fundus camera that photographs the fundus Ef, which is the observation site of the subject's eye E, and an optical coherence tomography device that performs OCT photography (OCT measurement, OCT scan) to obtain a tomographic image of the fundus Ef using OCT. Note that the Z direction in the figure is the front-back direction in which the ophthalmic apparatus 1 approaches or moves away from the subject's eye E, the Y direction is the up-down direction, and the X direction is the left-right direction.

[0024] As shown in Fig. 1, the ophthalmologic apparatus 1 includes a fundus camera unit 2, an OCT unit 100, an arithmetic and control unit 200, and a pair of anterior eye cameras 300. The fundus camera unit 2 has an optical system similar to that of a conventional fundus camera. The OCT unit 100 has an optical system for performing OCT photography of the fundus Ef. The arithmetic and control unit 200 is an arithmetic processing device such as a personal computer that executes various arithmetic processing and control processing.

[0025] [Fundus camera unit] The fundus camera unit 2 includes an illumination optical system 10 and an imaging optical system 30 as optical systems for acquiring a two-dimensional image (fundus image) showing the surface morphology of the fundus Ef of the subject's eye E. The illumination optical system 10 irradiates the fundus Ef with illumination light. The imaging optical system 30 guides fundus reflection light of the illumination light reflected by the fundus Ef to CMOS (Complementary Metal Oxide Semiconductor) type or CCD (Charge Coupled Device) type image sensors 35, 38. The imaging optical system 30 also guides the measurement light LS (see FIG. 2) output from the OCT unit 100 to the fundus Ef, and also guides the return light LS1 (see FIG. 2) that has passed through the fundus Ef to the OCT unit 100.

[0026] The illumination optical system 10 includes an observation light source 11, a reflecting mirror 12, a condenser lens 13, a visible light cut filter 14, an imaging light source 15, a mirror 16, relay lenses 17 and 18, an aperture 19, a relay lens 20, an aperture mirror 21, a dichroic mirror 46, and an objective lens 22.

[0027] The photographing optical system 30 includes, in addition to the objective lens 22, dichroic mirror 46, and aperture mirror 21 already described, a dichroic mirror 55, a focusing lens 31, a mirror 32, a half mirror 39A, an optotype display unit 39, a dichroic mirror 33, a condensing lens 34, an image sensor 35, a mirror 36, a condensing lens 37, and an image sensor 38.

[0028] The observation light source 11 is, for example, a halogen lamp or an LED (Light Emitting Diode) light source, and emits observation illumination light. The observation illumination light emitted from the observation light source 11 is reflected by a reflecting mirror 12, 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 once in the vicinity of 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 around the hole) of the aperture mirror 21, passes through a dichroic mirror 46, and is refracted by the objective lens 22 to illuminate the fundus Ef.

[0029] The fundus reflected light of the observation illumination light is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through a hole formed in the central region of the aperture mirror 21, passes through the dichroic mirror 55, passes through the focusing lens 31, and is reflected by the mirror 32. Furthermore, this fundus reflected light passes through the half mirror 39A, is reflected by the dichroic mirror 33, and is imaged on the light receiving surface of the image sensor 35 by the condenser lens 34. The image sensor 35 captures (receives) the fundus reflected light and outputs an image signal. The display device 3 displays an observation image based on the image signal output from the image sensor 35. When the focus of the photographing optical system 30 is adjusted to the anterior segment Ea of the subject's eye E, an observation image of the anterior segment Ea is displayed on the display device 3, and when the focus of the photographing optical system 30 is adjusted to the fundus Ef, an observation image of the fundus Ef is displayed on the display device 3.

[0030] The imaging light source 15 is, for example, a xenon lamp or an LED light source, and emits imaging illumination light. The imaging illumination light emitted from the imaging light source 15 is irradiated onto the fundus Ef through the same path as the observation illumination light described above. The fundus reflection light of the imaging illumination light is guided to the dichroic mirror 33 through the same path as the fundus reflection light of the observation illumination light, passes through the dichroic mirror 33, is reflected by a mirror 36, and is imaged on the light receiving surface of an image sensor 38 by a condenser lens 37.

[0031] The image sensor 38 captures (receives) the fundus reflected light and outputs an imaging signal. The display device 3 displays a captured image based on the imaging signal output from the image sensor 38. Note that the display device 3 that displays the observed image and the display device 3 that displays the captured image may be the same or different.

[0032] For example, a dot matrix liquid crystal display (LCD) and a matrix light emitting diode (LED) are used as the target display unit 39. This target display unit 39 displays the fixation target 90. In addition, since the target display unit 39 is a dot matrix LCD or the like, the display mode (shape, etc.) and display position of the fixation target 90 can be set arbitrarily.

[0033] A light beam of the fixation target 90 displayed on the target display unit 39 is partially reflected by the half mirror 39A, and then passes through the mirror 32, the focusing lens 31, the dichroic mirror 55, the hole of the aperture mirror 21, the dichroic mirror 46, and the objective lens 22 to be projected onto the subject's eye E. This makes it possible to present the fixation target 90 and the like to the subject's eye E.

[0034] Furthermore, the fundus camera unit 2 includes an alignment optical system 50 and a focus optical system 60, similar to conventional fundus cameras. The alignment optical system 50 generates an alignment index for aligning the fundus camera unit 2 with the subject's eye E. The focus optical system 60 generates a split index for focusing on the fundus Ef.

[0035] The alignment optical system 50 includes an LED 51, apertures 52, 53, and a relay lens 54, in addition to the objective lens 22, dichroic mirror 46, aperture mirror 21, and dichroic mirror 55 described above. The focus optical system 60 includes an LED 61, a relay lens 62, a split index plate 63, a two-hole aperture 64, a mirror 65, a condenser lens 66, and a reflecting rod 67, in addition to the objective lens 22, dichroic mirror 46, and aperture mirror 21 described above.

[0036] The alignment light emitted from the LED 51 of the alignment optical system 50 passes through the apertures 52, 53 and the relay lens 54, is reflected by the dichroic mirror 55, passes through the hole in the aperture mirror 21, transmits through the dichroic mirror 46, and is projected by the objective lens 22 onto the cornea of ​​the anterior segment Ea of the test eye E.

[0037] The corneal reflected light of the alignment light passes through the objective lens 22, the dichroic mirror 46, and the hole in the aperture mirror 21, and after a portion of it passes through the dichroic mirror 55, it passes through the focusing lens 31, the mirror 32, the half mirror 39A, the dichroic mirror 33, and the focusing lens 34 and is incident on the light receiving surface of the image sensor 35.

[0038] The image sensor 35 captures (receives) the corneal reflection light of the alignment light and outputs an image signal. As a result, the alignment index is displayed on the display device 3 together with the observation image of the anterior eye segment Ea described above. The examiner then performs alignment by performing operations similar to those of a conventional fundus camera. Alternatively, the arithmetic and control unit 200 may analyze the position of the alignment index and move the optical system to perform alignment (auto-alignment).

