Fundus imaging apparatus and fundus imaging control program

Abstract

To provide a fundus imaging apparatus and a fundus imaging control program that can execute OCT signal acquisition processing and imaging processing of a front image of the fundus continuously and properly.SOLUTION: The alignment position between a subject eye and an optical axis of an apparatus can be selectively set to either the first position where the entire light projection region and light reception region of a front imaging optical system are assumed to fit within a pupil region of the subject eye, or the second position that deviates from the first position. In combo-imaging, acquisition of the OCT signal and imaging of the front image are consecutively executed. A control unit executes combo-imaging in a state where the alignment position is set to the first position when the pupil size of the subject eye is equal to or greater than a threshold. The control unit executes combo-imaging in a state where at least the alignment position during imaging by the front imaging optical system is set to the second position when the pupil size of the subject eye is smaller than the threshold.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to a fundus imaging device that captures an image of the fundus of a subject's eye, and a fundus imaging control program executed by the fundus imaging device. [Background technology]

[0002] Various fundus photographing devices for photographing fundus images of a subject's eye are known. For example, the fundus photographing device described in Patent Document 1 includes both a fundus photographing optical system for photographing a front image of the fundus of the subject's eye and an OCT optical system for obtaining a tomographic image of the fundus of the subject's eye using a technology of optical interference. In other words, the fundus photographing device described in Patent Document 1 is a combined device of an OCT and a fundus camera. In the fundus photographing optical system described in Patent Document 1, light from an observation light source and an illumination light source passes through a ring slit and is irradiated onto the fundus of the subject's eye. Note that the observation image of the fundus photographed by the illumination light passing through the ring slit is used not only when photographing a front image of the fundus, but also when photographing a tomographic image of the fundus by the OCT optical system.

[0003] In addition, the fundus photography device described in Patent Document 2 forms the illumination light irradiated onto the fundus of the test eye into a slit shape, and captures a front image of the fundus by scanning the slit-shaped illumination light in a direction intersecting the extension direction of the slit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-195874 A [Patent Document 2] Patent Publication No. 2021-37178 Summary of the Invention [Problem to be solved by the invention]

[0005] In fundus photography using the fundus photography optical system described in Patent Document 1, the passing area of ​​the illumination light passing through the ring slit and the passing area of ​​the reflected light of the illumination light from the fundus are formed in a concentric shape on the pupil of the test eye. Therefore, if the pupil of the test eye is small, at least a part of the concentric area through which the light passes may be blocked by the iris. On the other hand, the measurement light from the OCT optical system is likely to be appropriately irradiated onto the fundus even if the pupil of the test eye is small. As a result, depending on the size of the pupil of the test eye, even if the photography is performed appropriately using the OCT optical system, the photography using the fundus photography optical system may not be performed appropriately.

[0006] A typical object of the present disclosure is to provide a fundus imaging device and a fundus imaging control program that are capable of continuously and appropriately executing a process of acquiring an OCT signal and a process of photographing a front image of the fundus. [Means for solving the problem]

[0007] A fundus imaging device provided by a typical embodiment of the present disclosure is a fundus imaging device that captures an image of the fundus of a subject's eye with the optical axis of the device aligned with the pupil of the subject's eye, and includes a front imaging optical system that forms a light projection area through which illumination light passes and a light receiving area from which fundus reflected light of the illumination light is extracted in different areas on the pupil of the subject's eye, forms illumination light that passes through the light projection area and irradiates the fundus in a slit shape, and captures a front image of the fundus by scanning the slit-shaped illumination light in a direction intersecting an extension direction, an OCT optical system that splits light emitted from an OCT light source into measurement light and reference light, and obtains an OCT signal by receiving the measurement light reflected by tissue and interference light of the reference light, an optical axis alignment unit that aligns the optical axis of the front imaging optical system with the optical axis of the OCT optical system on the optical axis of the device, and a drive unit that adjusts the positional relationship between the subject's eye and the optical axis of the device. and a control unit, which is capable of selectively setting an alignment position between the test eye and the optical axis of the device to either a first position, which assumes that all of the light projection area and the light receiving area of ​​the front imaging optical system fall within the pupil area of ​​the test eye, or a second position shifted from the first position, and when performing combo imaging for the same test eye, in which an OCT signal is obtained by the OCT optical system and a front image is captured by the front imaging optical system in succession, information regarding the size of the pupil of the test eye is obtained, and when the size of the pupil of the test eye is equal to or greater than a threshold value, the combo imaging is performed with the alignment position set to the first position, and when the size of the pupil of the test eye is less than the threshold value, the combo imaging is performed with at least the alignment position during imaging by the front imaging optical system set to the second position.

