Ophthalmic imaging equipment

Abstract

To provide an ophthalmologic imaging apparatus capable of acquiring a front image of an eye to be examined appropriately.SOLUTION: An ophthalmologic imaging apparatus includes: an OCT optical system for acquiring a tomographic image of the eye; an observation optical system having an optical scanner for displacing a scan line to a direction intersecting with the scan line on an eye to be examined for acquiring a front image based on a plurality of scan lines; OCT control means for controlling the OCT optical system and executing OCT imaging for acquiring tomographic images repeatedly; observation control means for acquiring a first front image by controlling the observation optical system, and repeatedly acquiring a second front image in which the scan lines are thinned for the first front image by controlling the observation optical system in parallel with the OCT imaging; and front image processing means for setting the first front image to image data for recording corresponding to the tomographic image acquired by the OCT imaging, and detecting a positional deviation caused during the OCT imaging by processing the second front image acquired repeatedly.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to an ophthalmologic imaging apparatus that captures an image of an eye to be examined. [Background technology]

[0002] There is known an ophthalmologic imaging device that includes an OCT (Optical Coherence Tomography) optical system for acquiring OCT data of a subject's eye and an optical system for acquiring a front image of the subject's eye. For example, in such a device, the front image is repeatedly acquired in parallel with the acquisition of the OCT data. Then, a deviation of the scanning position of the measurement light in the OCT optical system is detected based on the repeatedly acquired front images, and the scanning position is corrected based on the deviation (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-140491 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described device, the more frequently the deviation of the scanning position of the measurement light is detected, the more accurately the scanning position of the measurement light of the OCT optical system is corrected. However, for example, if the frame rate at which the front images are repeatedly acquired is increased in order to increase the deviation detection frequency, the image quality of the front images may be reduced. In this case, observation using the front images becomes difficult.

[0005] In view of the above problems, the present disclosure has as its technical object to provide an ophthalmologic imaging apparatus that can obtain a good front image of the subject's eye. [Means for solving the problem]

[0006] an observation optical system having an optical scanner for displacing a scanning line on the eye to be examined in a direction intersecting the scanning line and for acquiring a front image based on a plurality of scanning lines; an OCT control means for controlling the OCT optical system to perform OCT imaging to repeatedly acquire the tomographic images; an observation control means for controlling the observation optical system to acquire a first front image and for repeatedly acquiring a second front image obtained by thinning out the scanning lines from the first front image by controlling the observation optical system in parallel with the OCT imaging; and a front image processing means for setting the first front image as image data for recording corresponding to the tomographic image acquired by the OCT imaging, and for processing the repeatedly acquired second front image to detect positional deviation occurring during the OCT imaging. The observation control means acquires the first front image and the second front image based on an imaging signal for starting acquisition of the second front image. . an observation optical system having an optical scanner for displacing a scanning line on the subject's eye in a direction intersecting the scanning line and for acquiring a front image based on a plurality of scanning lines; an OCT control means for controlling the OCT optical system to perform OCT photography to repeatedly acquire the tomographic images; an observation control means for controlling the observation optical system to acquire a first front image and for repeatedly acquiring a second front image in which the scanning lines are thinned out relative to the first front image by controlling the observation optical system in parallel with the OCT photography; and a front image processing means for setting the first front image as image data for recording corresponding to the tomographic image acquired by the OCT photography, and for processing the repeatedly acquired second front image to detect positional deviations that occurred during the OCT photography, wherein the observation control means acquires the second front image during at least a part of the optimization process based on an optimization signal for starting the optimization process of the OCT photography, and acquires the first front image after the optimization process is completed. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating the configuration of an ophthalmologic imaging apparatus according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram illustrating the interval between scanning lines and the frame rate. [Figure 3] FIG. 2 is a flowchart showing the flow of operations in the present embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of a display screen displayed on a display unit. [Figure 5] 10 is a time chart of a control operation when a recorded image is saved and a capture operation is started. [Figure 6] FIG. 4 is a diagram illustrating an example of a display screen displayed on a display unit. DETAILED DESCRIPTION OF THE INVENTION

[0008] [overview] An embodiment of an ophthalmologic imaging apparatus according to the present disclosure will be described. The items grouped in < > below can be used independently or in conjunction with each other.

[0009] The ophthalmic imaging device of this embodiment (for example, imaging device 1) is a device for imaging an eye to be examined. For example, the ophthalmic imaging device includes an OCT optical system (for example, OCT optical system 100). Also, for example, the ophthalmic imaging device includes an observation optical system (for example, observation optical system 200). Also, for example, the ophthalmic imaging device includes OCT control means (for example, control unit 70). Also, for example, the ophthalmic imaging device includes observation control means (for example, control unit 70). Also, for example, the ophthalmic imaging device includes front image processing means (for example, control unit 70).

[0010] <OCT optical system> The OCT optical system is an optical system for processing an interference signal between measurement light and reference light irradiated to the eye to be examined and acquiring a tomographic image of the eye to be examined. For example, the OCT optical system may have a Fourier domain OCT optical system as a basic configuration. As the Fourier domain OCT optical system, it may be a spectral domain OCT (SD-OCT) optical system or a wavelength swept OCT (SS-OCT) optical system. Also, for example, the OCT optical system may have a time domain OCT (TD-OCT) as a basic configuration.

[0011] In addition, it is also possible to apply the technology of this embodiment to intensity OCT for detecting the reflection intensity of the eye to be examined, OCT angiography (for example, Doppler OCT) for detecting motion contrast data of the eye to be examined, polarization sensitive OCT (PS-OCT), multi-functional OCT in which intensity OCT and PS-OCT are combined, and the like.

