Ophthalmic apparatus

Abstract

To reduce a burden on a subject and to acquire an image with less distortion.SOLUTION: An ophthalmologic apparatus of the present disclosure includes a first photographing unit configured to perform photographing by two dimensionally scanning a subject's eye, a second photographing unit configured to perform photographing by three dimensionally scanning the subject's eye, and a correction unit configured to correct a position of scanning performed by the first photographing unit at a first time based on a first image obtained by scanning performed by the second photographing unit during the scanning and one of a second image obtained by scanning performed by the first photographing unit at a second time before the first time and a third image obtained by scanning performed by the second photographing unit at the second time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an ophthalmic apparatus that photographs an eye to be examined, a control method for the ophthalmic apparatus, and a program. [Background technology]

[0002] As ophthalmic devices, scanning laser ophthalmoscopes (SLOs) that photograph the fundus of the examinee's eye by laser scanning, and optical coherence tomography (OCTs) that obtain tomographic images of the examinee's eye by optical coherence tomography, have been put into practical use.

[0003] Conventional SLO uses a laser of one wavelength to capture a monochrome image of the subject's eye, but in recent years, color SLO has been put to practical use, which captures color images by using lasers of multiple wavelengths (for example, lasers of the three primary colors of light: red, green, and blue).

[0004] Furthermore, in order to save space and reduce costs, color SLO / OCT combined instruments, which combine color SLO and OCT into a single instrument, have also been put to practical use.

[0005] Color SLO, which uses multiple lasers, takes longer to capture images than SLO with a single laser. Longer capture times increase the likelihood that the patient's eye will move during imaging. If the patient's eye moves during imaging, distortion will occur in the captured image.

[0006] Here, Patent Documents 1 and 2 disclose a method of obtaining an image with little distortion by repeating image capture until the image distortion falls within an allowable range. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-162926 [Patent Document 2] Japanese Patent Publication No. 2020-162927 Summary of the Invention [Problem to be solved by the invention]

[0008] Here, in a method of repeating imaging until the image distortion falls within an acceptable range, for example, imaging time may become longer, and since the subject is asked by the photographer to refrain from blinking and to keep their eyes still during imaging, a longer imaging time may be a burden on the subject.

[0009] Therefore, an object of the present disclosure is to reduce the burden on the subject and acquire images with less distortion. [Means for solving the problem]

[0010] The ophthalmologic apparatus of the present disclosure includes: a first imaging unit that scans an eye to be examined in two dimensions to capture an image; a second imaging unit that scans the subject's eye in three dimensions to capture an image; a correction unit that corrects the position of a scan by the first imaging unit performed at a first time based on a first image obtained by a scan by the second imaging unit performed while the scan is being performed, and one of a second image obtained by a scan by the first imaging unit performed at a second time before the first time and a third image obtained by a scan by the second imaging unit; Equipped with. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to reduce the burden on the subject and obtain images with less distortion. [Brief explanation of the drawings]

[0012] [Figure 1] 1 shows a schematic configuration example of an SLO / OCT composite apparatus according to a first embodiment. [Figure 2] 2 illustrates a schematic configuration example of a control unit according to a first embodiment. [Figure 3]1 is a flowchart illustrating an outline of an imaging sequence according to the first embodiment. [Figure 4] 3 shows an example of a screen display according to the first embodiment. [Figure 5] 4 is a detailed flowchart of an imaging sequence according to the first embodiment. [Figure 6] FIG. 2 is a schematic diagram of a fundus tracking scan according to the first embodiment. [Figure 7] FIG. 3 is a schematic diagram of fundus tracking scan timing according to the first embodiment. [Figure 8] FIG. 10 is a schematic diagram of a fundus tracking scan according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative positions of components described in the following embodiments are arbitrary and can be changed depending on the configuration of the device to which the present disclosure is applied or various conditions. Furthermore, in this specification and drawings, components having substantially the same or functionally similar configurations are designated by the same reference numerals between the drawings, and redundant description will be omitted.

[0014] Example 1 The ophthalmologic apparatus of this embodiment is provided with a fundus image capturing unit that captures a two-dimensional frontal image of the fundus by scanning, and a tomographic image capturing unit that captures a three-dimensional tomographic image of the fundus of the subject's eye using information based on optical interference.

[0015] The SLO described in this embodiment includes a color SLO that captures color images using light of three color wavelengths, and an infrared SLO for alignment used to determine the capture position. In the following description, the direction that approximately coincides with the line of sight of the subject's eye E is referred to as the Z direction. Furthermore, the plane perpendicular to the Z direction is referred to as the XY plane, the horizontal direction is referred to as the X direction, and the vertical direction is referred to as the Y direction.

[0016] The configuration of this embodiment will be described below.

[0017] <Optical configuration of the device> The SLO optical configuration of the ophthalmologic apparatus according to this embodiment will be described with reference to the schematic diagram of Fig. 1. The SLO optical configuration is an example of the first imaging unit.

[0018] The optical output unit 100 includes an infrared laser light source 101IR that outputs infrared light, a red laser light source 101R that outputs light in a red wavelength range, a green laser light source 101G that outputs light in a green wavelength range, a blue laser light source 101B that outputs light in a blue wavelength range, a reflection mirror 102IR that reflects the infrared laser light, a wavelength branching mirror 102R that branches the red laser light, a wavelength branching mirror 102G that branches the green laser light, a wavelength branching mirror 102B that branches the blue laser light, a collimator lens 103IR that converts the infrared laser light into parallel light, a collimator lens 103R that converts the red laser light into parallel light, a collimator lens 103G that converts the green laser light into parallel light, and a collimator lens 103B that converts the blue laser light into parallel light. Note that the configuration of the optical output unit is not limited to this, and it is sufficient if it can output laser light having at least two different wavelength ranges.

[0019] A reflecting mirror 2, a perforated mirror 3, a focus lens 4, an optical scanning unit 5, a lens 6, a wavelength branching mirror 7, a wavelength branching mirror 8, and an objective lens 9 are arranged on the optical path of the light output from the optical output unit 100, and these constitute a fundus observation optical system.