[0039] The reflecting surface of the reflecting rod 67 is set on the optical path of the illumination optical system 10 when focus adjustment is performed by the focus optical system 60. The focusing light emitted from the LED 61 passes through the relay lens 62 and is separated into two light beams by the split index plate 63, and then passes through the two-hole diaphragm 64, the mirror 65, and the condenser lens 66 to form an image on the reflecting surface of the reflecting rod 67, and is reflected by this reflecting surface toward the relay lens 20. The focusing light further passes through the relay lens 20, the aperture mirror 21, the dichroic mirror 46, and the objective lens 22 to be projected onto the fundus Ef.

[0040] The fundus reflected light of the focusing light travels along the same path as the cornea reflected light of the alignment light and is imaged by the image sensor 35. The image sensor 35 images the fundus reflected light of the focusing light and outputs an image signal. As a result, the split index is displayed on the display device 3 together with the observation image. The arithmetic and control unit 200 described below automatically performs focusing by analyzing the position of the split index and moving the focusing lens 31 etc., as in the conventional method. Alternatively, the examiner may manually perform focusing while visually checking the split index.

[0041] The dichroic mirror 46 branches the optical path for OCT imaging from the optical path for fundus imaging. The dichroic mirror 46 reflects light in the wavelength band used for OCT imaging and transmits light for fundus imaging. The optical path for OCT measurement includes, in order from the OCT unit 100 side, a collimator lens unit 40, an optical path length changer 41, an optical scanner 42, a focusing lens 43, a mirror 44, and a relay lens 45.

[0042] The optical path length changing unit 41 is movable in the direction of the arrow shown in Fig. 1 and changes the optical path length of the measurement light LS (see Fig. 2) for OCT imaging. This change in the optical path length is used for correcting the optical path length according to the axial length of the subject's eye E, adjusting the interference state, etc. The optical path length changing unit 41 includes, for example, a corner cube and a mechanism for moving it.

[0043] The optical scanner 42 is, for example, a galvanometer scanner, and deflects (scans) the measurement light LS (see FIG. 2) emitted from the OCT unit 100 described later. The optical scanner 42 includes, for example, a galvanometer mirror that scans the measurement light LS in the x direction, a galvanometer mirror that scans the measurement light LS in the y direction, and a mechanism for independently driving these. This allows the measurement light LS to be scanned in any direction on the xy plane, so that the fundus Ef can be scanned in the XY directions (two-dimensionally scanned) with the measurement light LS.

[0044] The fundus camera unit 2 is provided with a pair of anterior eye cameras 300. The pair of anterior eye cameras 300 are so-called stereo cameras, and capture images of the anterior eye Ea from different directions substantially simultaneously. The pair of anterior eye cameras 300 are provided at positions outside the optical paths of the illumination optical system 10 and the photographing optical system 30. Each anterior eye camera 300 captures a photographed image of the subject eye E when the subject eye E is in substantially the same position (direction). Each photographed image is used by the arithmetic and control unit 200 to detect the relative position of the subject eye E with respect to the fundus camera unit 2, and the relative position detection result is further used for rough alignment of the fundus camera unit 2 with respect to the subject eye E.

[0045] Fig. 2 is a schematic diagram of the optical system of the OCT unit 100. As shown in Fig. 2 and the above-mentioned Fig. 1, the OCT light source 101 of the OCT unit 100 is a wavelength sweep type (wavelength scanning type) light source capable of sweeping (scanning) the wavelength of the emitted light like the light source of a general swept source type OCT device, and includes a laser light source including a resonator. The OCT light source 101 changes the output wavelength over time in the near-infrared wavelength range that is not visible to the human eye.

[0046] The OCT unit 100 is provided with an optical system for performing swept-source OCT. This optical system includes an interference optical system. This interference optical system has a function of splitting light L0 from an OCT light source 101 into measurement light LS and reference light LR, a function of superimposing return light LS1 of the measurement light LS from the subject's eye E and the reference light LR via the reference optical path to generate interference light LC, and a function of detecting this interference light LC. The detection result (detection signal) of the interference light LC obtained by the interference optical system is a signal indicating the spectrum of the interference light LC, and is sent to the arithmetic and control unit 200.

[0047] Light L0 output from an OCT light source 101 is guided by an optical fiber 102 to a polarization controller 103, where its polarization state is adjusted. The light L0 whose polarization state has been adjusted 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.

[0048] The reference light LR is guided by an optical fiber 110 to a collimator 111 where it is converted into a parallel beam, and is then guided to a corner cube 114 via an optical path length correction member 112 and a dispersion compensation member 113. The optical path length correction member 112 acts to match the optical path length of the reference light LR with the optical path length of the measurement light LS. The dispersion compensation member 113 acts to match the dispersion characteristics between the reference light LR and the measurement light LS.

[0049] Corner cube 114 (retroreflector) and corner cube movement mechanism 115 correspond to the optical path length changer of the present invention. Corner cube 114 is held by corner cube movement mechanism 115 so as to be movable along the incident direction of reference light LR. Corner cube movement mechanism 115 is an actuator that moves corner cube 114 along the incident direction of reference light LR, thereby changing the optical path length of reference light LR.

[0050] In this embodiment, both the optical path length changer 41 that changes the optical path length of the measurement light LS and the corner cube 114 that changes the optical path length of the reference light LR are provided, but only one of the optical path length changer 41 and the corner cube 114 may be provided. It is also possible to change the optical path length difference between the optical path length of the measurement light LS and the optical path length of the reference light LR using optical members other than these.

[0051] The reference light LR that has passed through the corner cube 114 passes through the dispersion compensation member 113 and the optical path length correction member 112, is converted from a parallel light beam to a focused light beam by the collimator 116, and enters the optical fiber 117. The reference light LR that has entered the optical fiber 117 is guided to a polarization controller 118 where its polarization state is adjusted, is guided by the optical fiber 119 to an attenuator 120 where the amount of light is adjusted, and is guided by the optical fiber 121 to a fiber coupler 122.

[0052] On the other hand, the measurement light LS generated by the fiber coupler 105 is guided by the optical fiber 127 and converted into a parallel beam by the collimator lens unit 40, and passes through the optical path length changing unit 41, the optical scanner 42, the focusing lens 43, the mirror 44, and the relay lens 45. The measurement light LS passing through the relay lens 45 is reflected by the dichroic mirror 46, refracted by the objective lens 22, and enters the subject's eye E. The measurement light LS is scattered and reflected at various depth positions in the subject's eye E. Return light LS1 of the measurement light LS from the subject's eye E 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.

[0053] The fiber coupler 122 generates an interference light LC between the return light LS1 incident via the optical fiber 128 and the reference light LR incident via the optical fiber 121. The fiber coupler 122 also generates a pair of interference lights LC by splitting the interference light LC at a predetermined split ratio (for example, 1:1). The pair of interference lights LC are guided to a detector 125 via optical fibers 123 and 124, respectively.

[0054] The detector 125 is, for example, a balanced photodiode. The balanced photodiode includes a pair of photodetectors that detect a pair of interference lights LC, respectively, and outputs a difference between a pair of detection results obtained by these photodetectors. The detector 125 sends this output (detection signal) to the DAQ 130, which is a data acquisition system.