[0012] For example, the tomographic image of the subject eye may be at least any one of an A-scan tomographic image, a B-scan tomographic image, a three-dimensional tomographic image, etc. Note that the B-scan tomographic image may be a tomographic image obtained by scanning the measurement light in any direction in the XY direction along the scanning line (transverse position). This may include a two-dimensional OCT angiographic image or the like. The three-dimensional tomographic image may be a tomographic image obtained by two-dimensionally scanning the measurement light. This may include a three-dimensional OCT angiographic image. Also, for example, the tomographic image of the subject eye may be an en face image based on such a tomographic image. This may include an OCT en face image, an en face motion contrast image, etc.

[0013] <OCT control means> The OCT control means executes OCT imaging that controls the OCT optical system to repeatedly acquire tomographic images. For example, the OCT control means may scan the measurement light on the subject eye and acquire an interference signal at each scanning position on the subject eye. The measurement light may be scanned in either the X direction or the Y direction along a scanning line corresponding to various scanning patterns (as an example, line, cross, multi, map, radial, circle, etc.), or may be two-dimensionally scanned. Also, for example, the OCT control means may acquire a tomographic image based on the interference signal at each scanning position.

[0014] The OCT control means may acquire a tomographic image based on the interference signal with respect to the scanning position of the measurement light on the subject eye. Also, the OCT control means may acquire a motion contrast image based on at least two interference signals acquired at different times with respect to the same scanning position of the measurement light on the subject eye. Of course, the OCT control means may acquire an image different from the tomographic image and the motion contrast image.

[0015] <Observation optical system> The observation optical system has an optical scanner (e.g., a galvanometer scanner 212) that displaces a scanning line that scans the observation light on the subject's eye in a direction that intersects with the scanning line, and is an optical system for acquiring a front image based on a plurality of scanning lines. For example, a reflective mirror (e.g., a galvanometer mirror, a polygon mirror, a resonant scanner, etc.) may be used as the optical scanner. Alternatively, an acousto-optical element that changes the traveling direction of light may be used as the optical scanner.

[0016] The observation optical system may be any optical system that scans the subject's eye with observation light and acquires a front image of the subject's eye. For example, it may be an SLO optical system that scans the subject's eye with observation light two-dimensionally and acquires an SLO front image of the subject's eye. Of course, it may be an optical system other than the SLO optical system.

[0017] <Observation control means> The observation control means controls the observation optical system to acquire a first front image, and also controls the observation optical system in parallel with the OCT imaging to repeatedly acquire a second front image in which the scanning lines are thinned out relative to the first front image.

[0018] The observation control means may acquire a first front image by controlling the optical scanner under certain observation conditions. The observation control means may also acquire a second front image by changing the observation conditions and controlling the optical scanner. For example, the observation control means may change the observation conditions and adjust the displacement amount of the scanning lines. As an example, the displacement amount of the scanning lines may be adjusted by changing the scanning speed in the direction intersecting the scanning lines. This changes the spacing between the scanning lines, and the number of scanning lines in the second front image relative to the first front image can be thinned.

[0019] The number of scanning lines for acquiring the second front image may be smaller than the number of scanning lines for acquiring the first front image. For example, the number of scanning lines for the second front image may be half the number of scanning lines for the first front image. Of course, the number of scanning lines may be different from half.

[0020] For example, by thinning out the number of scanning lines, the time required to acquire one front image in the observation optical system is shortened, resulting in an increased frame rate. In other words, the frame rate at which the second front image is repeatedly acquired is higher than the frame rate at which the first front image is acquired. As a result, the second front image has higher image quality than the first front image.

[0021] The angles of view of the first front image and the second front image may be maintained or changed. As an example, if the angles of view of these front images are maintained, the scanning lines may be thinned out so that the intervals between the scanning lines in the sub-scanning direction are increased. Of course, the method of thinning out the scanning lines is not limited to this.

[0022] The observation control means may acquire the first front image and the second front image based on an imaging signal for starting acquisition of the second front image. For example, the imaging signal may be output by the examiner operating the operating means. Also, for example, the imaging signal may be output based on a program that automatically proceeds with imaging of the subject's eye. Note that the imaging signal for starting acquisition of the second front image may also serve as a signal for acquiring a tomographic image. However, in this case, acquisition of the tomographic image and start of acquisition of the second front image do not necessarily have to be performed at the same time.

[0023] The first front image may be acquired at any timing based on the imaging signal. For example, the first front image may be an image that has already been captured before the imaging signal is received, and such an image may be acquired as the first front image in response to the imaging signal. Furthermore, for example, the first front image may be an image that is captured after the imaging signal is received, and the first front image may be captured and acquired in response to the imaging signal.

[0024] In this embodiment, the observation control means may acquire the front image immediately before receiving the imaging signal as the first front image based on an imaging signal for starting acquisition of the second front image, and may switch from acquiring the first front image to acquiring the second front image. This allows the observation control means to start acquiring the second front image immediately after receiving the imaging signal. This prevents OCT imaging from being performed at a position other than the desired position due to eye movement or the like between the time when the imaging signal is acquired and the time when the first second front image is acquired (details will be described later). Furthermore, there may be a mismatch between the time when the examiner wants to capture a front image of the subject's eye and the time when the imaging signal is input, causing the subject's eye to move (e.g., blink) at the time the imaging signal is input. Even in such a case, by acquiring the front image immediately before inputting the imaging signal, it is possible to acquire the front image of the subject's eye at the time when the examiner wants to capture it.