[0008] A fundus photography control program provided by an exemplary embodiment of the present disclosure is a fundus photography control program executed in a fundus photography device that photographs an image of the fundus of a subject's eye with an optical axis of the device aligned with a pupil of the subject's eye, the fundus photography control program including: a front photography optical system that forms, on the pupil of the subject's eye, a light projection area through which illumination light passes and a light receiving area from which fundus reflected light of the illumination light is extracted, in different areas; and forms the illumination light that passes through the light projection area to irradiate the fundus in a slit shape, and photographs a front image of the fundus by scanning the slit-shaped illumination light in a direction intersecting an extension direction; an OCT optical system that splits light emitted from an OCT light source into measurement light and reference light, and obtains an OCT signal by receiving the measurement light reflected by tissue and interference light of the reference light; an optical axis alignment unit that aligns the optical axis of the front photography optical system and the optical axis of the OCT optical system on the optical axis of the device; a drive unit that adjusts the positional relationship between the optical axes of the subject's eye and the device; and a control unit, and an alignment position between the first position and the second position can be selectively set to either a first position where the light projection area and the light receiving area of ​​the front photographing optical system are assumed to be all within the pupil area of ​​the test eye, or a second position shifted from the first position, and the fundus photographing control program is executed by the control unit to cause the fundus photographing device to execute the following steps when performing combo photographing of the same test eye, in which acquisition of an OCT signal by the OCT optical system and photographing a front image by the front photographing optical system are performed consecutively: a pupil information acquisition step of acquiring information about the size of the pupil of the test eye; a first photographing step of performing the combo photographing with the alignment position set to the first position when the size of the pupil of the test eye is equal to or larger than a threshold; and a second photographing step of performing the combo photographing with at least the alignment position during photographing by the front photographing optical system set to the second position when the size of the pupil of the test eye is less than the threshold.

[0009] According to the fundus imaging device and fundus imaging control program of the present disclosure, the process of acquiring an OCT signal and the process of photographing a front image of the fundus are performed continuously and appropriately. [Brief description of the drawings]