[0055] The DAQ 130 is supplied with a clock KC from the OCT light source 101. The OCT light source 101 generates the clock KC in synchronization with the output timing of each wavelength of the light L0 swept within a predetermined wavelength range. For example, the OCT light source 101 optically delays one of two branched lights obtained by branching the light L0 of each output wavelength, and then generates the clock KC based on the result of detecting the combined light. The DAQ 130 samples the detection signal input from the detector 125 based on the clock KC.

[0056] Furthermore, the DAQ 130 sends the sampling results of the detection signal from the detector 125 to the arithmetic and control unit 200. The arithmetic and control unit 200 forms a reflection intensity profile for each A-line by performing a Fourier transform or the like on the spectral distribution based on the sampling data for each series of wavelength scans (for each A-line). Furthermore, as shown in Fig. 4 described below, the arithmetic and control unit 200 forms an A-scan image 400 by imaging the reflection intensity profile for each A-line, thereby forming a B-scan image 402 of the fundus Ef.

[0057] Fig. 3 is a functional block diagram of the arithmetic control unit 200 according to the first embodiment. Note that in Fig. 3, configurations that are not related to OCT imaging of the ophthalmic apparatus 1 are omitted as appropriate (the same applies to Fig. 13 described later).

[0058] 3, the arithmetic and control unit 200 controls the overall operation of each part of the ophthalmologic apparatus 1. In addition to the already-described fundus camera unit 2, display device 3, and OCT unit 100, the arithmetic and control unit 200 is connected to an operation unit that accepts various input operations by an examiner, a moving mechanism (actuator) that moves the fundus camera unit 2 relative to the subject's eye E, and the like, which are not shown in the figure.

[0059] The arithmetic control unit 200 includes an arithmetic circuit configured with various processors and memories, etc. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., simple programmable logic devices (SPLD), complex programmable logic devices (CPLD), and field programmable gate arrays (FPGA)). The various functions of the arithmetic control unit 200 may be realized by one processor, or may be realized by multiple processors of the same type or different types.

[0060] The arithmetic and control unit 200 functions as a fundus photography control unit 202 and an OCT control unit 204 by executing a control program stored in a storage unit (not shown).

[0061] The fundus photography control unit 202 controls each part of the fundus camera unit 2, the anterior eye camera 300, a moving mechanism (not shown), etc., to perform fundus photography by the ophthalmologic apparatus 1. Note that specific processes for fundus photography, such as alignment of the fundus camera unit 2 with respect to the subject's eye E and fundus photography by the fundus camera unit 2, are well-known techniques, and therefore detailed explanations thereof will be omitted here.

[0062] The OCT control unit 204 controls each part of the fundus camera unit 2, each part of the OCT unit 100, the anterior eye camera 300, and a moving mechanism (not shown) to perform alignment and OCT photography of the fundus Ef by the ophthalmic apparatus 1. As shown in FIG. 4 described later, this OCT photography includes normal OCT photography for acquiring a fundus tomographic image 403, which is a tomographic image of the fundus Ef, and 3D OCT photography for acquiring 3D data 404 (also called a 3D image, 3D model, or C-scan image) of the fundus Ef. Note that the normal OCT photography and the function of the OCT control unit 204 when performing this normal OCT photography are publicly known techniques, and therefore a detailed description thereof will be omitted here. The following description will be given assuming that the ophthalmic apparatus 1 performs 3D OCT photography.

[0063] Fig. 4 is an explanatory diagram for explaining three-dimensional OCT photography. As shown by symbols IVA and IVB in Fig. 4, in three-dimensional OCT photography, a 3D(H) scan (also called a C scan) is performed, which is a three-dimensional scan in which a B scan (line scan) in the X direction of the fundus Ef is repeatedly performed while changing the scan position in the Y direction within a two-dimensional scanning range RA of a predetermined measuring light LS. As a result, a B scan image 402 is obtained in which an A scan image 400 in the Z direction (A scan direction), which is the depth direction of the fundus Ef, is arranged along the X direction (B scan direction) for each scan position of the 3D(H) scan.

[0064] Each B-scan image 402 at each scan position of the 3D(H) scan includes a fundus tomographic image 403. As a result, as shown by reference symbol IVC in Fig. 4, three-dimensional data 404 of the fundus Ef can be generated based on each B-scan image 402. In this case, the Z direction corresponds to the A-scan direction of the present invention, the X direction corresponds to the B-scan direction of the present invention, and the Y direction corresponds to the vertical direction of the present invention.

[0065] Instead of performing a 3D(H) scan, a 3D(V) scan may be performed, which is a three-dimensional scan in which a B-scan in the Y direction of the fundus Ef is repeatedly performed while changing the scan position in the X direction, to generate three-dimensional data 404 of the fundus Ef. In this case, the Y direction corresponds to the B-scan direction of the present invention, and the X direction corresponds to the vertical direction of the present invention.

[0066] 3, before the start of three-dimensional OCT imaging, the OCT control unit 204 functions as an alignment control unit 210, a live display control unit 212, and an optical path length acquisition unit 214. When performing three-dimensional OCT imaging, the OCT control unit 204 also functions as a pre-scan control unit 216, a tomographic shape acquisition unit 218, a main scan control unit 220, an image formation unit 222, an optical path length adjustment control unit 224, and a three-dimensional data generation unit 226.

[0067] The alignment control unit 210 detects the relative position of the fundus camera unit 2 with respect to the subject's eye E based on, for example, an image of the anterior eye Ea captured by a pair of anterior eye cameras 300, and drives a moving mechanism (not shown) based on the detection result of the relative position, thereby performing rough alignment of the fundus camera unit 2 with respect to the subject's eye E. The alignment control unit 210 also executes projection of alignment light onto the anterior eye Ea by the alignment optical system 50, and imaging of corneal reflection light of the alignment light by the image sensor 35. The alignment control unit 210 detects the relative position of the fundus camera unit 2 with respect to the subject's eye E based on an imaging signal output from the image sensor 35, and drives a moving mechanism (not shown) based on the detection result of the relative position, thereby performing precise alignment of the fundus camera unit 2 with respect to the subject's eye E.

[0068] Fig. 5 is an explanatory diagram for explaining the scanning of the measuring light LS from before the imaging of the three-dimensional OCT imaging [3D(H) scan] to the completion of the imaging. Fig. 6 is an explanatory diagram for explaining the scanning of the measuring light LS from before the imaging of the three-dimensional OCT imaging [3D(V) scan] to the completion of the imaging.

[0069] As indicated by the symbols VA in Figures 3 and 5, before three-dimensional OCT photography [3D(H) scan], the live display control unit 212 controls each component of the fundus camera unit 2 and each component of the OCT unit 100 to perform OCT photography for live display and cause the display device 3 to display a fundus tomographic image 403 live.