[0025] In this embodiment, the OCT control means may perform focus adjustment, adjustment of the optical path length difference between the reference optical path and the measurement optical path, and adjustment of the polarization of the measurement light as part of the optimization process for OCT imaging. In this case, the observation control means may acquire a second front image during at least part of the optimization process based on an optimization signal for starting the optimization process for OCT imaging, and acquire a first front image after the optimization process is completed. That is, when the optimization process for OCT imaging is performed, the observation optical system may be controlled to acquire the second front image by thinning out at least some of the scanning lines from the first front image. Furthermore, after the optimization process for OCT imaging is completed, the observation optical system may be controlled to restore the number of scanning lines. In this way, the frame rate of the front image is increased when the optimization process for OCT imaging is performed. For example, the optimization process for OCT imaging is performed with reference to the image quality of the front image acquired in real time. Therefore, increasing the frame rate for acquiring the front image allows for efficient adjustment of the imaging conditions for OCT imaging. As an example, by increasing the frame rate of the front image, the focus of the front image is adjusted more quickly, and further, the focus of the tomographic image is adjusted in conjunction with the focus of the front image, thereby enabling efficient focus adjustment.

[0026] <Front image processing means> The front image processing means sets the first front image as image data for recording corresponding to the tomographic image acquired by OCT imaging. Generally, the first image in the repeated front images (i.e., the first front image obtained by thinning out the number of scanning lines) that corresponds to the tomographic image acquired by OCT imaging is often set as image data for recording. This is because it is easy to correlate the tomographic image in the OCT optical system with the front image in the observation optical system. However, as described above, this may result in a decrease in image quality, making it impossible to perform appropriate observation. In this embodiment, the first front image has a higher number of scanning lines than the second front image, resulting in better image quality. By using such a first front image, the subject's eye can be observed appropriately.

[0027] The front image processing means further processes the repeatedly acquired second front images to detect misalignment that occurred during OCT imaging. The second front images have a lower image quality due to the thinning of the number of scan lines, but have a higher frame rate than the first front images. Therefore, by using such second front images, the frequency of misalignment detection can be increased.

[0028] The front image processing means may detect misalignment that occurs during OCT imaging each time a second front image is acquired. For example, the front image processing means may detect misalignment through image processing by comparing the second front image repeatedly acquired by the observation optical system with a reference image for detecting misalignment. Note that the reference image may be set to either the first front image or the second front image.

[0029] For example, the scanning position of the observation hole may be corrected by the observation control means based on the positional deviation detected by the front image processing means. Also, for example, the scanning position of the measurement light may be corrected by the OCT control means based on the positional deviation detected by the front image processing means. Since the movement of the subject's eye is tracked and the scanning position is changed as appropriate, an appropriate tomographic image can be obtained.

[0030] In this embodiment, the first front image may be stored as image data for recording and used for follow-up. That is, even if the subject's eye is photographed on a different day, different image data for recording, in which the scanning positions of the measurement light are consistent with each other, can be easily obtained by using the first front image (an image in which the scanning lines are not thinned out). The process performed during follow-up can use the method described in JP 2021-53197 A.

[0031] [Example] In the following description, a fundus imaging device that captures images of the fundus of a subject's eye will be used as an example of an ophthalmic imaging device. However, the ophthalmic imaging device is not limited to a fundus imaging device, and may include an anterior segment imaging device that captures images of the anterior segment of a subject's eye.

[0032] Referring to FIG. 1, the schematic configuration of the ophthalmic imaging device 10 according to this embodiment will be described. The ophthalmic imaging device 10 of this embodiment mainly includes an OCT optical system 100, an observation optical system 200, a fixation target projection unit 300, and a control unit 70.

[0033] <OCT optical system> The OCT optical system 100 is an optical interference optical system for acquiring a tomographic image of the tissue (e.g., fundus Ef) of the subject eye E, and has a configuration of an optical coherence tomography (OCT). Specifically, the OCT optical system 100 mainly includes a measurement light source 102, a coupler (optical splitter) 104, a measurement optical system 106, a reference optical system 110, and a detector (light receiving element) 120. <

[0034] More specifically, the coupler (optical splitter) 104 splits the light emitted from the measurement light source 102 into the optical path of the measurement optical system 106 and the optical path of the reference optical system 110. The measurement optical system 106 guides the measurement light to the fundus Ef of the eye E. The reference optical system 110 generates reference light. The OCT optical system 100 combines the measurement light reflected by the fundus Ef and the reference light. The detector 120 (light receiving element) receives the combined light.

[0035] The OCT optical system 100 includes an irradiation position changing unit (e.g., an optical scanner 108, a fixation target projection unit 300) for changing the irradiation position of the measurement light on the fundus Ef in order to change the imaging position on the fundus Ef. The control unit 70 controls the operation of the irradiation position changing unit based on the set imaging position information, and acquires a tomographic image based on the light receiving signal from the detector 120.

[0036] The detector 120 (light receiving element) detects the interference state between the measurement light and the reference light. In the case of Fourier-domain OCT, the detector 120 detects the spectral intensity of the interference light, and a depth profile (A-scan signal) in a predetermined range is acquired by Fourier transforming the spectral intensity data. Various OCTs can be used in the ophthalmic imaging apparatus 10. For example, the ophthalmic imaging apparatus 10 may use any of spectral-domain OCT (SD-OCT), swept-source OCT (SS-OCT), time-domain OCT (TD-OCT), etc.

[0037] The optical scanner 108 scans the fundus of the subject's eye with light emitted from a measurement light source. For example, the optical scanner 108 scans the fundus with measurement light two-dimensionally (in the X and Y directions (transverse directions)). The optical scanner 108 is disposed at a position approximately conjugate with the pupil. The optical scanner 108 is, for example, two galvanometer mirrors, and the reflection angle thereof is arbitrarily adjusted by the drive mechanism 50.

[0038] As a result, the reflection (traveling) direction of the light beam emitted from the light source 102 is changed, and the light beam is scanned in any direction on the fundus Ef. This changes the imaging position on the fundus Ef. The optical scanner 108 may be configured to deflect light. For example, a reflecting mirror (galvanometer mirror, polygon mirror, resonant scanner), an acousto-optic element (AOM) that changes the traveling (deflection) direction of light, or the like may be used.