[0010] [Figure 1] 1 is a side view showing the external configuration of a fundus photographing device 1 of the present embodiment. [Diagram 2] 1 is a schematic diagram of an optical system of a fundus photographing apparatus 1 of the present embodiment. [Diagram 3] 1 is a schematic diagram of a front photographing optical system 10 according to the present embodiment. [Figure 4] 13 is a diagram showing an example of a fundus observation image 60 in which split indices M1 and M2 are captured. FIG. [Diagram 5] 2 is a schematic diagram of an anterior eye observation optical system 40 according to the present embodiment. FIG. [Figure 6] 1 is a schematic diagram of an OCT optical system 200 according to the present embodiment. [Figure 7] FIG. 2 is a block diagram showing a control system of the fundus photographing apparatus of the present embodiment. [Figure 8] 13 is a diagram illustrating an example of the positions of light-projecting regions P1, P2 and a light-receiving region R on an anterior-segment observation image when the size of the pupil is equal to or larger than a threshold value. FIG. [Figure 9] 13 is a diagram illustrating an example of the positions of light-projecting regions P1, P2 and a light-receiving region R on an anterior-segment observation image when the size of the pupil is less than a threshold value. FIG. [Figure 10] 4 is a flowchart of a combo photography control process executed by the fundus photography apparatus 1 of the first embodiment. [Figure 11] 13 is a flowchart of a combo photography control process executed by a fundus photography apparatus 1 of a second embodiment. [Figure 12] 13 is a flowchart of a combo photography control process executed by a fundus photography apparatus 1 of a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Summary> The fundus imaging device exemplified in the present disclosure captures an image of the fundus of the subject's eye with the optical axis of the device aligned with the pupil of the subject's eye. The fundus imaging device includes a front imaging optical system, an OCT optical system, an optical axis alignment unit, a drive unit, and a control unit. The front imaging optical system forms a light projection area that passes illumination light and a light receiving area that extracts fundus reflected light of the illumination light in different areas on the pupil of the subject's eye. The front imaging optical system also forms illumination light that passes through the light projection area on the pupil and irradiates the fundus on a slit, and scans the slit-shaped illumination light on the fundus in a direction intersecting the extension direction to capture a front image of the fundus. The OCT optical system splits light emitted from an OCT light source into measurement light and reference light, and acquires an OCT signal by receiving the measurement light reflected by the tissue and the interference light of the reference light. The optical axis alignment unit aligns the optical axis of the front imaging optical system with the optical axis of the OCT optical system on the optical axis of the device. The drive unit adjusts the positional relationship between the optical axis of the subject's eye and the optical axis of the device. The control unit controls the fundus imaging device. The control unit can selectively set the alignment position between the subject's eye and the optical axis of the device to either a first position where all of the light projection area and light reception area of ​​the front imaging optical system are assumed to be within the pupil area of ​​the subject's eye, or a second position shifted from the first position. The fundus imaging device can perform combo imaging for the same subject's eye, which successively performs acquisition of an OCT signal by the OCT optical system and capture of a front image by the front imaging optical system. When performing combo imaging, the control unit executes a pupil information acquisition step of acquiring information regarding the size of the pupil of the subject's eye. When the size of the pupil of the subject's eye is equal to or greater than a threshold value, the control unit executes combo imaging with the alignment position set to the first position. When the size of the pupil of the subject's eye is less than the threshold value, the control unit executes combo imaging with at least the alignment position during imaging by the front imaging optical system set to the second position.

[0012] According to the fundus imaging device of the present disclosure, when the size of the pupil of the subject's eye is equal to or larger than a threshold value, the front image is easily captured appropriately with all of the light projection area and light receiving area of ​​the front imaging optical system being within the pupil area of ​​the subject's eye. In this case, the fundus imaging device can perform combo imaging without changing the positional relationship between the subject's eye and the optical axis of the device during front image capture and OCT signal acquisition. In addition, when the size of the pupil of the subject's eye is less than a threshold value, the fundus imaging device sets the alignment position at least during front image capture to the second position. As a result, when the front image is captured, a part of the light projection area and the light receiving area is intentionally placed outside the pupil area, so that the other part is easily positioned within the pupil area. Therefore, the fundus imaging device of the present disclosure can appropriately perform the OCT signal acquisition process and the front image capture process of the fundus in succession according to the size of the pupil of the subject's eye.

[0013] The technology exemplified in the present disclosure can be applied to both the case where the alignment position is automatically adjusted and the case where the alignment position is manually adjusted by the user. That is, when the size of the pupil of the subject's eye is equal to or larger than a threshold value, the control unit may control the driving unit to execute the combo shooting in a state where the alignment position is automatically adjusted to the set first position. When the size of the pupil of the subject's eye is less than a threshold value, the control unit may control the driving unit to execute the combo shooting in a state where at least the alignment position during shooting by the front shooting optical system is automatically adjusted to the set second position. In this case, the combo shooting is more easily executed. Also, when the size of the pupil of the subject's eye is equal to or larger than a threshold value, the control unit may output a guidance for guiding the alignment position to the set first position (for example, a guidance display to the first position, etc.). When the size of the pupil of the subject's eye is less than a threshold value, the control unit may output a guidance for guiding at least the alignment position during shooting by the front shooting optical system to the set second position. In this case, the user can confirm the output guidance and execute combo shooting with the alignment position adjusted to an appropriate position.

[0014] The second position shifted from the first position may be a position where at least one of the light projection area and the light receiving area of ​​the front photographing optical system is assumed to be partly outside the pupil area of ​​the subject's eye. In this case, by intentionally placing part of the light projection area and the light receiving area outside the pupil area, the other part is more likely to be located within the pupil area.