[0070] Specifically, the live display control unit 212 controls the OCT light source 101 and the optical scanner 42 to repeatedly execute a B-scan (see symbol B1) in the X direction at a predetermined specific scan position VC within the scanning range RA. The specific scan position VC is set, for example, to an X-scan line passing through the center position of the scanning range RA in the Y direction. During execution of this B-scan, the live display control unit 212 repeatedly executes detection of the interference light LC by the detector 125, output of the detection signal, and sampling of the detection signal by the DAQ 130. As a result, the live display control unit 212 repeatedly executes formation of a B-scan image 402 of the fundus Ef and output of this B-scan image 402 to the display device 3 based on the sampling data output from the DAQ 130. As a result, the B-scan image 402 of the fundus Ef is live-displayed on the display device 3.

[0071] 6, before three-dimensional OCT imaging [3D(V) scan], the live display control unit 212 controls the OCT light source 101 and the optical scanner 42 to repeatedly execute a B-scan (see symbol B1) in the Y direction at a specific scan position HC within the scanning range RA. The specific scan position HC is set, for example, to a Y scan line passing through the center position of the scanning range RA in the X direction.

[0072] Moreover, the live display control unit 212 adjusts the optical path length (hereinafter, abbreviated as target optical path length) of at least one of the measurement light LS and the reference light LR during live display. Specifically, when the target optical path length that can adjust the position of a predetermined area (desired area) of the fundus tomographic image 403 in the B-scan image 402 to a predetermined reference position (Z-designated position) is set as the "optimum optical path length", the live display control unit 212 executes optical path length adjustment to adjust the target optical path length to the optimal optical path length based on the detection signal of the interference light LC detected by the detector 125, etc. (see Patent Document 1 above). Moreover, the reference position is appropriately set and adjusted so that the entire fundus tomographic image 403 (including almost the entirety) fits within the B-scan image 402 (within the frame) (see Patent Document 1 above).

[0073] The optical path length acquisition unit 214 acquires optimal optical path length information indicating the optimal optical path length adjusted by the live display control unit 212. The optimal optical path length information includes position information of the corner cubes and the like constituting the optical path length changing unit 41 when the target optical path length includes the optical path length of the measurement light LS, and includes position information of the corner cube 114 when the target optical path length includes the optical path length of the reference light LR. The optimal optical path length information also includes information indicating specific scan positions VC, HC within the scanning range RA.

[0074] The timing of acquisition of the optimal optical path length information by the optical path length acquisition unit 214 is not particularly limited as long as it is at least before execution of a main scan [3D(H) scan or 3D(V) scan] described below.

[0075] The prescan control unit 216, the tomographic shape acquisition unit 218, the main scan control unit 220, the image forming unit 222, the optical path length adjustment control unit 224, and the three-dimensional data generation unit 226 execute operations related to three-dimensional OCT imaging. Here, the three-dimensional OCT imaging of this embodiment includes a prescan for grasping the tomographic shape of the fundus Ef, and a main scan for executing the above-mentioned 3D(H) scan or 3D(V) scan.

[0076] 3 and 5, when the main scan is a 3D(H) scan, the prescan control unit 216 controls the OCT light source 101 and the optical scanner 42 to perform a prescan (see symbol B2) which is a B-scan in the Y direction at a specific scan position HC once (may be performed multiple times) on the fundus Ef. Note that the scan position of the prescan may be shifted in the X direction from the specific scan position HC.

[0077] Furthermore, the pre-scan control unit 216 causes the detector 125 to detect the interference light LC and the DAQ 130 to sample the detection signal during the execution of the pre-scan.

[0078] 6, when the main scan is a 3D (V) scan, the prescan control unit 216 controls the OCT light source 101 and the optical scanner 42 to execute a prescan (see symbol B2), which is a B-scan in the X direction at a specific scan position VC on the fundus Ef, once. Here, the scan position of the prescan may be shifted in the Y direction from the specific scan position VC, for example.

[0079] 3, the tomographic shape acquisition unit 218 forms a B-scan image 402 based on sampling data output from the DAQ 130 in response to a detection signal of the interference light LC detected by the detector 125 during execution of the pre-scan. Next, the tomographic shape acquisition unit 218 detects the tomographic shape of the fundus Ef based on this B-scan image 402.

[0080] Specifically, the tomographic shape acquisition unit 218 detects a specific layer of the fundus Ef, for example, an internal limiting membrane (ILM) layer 403a (see FIG. 7) from the B-scan image 402 using a known method. Then, the tomographic shape acquisition unit 218 detects the tomographic shape of the fundus Ef based on the shape of the detected ILM layer 403a. This makes it possible to grasp the change in the tomographic shape of the fundus Ef along the scanning direction of the pre-scan (see FIG. 7).

[0081] After the tomographic shape acquisition part 218 acquires the tomographic shape of the fundus Ef, the main scan control part 220 controls the OCT light source 101 and the optical scanner 42 to execute a 3D(H) scan indicated by symbol VC in Fig. 5 or a 3D(V) scan indicated by symbol VIC in Fig. 6 as the main scan (see symbol B3). At this time, each time the scanning position of the 3D(H) scan is changed in the Y direction or the scanning position of the 3D(V) scan is changed in the X direction, the optical path length adjustment control part 224 described later adjusts the target optical path length.

[0082] Furthermore, the main scan control unit 220 causes the detector 125 to detect the interference light LC and the DAQ 130 to sample the detection signal during the main scan.

[0083] The image forming section 222 generates a B-scan image 402 for each scan position of the main scan based on sampling data output from the DAQ 130 in response to a detection signal of the interference light LC detected by the detector 125 during execution of the main scan.

[0084] Fig. 7 is an explanatory diagram for explaining adjustment of the target optical path length by the optical path length adjustment control unit 224 during execution of the main scan. Note that Fig. 7 will be described taking as an example a case where a 3D(H) scan is executed as the main scan.

[0085] 3 and 7, the optical path length adjustment control unit 224 acquires optimal optical path length information from the optical path length acquisition unit 214, and also acquires the tomographic shape of the fundus Ef along the Y direction from the tomographic shape acquisition unit 218. Then, the optical path length adjustment control unit 224 adjusts the target optical path length to the optimal optical path length for each scanning position of the 3D(H) scan by driving at least one of the optical path length changing unit 41 and the corner cube moving mechanism 115 based on the optimal optical path length information and the tomographic shape of the fundus Ef. In the following, the adjustment of the target optical path length will be described as being performed by moving the corner cube 114 by the corner cube moving mechanism 115.

[0086] Specifically, the optical path length adjustment control unit 224 adjusts the aforementioned specific scan position VC (including its neighboring scan positions) among the scan positions of the 3D(H) scan to the optimal optical path length adjusted by the aforementioned live display control unit 212, i.e., the optimal optical path length indicated by the optimal optical path length information acquired by the optical path length acquisition unit 214. As a result, the position of the fundus tomographic image 403 in the B-scan image 402 obtained at the specific scan position VC is adjusted to the reference position, and the entire fundus tomographic image 403 fits within this B-scan image 402.

[0087] On the other hand, for each scan position of the 3D(H) scan other than the specific scan position VC, the optical path length adjustment control unit 224 determines the optimal optical path length based on the tomographic shape of the fundus Ef detected by the tomographic shape acquisition unit 218 and the optimal optical path length information acquired by the optical path length acquisition unit 214.