[0039] The reference optical system 110 generates reference light. As described above, the reference light is combined with reflected light obtained by reflection of the measurement light at the fundus Ef. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type. The reference optical system 110 is formed, for example, by a reflective optical system (e.g., a reference mirror) and reflects the light from the coupler 104 back to the coupler 104, where it is guided to the detector 120. As another example, the reference optical system 110 is formed by a transmission optical system (e.g., an optical fiber) and guides the light from the coupler 104 to the detector 120 by transmitting it rather than returning it.

[0040] The reference optical system 110 has a configuration for changing the optical path length difference between the measurement light and the reference light by moving an optical member in the reference light path. For example, a reference mirror is moved in the optical axis direction. The configuration for changing the optical path length difference may be disposed in the measurement light path of the measurement optical system 106.

[0041] <Observation optical system> The observation optical system (front image observation device) 200 is provided to obtain a front image of the fundus oculi Ef. The observation optical system 200 includes, for example, a scanning unit 210 that two-dimensionally scans the fundus with measurement light (e.g., infrared light) emitted from a light source 201, and a second light-receiving element 209 that receives fundus reflected light via a confocal aperture 208 arranged at a position approximately conjugate with the fundus, and has the device configuration of a so-called ophthalmic scanning laser ophthalmoscope (SLO).

[0042] The scanning unit 210 scans the fundus Ef of the subject's eye with light emitted from the light source 201. For example, the scanning unit 210 scans the fundus two-dimensionally (in X and Y directions (transverse directions)) with light. The scanning unit 210 includes, for example, two optical scanners: a polygon scanner 211 for main scanning and a galvanometer scanner 212 for sub-scanning. In other words, the scanning unit 210 includes the polygon scanner 211 that scans light in the direction of a scan line (the X direction in FIG. 2), and the galvanometer scanner 212 that displaces the scan line in a direction intersecting the scan line (the Y direction in FIG. 2). For example, the control unit 70, which will be described later, controls the driving of the polygon scanner 211 and the galvanometer scanner 212, and the fundus is scanned two-dimensionally with light from the light source 201.

[0043] <Fixation target projection unit> The fixation target projection unit 300 has an optical system for guiding the line of sight of the subject's eye E. The projection unit 300 has a fixation target to be presented to the eye E, and can guide the eye E in a plurality of directions.

[0044] For example, the fixation target projection unit 300 has a visible light source that emits visible light and changes the presentation position of the target two-dimensionally. This changes the line of sight, and as a result, changes the imaging region. For example, when the fixation target is presented from the same direction as the imaging optical axis, the center of the fundus is set as the imaging region. On the other hand, when the fixation target is presented upward relative to the imaging optical axis, the upper part of the fundus is set as the imaging region. In other words, the imaging region is changed depending on the position of the target relative to the imaging optical axis.

[0045] The fixation target projection unit 300 may have various configurations, such as a configuration in which the fixation position is adjusted by the lighting position of LEDs arranged in a matrix, a configuration in which light from a light source is scanned using an optical scanner and the fixation position is adjusted by controlling the lighting of the light source, etc. Furthermore, the projection unit 300 may be an internal fixation light type or an external fixation light type.

[0046] <Control unit> The control unit 70 includes a CPU (processor), RAM, ROM, etc. The CPU of the control unit 70 controls the ophthalmic imaging apparatus 10. The RAM temporarily stores various types of information. The ROM of the control unit 70 stores various programs, initial values, etc. for controlling the operation of the ophthalmic imaging apparatus 10.

[0047] The control unit 70 is electrically connected to a nonvolatile memory (hereinafter simply referred to as memory) 72, an operation unit 74, a display unit 75, and the like. The memory 72 is a non-transitory storage medium that can retain its stored contents even when the power supply is cut off. For example, a hard disk drive, a flash ROM, or a USB memory that is detachably attached to the ophthalmic imaging apparatus 10 can be used as the memory 72. The memory 72 stores an imaging control program for controlling the capture of front images and tomographic images by the ophthalmic imaging apparatus 10. The memory 72 also stores various information related to imaging, such as information on the imaging positions of the captured two-dimensional tomographic images, three-dimensional images, front images, and tomographic images. The examiner inputs various operational instructions to the operation unit 74.

[0048] The operation unit 74 outputs a signal corresponding to the input operation instruction to the control unit 70. The operation unit 74 may be, for example, at least one of a mouse, a joystick, a keyboard, a touch panel, etc. The display unit 75 may be a display mounted on the main body of the ophthalmic imaging apparatus 10, or a display connected to the main body. A display of a personal computer (hereinafter referred to as "PC") may also be used. Multiple displays may be used in combination. The display unit 75 displays various images including tomographic images and front images captured by the ophthalmic imaging apparatus 10.

[0049] The control unit 70 may be configured with multiple control units (i.e., multiple processors). For example, the control unit 70 of the ophthalmic imaging apparatus 10 may be configured with a setting control unit provided in a PC and an operation control unit that controls the operation of the OCT optical system 100, etc. In this case, for example, the setting control unit of the PC may set the imaging position of the tomographic image, etc. based on the operation of an operation unit connected to the PC, and instruct the operation control unit on the set content. The operation control unit may control the imaging operation of each component of the ophthalmic imaging apparatus 10 in accordance with the instructions from the setting control unit. Furthermore, the process of generating (acquiring) an image based on a received light signal may be performed by either the operation control unit or the setting control unit.

[0050] For example, the control unit 70 acquires a tomographic image by image processing based on the light receiving signal output from the detector 120 of the OCT optical system 100, and acquires a front image based on the light receiving signal output from the light receiving element of the observation optical system 200. In addition, the control unit 70 controls the fixation target projection unit 300 to change the fixation position.