[0015] In detail, the front photographing optical system may form a light projection area in each of two areas symmetrical (e.g., bilaterally symmetrical) with respect to the optical axis of the device on the pupil of the subject's eye, and may form a light receiving area between the two light projection areas (e.g., an area through which the optical axis of the device passes). The second position may be a position where one of the two light projection areas, the light receiving area, and a pupil image by the OCT optical system are at least within the pupil area of ​​the subject's eye. In this case, even if the pupil of the subject's eye is small, light projection and reception required for photographing are appropriately performed. The second position may be a predetermined position (e.g., a position with a constant amount of deviation from the first position) or may be appropriately changed. For example, the fundus photographing device may search for a second position where one of the two light projection areas, the light receiving area, and a pupil image by the OCT optical system are at least within the pupil area of ​​the subject's eye based on an observed image or the like every time photographing is performed, and set the searched position as the second position.

[0016] The front photographing optical system may photograph a front image of the fundus by irradiating the fundus with illumination light, which is visible light. In combo photographing, the fundus photographing device may continuously photograph a front image by the front photographing optical system after acquiring an OCT signal by the OCT optical system. By photographing a front image using visible light, it is possible to appropriately photograph a color front image of the fundus. On the other hand, when photographing a front image using visible light, the pupil of the test eye may contract, and it may become difficult for the OCT measurement light to pass through the pupil when acquiring an OCT signal thereafter. In response to this, by continuously photographing a front image by the front photographing optical system after acquiring an OCT signal by the OCT optical system, it is possible to appropriately suppress the influence of miosis caused by visible light.

[0017] When the size of the pupil of the subject's eye is less than the threshold value, the control unit may execute the combo imaging in a state where both the alignment positions when acquiring the OCT signal by the OCT optical system and when capturing the front image by the front image capturing optical system are set to the second position. In this case, it is possible to omit the operation for adjusting the alignment position between acquiring the OCT signal and capturing the front image. Therefore, the combo imaging can be executed more smoothly. The possibility that the subject may feel uncomfortable due to the device moving during the combo imaging is also reduced.

[0018] The front photographing optical system may be capable of photographing an observation image of the fundus by irradiating the fundus with illumination light, which is invisible light. When acquiring an OCT signal by the OCT optical system, the control unit may adjust the OCT optical system based on an observation image photographed by the front observation optical system with the alignment position set to the second position. In this case, even when acquiring an OCT signal, the OCT optical system is appropriately adjusted based on an observation image photographed by the front photographing optical system. In addition, in a conventional device, if the pupil of the subject's eye is small, even when adjusting the OCT optical system using an observation image photographed by the front photographing optical system, illumination light for photographing the observation image may not be appropriately irradiated to the fundus, and the adjustment of the OCT optical system may not be appropriately performed. In contrast, the fundus photographing device of the present disclosure sets the alignment position when acquiring an OCT signal by the OCT optical system to the second position, and thereby adjusts the OCT optical system based on an observation image appropriately photographed by the front observation optical system. Therefore, even when the pupil of the subject's eye is small, both the acquisition process of the OCT signal and the photographing process of the front image of the fundus are easily performed appropriately.

[0019] When the size of the pupil of the subject's eye is less than a threshold value, the control unit may execute combo imaging in a state in which the alignment position when acquiring an OCT signal by the OCT optical system is set to a first position and the alignment position when imaging by the front imaging optical system is set to a second position. In this case, the tilt of the image acquired by the OCT optical system is appropriately suppressed, making it easier to acquire an OCT signal with higher accuracy.

[0020] The control unit may acquire information on the size of the pupil of the subject's eye after acquiring an OCT signal by the OCT optical system with the alignment position set to the first position. The control unit may perform combo shooting by capturing a front image by the front photographing optical system while keeping the alignment position set to the first position when the size of the pupil of the subject's eye is equal to or larger than a threshold. The control unit may perform combo shooting by changing the alignment position to the second position and capturing a front image by the front photographing optical system when the size of the pupil of the subject's eye is less than a threshold. The size of the pupil of the subject's eye is likely to change depending on various influences (for example, the amount of light entering the subject's eye, etc.). Therefore, by acquiring information on the size of the pupil of the subject's eye after performing an acquisition process of an OCT signal with the alignment position set to the first position, information on the size of the pupil of the subject's eye immediately before capturing a front image of the fundus is acquired. As a result, information on the size of the pupil is more likely to be acquired appropriately. Furthermore, when the amount by which the alignment position is changed from the first position to the second position is varied depending on the size of the pupil, the amount by which the alignment position is changed can also be easily set appropriately.