[0088] Specifically, the optical path length adjustment control unit 224 detects a change in the Z position of the fundus Ef (ILM layer 403a) along the Y direction based on the tomographic shape of the fundus Ef detected by the tomographic shape acquisition unit 218. As a result, the optical path length adjustment control unit 224 detects (estimates) the Z direction distance DZ from an arbitrary Z reference (Z0) to the fundus Ef (ILM layer 403a) for each scan position of the 3D (H) scan. The difference in the Z direction distance DZ for each scan position indicates the difference in the optical path length of the measurement light LS. Therefore, the optical path length adjustment control unit 224 calculates the difference ΔZ between the Z direction distance DZ of the specific scan position VC and the Z direction distance DZ of the other scan positions, and corrects the optimal optical path length of the specific scan position VC indicated by the optimal optical path length information based on this difference ΔZ, thereby determining the optimal optical path length corresponding to the other scan positions.

[0089] In this way, the optical path length adjustment control unit 224 determines the optimal optical path length for each scan position of the 3D(H) scan, and thereby drives the corner cube moving mechanism 115 for each scan position during execution of the 3D(H) scan to adjust the target optical path length to the optimal optical path length. As a result, even if the fundus Ef is significantly curved, it is possible to adjust the position (Z direction position) of the fundus tomographic image 403 of the B-scan image 402 obtained for each scan position to the reference position, that is, to fit the entire fundus tomographic image 403 within each B-scan image 402.

[0090] Even when a 3D (V) scan is performed as the main scan, the optical path length adjustment control unit 224 determines the optimal optical path length for each scan position of the 3D (V) scan, and drives the corner cube moving mechanism 115 for each scan position while the 3D (V) scan is being performed to adjust the target optical path length to the optimal optical path length.

[0091] The three-dimensional data generating unit 226 generates three-dimensional data 404 of the fundus Ef by a known method based on the B-scan image 402 for each scan position of the main scan formed by the image forming unit 222. The three-dimensional data generating unit 226 outputs the generated three-dimensional data 404 to the display device 3 and a storage unit (not shown). As a result, the three-dimensional data 404 is displayed on the display device 3 and stored in the storage unit.

[0092] [Operation of the first embodiment] 8 is a flowchart showing a flow of a 3D OCT photographing process of a fundus oculi Ef by the ophthalmic apparatus 1 of the first embodiment, which relates to a control method for an ophthalmic apparatus of the present invention. Note that the following description will be given taking as an example a case where a 3D(H) scan is performed as a main scan for the 3D OCT photographing.

[0093] 8, after the face of the subject is supported by a face support unit (not shown) of the ophthalmologic apparatus 1, the alignment control unit 210 performs alignment (rough alignment and fine alignment) of the fundus camera unit 2 with respect to the subject's eye E using a pair of anterior eye cameras 300, an alignment optical system 50, an image sensor 35, etc. (Step S1). A focus control unit (not shown) also performs a known focus adjustment.

[0094] After the alignment is completed, the live display control unit 212 controls each part of the fundus camera unit 2 and each part of the OCT unit 100 to perform OCT photography for live display. The live display control unit 212 also repeatedly forms a B-scan image 402 at the specific scan position VC and outputs the B-scan image 402 to the display device 3. As a result, the B-scan image 402 is live displayed on the display device 3 (step S2). At this time, the live display control unit 212 determines an optimal optical path length at the specific scan position VC by a known method, and drives the corner cube moving mechanism 115 to adjust the target optical path length to the optimal optical path length.

[0095] The optical path length acquisition unit 214 acquires optimal optical path length information indicating the optimal optical path length at a specific scan position VC adjusted by the live display control unit 212 before the start of pre-scanning, and outputs this optimal optical path length information to the optical path length adjustment control unit 224 (step S3, which corresponds to the optical path length acquisition step of the present invention).

[0096] Next, 3D OCT photography of the fundus Ef is started. First, the prescan control unit 216 controls the OCT light source 101 and the optical scanner 42 to execute a prescan (B scan in the Y direction) once on the fundus Ef at a specific scan position HC as shown by reference symbol VB in Fig. 5 (step S4). At the same time, the prescan control unit 216 executes detection of the interference light LC by the detector 125 and sampling of the detection signal by the DAQ 130 during the execution of the prescan (step S5).

[0097] Next, the tomographic shape acquisition unit 218 forms a B-scan image 402 based on sampling data output from the DAQ 130 in response to a detection signal of the interference light LC detected by the detector 125 during execution of the pre-scan (step S6).Then, the tomographic shape acquisition unit 218 detects the tomographic shape of the fundus Ef by detecting the ILM layer 403a from the B-scan image 402, and outputs the tomographic shape detection result to the optical path length adjustment control unit 224 (step S7, which corresponds to a tomographic shape acquisition step of the present invention).

[0098] When the optical path length adjustment control unit 224 acquires the optimal optical path length information from the optical path length acquisition unit 214 and the tomographic shape detection result from the tomographic shape acquisition unit 218, it determines the optimal optical path length for each scan position of the 3D(H) scan based on the optimal optical path length information and the tomographic shape detection result as shown in Fig. 7. Then, the main scan control unit 220 controls the OCT light source 101 and the optical scanner 42 to start the main scan [3D(H) scan] on the fundus Ef as shown by symbol VC in Fig. 5 (step S8).

[0099] First, the optical path length adjustment control unit 224 drives the corner cube moving mechanism 115 to adjust the target optical path length to an optimal optical path length corresponding to the first scan position of the 3D(H) scan (step S9, which corresponds to the optical path length adjustment control step of the present invention). After this adjustment, the main scan control unit 220 controls the OCT light source 101 and the optical scanner 42 to execute a B scan at the first scan position (step S10). At the same time, the main scan control unit 220 executes detection of the interference light LC by the detector 125 and sampling of the detection signal by the DAQ 130 during the execution of the B scan (step S11).

[0100] Then, for the next scan position of the 3D(H) scan (NO in step S12, step S13), the target optical path length is adjusted to the optimal optical path length (step S9), a B scan is performed (step S10), and the interference light LC is detected and the detection signal is sampled (step S11). Similarly, the process of step S13 and the processes from step S9 to step S11 are repeatedly performed for each remaining scan position of the 3D(H) scan.

[0101] When the main scan [3D(H) scan] is completed (YES in step S12), the image forming unit 222 forms a B-scan image 402 for each scan position of the main scan (step S14). Note that step S14 may be executed between steps S11 and S12.

[0102] The three-dimensional data generating unit 226 generates three-dimensional data 404 of the fundus oculi Ef by a known method based on the B-scan image 402 for each scan position of the main scan formed by the image forming unit 222 (step S15, which corresponds to a three-dimensional data generating step of the present invention). This three-dimensional data 404 is displayed on the display device 3 and stored in a storage unit (not shown).

[0103] [Effects of the first embodiment] 9 is an explanatory diagram comparing B-scan images 402 (reference characters IXA1 to IXA3) at each scanning position of the main scan formed by a conventional method with B-scan images 402 (reference characters IXB1 to IXB3) at each scanning position of the main scan formed by the ophthalmic apparatus 1 of the first embodiment. Note that reference character ZP in the figure indicates the reference position of a fundus tomographic image 403 in the B-scan image 402.