[0051] For example, the control unit 70 controls the scanning unit 210. FIG. 2 is a diagram illustrating the interval between scan lines and the frame rate. FIG. 2(a) illustrates a case where scan lines are not thinned. FIG. 2(b) illustrates a case where scan lines are thinned. The control unit 70 controls the scanning unit 210 of the observation optical system 200 to adjust the number of scan lines forming the front image. For example, the control unit 70 controls the polygon scanner 211 to scan light in the main scanning direction. Also, for example, the control unit 70 drives the galvano scanner 212 in a stepwise manner in accordance with the operation of the polygon scanner 211 to move the light in the sub-scanning direction by a predetermined displacement amount. Therefore, the control unit 70 controls the stepwise drive amount of the galvano scanner 212 to change the interval between scan lines and adjust the number of scan lines forming the front image. Note that the larger (wider) the interval between scan lines is, the fewer scan lines forming the front image. As a result, the time required to capture each front image is reduced (i.e., the frame rate is increased), but the image quality of the front image is reduced.

[0052] For example, the control unit 70 controls the display screen of the display unit 75. The acquired tomographic images and front images are output to the display unit 75 as still images or moving images, and are also stored in the memory 72. The control unit 70 controls each component of the OCT optical system 100, the observation optical system 200, and the fixation target projection unit 300 based on an operation signal output from the operation unit 74.

[0053] [Operation] The control operation of the device having the above configuration will be described with reference to the flowchart of Fig. 3. In this embodiment, a case where a tomographic image of the fundus oculi Ef of the subject's eye is acquired will be described.

[0054] <S1:アライメント> The examiner instructs the subject to gaze at the fixation target on the fixation target projection unit 300. An observation image of the anterior eye segment captured by a camera for observing the anterior eye segment (not shown) is displayed on the display unit 75. The examiner then operates the operation unit 74 to start alignment so that the measurement optical axis is positioned at the center of the pupil of the anterior eye segment.

[0055] The control unit 70 controls the galvanometer scanner 212 based on an operation signal from the operation unit 74 to scan the measurement light at a predetermined number of scan lines (i.e., a predetermined interval between scan lines). For example, in this way, in alignment, a front image is repeatedly acquired at a frame rate A1 (for example, 12.5 kHz) (see FIG. 2(a)). Note that the value of the frame rate A1 is not limited to this.

[0056] Furthermore, the control unit 70 controls the driving of the optical scanner 108 based on an operation signal from the operation unit 74, and scans the fundus with the measurement light in a predetermined direction. The control unit 70 acquires a light receiving signal corresponding to a predetermined scanning region from the output signal output from the detector 120, thereby repeatedly acquiring tomographic images at a predetermined frame rate (for example, 100 kHz).

[0057] In this way, the control unit 70 acquires a front image by the observation optical system 200 and a tomographic image by the OCT optical system 100 at any time.

[0058] FIG. 4 is a diagram showing an example of a display screen displayed on the display unit 75. The control unit 70 displays the front image 20, the pointer 25, and the tomographic image 30 acquired by the observation optical system 20 on the display unit 75. The scanning pattern 25 is an index indicating the measurement position (acquisition position) of the tomographic image on the front image. The scanning pattern 25 is electrically displayed on the front image on the display unit 75. Note that the front image 20 and the tomographic image 30 are moving images updated at the above-described frame rate.

[0059] The control unit 70 displays a pointer 21 (for example, a cross mark, a dot mark, a pen mark, etc.) on the display unit 75. The control unit 70 moves the pointer 21 based on an operation signal from the operation unit 74.

[0060] In the present embodiment, in a state where the pointer 21 is aligned with the front image 20, when the operation unit 74 is operated (for example, a drag operation, a click operation), the shooting conditions can be set. The pointer 21 is used to specify an arbitrary position on the display unit 75.

[0061] <S2: Setting of Scan Lines> Hereinafter, as an example, a case where a line scan pattern is set as the scanning pattern will be described. Note that the scanning pattern 25 is preset in an arbitrary shape based on the operation of the examiner. For example, it is selected from a plurality of prepared scanning patterns.

[0062] When the tomographic image and the front image are displayed on the same screen, the examiner sets the position of the tomographic image to be captured from the front image on the display unit 75. Here, the examiner moves the scanning pattern 25 with respect to the front image by performing a moving operation (for example, a drag operation) using the operation unit 74.

[0063] When the scanning pattern 25 is moved with respect to the front image 20 by the examiner, the control unit 70 sets the scanning position as needed. Then, the control unit 70 acquires a tomographic image at the scanning position corresponding to the set position. And the acquired tomographic image is displayed on the display screen of the display unit 75 as needed. Also, the control unit 70 changes the scanning position of the measurement light based on the operation signal output from the operation unit 74, and displays the scanning pattern 25 at the display position corresponding to the changed scanning position. Thus, the control unit 70 updates the moving image of the tomographic image by continuously executing the setting of the scanning position and the acquisition of the tomographic image at a certain frame rate.

[0064] <S3: Optimization of Imaging Conditions> When the examiner sets the position of the scanning pattern 25, the examiner operates the operation unit 74 to start the optimization of the imaging conditions. The control unit 70 starts the optimization control based on the operation signal from the operation unit 74. For example, by performing the optimization control, an organization desired by the examiner (here, the fundus) can be observed with high sensitivity and high resolution. For example, the optimization control for the OCT optical system 100 is the adjustment of the optical path length, the focus adjustment, and the adjustment of the polarization state (polarizer adjustment), and the optimization control for the SLO optical system is the focus adjustment.