[0020] Light output from the light output unit 100 is reflected by the reflecting mirror 2 and passes through a hole formed on the optical axis of the perforated mirror 3. The light scanning unit 5 uses a polygon mirror in the X direction and a galvanometer mirror in the Y direction to scan light in the mutually orthogonal X and Y directions, which are arranged adjacent to each other in the optical axis direction (tandem arrangement). Other devices, such as a resonant mirror, may also be used as the component for scanning light. The light reflected by the wavelength branching mirrors 7 and 8 passes through the objective lens 9 and reaches the fundus Ef of the subject's eye E.

[0021] Furthermore, the light reflected by the fundus Ef returns along the same optical path as when it entered the fundus and is reflected by the peripheral portion of the perforated mirror 3. The optical path of the light reflected by the perforated mirror 3 reaches a light receiving unit 200, which includes a lens 201, an aperture 203, a wavelength cut filter 204, and a light receiving element 202 such as an APD (Avalanche Photo Diode). Note that a PMT (Photomultiplier Tube) or an MPPC (Multi-Pixel Photon Counter) may also be used as the light receiving element 202. In addition, while the wavelength cut filter 204 is arranged on the optical path in FIG. 1 , the wavelength cut filter 204 and the wavelength cut filter 205 arranged outside the optical path can be selectively arranged on the optical path by a driving unit (not shown). The wavelength cut filter 204 and the wavelength cut filter 205 each have the property of blocking light of different wavelengths.

[0022] Anterior-segment illumination light sources 303a and 303b are arranged around the objective lens 9. An image of the anterior segment of the subject's eye E illuminated by these light sources passes through the objective lens 9, transmits through the wavelength branching mirror 8, and is formed on the imaging surface of the two-dimensional imaging element 302 by the lens 301.

[0023] Next, the OCT optical configuration of the ophthalmologic apparatus according to this embodiment will be described with reference to the schematic diagram of Fig. 1. The OCT optical configuration is an example of a second imaging unit.

[0024] A measurement optical system including a lens 501, a mirror 502, an optical scanning unit 503, a focus lens 504, a collimator lens 505-1, and a fiber end 505-2 is arranged on the optical axis in the transmission direction of the wavelength branching mirror 7. The optical scanning unit 503 includes an X scanner 503-1 and a Y scanner 503-2. The X scanner 503-1 and the Y scanner 503-2 are configured with any deflection means such as a galvanometer mirror, and function as a scanning unit that scans the fundus Ef of the subject's eye E with measurement light. The centers of the X scanner 503-1 and the Y scanner 503-2 are optically conjugate with the pupil position of the subject's eye E. Although the optical path between the X scanner 503-1 and the Y scanner 503-2 is configured within the plane of the paper in FIG. 1 , it is actually configured perpendicular to the plane of the paper. The scanning unit that scans the measurement light may be configured using a MEMS mirror or the like that can deflect light in two dimensions with a single mirror.

[0025] In this embodiment, the X scanner 503-1 can scan the measurement light in the X direction, and the Y scanner 503-2 can scan the measurement light in the Y direction perpendicular to the X direction. In this embodiment, an example is described in which scanning is performed with the X direction as the main scanning direction and the Y direction as the sub-scanning direction, but the scanning directions are not limited to this. The main scanning direction and the sub-scanning direction in such scanning may be directions that intersect with each other. For example, the Y direction may be the main scanning direction and the X direction may be the sub-scanning direction. Alternatively, the main scanning direction and the sub-scanning direction may be oblique directions that intersect with each other and have components in the X and Y directions. The scanning pattern may be, for example, a 3D scan, a radial scan, a cross scan, a Lissajous scan, a circle scan, or a raster scan.

[0026] The measurement light source 507 is a light source that emits light to obtain measurement light to be incident on the measurement optical path. In this embodiment, the measurement light in the OCT optical system is emitted from a fiber end 505-2 of an optical fiber 506-2 as a light source, and the fiber end 505-2 has an optical conjugate relationship with the fundus Ef of the subject's eye E. The fiber end 505-2 is disposed at the focal position of a collimator lens 505-1, and the measurement light is emitted as a parallel beam from the fiber end 505-2 acting as a light source after passing through the collimator lens 505-1. The collimator lens 505-1 and the fiber end 505-2 form a coherence gate 505.

[0027] The focus lens 504 is a lens for adjusting the focus of the OCT optical system, and is driven in the optical axis direction indicated by the arrow in the figure by a driving unit such as a motor (not shown) controlled by the control unit 50. The focus adjustment is performed so that the measurement light is imaged on the fundus Ef. The focus lens 504 is disposed between the fiber end 505-2, which serves as the measurement light source, and the X scanner 503-1 and Y scanner 503-2, which function as scanning units. By the focus adjustment described above, an image of the measurement light emitted from the fiber end 505-2 can be formed on the fundus Ef of the subject's eye E, and the return light from the fundus Ef can be efficiently returned to the optical fiber 506-2.

[0028] Next, a description will be given of the optical path from measurement light source 507, and the configuration of reference optical system and spectroscope 600. Note that the OCT optical system is configured by the above-mentioned measurement optical system, optical members included in the optical path from measurement light source 507, reference optical system, and spectroscope 600. Furthermore, a Michelson interferometer is configured by measurement light source 507, optical coupler 506, optical fibers 506-1 to 506-4, lens 508, dispersion compensation glass 509, reference mirror 510, and spectroscope 600.

[0029] In this embodiment, an SLD (Super Luminescent Diode), which is a typical low-coherence light source, is used as the measurement light source 507. Although an SLD is selected as the type of light source here, any light source that can emit low-coherence light may be used, for example, an ASE (Amplified Spontaneous Emission) light source. As the central wavelength of the measurement light, for example, a wavelength of near-infrared light may be used in consideration of measuring the eye.

[0030] The optical fibers 506-1 to 506-4 are single-mode optical fibers connected to and integrated with the optical coupler 506. Light emitted from the measurement light source 507 is guided to the optical coupler 506 via the optical fiber 506-1. The light guided to the optical coupler 506 is split by the optical coupler 506 into measurement light directed toward the optical fiber 506-2 side and reference light directed toward the optical fiber 506-3 side. Here, the optical coupler 506 functions as an example of a splitter that splits the light from the measurement light source 507 into measurement light and reference light.

[0031] As described above, in this embodiment, the measurement light in the OCT optical system is emitted from the fiber end of the optical fiber 506-2 as a light source. The measurement light travels through the optical path of the measurement optical system described above, is irradiated onto the fundus Ef of the subject's eye E, which is the observation target, and is reflected and scattered by the retina, and reaches the optical coupler 506 again through the same optical path as returned light.