[0104] 9, the scan position of the "middle of the main scan" is close to the specific scan position HC during the live display described above, whereas the scan position of the "beginning of the main scan" or the "end of the main scan" is far from the specific scan position HC. For this reason, particularly when the scanning range RA is set to a wide angle, the difference ΔZ between the Z direction distance DZ at the scan position of the "beginning of the main scan" or the "end of the main scan" and the Z direction distance DZ at the specific scan position VC becomes large due to the curvature of the fundus Ef as shown in FIG.

[0105] In this state, if a main scan is performed using a conventional method, that is, if a main scan is performed with the optimal optical path length set for the specific scan position VC, the fundus tomographic image 403 is adjusted to the reference position for the B-scan image 402 (see symbol IXA2) acquired at the scan position "middle of the main scan". On the other hand, for the B-scan images 402 (see symbols IXA1 and IXA3) acquired at the scan positions "beginning of the main scan" or "end of the main scan", the fundus tomographic image 403 is not adjusted to the reference position, and part of the fundus tomographic image 403 is aliased (see symbol ER in the figure).

[0106] In contrast, in the ophthalmologic apparatus 1 of the first embodiment, the target optical path length is adjusted to the optimal optical path length for each scan position of the main scan based on the tomographic shape of the fundus Ef and the optimal optical path length information at the specific scan position HC, so that the fundus tomographic image 403 in the B-scan image 402 can be adjusted to the reference position at each scan position (see symbols IXB1 to IXB3). In addition, it is only necessary to determine the optimal optical path length for each scan position of the main scan based on the tomographic shape of the fundus Ef and the optimal optical path length information at the specific scan position HC, and there is no need to perform Auto Z or the like at each scan position as in the past. As a result, the position of the fundus tomographic image 403 in the B-scan image 402 formed at each scan position can be easily adjusted to the reference position. This makes it possible to easily generate good three-dimensional data 404 of the fundus Ef.

[0107] [Second embodiment] Next, an ophthalmic apparatus 1 according to a second embodiment of the present invention will be described. In the ophthalmic apparatus 1 according to the first embodiment, a prescan is performed only once, and the tomographic shape acquisition unit 218 detects the tomographic shape of the fundus Ef based on the result of detecting the ILM layer 403a from the B-scan image 402 obtained by the prescan. At this time, it takes time to detect the ILM layer 403a, so there is a risk that it will take time to photograph the 3D OCT of the fundus Ef. Therefore, in the ophthalmic apparatus 1 according to the second embodiment, the 3D OCT of the fundus Ef is performed in a shorter time than in the first embodiment.

[0108] The ophthalmic apparatus 1 of the second embodiment has basically the same configuration as the ophthalmic apparatus 1 of the first embodiment, except that the functions of the prescan control unit 216, the tomographic shape acquisition unit 218, and the optical path length adjustment control unit 224 are different from those of the first embodiment. Therefore, the same reference numerals are used for the same components in terms of function or configuration as those of the first embodiment, and the description thereof will be omitted.

[0109] Fig. 10 is an explanatory diagram for explaining a prescan in the second embodiment. Note that, in Fig. 10, symbol XA indicates a prescan performed before a 3D (H) scan, and symbol XB indicates a prescan performed before a 3D (V) scan.

[0110] 10, when the main scan is a 3D(H) scan, the prescan control unit 216 of the second embodiment controls the OCT light source 101 and the optical scanner 42 to perform a B-scan (see symbol B2) in the X direction at a plurality of different scan positions in the Y direction on the fundus Ef as a prescan. Note that the number of scan positions in the prescan is not particularly limited.

[0111] Furthermore, as shown by symbol XB in FIG. 10, when the main scan is a 3D (V) scan, the prescan control unit 216 of the second embodiment controls the OCT light source 101 and the optical scanner 42 to perform a B scan (see symbol B2) in the Y direction as a prescan at a plurality of different scan positions in the X direction on the fundus Ef.

[0112] The tomographic shape acquisition unit 218 of the second embodiment forms a B-scan image 402 for each scan position of the pre-scan based on sampling data output from the DAQ 130 in response to a detection signal of the interference light LC detected by the detector 125 during execution of the pre-scan. Next, the tomographic shape acquisition unit 218 predicts the tomographic shape of the fundus Ef based on the B-scan image 402 at each scan position.

[0113] Fig. 11 is an explanatory diagram for explaining the prediction process of the tomographic shape of the fundus Ef by the tomographic shape acquisition unit 218 of the second embodiment. As shown in Fig. 11, the tomographic shape acquisition unit 218 of the second embodiment calculates the Z position of the fundus tomographic image 403 in the B-scan image 402 for each pre-scanning scan position, for example, ZMEAN representing the average height position in the Z direction, from each B-scan image 402 for each pre-scanning scan position by a known method. Then, the tomographic shape acquisition unit 218 of the second embodiment predicts the tomographic shape of the fundus Ef (see symbol K) based on the calculation result of ZMEAN for each scan position.

[0114] The optical path length adjustment control unit 224 of the second embodiment determines the optimal optical path length for each scan position of the main scan and adjusts the target optical path length during the main scan, similar to the first embodiment, based on the tomographic shape of the fundus Ef predicted by the tomographic shape acquisition unit 218 and the optimal optical path length information acquired by the optical path length acquisition unit 214.

[0115] 12 is a flowchart showing the flow of 3D OCT photographing processing of the fundus oculi Ef by the ophthalmologic apparatus 1 of the second embodiment. Note that the processing up to step S3 is the same as that of the first embodiment shown in FIG. 8, so a description thereof will be omitted here.

[0116] After the process of step S3, a prescan is started in the same manner as in the first embodiment (step S4A). The prescan control unit 216 controls the OCT light source 101 and the optical scanner 42 to execute a B scan at the first scan position of the prescan (step S4B). At the same time, the prescan control unit 216 executes detection of the interference light LC by the detector 125 and sampling of the detection signal by the DAQ 130 during execution of the B scan (step S4C).

[0117] Then, for the next scan position of the prescan (NO in step S4D, step S4E), a B scan (step S4B) is performed, and the interference light LC is detected and the detection signal is sampled (step S4C). Similarly, the process of step S4E and the processes from step S4B to step S4C are repeatedly performed for each of the remaining scan positions of the B scan in the prescan.

[0118] When the pre-scan is completed (YES in step S4D), the tomographic shape acquisition unit 218 forms a B-scan image 402 for each scanning position of the pre-scan, and predicts the tomographic shape of the fundus Ef based on the results of calculating ZMEAN from each B-scan image 402 as shown in Fig. 11 (step S4G). Compared to the case where the ILM layer 403a is detected as in the first embodiment described above, the accuracy of the tomographic shape of the fundus Ef is inferior, but the tomographic shape of the fundus Ef can be obtained in a short time.

[0119] Thereafter, similarly to the first embodiment shown in FIG. 8, the processes from step S8 onwards are executed.