[0065] In this embodiment, as an optimization of the OCT optical system 100, the optimization control may be performed in the order of the first automatic optical path length adjustment, focus adjustment, second automatic optical path length adjustment, and polarizer adjustment. For example, the control unit 70 initializes by setting a reference mirror (not shown) included in the reference optical system 110 to the initial position and setting a focusing lens (not shown) to the initial position. Subsequently, the control unit 70 performs the first optical path length adjustment by moving the reference mirror in one direction from the initial position. Further, the control unit 70 performs focus adjustment by moving the focusing lens in one direction from the initial position so as to be focused on the fundus Ef. Further, the control unit 70 performs the second optical path length adjustment (i.e., fine adjustment of the optical path length) by moving the reference mirror in the optical axis direction. Further, the control unit 70 adjusts the polarization state of the measurement light by moving a polarizer (not shown) to a position where the interference light can be strongly received (i.e., a position where the polarization states of the measurement light and the reference light match). As an optimization of the observation optical system 200, the control unit 70 may perform focus adjustment by moving a focusing lens (not shown) in the same manner as the OCT optical system.

[0066] <S4: Saving the Recorded Image> FIG. 5 is a time chart of the control operation. The horizontal width of the rectangle in the figure represents the length of time required to acquire a frontal image or a tomographic image. Further, the arrow α represents an input from the observation optical system 200 to the control unit 70. Further, the arrow β represents an input from the control unit 70 to the OCT optical system 100.

[0067] The control unit 70 repeatedly acquires frontal images at the frame rate A1 as shown in FIG. 2(a) above from alignment (S1) to optimization of the shooting conditions (S3). Here, when the optimization of the shooting conditions is completed, the examiner operates the operation unit 74 to input a release signal to the control unit 70 (see the white arrow in FIG. 5). When the release signal is input, the control unit 70 stores the frontal image G1 captured immediately before the release signal is input in the memory 72. In this embodiment, the stored frontal image G1 is referred to as a recorded image. According to this, a frontal image with higher image quality can be acquired than the frontal image captured during tracking described later.

[0068] <S5: Acquisition operation> Next, the control unit 70 starts an acquisition operation of a tomographic image (B-scan image) at a scanning position based on the setting of the scanning pattern 25 (<S51: Acquisition of tomographic image>). Also, in parallel with the acquisition of the tomographic image, the control unit 70 repeatedly acquires frontal images (frontal images g1, g2, …, g(n)) and monitors the movement of the eyes (<S52: Monitoring of eye movement>). For example, after the frontal image G1 is acquired based on the input of a release signal, the acquisition operation of the frontal image g1 is subsequently performed, so that a deviation is unlikely to occur between the recorded image and the frontal image g1.

[0069] <S51: Acquisition of tomographic image> In order for the control unit 70 to acquire a plurality of tomographic images at the same scanning position, the scanning at a substantially the same position on the fundus is repeated at a predetermined frame rate (e.g., 100 kHz). Specifically, the control unit 70 scans the measurement light a plurality of times using the optical scanner 108 with respect to the set scanning position. Then, the control unit 70 generates a plurality of frames (n frames (n≧2)) of tomographic images at the same scanning position.

[0070] <S52: Monitoring of eye movement> In parallel with acquiring a plurality of tomographic images, the control unit 70 repeatedly acquires one frontal image and monitors the movement of the eyes. For example, in this embodiment, the frame rate for acquiring the tomographic image is four times the frame rate for acquiring the frontal image. That is, every time four tomographic images are acquired, one frontal image is obtained, and based on this, the movement of the eyes is monitored.

[0071] <Increase in frame rate> To monitor eye movement, the control unit 70 controls the galvanometer scanner 212 to significantly change the interval between scan lines and thin out the scan lines of the measurement light (see FIG. 2(b)). For example, the control unit 70 doubles the interval between scan lines before and after a release signal is input. This halves the number of scan lines forming the front image, and halves the time required to acquire one front image. In addition, the frame rate of the front image is changed from frame rate A1 (e.g., 12.5 kHz) to frame rate A2 (e.g., 25 kHz), which is twice as fast. For example, increasing the frame rate increases the frequency of determining whether or not there is eye movement and correcting the scanning position, allowing more suitable tomographic images to be acquired.

[0072] <Tracking> The control unit 70 determines whether or not there is eye movement each time a front image is acquired at the frame rate A2, and corrects the scanning position of the measurement light. First, the control unit 70 sets a reference image for detecting positional deviation of the front image. Note that the reference image used is the front image g1 acquired first after the frame rate for acquiring the front image is changed to A2. Of course, another front image may be used as the reference image.

[0073] The control unit 70 then captures a live image of the front image (see arrow α in FIG. 5). The control unit 70 calculates the positional deviation between the reference image g1 and the repeatedly generated live front images (g2, g3, g4, ...) through image processing. This allows the amount of deviation in the imaging position of the tomographic image to be detected in real time. The amount of deviation is updated whenever a new amount of deviation between the front images (g2, g3, g4, ...) and the reference image g1 is detected.

[0074] The control unit 70 determines whether the amount of deviation satisfies an allowable range (for example, a predetermined threshold value). Here, the control unit 70 determines whether the amount of deviation from the reference image satisfies the allowable range each time one frame of a front image is acquired. In other words, the control unit 70 acquires the determination result for each of the front images acquired continuously in real time.

[0075] And when the deviation amount does not satisfy the allowable range (for example, a predetermined threshold value), the control unit 70 controls the optical scanner 108 to correct the OCT imaging position (see FIG. 5, arrow β). For example, the control unit 70 appropriately drives and controls the two galvanometer mirrors of the optical scanner 108 so that the deviation of the scanning position is corrected. As a result, since the scanning position is corrected, the imaging position is corrected.

[0076] The above operation is repeated until a predetermined number of tomographic images are acquired or an end operation is performed by the examiner.

[0077] <S6: Image synthesis> Next, the control unit 70 synthesizes the plurality of acquired tomographic images to obtain a single synthesized image. The control unit 70 sets the OCT image acquired in parallel with the reference image g1 as an OCT template. Further, the control unit 70 obtains addition average data by synthesizing the tomographic images with respect to the OCT template. The obtained addition average data is stored in the memory 74. Note that the addition average data may be the addition average image itself or the luminance information (luminance information obtained by adding the luminances of each image) that is the basis of the addition average image. When synthesizing the images, it is preferable that the control unit 70 performs alignment between the tomographic images by image processing (for example, refer to Japanese Patent Application Laid-Open No. 2010-110392 for the alignment method).