[0032] On the other hand, the reference light passes through optical fiber 506-3, lens 508, and dispersion compensation glass 509 inserted to match the dispersion of the measurement light and the reference light, and reaches and is reflected by reference mirror 510. The reference light reflected by reference mirror 510 returns along the same optical path and reaches optical coupler 506 again.

[0033] The reference light and measurement light (return light) that reach the optical coupler 506 again are multiplexed by the optical coupler 506. Here, when the optical path lengths of the measurement light and the reference light become approximately the same, this multiplexing causes interference between the respective lights. A coherence gate 505, consisting of a collimator lens 505-1 and a fiber end 505-2 of the OCT optical system, is held so that its positional relationship can be adjusted as a whole in the optical axis direction indicated by the arrow in the figure by a driving unit such as a motor (not shown). By using the coherence gate 505, the optical path length of the measurement light, which varies depending on the subject's eye E, can be adjusted to the optical path length of the reference light. The obtained interference light is guided to the spectroscope 600 via an optical fiber 506-4.

[0034] The spectrometer 600 is provided with a lens 601, a diffraction grating 602, a lens 603, and a line sensor 604. Interference light emitted from the optical fiber 506-4 becomes approximately parallel light via the lens 601, is then dispersed by the diffraction grating 602, and is imaged on the line sensor 604 by the lens 603. Each element in the line sensor 604 generates an interference signal according to the received light, and the line sensor 604 sends the interference signal to the control unit 50. The control unit 50 samples the interference signal received from the line sensor 604 at a predetermined timing, and performs predetermined signal processing to generate a tomographic image.

[0035] Although the OCT optical system in this embodiment is described as a spectral domain OCT (SD-OCT) using an SLD as a light source, the configuration of the OCT optical system according to the present disclosure is not limited to this. For example, the present disclosure can also be applied to any other type of OCT configuration, such as a swept-wavelength OCT (SS-OCT) using a swept-wavelength light source that can sweep the wavelength of the emitted light.

[0036] The optical systems of this device are arranged on a stage (not shown). The control unit 50 controls the stage, which includes three drive units, to move each optical system in three dimensions (X, Y, Z) relative to the subject's eye E. This allows the control unit 50 to align each optical system with the subject's eye E.

[0037] <Device control unit> Next, the control unit that controls the device configured as shown in FIG. 1 will be described with reference to the schematic diagram of FIG.

[0038] A control unit 50 that controls this device includes a wavelength switching unit 51, an optical scanning control unit 52, an image generation unit 53, a synthesis processing unit 54, a display control unit 55, etc. The control unit 50 is also connected to the optical output unit 100, the focus lens 4, the optical scanning unit 5, the light receiving unit 200, the anterior eye imaging unit 300, the anterior eye illumination light sources 303a and 303b, the optical operation unit 503, the focus lens 504, the coherence gate 505, the measurement light source 507, the reference mirror 510, the spectrometer 600, etc. The control unit is also connected to a display unit 400, a drive unit, a memory, etc. The optical scanning control unit 52 is an example of a correction unit.

[0039] <Shooting sequence> Next, a method for photographing the fundus oculi Ef of the subject's eye E using the apparatus configured as shown in FIG. 1 will be described with reference to the flowchart of FIG. 3 and the schematic diagram of FIG.

[0040] In step S0, an imaging mode is selected using a mode selection button (not shown). The imaging modes include, for example, left and right eyes, frontal fundus image and tomographic image (SLO and OCT) imaging, scan mode, etc.

[0041] When the photographing mode is selected, the control unit 50 controls a drive unit (not shown) to insert a wavelength cut filter 204 into the optical path of the light receiving unit 200 .

[0042] In step S1, an anterior eye image of the subject's eye E is generated and displayed in the anterior eye display area 401 of the display unit 400. Specifically, when the subject's eye E is placed in front of this device, the anterior eye image of the subject's eye E is illuminated by light emitted from the anterior eye illumination light sources 303a and 303b. The image of the anterior eye illuminated in this manner passes through the objective lens 9, transmits through the wavelength branching mirror 8, and is formed on the imaging surface of the imaging element 302 by the lens 301. A video signal from the imaging element 302 is input to the control unit 50.

[0043] The control unit 50 converts the video signal into digital data in real time to generate an anterior eye image, and then the control unit 50 displays the generated anterior eye image in the anterior eye display area 401.

[0044] The control unit 50 controls the drive unit within the stage to drive it up, down, left, right, forward, and backward. The optical axis of the optical system is adjusted to coincide with the center of the imaging plane. Therefore, the amount of eccentricity between the center of the pupil of the anterior eye image captured by the anterior eye observation unit 300 and the imaging center corresponds to the amount of eccentricity between the subject's eye E and the optical system.

[0045] In step S2, the position is adjusted so that the pupil center of the subject's eye E coincides with the optical axis. Specifically, the control unit 50 determines the decentering and focus state of the subject's eye E based on the anterior segment image of the subject's eye, particularly the iris pattern. The control unit 50 then controls the drive unit within the stage to adjust the position so that the pupil center coincides with the optical axis, and adjusts the position in the optical axis direction so that the contrast of the iris pattern is maximized. In this way, the control unit 50 maintains a constant distance (working distance) between the pupil of the subject's eye E, which is on the same plane as the iris, and the objective lens 9 of the optical system. The operator can check the optical axis decentering from the anterior segment image displayed in the anterior eye display area 401.

[0046] In step S3, a frontal fundus image (hereinafter referred to as a fundus observation image) for alignment of the subject's eye E is generated and displayed in the fundus display area 402 of the display unit 400. Specifically, when the eccentricity between the pupil center and the imaging center becomes equal to or less than a predetermined value as a result of the position adjustment in step S2, the wavelength switching unit 51 turns on the infrared laser light source 101IR. At this time, the red laser light source 101R, the green laser light source 101G, and the blue laser light source 101B are turned off. The infrared laser light (hereinafter referred to as observation light) output from the infrared laser light source 101IR is converted into parallel light by the collimator lens 103IR, reflected by the reflecting mirror 2, passes through the hole in the perforated mirror 3, transmits through the focus lens 4, and transmits through the optical scanning unit 5 and lens 6. The light transmitted through lens 6 is further reflected by wavelength branching mirrors 7 and 8 and passes through the objective lens 9 to the fundus Ef via the pupil of the subject's eye E. At this time, the observation light is two-dimensionally scanned on the fundus oculi Ef by the operation of the optical scanning unit 5. The frontal fundus image is an example of a second image. The time related to step S3 is an example of a second time.