[0021] However, it is also possible to change the timing of acquiring information about the size of the pupil of the subject's eye. For example, information about the size of the pupil of the subject's eye may be acquired before the OCT optical system acquires an OCT signal. Even in this case, combo photography is performed appropriately according to the size of the pupil.

[0022] When the control unit determines that the alignment position needs to be changed, the control unit may execute at least one of a notification process and a storage process to the effect that the alignment position needs to be changed. In this case, the examiner or the subject can accurately grasp that the alignment position will be changed, and can proceed with imaging while recognizing that the alignment position will be changed or that it is necessary to change the alignment position.

[0023] The fundus photographing device may further include an anterior-segment observation optical system for photographing an anterior-segment observation image of the subject's eye. The control unit may obtain information on the size of the pupil of the subject's eye based on the anterior-segment observation image photographed by the anterior-segment observation optical system. In this case, the size of the pupil of the subject's eye that is actually photographed can be more appropriately grasped.

[0024] The fundus photographing device may further include an optical axis alignment unit that aligns the optical axis of the anterior segment observation optical system with the optical axis of the device. In this case, the anterior segment of the subject's eye is photographed from a direction along the optical axis of the device that is aligned with the pupil of the subject's eye when fundus photographing is performed. This makes it easier to obtain information about the size of the pupil with higher accuracy. However, the optical axis of the anterior segment observation optical system may be inclined with respect to the optical axis of the device. Even in this case, the pupil of the subject's eye is appropriately photographed.

[0025] The fundus photographing device may further include a split target projection optical system that projects two split targets, the separation state of which changes depending on the focus state, onto the fundus of the subject's eye. In the pupil information acquiring step, the control unit may acquire information on the size of the pupil of the subject's eye based on the state of the split target reflected in the observation image of the fundus. In this case, the split target for grasping the focus state is used to appropriately acquire information on the size of the pupil.

[0026] A specific method for acquiring information about the pupil size based on the state of the split index can be appropriately selected. For example, the control unit may perform a calculation process on the split index reflected in the fundus observation image, and determine that the pupil size is less than the threshold value when the proportion of the split index that is missing is greater than a threshold value.

[0027] It is also possible to change the method of acquiring information about the size of the pupil. For example, the smaller the pupil, the lower the brightness, contrast, and image quality due to vignetting of the fundus observation image may be. Therefore, the control unit may acquire information about the size of the pupil based on at least one of the brightness, contrast, and vignetting of the fundus observation image. In this case, the split target projection optical system may not be provided. The fundus photographing device may capture an anterior segment observation image of the subject's eye using a fundus observation optical system capable of observing the fundus, and acquire information about the size of the pupil of the subject's eye based on the captured anterior segment observation image. In this case, the fundus photographing device may capture the anterior segment observation image by adjusting the relative position of the fundus observation optical system and the subject's eye to a relative position where the fundus observation optical system can capture the anterior segment of the subject's eye, and adjusting the focus. When the fundus observation optical system is used to capture the anterior segment observation image, the size of the pupil is appropriately detected based on the anterior segment observation image even if the anterior segment observation optical system is not provided separately from the fundus observation optical system.

[0028] The fundus photographing device may further include a split index projection optical system that projects two split indices, the separation state of which changes according to the focus state, onto the fundus of the subject's eye. The control unit may determine whether or not the focus state of the subject's eye can be detected using the two split indices based on the photographed image of the subject's eye. When the control unit determines that the focus state of the subject's eye cannot be detected using the two split indices, the control unit may execute a process of acquiring the focus state by decentering the position of the optical axis of the device relative to the subject's eye compared to when the focus state can be detected, or a process of acquiring the focus state detected by the OCT optical system. When the pupil of the subject's eye is small, the two split indices may not be appropriately projected onto the fundus. Therefore, when the control unit determines that the focus state of the subject's eye cannot be detected using the two split indices, the focus state can be appropriately detected even when the pupil of the subject's eye is small by changing the detection direction of the focus state.