[0078] The control unit 70 also determines the suitability of the tomographic image to be used in the addition process using the amount of deviation from the reference image. The control unit 70 then uses the tomographic image for which the amount of deviation is determined to be within the allowable range for addition with the OCT template. The control unit 70 does not use the tomographic image for which the amount of deviation is determined to be outside the allowable range for addition with the OCT template. The suitability of the tomographic image to be used in addition with the OCT template may be determined using factors such as the positional deviation or correlation between the tomographic images. This allows selective synthesis of tomographic images that are likely to have been acquired at the same position as the preset scanning position, thereby enabling the acquisition of a more accurate tomographic image (synthesized image). Of course, the image synthesis method is not limited to this. For example, the method described in Japanese Patent Application Laid-Open No. 2014-140491 may be referenced as an image synthesis method.

[0079] The suitability of the tomographic images to be used in the addition process may be determined as appropriate during the capture operation. For example, each time a front image is acquired, it may be determined whether or not the tomographic images acquired in parallel are to be used in the addition process. In this case, the control unit 70 can end the capture operation when a predetermined number of tomographic images to be used in the addition process have been acquired. This makes it easier to acquire a composite image with the desired image quality.

[0080] The control unit 70 displays the composite image and the recorded image on the display unit 75 (see FIG. 6). The scanning pattern 25 may be superimposed on the recorded image. This allows the examiner to observe the high-quality recorded image together with the composite image.

[0081] As described above, for example, in the ophthalmologic imaging apparatus of this embodiment, the control unit 70 controls the observation optical system to acquire a first front image (recorded image), and controls the observation optical system in parallel with OCT imaging to repeatedly acquire a second front image in which the scanning lines of the first front image are thinned out. The control unit 70 also sets the first front image as image data for recording corresponding to the tomographic image acquired by OCT imaging, and further processes the repeatedly acquired second front image to detect positional deviations that occurred during OCT imaging.

[0082] This allows a high-quality front image to be acquired as a recorded image, making it possible to observe the eye to be examined well using the recorded image. For example, the high image quality makes it easier to observe the fine tissues of the fundus (e.g., capillaries, etc.).

[0083] This also allows the frequency of correcting the scanning position of the measurement light in the OCT optical system to be increased. For example, when increasing the frame rate of the front image, the imaging field angle of the subject's eye may or may not be changed. When the imaging field angle of the subject's eye is not changed, the tracking range is wider than when the imaging field angle is changed and reduced, so it can also be used even when the subject's eye moves significantly.

[0084] The frame rate can also be increased by increasing the scanning speed of the measurement light in the observation optical system and increasing the sampling rate. However, increasing the scanning speed of the measurement light requires increasing the rotation speed of the polygon scanner, which can easily place a load on the polygon scanner. Furthermore, increasing the sampling rate may shorten the exposure time, reducing the sensitivity for acquiring the front image. According to this embodiment, the frame rate can be increased without increasing the scanning speed and sampling rate of the measurement light. In other words, the frame rate can be increased while suppressing an increase in the load on the polygon scanner and a decrease in the sensitivity of the front image.

[0085] Furthermore, for example, in the ophthalmologic imaging apparatus of this embodiment, the control unit 70 acquires the first front image and the second front image based on an imaging signal (for example, a release signal) for starting acquisition of the second front image. In this case, after acquiring the first front image, the second front image is acquired without any time interval. This reduces the occurrence of a misalignment between the first front image and the second front image due to movement of the subject's eye between the acquisition of the first front image and the acquisition of the second front image.

[0086] Also, for example, in the ophthalmic photography device of this embodiment, the control unit 70 acquires the front image immediately before receiving the photography signal as the first front image based on the photography signal for starting the acquisition of the second front image, and switches from acquiring the first front image to acquiring the second front image.

[0087] [Example of transformation] In this embodiment, the case where the scan lines are thinned out by half by controlling the scanning of the galvano scanner has been described, but the present invention is not limited to this. For example, the scan lines do not have to be thinned out by half. As an example, if the interval between scan lines is tripled, the scan lines can be thinned out by one-third. For example, the larger the interval between scan lines, the more scan lines can be thinned out. In this case, the frame rate for acquiring the front image increases, allowing for more frequent tracking.

[0088] Furthermore, in this embodiment, when a release signal is input, the front image immediately before the release signal is stored, but this is not limiting. As an example, a new front image may be acquired and stored after the release signal is input. Specifically, when the release signal is input, the control unit 70 may control the observation optical system 200 to acquire a new front image without thinning out the scanning lines (i.e., at the frame rate A1) and store it in the memory 72 as a recorded image. Thereafter, the control unit 70 may thin out the scanning lines and acquire a front image at the frame rate A2.

[0089] Furthermore, the timing of obtaining the recorded image does not necessarily have to be based on a release signal. For example, a front image obtained when alignment is completed or when a scan line is set may be stored in the memory 72 as a recorded image. For example, a front image may be obtained after image synthesis and stored in the memory 72 as a recorded image. In this case, the control unit 70 may return the number of scanning lines for scanning the measurement light to the state before thinning out, and capture the front image.

[0090] In addition, in this embodiment, although the case where <S3: Saving of High-Quality Front Image> and <S4: Acquisition of Tomographic Image> are sequentially performed has been described, the present invention is not limited to this. As an example, while acquiring a high-quality front image with the observation optical system 200, the OCT optical system may start acquiring a tomographic image.