[0047] The observation light is reflected and scattered by the layers constituting the retina of the fundus oculi Ef, and returns as returned light along the same optical path as the incident light. The returned light is reflected by the peripheral portion of the perforated mirror 3, passes through the lens 201, passes through the diaphragm 203, passes through the wavelength cut filter 204, and is guided to the light receiving element 202. A light intensity signal output from the light receiving element 202 is converted into a digital signal in real time by an A / D converter (not shown), and then input to the control unit 50. The image generation unit 53 generates a fundus observation image from the input digital signal. The display control unit 55 then displays the generated fundus observation image in the fundus display area 402. The operator checks this fundus observation image and adjusts the focus by operating the focus adjustment button 404 on the display unit 400 so that the fundus observation image is brightest.

[0048] In step S4, the position of the internal fixation light is adjusted. Specifically, after generating and displaying the fundus observation image in step S3, the control unit 50 turns on the internal fixation light source IF and starts displaying the internal fixation light. The light is converted into parallel light by the collimator lens 103G and reaches the fundus Ef of the subject's eye E via the same optical path as the observation light described above.

[0049] The display control unit 55 displays an X mark 403 on the fundus display area 402 in accordance with the display position of the internal fixation light on the fundus oculi Ef. The operator specifies a desired position by manipulating the position of the X mark 403. The control unit 50 controls the timing of turning on the internal fixation light light source IF in accordance with the position specified by the operator, and displays the internal fixation light at the position specified by the operator.

[0050] At this time, a wavelength cut filter 204 arranged in the optical path in front of the light receiving element 202 blocks light of the wavelength of the internal fixation lamp light source IF. This prevents the light of the internal fixation lamp from appearing as noise in the fundus observation image. In addition, the wavelength cut filter 204 is arranged in the optical path between the diaphragm 203 and the light receiving element 202. This prevents any positioning error in the wavelength cut filter 204 from affecting the amount of light passing through the diaphragm 203.

[0051] If the photography mode selection in S0 includes the selection of fundus tomographic imaging, the process proceeds to S5, whereas if only frontal fundus imaging is selected, the process proceeds to S6.

[0052] In step S5, a fundus tomographic image for adjusting the coherence gate of the subject's eye E (hereinafter referred to as the "observation tomographic image") is generated and displayed in the tomographic image display area 405 of the display unit 400. The observation tomographic image may be a preview image obtained by roughly scanning the fundus Ef at high speed for various adjustments. The operator checks this observation tomographic image and adjusts the coherence gate by operating the coherence gate adjustment button 406 on the display unit 400 so that an image of the retinal layer is displayed at a predetermined position in the tomographic image display area 405. Furthermore, the operator can adjust the size and position of a frame 407 on the fundus display area 402 to specify the shooting position for the fundus tomographic image.

[0053] In step S6, the photographing button 408 on the display unit 400 is used as an input to photograph a front image and a tomographic image of the fundus. The photographing flow of the front image and the tomographic image of the fundus will be described in detail later. The photographed front image and the tomographic image of the fundus are stored in the memory unit 56.

[0054] In step S7, the images captured in step S6 are displayed. The captured frontal and tomographic images of the fundus may be displayed in the fundus display area 402 and the tomographic display area 405, or may be displayed in separate display areas.

[0055] The device may perform steps S1 to S5 in parallel. For example, the generation and position adjustment of an anterior segment image, the generation of a fundus observation image and adjustment of the internal fixation lamp position, and the generation of an observation tomographic image may be performed in parallel. In this case, the infrared laser light source 101IR used for the observation light and the internal fixation lamp light source IF used to display the internal fixation lamp are turned on, while the red laser light source 101R, green laser light source 101G, and blue laser light source 101B are turned off. Note that the light source used for the internal fixation lamp only needs to have a wavelength different from that of the light source used for the SLO. This allows the wavelength cut filter 204 to block only the light of the wavelength used for the internal fixation lamp, thereby preventing the light from the internal fixation lamp from being mixed in as noise in the SLO image.

[0056] <Fundus tomography and frontal fundus imaging sequence> Next, the details of the photographing flow in step S6 will be described with reference to the flowchart in FIG.

[0057] The control unit 50 detects that the photographing button 405 has been pressed and starts photographing a tomographic image of the fundus.

[0058] In step S601, a front image of the fundus for fundus tracking is stored in the storage unit 56 as a reference image.

[0059] In step S0, if the photography mode selected includes fundus tomographic imaging, the process proceeds to step S602, and if only fundus frontal imaging is selected, the process proceeds to step S604.

[0060] In step S602, the optical scanning control unit 52 controls the optical scanning unit 503 based on the specified imaging range to scan the fundus Ef with the measurement light, thereby performing a 3D scan of the subject's eye E. Furthermore, in parallel with the fundus tomographic image capture, a front image of the target fundus (target image) is captured. The control unit 50 calculates the positional deviation between the target image and the reference image as the amount of movement of the fundus Ef. Based on the calculated amount of movement, the optical scanning control unit 52 performs correction control of the irradiation position of the measurement light by the optical scanning unit 503.

[0061] The apparatus sequentially captures images in the scan mode selected as the imaging mode, and repeats capturing cross-sectional images of the fundus until the imaging in the selected scan mode is completed.

[0062] In step S603, the image generation unit 53 generates a projection image (pseudo SLO image) using the fundus tomographic image captured in step S602, and stores the projection image (pseudo SLO image) in the storage unit 56 as a reference image for fundus tracking. The projection image (pseudo SLO image) is an example of a third image. Because a fundus observation image cannot be captured while a frontal fundus image is being captured by SLO, a fundus tomographic image captured by OCT is used as the target image. Therefore, it is preferable that the target image and the reference image are captured using the same OCT optical system. This is because, if the same OCT optical system is used, errors due to the characteristics of the optical system are not added.