[0029] The method of determining whether or not the focus state can be detected by the two split indices can be appropriately selected. For example, the control unit may determine that the focus state cannot be detected by the two split indices when the size of the pupil of the subject's eye is less than a focus determination threshold. The focus determination threshold may be a value different from or the same as a threshold for determining the alignment position when capturing a front image. The control unit may also determine whether or not the focus state can be detected by the two split indices by projecting the two split indices with the optical axis of the device placed at a normal position (e.g., the corneal apex or the pupil center) with respect to the subject's eye, and determining whether or not the two split indices are captured in the fundus observation image.

[0030] A specific method for detecting the focus state when it is impossible to detect the focus state using two split indices can also be appropriately selected. For example, the control unit may decenter the optical axis of the device so that only one of the two split indices is projected onto the fundus. The control unit may detect the focus state based on the position of one split indices reflected in the observation image of the fundus. In this case, the focus state is appropriately detected using one split indices. Furthermore, the control unit may detect the focus state of the subject's eye by searching for the OCT focus after completing the adjustment of the optical path length of the OCT optical system.

[0031] <Embodiment> A typical embodiment according to the present disclosure will be described below. The fundus imaging device 1 of this embodiment can both capture a front image of the fundus of the subject eye and obtain an OCT signal for the fundus. The fundus imaging device 1 of this embodiment irradiates illumination light (visible light in this embodiment) in a slit shape on the fundus of the subject eye, and scans the illumination light in a direction intersecting the extension direction of the slit. The fundus imaging device 1 captures a two-dimensional front image of the fundus (at least a color front image in this embodiment) by receiving fundus reflection light of the illumination light. That is, the fundus imaging device 1 of this embodiment captures a front image of the fundus by a slit scanning method.

[0032] <Appearance of the device> The external configuration of the fundus photographing device 1 will be described with reference to Fig. 1. The fundus photographing device 1 has a photographing unit 3. The photographing unit 3 is equipped with an optical system shown in Fig. 2 etc. The fundus photographing device 1 has a housing 6, a base 7, a drive unit 8, a face support unit 9, and a face photographing camera 110, which are used to adjust the positional relationship between the subject's eye E and the photographing unit 3 (the positional relationship between the subject's eye E and the optical axis of the fundus photographing device 1).

[0033] The drive unit 8 can move the photographing unit 3 in the left-right direction (X direction), up-down direction (Y direction), and front-back direction (Z direction, in other words, working distance direction) relative to the base 7. In other words, the drive unit 8 adjusts the positional relationship between the subject's eye E and the optical axis of the device by moving the relative positions of the photographing unit 3 and the subject's eye E in three-dimensional directions. The drive unit 8 includes an actuator for moving the photographing unit 3 in each of the predetermined movable directions. The drive unit 8 is driven based on a control signal from the control unit 100. The face support unit 9 supports the subject's face. The face support unit 9 is fixed to the base 7.

[0034] The face photographing camera 110 is fixed to the housing 6 so that its positional relationship with the photographing unit 3 is constant. The face photographing camera 110 photographs the face of the subject. The control unit 100 identifies the position of the subject's eye E from the photographed face image, and aligns the photographing unit 3 with the identified position of the subject's eye E by controlling the driving of the driving unit 8. The fundus photographing device 1 also includes a monitor 120. The monitor (display unit) 120 displays various images (for example, a fundus observation image, a fundus photographed image (fundus image), an anterior segment observation image, etc.).