[0091] Also, when optimizing the shooting conditions (S3: Optimization of Shooting Position), the control unit 70 may control the scanning unit 210 to thin out the scanning lines and increase the frame rate. According to this, it is easier to perform the optimization suitably. Also, according to this, the time for optimization may be shortened. When increasing the frame rate during optimization, the state where the frame rate has been increased may be maintained until a release signal is input. When maintaining the state where the frame rate has been increased, in order to acquire a high-quality recorded image, the scanning may be performed with the frame rate decreased (without thinning out the scanning lines). Also, when a high-quality recorded image has been acquired, the frame rate may be increased again.

[0092] In addition, in the ophthalmic imaging apparatus of this embodiment, the control unit 70 may correct the image misalignment between the recorded image and the reference image. The image misalignment is the misalignment caused by thinning out the scanning lines. For example, when acquiring a front image by thinning out the scanning lines in this embodiment, the control unit 70 complements the pixels of the portion that was not scanned because the scanning lines were thinned out by image processing. When setting the scanning pattern 25 for the image complemented by such image processing, the scanning pattern 25 may be set at a position different from the position desired by the examiner, and tracking may be performed. In contrast, the control unit 70 acquires the image misalignment and uses it for correction.

[0093] For example, in this case, the control unit 70 may determine the image misalignment by comparing the recorded image with a reference image. Alternatively, for example, in this case, the control unit 70 may perform image processing on the recorded image to generate a new image by removing pixels corresponding to the thinned scan lines and then compare the original recorded image with the new image to determine the image misalignment. Note that the image misalignment may be determined based on experiments, simulations, machine learning, etc. By correcting the image misalignment, the examiner can set the scanning pattern 25 at the desired position, and the control unit 70 can perform tracking, allowing for optimal image acquisition.

[0094] In this embodiment, the OCT image acquired in parallel with the setting of the reference image g1 of the front image is set as the OCT template, but this is not limiting. For example, the OCT template may be selectively determined from a plurality of captured tomographic images. As an example, the suitability of the template image may be determined by the method described in Japanese Patent Application Laid-Open No. 2014-140491, and a suitable tomographic image may be set as the OCT template.

[0095] In this embodiment, a case has been described in which multiple tomographic images are acquired for one scanning position using the OCT optical system 100, but the present invention is not limited to this. For example, in this embodiment, a motion contrast image (angiography image) may be acquired. In this case, the control unit 70 can acquire motion contrast by comparing multiple tomographic images acquired by scanning the same position a predetermined number of times (for example, four times). For details on the method of acquiring motion contrast, refer to the method described in Japanese Patent Application Laid-Open No. 2017-6181. In this way, even when acquiring OCT data other than tomographic images, OCT data can be acquired preferably while acquiring a high-quality front image for recording.

[0096] Here, the control unit 70 may synchronize the cycle at which the front images are acquired with the cycle at which the motion contrast images are acquired. In other words, the frame rate at which the front images are acquired may be matched with the frame rate at which the motion contrast images are acquired. This eliminates the need to wait for scanning of the tomographic images or front images for tracking, making control by the control unit 70 easier. [Explanation of symbols]

[0097] 1. Ophthalmic imaging equipment 70 Control Unit 100 OCT optics 200 Observation Optical System 210 Scanning unit 212 Galvanometer Scanner

Claims

1. an OCT optical system for acquiring a tomographic image of the subject's eye using interference between measurement light and reference light irradiated onto the subject's eye; an observation optical system having an optical scanner that displaces a scanning line on the subject's eye in a direction intersecting the scanning line, and that acquires a front image based on a plurality of scanning lines; an OCT control means for controlling the OCT optical system to perform OCT imaging to repeatedly acquire the tomographic images; an observation control means for controlling the observation optical system to acquire a first front image, and for repeatedly acquiring a second front image in which the scanning lines of the first front image are thinned out by controlling the observation optical system in parallel with the OCT imaging; a front image processing means for setting the first front image as image data for recording corresponding to the tomographic image acquired by the OCT imaging, and further processing the second front image repeatedly acquired to detect positional deviation occurring during the OCT imaging; The ophthalmologic photographing apparatus according to claim 1, wherein the observation control means acquires the first front image and the second front image based on an imaging signal for starting acquisition of the second front image.

2. 2. The ophthalmologic photographing apparatus according to claim 1, The observation control means acquires the front image immediately before receiving the photographing signal as the first front image based on the photographing signal, and switches from acquiring the first front image to acquiring the second front image.

3. The ophthalmic apparatus according to claim 1 or 2, The ophthalmologic imaging device is characterized in that the observation control means acquires the second front image during at least a part of the optimization process based on an optimization signal for starting the optimization process of the OCT imaging, and acquires the first front image after the optimization process is completed.

4. An OCT optical system for acquiring a tomographic image of the test eye using interference between measurement light irradiated onto the test eye and reference light; an observation optical system having an optical scanner that displaces a scanning line on the subject's eye in a direction intersecting the scanning line, and that acquires a front image based on a plurality of scanning lines; an OCT control means for controlling the OCT optical system to perform OCT imaging to repeatedly acquire the tomographic images; an observation control means for controlling the observation optical system to acquire a first front image, and for repeatedly acquiring a second front image in which the scanning lines of the first front image are thinned out by controlling the observation optical system in parallel with the OCT imaging; a front image processing means for setting the first front image as image data for recording corresponding to the tomographic image acquired by the OCT imaging, and further processing the second front image repeatedly acquired to detect positional deviation occurring during the OCT imaging; The ophthalmologic imaging device is characterized in that the observation control means acquires the second front image during at least a part of the optimization process based on an optimization signal for starting the optimization process of the OCT imaging, and acquires the first front image after the optimization process is completed.

5. In the ophthalmic apparatus according to any one of claims 1 to 4, An ophthalmologic imaging apparatus, characterized in that the OCT control means acquires a motion contrast image based on at least two of the interference signals acquired at different times for the same scanning position of the measurement light on the subject's eye.

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