[0063] If the selected shooting mode does not include 3D scanning, a 3D scan may be performed to generate a pseudo-SLO image, and the generated pseudo-SLO image may be used as the reference image, or the frontal fundus image stored in step S601 may be used as the reference image.

[0064] The time period related to S601 to S604 is an example of the second time period.

[0065] If the photographing mode is set to photographing a frontal fundus image, the process proceeds to step S604.

[0066] In step S604, the wavelength switching unit 51 turns off the observation light (infrared laser light source 101IR). Furthermore, the optical scanning control unit 52 controls the optical scanning unit 5 to move the optical scanning unit 5 to the imaging start position. Note that the timing for turning off the observation light and moving the scanning unit 5 to the imaging start position may be arbitrary.

[0067] In step S605, the red laser light source 101R is turned on. When the wavelength switching unit 51 detects that the scanning unit 5 has moved to a predetermined scanning position, it turns on the red laser light source 101R. Then, the light intensity signal output from the light receiving unit 200 is converted into a digital signal and then input to the control unit 50. As a result, the control unit 50 acquires the digital signal of the red laser light. Furthermore, while capturing a frontal fundus image, a tomographic image of the fundus (target image) is captured. The control unit 50 calculates the positional deviation between the target image and the reference image as the amount of movement of the fundus Ef. Based on the calculated amount of movement, the optical scanning control unit 52 performs correction control of the irradiation position of the measurement light by the optical scanning unit 5. Details of fundus tracking in capturing a frontal fundus image will be described later.

[0068] At this time, the internal fixation light source IF is lit with its lighting timing controlled so as to display the internal fixation light according to the position specified by the operator. Specifically, while the red laser light remains lit while imaging is being performed, the internal fixation light source IF is controlled to turn on and off at shorter intervals to display the internal fixation light at the position specified by the operator. Since the fixation light is displayed with light of a wavelength different from the imaging wavelength, this is advantageous in improving the visibility of the fixation light.

[0069] When scanning with the red laser light is completed, wavelength switching unit 51 turns off red laser light source 101R.

[0070] In step S606, the blue laser light source 101B is turned on. The blue front fundus image capturing and fundus tracking are the same as those for the red front fundus image capturing (S605).

[0071] In step S607, the green laser light source 101G is turned on. Green front fundus image capturing and fundus tracking are the same as red front fundus image capturing (S605).

[0072] By performing the operations from step S605 to step S607 described above, the control unit 50 acquires a digital signal output by scanning with the red laser light, a digital signal output by scanning with the green laser light, and a digital signal output by scanning with the blue laser light. Note that the time related to the operations from step S605 to step S607 is an example of a first time. Also, the red, blue, and green front fundus images obtained by the operations from step S605 to step S607 are examples of first images.

[0073] In this embodiment, the red, blue, and green laser light sources each irradiate the subject's eye with the same optical power, and imaging is performed in the order of wavelengths that produce the lowest miosis rate in the eye's light reflex. However, the gist of the present disclosure is that imaging is performed in the order of lowest miosis rate, and if the miosis rate changes due to the amount of light irradiated to the subject's eye being different for each wavelength, this wavelength order is not essential.

[0074] After the photographing is completed, the wavelength switching unit 51 turns on the infrared laser light source 101IR as observation light.

[0075] After the photographing is completed, the image generating unit 53 generates a red fundus image from the digital signal output by scanning with the red laser light, generates a green fundus image from the digital signal output by scanning with the green laser light, and generates a blue fundus image from the digital signal output by scanning with the blue laser light. Then, the synthesis processing unit 54 synthesizes the red, green, and blue fundus images to generate a three-color pseudo-color fundus image. When synthesizing the fundus images of each color, positional deviation correction may be performed. The method of positional deviation correction will be described later. The synthesis processing unit 54 is an example of an image correcting unit. The red, green, and blue fundus images are examples of a fourth image.

[0076] <Fundus tracking> Next, the fundus tracking in the frontal fundus image capture in steps S605 to S607 will be described in detail with reference to Figures 5, 6, and 7. Fundus tracking is a process for correcting the irradiation position of the measurement light to follow the movement of the subject's eye when the subject's eye moves during frontal fundus image capture by SLO. In the fundus tracking of the present disclosure, a fundus tomographic image captured by OCT is used to detect whether the subject's eye has moved.

[0077] FIG. 5(b) is a detailed flowchart of step S605 (capturing a frontal image of the red fundus) in FIG. 5(a).

[0078] When the photographing of the frontal image of the red fundus is started in step S605, the optical scanning control unit 52 controls the optical scanning unit 5 to start scanning with the red laser light in step S611.

[0079] Subsequently, in step S612, the control unit 50 acquires a tomographic image of the fundus (target image).

[0080] Subsequently, in step S613, the control unit 50 compares the fundus tomographic image (target image) with the reference image to detect whether or not there is a positional deviation.

[0081] Next, in step S614, if there is a positional deviation, the process proceeds to step S615, whereas if there is no positional deviation, the process proceeds to step S616.

[0082] If there is a positional deviation, the optical scanning control unit 52 performs correction control of the irradiation position of the measurement light by the optical scanning unit 5 in step S615.

[0083] Subsequently, in step S616, the control unit 50 determines whether scanning by the optical scanning unit 5 has been completed, and if not, returns to step S612. If completed, the process of photographing a frontal image of the red fundus is terminated.

[0084] In fundus tracking, the target image, that is, a fundus tomographic image, needs to be acquired in a short time. This is because feedback control (control for acquiring a fundus tomographic image, calculating the amount of positional deviation, and correcting the irradiation position of the measurement light according to the calculated amount of positional deviation) needs to be performed while the frontal fundus image is being captured by SLO. Therefore, when acquiring the target image, that is, a fundus tomographic image, it is advisable to reduce the number of scans or the imaging angle of view (scan length). On the other hand, it is necessary to be able to accurately calculate the amount of positional deviation even when the imaging angle of view is reduced. To accurately calculate the amount of positional deviation, it is necessary to scan an area that includes feature points for calculating the amount of positional deviation.

[0085] In the present disclosure, the number of scans for acquiring the target image is made smaller than the number of scans for acquiring the tomographic image in S602, and the imaging angle of view (scan length) for acquiring the target image is made smaller than the imaging angle of view (scan length) for acquiring the tomographic image in S602, thereby increasing the frequency of acquiring the target image during fundus front image capture.