[0035] <Optical system> The optical system of the fundus photographing device 1 will be described with reference to FIG. 2. The fundus photographing device 1 of this embodiment includes a front photographing optical system 10, an anterior eye observation optical system 40, and an OCT optical system 200. The front photographing optical system 10 also serves as a fundus observation optical system for photographing an observation image of the fundus of the subject's eye. In this embodiment, the objective lens 22 is shared by each optical system. In addition, the optical axis of the front photographing optical system 10, the optical axis of the anterior eye observation optical system 40, and the optical axis of the OCT optical system 200 are aligned on the optical axis L of the device extending from the objective lens 22 to the subject's eye E side. In this embodiment, the optical axis of the anterior eye observation optical system 40 and the optical axis of the OCT optical system 200 are made coaxial by the half mirror 45. In this embodiment, the optical axes of the anterior eye observation optical system 40 and the OCT optical system 200, which are made coaxial by the half mirror 45, and the optical axis of the front photographing optical system 10 are made coaxial by the dichroic mirror (optical axis alignment unit) 43. For example, light from the optical system is guided to the subject's eye via an objective lens 22. Each optical system will be described in detail below.

[0036] <Frontal shooting optical system> The front photographing optical system 10 will be described with reference to Fig. 3. In Fig. 3, a "△" is added to the position conjugate with the pupil of the subject's eye on the photographing optical axis, and an "X" is added to the position conjugate with the fundus on the photographing optical axis.

[0037] The front photographing optical system 10 includes an irradiation optical system 10A and a light receiving optical system 10B. The irradiation optical system 10A includes a light source unit 11, a lens 13, a slit-shaped member 15A, lenses 17A and 17B, a mirror 18, a mirror with a hole 20, and an objective lens 22. The light receiving optical system 10B includes an objective lens 22, a mirror with a hole 20, lenses 25A and 25B, a slit-shaped member 15B, and an imaging element 28.

[0038] The light source unit 11 has a plurality of types of light sources with different wavelength bands. For example, the light source unit 11 includes visible light sources 11A and 11B, and infrared light sources 11C and 11D that emit invisible light. That is, the light source unit 11 of this embodiment is provided with two light sources for each wavelength. The two light sources with the same wavelength are arranged away from the optical axis L on the pupil conjugate plane. The two light sources with the same wavelength are arranged along the X direction, which is the scanning direction in FIG. 3, and are arranged axially symmetrically with respect to the optical axis L. As shown in FIG. 3, the outer peripheral shape of the two light sources may be a rectangle shape in which the direction intersecting the scanning direction is longer than the scanning direction.

[0039] Light from two light sources having the same wavelength passes through the lens 13 and is irradiated onto the slit-shaped member 15A. In this embodiment, the slit-shaped member 15A has a light-transmitting portion (aperture) formed in an elongated shape along the Y direction. This causes the illumination light to be formed in a slit shape on the fundus conjugate plane (the area illuminated in a slit shape on the fundus Er is illustrated as symbol B).

[0040] The slit-shaped member 15A is displaced by a driving unit (not shown) so that the light-transmitting portion crosses the optical axis L in the X direction. As a result, the scanning of the illumination light in this embodiment is realized. In this embodiment, scanning is also performed by the slit-shaped member 15B on the light-receiving system side. In this embodiment, the slit-shaped members 15A and 15B on the light-projecting side and the light-receiving side are driven in conjunction with each other by one driving unit (actuator). This forms a scanning unit including the slit-shaped members 15A and 15B. The scanning unit may be, for example, an optical chopper. For details of the optical system using the optical chopper, please refer to, for example, "JP Patent Publication No. 2019-118721" by the present applicant.

[0041] In the irradiation optical system 10A, the images of the light sources are relayed by the optical system from the lens 13 to the objective lens 22, and are formed on the pupil conjugate plane. That is, on the pupil conjugate plane, pupil images by the two light sources are formed at positions separated in the scanning direction. As a result, in this embodiment, two light projection regions P1 and P2 are formed as images of the two light sources at positions different from the optical axis L of the device on the pupil conjugate plane (positions symmetrical about the optical axis L in this embodiment).

[0042] The slit-shaped light passing through the slit-shaped member 15A is relayed by the optical system from the lens 17A to the objective lens 22, and forms an image on the fundus Er. This forms a slit-shaped illumination light on the fundus Er. The illumination light is reflected on the fundus Er and extracted from the pupil Ep.