[0120] As described above, in the ophthalmologic apparatus 1 of the second embodiment, the tomographic shape of the fundus Ef can be obtained in a short time by predicting the tomographic shape of the fundus Ef based on the B-scan images 402 obtained at multiple pre-scanning positions, and as a result, 3D OCT photography of the fundus Ef can be performed in a short time. Also, the same effects as those of the first embodiment can be obtained.

[0121] In the second embodiment, as shown in Fig. 10, when the main scan is a 3D(H) scan, a B scan in the X direction is performed for each prescan scan position, but the scan direction of the B scan during the prescan is not particularly limited as long as the tomographic shape of the fundus Ef can be predicted. Similarly, in the second embodiment, when the main scan is a 3D(V) scan, a B scan in the Y direction is performed for each prescan scan position, but the scan direction of the B scan during the prescan is not particularly limited.

[0122] [Third embodiment] 13 is a functional block diagram of the arithmetic control unit 200 of the ophthalmic apparatus 1 of the third embodiment. In each of the above embodiments, a prescan is performed before the main scan to detect or predict the tomographic shape of the fundus Ef, but if the scanning range RA is not wide-angle, for example, the position of the fundus tomographic image 403 in the B-scan image 402 formed at each scanning position of the main scan will be approximately close to the reference position even if the optical path length adjustment control unit 224 does not perform the optical path length adjustment. Therefore, if the scanning range RA is not wide-angle, there is no need to perform a prescan, and by omitting the prescan, the 3D OCT photography of the fundus Ef can be completed in a short time. Therefore, in the ophthalmic apparatus 1 of the third embodiment, the execution and omission of the prescan are automatically switched depending on the scanning range RA.

[0123] As shown in FIG. 13, the ophthalmic apparatus 1 of the third embodiment has a configuration basically the same as that of the ophthalmic apparatus 1 of each of the above-mentioned embodiments, except that the arithmetic control unit 200 further functions as a mode switching unit 228, and the functions of the pre-scan control unit 216, the tomographic shape acquisition unit 218, and the optical path length adjustment control unit 224 are partially different.

[0124] The mode switching unit 228 selectively switches the operation mode of the main scan executed by the ophthalmic apparatus 1 (main scan control unit 220) between a normal mode and a wide-angle mode in response to a mode switching operation input to an operation unit (not shown). The normal mode is a mode in which the scanning range RA is set to, for example, a range of 6 mm x 6 mm (corresponding to the first range of the present invention). The wide-angle mode is a mode in which the scanning range RA is set to a wider angle than that in the normal mode, for example, a range of 21 mm x 21 mm (corresponding to the second range of the present invention). The scanning range RA in the normal mode and the wide-angle mode can be changed as appropriate.

[0125] In the wide-angle mode, the examiner may attach a wide-angle lens (not shown) to the objective lens 22, or the wide-angle lens may be automatically attached by a lens insertion / removal mechanism (not shown) under the control of the mode switching unit 228.

[0126] The prescan control unit 216, the tomographic shape acquisition unit 218, and the optical path length adjustment control unit 224 of the third embodiment operate only when the operation mode of the main scan is the wide-angle mode, and do not operate when the operation mode is the normal mode.

[0127] 14 is a flowchart showing the flow of 3D OCT photographing processing of the fundus oculi Ef by the ophthalmologic apparatus 1 of the third embodiment. Note that the processing up to step S3 is the same as that of the first embodiment shown in FIG. 8, so a description thereof will be omitted here.

[0128] When the mode switching unit 228 switches the operation mode of the main scan to the wide-angle mode in response to a mode switching operation input to an operation unit (not shown) (YES in step S3A), the same processing from step S4 onwards as in the first embodiment shown in Fig. 8 is executed. Note that the processing from step S4A onwards in the second embodiment shown in Fig. 12 may be executed. This provides the same effects as in the above-mentioned embodiments.

[0129] On the other hand, when the mode switching unit 228 switches the operation mode of the main scan to the normal mode (NO in step S3A), the pre-scan is not executed, and the main scan control unit 220 controls the OCT light source 101, the optical scanner 42, the detector 125, and the DAQ 130 to execute the main scan (step S8A). During the execution of the main scan, the optical path length adjustment control unit 224 does not adjust the optical path length.

[0130] Then, when the main scan is completed, the image forming unit 222 forms a B-scan image 402 for each scan position of the main scan (step S14A). Thereafter, the three-dimensional data generating unit 226 generates three-dimensional data 404 in the same manner as in each of the above embodiments (step S15).

[0131] As described above, in the third embodiment, when the operating mode of the main scan is normal mode, i.e., when the scanning range RA is not wide-angle, the optical path length adjustment during the pre-scan and main scan can be omitted, thereby making it possible to complete 3D OCT photography of the fundus Ef in a short time.

[0132] [others] In each of the above embodiments, the optical path length adjustment is performed by the optical path length adjustment control unit 224 for each scanning position of the main scan, but for example, the optical path length adjustment may be performed every time the scanning position advances a certain number of lines, that is, the optical path length adjustment may be performed intermittently. Also, the optical path length adjustment may be performed only at the scanning position where the difference ΔZ exceeds a predetermined threshold. Furthermore, in response to the fact that the curvature is stronger at both ends of the cross section of the fundus Ef, as in the cross-sectional shape of the fundus Ef shown in FIG. 7 described above, the optical path length adjustment control unit 224 may perform the optical path length adjustment for each scanning position or at short intervals at the "beginning of the main scan" and the "end of the main scan", and conversely, perform the optical path length adjustment at long intervals at the "middle of the main scan".

[0133] In each of the above embodiments, the ophthalmic apparatus 1 performs 3D OCT photography of the fundus Ef of the subject's eye E, but the present invention can also be applied to the case where 3D OCT photography of other observed parts of the subject's eye E is performed.

[0134] In each of the above embodiments, the scanning position of the B scan is changed vertically to both the A scan direction and the B scan direction while the main scan is being performed, but the method of changing the scanning position of the B scan is not particularly limited as long as it is possible to scan the entire scanning range RA.

[0135] In each of the above embodiments, an ophthalmic apparatus 1 that performs swept-source type OCT imaging has been described as an example, but the present invention can be applied to an ophthalmic apparatus 1 that performs various well-known types of OCT imaging, such as spectral domain type OCT imaging.