[0086] Furthermore, in this disclosure, the optic disc and the like are used as feature points for calculating the amount of positional displacement, and therefore the imaging angle of view (imaging area) is the area indicated by the dashed line in FIG. 6(a). This area includes the optic disc D, macula M, and large blood vessels B1 to B4. Because these are easily recognized as feature points, it is desirable to acquire the target image by scanning through these points in particular within this area. Note that the horizontal distance within this area is the distance from the optic disc D to the macula M, and the vertical distance is the distance that includes the large blood vessels B1 to B4. Examples of scanning include cross scans (one horizontal scan and one vertical scan) that pass through the optic disc, such as X scan L1 and Y scan L2, and cross scans that pass through large blood vessels, such as X scan L3 and Y scan L4. As in X scan L1 and Y scan L4, the X scan may be a scan that passes through the optic disc, and the Y scan may be a scan that passes through large blood vessels. The scanning position may be a scanning position that passes through a point (feature point) where there is a large change in brightness in the reference image stored in step S601 or S603.

[0087] Here, a specific fundus tracking process will be described with reference to Fig. 6. The graph on the bottom of Fig. 6(a) shows the luminance value at the L1 position in the reference image and the luminance value of the X scan L1, which is the target image, and the graph on the right shows the luminance value at the L2 position in the reference image and the luminance value of the Y scan L2, which is the target image.

[0088] If the position of the feature point of the luminance value at the L1 position in the reference image is x1 and the position of the feature point of the luminance value of the X-scan L1, which is the target image, is x2, the control unit 50 calculates the amount of displacement dx from x2 - x1. Then, the optical scanning control unit 52 uses the amount of displacement dx to control the correction of the irradiation position of the measurement light by the optical scanning unit 5. Also, if the position of the feature point of the luminance value at the L2 position in the reference image is y1 and the position of the feature point of the luminance value when the Y-scan L2, which is the target image, is corrected by dx is y2, the control unit 50 calculates the amount of displacement dy from y2 - y1. Then, the optical scanning control unit 52 uses the amount of displacement dy to control the correction of the irradiation position of the measurement light by the optical scanning unit 5.

[0089] Even if a cross scan with a reduced angle of view is used as the target image, it is difficult to measure the target image with one A-scan for capturing a frontal fundus image, calculate the deviation, and perform position correction to detect deviation. It is more realistic to perform deviation detection with multiple A-scans for capturing a frontal fundus image. For this reason, Figure 7 shows an example in which the number of scans is reduced without reducing the imaging angle of view. In Figure 7, position deviation is detected by scanning at equal intervals, such as X1 to X9.

[0090] When capturing red, green, and blue front fundus images by performing the operations from step S605 to step S607 described above, it is desirable to acquire the target image, that is, the fundus tomographic image, at the same time. An example is shown in FIG. 6(b). The left diagram of FIG. 6(b) shows the capture of a front fundus image using a red laser in step S605. In this capture, the target image, that is, the fundus tomographic image, is acquired by four scans, L1R to L4R. The middle diagram of FIG. 6(b) shows the capture of a front fundus image using a blue laser. In this capture, the target image, that is, the fundus tomographic image, is acquired by four scans, L1B to L4B. The right diagram of FIG. 6(b) shows the capture of a front fundus image using a green laser. In this capture, the target image, that is, the fundus tomographic image, is acquired by four scans, L1G to L4G. As shown by the dashed lines in Figure 6(b), horizontal scans L1R, L1B, and L1G are performed at the same time. Similarly, L3R, L3B, and L3G are performed at the same time. Similarly, vertical scans L2R, L2B, and L2G are performed at the same time. Similarly, L4R, L4B, and L4G are performed at the same time. In this way, by acquiring the target fundus tomographic images at the same time, it is possible to reduce color bleeding in the pseudo-color fundus image obtained by combining the red, green, and blue fundus images.

[0091] <Position misalignment correction> Next, the correction of positional deviation of the frontal fundus image performed by the synthesis processing unit 54 will be described with reference to FIG.

[0092] Fig. 7 shows a front fundus image captured by SLO. While the front fundus image is shown as one captured using a red laser, it may also be one captured using a blue laser or a green laser. Fig. 7 also shows X1 to X9 as areas where the synthesis processor 54 detects misalignment. The synthesis processor 54 compares, for example, the upper image and the lower image of X1 to detect whether misalignment has occurred.

[0093] If a positional deviation is detected, the synthesis processing unit 54 corrects the frontal fundus image according to the amount of positional deviation. For example, if no positional deviation is detected at X1 but a positional deviation is detected at X2, it is determined that a positional deviation has occurred between X1 and X2, and the frontal fundus image is corrected according to the amount of positional deviation at X2. Alternatively, without performing correction, the area between X1 and X2 may be displayed as a low-reliability area (an area where there is a possibility of positional deviation), superimposed on the frontal fundus image.

[0094] Furthermore, when misalignment is detected consecutively, the image may be corrected by interpolation, assuming that the amount of movement of the fundus oculi Ef is linear. For example, when misalignment is detected at X5 and at X6, the image between X5 and X6 may be corrected by interpolation. Here, the interpolation is a process of estimating the amount of misalignment of the image between X5 and X6 (strip-shaped image) using the amount of misalignment of X5 and the amount of misalignment of X6, and correcting the amount of misalignment of the image between X5 and X6 using the estimated amount of misalignment.

[0095] Furthermore, for example, if a positional deviation is detected in the red frontal fundus image but not in the blue frontal fundus image, the synthesis processing unit 54 may correct the amount of positional deviation in the red frontal fundus image using the blue frontal fundus image. Specifically, for example, if a positional deviation is detected at X2 in the red frontal fundus image, the synthesis processing unit 54 may correct the image between X1 and X2 in the red frontal fundus image (a strip-shaped image) using feature points such as blood vessels included in X1 to X2 in the blue frontal fundus image. The red frontal fundus image is an example of the fourth image, and the blue frontal fundus image is an example of the fifth image.

[0096] The synthesis processing unit 54 may perform synthesis processing to synthesize the red fundus image, the green fundus image, and the blue fundus image after correcting the positional deviation using the above-mentioned method.

[0097] <Chromatic aberration correction> When performing the above-described positional deviation correction, lateral chromatic aberration correction may also be performed. Lateral chromatic aberration refers to the change in imaging magnification depending on the wavelength used. Basically, the magnification changes depending on the wavelength around the optical axis, and the rate of change can be considered to be approximately linear. Therefore, when attempting to perform detailed alignment, for example, the magnifications of a red fundus image and a blue fundus image are different, and alignment at the center may result in misalignment at the edge of the angle of view. Therefore, by performing alignment after correcting this lateral chromatic aberration, more accurate alignment can be performed, making it possible to obtain clear color fundus images.

[0098] When the reference image is a fundus observation image and the target image is a fundus tomographic image, the wavelengths of the light sources used to acquire the images are different. Therefore, when calculating the amount of deviation in fundus tracking, the accuracy is improved by correcting the chromatic aberration of magnification before calculation.

[0099] <Axial chromatic aberration correction> It is further preferable to capture each color at the optimal focus position in steps S605, S606, and S607. To capture an RGB color SLO image as in the present disclosure, it is necessary to adjust the focus over a very wide range of wavelength bands. However, it is extremely difficult to achieve focus at the same point in all wavelength bands with a refractive optical system due to the effects of axial chromatic aberration. Therefore, when capturing each color, it is preferable to adjust the focus to the optimal position before scanning the light, and then start scanning the light to acquire data.

[0100] Specifically, the focus is adjusted when observing the fundus using an infrared laser light source (IR laser light source). At this time, the observation image may be displayed on a display member, and the displayed image may be observed and focused with the eyes. Automatic control may also be performed to maximize the brightness value of the obtained image.

[0101] With this configuration, it is possible to reduce the burden on the subject when photographing a frontal fundus image and to obtain an image of the subject's eye with little distortion.

[0102] In this embodiment, it has been described that the fundus tomographic image (target image) is compared with the reference image, and if there is a positional deviation, the light scanning unit 5 corrects the irradiation position of the measurement light. However, this is not limited to this. For example, the fundus front image (target image) may be compared with the reference image, and if there is a positional deviation, the light scanning unit 503 may correct the irradiation position of the measurement light.

[0103] Example 2 In Example 1, fundus tracking scans for photographing a frontal fundus image were performed using cross scans (one horizontal scan and one vertical scan), and correction for XY deviation was performed. However, this scanning method cannot detect rotational deviation of the subject's eye E. In this example, the fundus tracking scanning method is changed to accommodate rotational deviation. The device configuration and flowchart are the same as those in Example 1, and therefore a description thereof will be omitted.

[0104] As a fundus tracking scan, for example, by performing two scans in the same direction, such as X scan L1, X scan L3, and Y scan L2 or X scan L1, Y scan L2, and Y scan L4 in Figure 6, it is possible to detect rotational misalignment in addition to XY misalignment.

[0105] Rotational misalignment can also be detected by performing a roughly circular scan as shown in Figure 8. The circular scan S1 is designed to pass through the optic disc and large blood vessels, which are characteristic points.

[0106] By scanning in a roughly circular shape, the amount of scanning can be reduced, and the frequency of acquiring target images during frontal fundus image capture can be increased. Note that rotational misalignment can also be detected by scanning in an elliptical shape, not just a circular shape.

[0107] (Other embodiments) The disclosed technology can also be realized by executing the following process. That is, the disclosed technology can also be realized by supplying software (programs) that realize one or more functions of the various embodiments described above to a system or device via a network or a storage medium, and having a computer (or a CPU, MPU, or the like) of the system or device read and execute the programs. The computer has one or more processors or circuits, and may include multiple separate computers or a network of multiple separate processors or circuits to read and execute computer-executable instructions. In this case, the processor or circuit may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), or a field-programmable gateway (FPGA). The processor or circuit may also include a digital signal processor (DSP), a data flow processor (DFP), or a neural processing unit (NPU).

[0108] (Configuration 1) a first imaging unit that scans the subject's eye in two dimensions to capture an image; a second imaging unit that scans the subject's eye in three dimensions to capture an image; a correction unit that corrects the position of a scan by the first imaging unit performed at a first time based on a first image obtained by a scan by the second imaging unit performed while the scan is being performed, and one of a second image obtained by a scan by the first imaging unit performed at a second time before the first time and a third image obtained by a scan by the second imaging unit; An ophthalmic device comprising:

[0109] (Configuration 2) 2. The ophthalmologic apparatus according to configuration 1, wherein the number of scans performed by the second imaging unit in the first period is smaller than the number of scans performed by the second imaging unit in the second period.

[0110] (Configuration 3) 3. The ophthalmologic apparatus according to configuration 1 or 2, wherein the number of scans performed by the second imaging unit during the first period is one in the horizontal direction and one in the vertical direction of the subject's eye.

[0111] (Configuration 4) An ophthalmologic apparatus according to any one of configurations 1 to 3, wherein the number of scans performed by the second photographing unit during the first time period is two in one of the horizontal and vertical directions of the subject's eye and one in the other.

[0112] (Configuration 5) 5. The ophthalmologic apparatus according to any one of configurations 1 to 4, wherein at least one of the scans performed by the second imaging unit during the first time period is a scan passing through the optic disc of the subject's eye.

[0113] (Configuration 6) 6. The ophthalmologic apparatus according to any one of configurations 1 to 5, wherein the scan performed by the second imaging unit at the first time is a circular or elliptical scan surrounding the optic disc.

[0114] (Configuration 7) 7. The ophthalmologic apparatus according to any one of configurations 1 to 6, wherein the position of the scan performed by the second photographing unit at the first time is determined based on the luminance of the second image or the luminance of the third image.

[0115] (Configuration 8) the scanning by the first imaging unit includes scanning with an infrared laser light, scanning with a red laser light, scanning with a blue laser light, and scanning with a green laser light; the scanning performed by the first imaging unit at the first time period includes scanning with the red laser light, scanning with the blue laser light, and scanning with the green laser light; 8. The ophthalmologic apparatus according to any one of configurations 1 to 7, wherein the scanning performed by the first photographing unit at the second time is scanning with the infrared laser light.