[0136] In each of the above embodiments, the ophthalmic device 1 has been described as an example of a combination device of a fundus camera and an optical coherence tomograph, but the ophthalmic device 1 may be composed of only an optical coherence tomograph, and the present invention can be applied to various devices capable of performing 3D OCT photography of the observed area of ​​the subject's eye E. [Explanation of symbols]

[0137] 1…Ophthalmology equipment 2...Fundus camera unit 3...Display device 10...Illumination optical system 11... Observation light source 12...Reflective mirror 13...Condenser lens 14...Visible light cut filter 15…Light source 16…Mirror 17…Relay lens 18…Relay lens 19…Aperture 20…Relay lens 21...Perforated mirror 22...Objective lens 30...Photographic optical system 31...Focusing lens 32…Mirror 33…Dichroic mirror 34...Condenser lens 35...Image sensor 36…Mirror 37...Condenser lens 38...Image sensor 39…Optotype display section 39A…Half mirror 40...Collimator lens unit 41...Optical path length changing section 42...Optical scanner 43...Focusing lens 44…Mirror 45…Relay lens 46…Dichroic mirror 50...Alignment optical system 51...LED 52…Aperture 53…Aperture 54…Relay lens 55…Dichroic mirror 60...Focus optical system 61...LED 62...Relay lens 63…Split indicator plate 64…Two-hole aperture 65…Mirror 66...Condenser lens 67...Reflector rod 90...Fixation target 100…OCT unit 101…OCT light source 102...Optical fiber 103...Polarization controller 104...Optical fiber 105...Fiber coupler 110...Optical fiber 111…Collimator 112...Optical path length correction member 113...Dispersion compensation member 114…Corner cube 115...Corner cube moving mechanism 116…Collimator 117...Optical fiber 118...Polarization controller 119...Fiber optics 120…Attenuator 121...Optical fiber 122…Fiber coupler 123...Optical fiber 124...Optical fiber 125…Detector 127...Optical fiber 128...Optical fiber 200...Calculation and control unit 202... Fundus photography control unit 204...OCT control unit 210...Alignment control unit 212...Live display control unit 214...Optical path length acquisition section 216...Prescan control unit 218…Fault shape acquisition section 220...Main scan control unit 222...Image forming unit 224...Optical path length adjustment control unit 226…3D data generation section 228…Mode switching section 300…Anterior eye camera 400…A-scan image 402…B-scan image 403... Fundus tomography 403a…ILM layer 404...3D data DZ…Z direction distance E…Examined eye Ea…anterior segment Ef…fundus HC…specific scan position KC…Clock L0…light LC…Interference light LR: Reference light LS…Measuring light LS1…return light RA…Scanning range VC: Specific scan position ΔZ…difference

Claims

1. an interference optical system that splits light emitted from a light source into measurement light and reference light, irradiates an observation site of a subject's eye with the measurement light, and detects interference light between the reference light and return light from the observation site irradiated with the measurement light; an optical path length changing unit provided in the interference optical system and configured to change an optical path length of at least one of the measurement light and the reference light; an optical scanner that scans the measurement light over the observation site; a prescan control unit that controls the optical scanner to perform a prescan, which is a B-scan, on the region to be observed; a tomographic shape acquisition unit that forms a B-scan image of the observed region based on a detection signal of the interference light detected by the interference optical system during execution of the pre-scan, and detects or predicts a tomographic shape of the observed region based on the B-scan image; a main scan control unit that controls the optical scanner to execute a three-dimensional scan as a main scan by repeatedly executing the B-scan while changing a scan position of the B-scan with respect to the object to be observed; an optical path length acquisition unit that acquires, when an optical path length that allows a position of a tomographic image of the observation site in the B-scan image to be adjusted to a predetermined reference position is defined as an optimal optical path length, the optimal optical path length at a specific scan position of the main scan at least before execution of the main scan; an optical path length adjustment control unit that controls the optical path length changing unit to adjust the optical path length to the optimal optical path length during execution of the main scan, based on the tomographic shape detected or predicted by the tomographic shape acquisition unit and the optimal optical path length acquired by the optical path length acquisition unit; a three-dimensional data generating unit that generates three-dimensional data of the subject region based on a detection signal of the interference light detected by the interference optical system during execution of the main scan; An ophthalmic apparatus comprising:

2. 2. The ophthalmologic apparatus according to claim 1, wherein, in a case where a direction perpendicular to both an A scan direction and a B scan direction when performing the B scan on the observed site is defined as a vertical direction, the main scan control unit controls the optical scanner to repeatedly perform the B scan as the main scan while changing the scan position along the vertical direction.

3. the prescan control unit controls the optical scanner to perform the B-scan in the perpendicular direction to the object to be observed as the prescan; The ophthalmologic apparatus according to claim 2 , wherein the tomographic shape acquisition unit detects a specific layer of the observed region from the B-scan image, and detects the tomographic shape based on a shape of the specific layer.

4. the pre-scan control unit controls the optical scanner to execute the B-scan at a plurality of the scanning positions different from each other as the pre-scan; 2. The ophthalmologic apparatus according to claim 1, wherein the tomographic shape acquisition unit forms the B-scan image for each of the scan positions of the pre-scan, and predicts the tomographic shape based on a result of detecting the position of the tomographic image in the B-scan image for each of the scan positions.

5. The operation mode of the main scan by the main scan control unit can be selectively switched between a normal mode in which a scanning range of the measurement light is set to a first range and a wide-angle mode in which a scanning range of the measurement light is set to a second range wider than the first range, 5. An ophthalmic apparatus according to claim 1, wherein the pre-scan control unit, the tomographic shape acquisition unit, the optical path length acquisition unit, and the optical path length adjustment control unit operate only when the operating mode is the wide-angle mode.

6. A display device; a live display control unit that executes, before the prescan, the B-scan of the specific scan position by the optical scanner, formation of the B-scan image based on a detection signal of the interference light detected by the interference optical system, and display of the B-scan image by the display device; Equipped with the live display control unit adjusts the optical path length to the optimal optical path length based on a detection signal of the interference light detected by the interference optical system; The ophthalmologic apparatus according to claim 1 , wherein the optical path length acquisition unit acquires the optimal optical path length adjusted by the live display control unit before the pre-scan.

7. an image forming unit that forms the B-scan image for each of the scan positions based on a detection signal of the interference light detected by the interference optical system for each of the scan positions during execution of the main scan, The ophthalmologic apparatus according to claim 1 , wherein the three-dimensional data generation unit generates the three-dimensional data based on the B-scan image formed for each scan position by the image forming unit.

8. an interference optical system that splits light emitted from a light source into measurement light and reference light, irradiates an observation site of a subject's eye with the measurement light, and detects interference light between the reference light and return light from the observation site irradiated with the measurement light; an optical path length changing unit provided in the interference optical system and configured to change an optical path length of at least one of the measurement light and the reference light; an optical scanner that scans the measurement light over the observation site; A method for controlling an ophthalmic apparatus comprising: a tomographic shape acquiring step of forming a B-scan image of the observed region based on a detection signal of the interference light detected by the interference optical system while the optical scanner is performing a prescan, which is a B-scan, on the observed region, and detecting or predicting a tomographic shape of the observed region based on the B-scan image; an optical path length acquiring step of acquiring the optimal optical path length at a specific scan position of the main scan at least before the main scan is performed, where the optical path length is an optimal optical path length that allows a position of a tomographic image of the observed region in the B-scan image to be adjusted to a predetermined reference position; an optical path length adjustment control step of controlling the optical path length changing unit to adjust the optical path length to the optimal optical path length during execution of the main scan, based on the tomographic shape detected or predicted in the tomographic shape acquisition step and the optimal optical path length acquired in the optical path length acquisition step; a three-dimensional data generating step of generating three-dimensional data of the object to be observed based on a detection signal of the interference light detected by the interference optical system during the execution of the main scan; A method for controlling an ophthalmic apparatus having the above-mentioned features.

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