[0116] (Configuration 9) a scanning position of the second imaging unit performed while scanning with the red laser light is being performed; a scanning position of the second imaging unit performed while scanning with the blue laser light is being performed; a scanning position of the second imaging unit performed while scanning with the green laser light is being performed; 9. The ophthalmic apparatus of claim 8, wherein

[0117] (Configuration 10) an image correcting unit that corrects a fourth image obtained by scanning by the first imaging unit performed at the first time; 10. The ophthalmologic apparatus according to any one of configurations 1 to 9, wherein the image correction unit corrects the fourth image based on the first image and one of the second image and the third image.

[0118] (Configuration 11) 11. The ophthalmologic apparatus according to configuration 10, wherein the image correction unit detects a positional deviation in the fourth image, and when a plurality of positional deviations are detected, corrects the fourth image by interpolation processing.

[0119] (Configuration 12) The ophthalmologic apparatus of configuration 10 or 11, wherein the image correction unit detects a positional shift in the fourth image, and when the positional shift is detected, corrects the fourth image using the fifth image that is different from the fourth image.

[0120] (Configuration 13) a first imaging unit and a second imaging unit that scan an eye to capture an image, one of the first imaging unit and the second imaging unit scans the subject's eye in two dimensions to capture an image, and the other scans the subject's eye in three dimensions to capture an image; a correction unit that corrects the position of a scan by the first imaging unit performed at a first time based on a first image obtained by a scan by the second imaging unit performed while the scan is being performed, and one of a second image obtained by a scan by the first imaging unit performed at a second time before the first time and a third image obtained by a scan by the second imaging unit; An ophthalmic device comprising:

[0121] (Method 1) a first imaging unit that scans the subject's eye in two dimensions to capture an image; a second imaging unit that scans the subject's eye in three dimensions to capture an image; A control method for an ophthalmic apparatus comprising: A control method for an ophthalmic apparatus, comprising a correction step of correcting the position of the scanning of the first photographing unit performed at a first time based on a first image obtained by scanning of the second photographing unit performed while the first scanning is being performed, and one of a second image obtained by scanning of the first photographing unit performed at a second time before the first time and a third image obtained by scanning of the second photographing unit.

[0122] (Program 1) A program for executing the method for controlling an ophthalmic apparatus according to Method 1. [Explanation of symbols]

[0123] 100 Optical output section 5 Optical scanning unit 507 Measurement light source 503 Optical scanning unit 50 control section 52 Scanning control section 53 Image generation unit 56 Memory section

Claims

1. a first imaging unit that scans the subject's eye in two dimensions to capture an image; a second imaging unit that scans the subject's eye in three dimensions to capture an image; a correction unit that corrects the position of a scan by the first imaging unit performed at a first time based on a first image obtained by a scan by the second imaging unit performed while the first scan is being performed, and one of a second image obtained by a scan by the first imaging unit performed at a second time before the first time and a third image obtained by a scan by the second imaging unit; An ophthalmic device comprising:

2. The ophthalmologic apparatus according to claim 1 , wherein the number of scans performed by the second imaging unit during the first period is smaller than the number of scans performed by the second imaging unit during the second period.

3. 2. The ophthalmologic apparatus according to claim 1, wherein the number of scans performed by the second imaging unit during the first period is one in the horizontal direction and one in the vertical direction of the subject's eye.

4. 2. The ophthalmologic apparatus according to claim 1, wherein the number of scans performed by the second imaging unit during the first period is two in one of the horizontal and vertical directions of the subject's eye and one in the other direction.

5. 2. The ophthalmologic apparatus according to claim 1, wherein at least one of the scans performed by the second imaging unit during the first time period is a scan that passes through the optic disc of the subject's eye.

6. 2. The ophthalmologic apparatus according to claim 1, wherein the scanning performed by the second imaging unit during the first period is a circular or elliptical scanning that surrounds the optic disc.

7. The ophthalmologic apparatus according to claim 1 , wherein the position of the scan performed by the second imaging unit at the first time is determined based on the luminance of the second image or the luminance of the third image.

8. the scanning by the first imaging unit includes scanning with an infrared laser light, scanning with a red laser light, scanning with a blue laser light, and scanning with a green laser light; the scanning performed by the first imaging unit during the first time period includes scanning with the red laser light, scanning with the blue laser light, and scanning with the green laser light; The ophthalmologic apparatus according to claim 1 , wherein the scanning performed by the first photographing unit during the second period is scanning with the infrared laser light.

9. a scanning position of the second imaging unit performed while scanning with the red laser light is being performed; a scanning position of the second imaging unit performed while scanning with the blue laser light is being performed; a scanning position of the second imaging unit performed while scanning with the green laser light is being performed; The ophthalmic apparatus according to claim 8, wherein

10. an image correcting unit that corrects a fourth image obtained by scanning the first imaging unit at the first time; The ophthalmologic apparatus according to claim 1 , wherein the image corrector corrects the fourth image based on the first image and one of the second image and the third image.

11. The ophthalmologic apparatus according to claim 10 , wherein the image correcting unit detects a positional deviation in the fourth image, and when a plurality of positional deviations are detected, corrects the fourth image by interpolation processing.

12. The ophthalmologic apparatus according to claim 10 , wherein the image correction unit detects a positional deviation in the fourth image, and when the positional deviation is detected, corrects the fourth image using the fifth image that is different from the fourth image.

13. a first imaging unit and a second imaging unit that scan an eye to capture an image, one of the first imaging unit and the second imaging unit scans the subject's eye two-dimensionally to capture an image, and the other scans the subject's eye three-dimensionally to capture an image, a correction unit that corrects the position of a scan by the first imaging unit performed at a first time based on a first image obtained by a scan by the second imaging unit performed while the first scan is being performed, and one of a second image obtained by a scan by the first imaging unit performed at a second time before the first time and a third image obtained by a scan by the second imaging unit; An ophthalmic device comprising:

14. a first imaging unit that scans the subject's eye in two dimensions to capture an image; a second imaging unit that scans the subject's eye in three dimensions to capture an image; A control method for an ophthalmic apparatus comprising: A control method for an ophthalmic device, comprising a correction step of correcting the position of a scan of the first photographing unit performed at a first time based on a first image obtained by a scan of the second photographing unit performed while the first scan is being performed, and one of a second image obtained by a scan of the first photographing unit performed at a second time before the first time and a third image obtained by a scan of the second photographing unit.

15. A program for executing the method for controlling an ophthalmic apparatus according to claim 14.

Images