[0043] The perforated mirror 20 is an optical path coupling section that couples the optical paths of the irradiation optical system 10A and the light receiving optical system 10B. The perforated mirror 20 reflects the illumination light from the light source unit 11 toward the subject's eye E, and transmits a portion of the fundus reflected light from the subject's eye E that has passed through the opening toward the photographing element 28. As the optical path coupling member, various beam splitters other than the perforated mirror 20 can be used. For example, instead of the perforated mirror 20, a mirror in which the light transmitting section and the reflecting section are reversed may be used as the optical path coupling section. However, in this case, the independent optical path of the light receiving optical system 10B is placed on the reflecting side of the mirror, and the independent optical path of the irradiation optical system 10A is placed on the transmitting side of the mirror. The perforated mirror and the mirror as an alternative means can also be further replaced with a combination of a half mirror and a light blocking section, respectively.

[0044] Since the aperture of the perforated mirror 20 is conjugate with the pupil of the subject's eye, the fundus reflected light used for imaging is limited to a portion that passes through the image of the aperture of the perforated mirror (pupil image) on the pupil of the subject's eye. Therefore, the image of the aperture on the pupil of the subject's eye becomes the light receiving area R in this embodiment. In this embodiment, the optical axis L of the device passes through the light receiving area R. The light receiving area R is formed between two light projection areas P1, P2 (images of two light sources). In addition, as a result of appropriately setting the imaging magnification of each image, the diameter of the aperture, and the arrangement interval between the two light sources, the light receiving area R and the two light projection areas P1, P2 are formed so as not to overlap each other on the pupil.

[0045] The fundus reflected light that passes through the objective lens 22 and the aperture of the perforated mirror 20 forms an image of a slit-shaped region of the fundus Er at a fundus conjugate position via the lenses 25A and 25B. The light-transmitting portion of the slit-shaped member 15B is disposed at the position of image formation, thereby eliminating harmful light.

[0046] The photographing element 28 is disposed at a fundus conjugate position. In this embodiment, a relay optical system 27 is provided between the slit-shaped member 15B and the photographing element 28. The relay optical system 27 allows both the slit-shaped member 15B and the photographing element 28 to be in a fundus conjugate relationship. As a result, both the removal of harmful light and the formation of an image are performed well. Alternatively, the relay optical system 27 between the photographing element 28 and the slit-shaped member 15B may be omitted, and the two may be disposed close to each other. In this embodiment, a device having a two-dimensional light receiving surface is used as the photographing element 28. For example, at least one of a CMOS, a two-dimensional CCD, etc. may be used as the photographing element 28. An image of the slit-shaped region of the fundus Er formed at the light-transmitting portion of the slit-shaped member 15B is projected onto the photographing element 28. The photographing element 28 is sensitive to both infrared light and visible light.

[0047] In this embodiment, as the slit-shaped illumination light is scanned on the fundus Er, an image (slit-shaped image) of the scanning position on the fundus Er is sequentially projected for each scanning line of the imaging element 28. In this manner, the entire image of the scanning range is projected in a time-division manner onto the imaging element 28. As a result, a front image (two-dimensional reflection image) of the fundus is captured as the entire image of the scanning range.

[0048] In this embodiment, the scanning unit in the light receiving optical system 10B is a device that mechanically scans the slit, but this is not necessarily limited to this. For example, the scanning unit on the light receiving optical system 10B side may be a device that electronically scans the slit. As an example, when the imaging element 28 is a CMOS, the slit may be scanned by the rolling shutter function of the CMOS. In this case, the area exposed on the imaging surface is displaced in synchronization with the scanning unit in the irradiation optical system 10A, so that the front image can be captured efficiently while removing harmful light. Also, a liquid crystal shutter or the like can be used as a scanning unit that electronically scans the slit.

[0049] The front photographing optical system 10 has a diopter correction unit. In this embodiment, diopter correction units (diopter correction optical systems 17 and 25) are provided in the independent optical paths of the projection optical system 10A and the light receiving optical system 10B. However, the diopter correction units may be provided in the common optical path of the projection optical system 10A and the light receiving optical system 10B.

[0050] Hereinafter, for convenience, the illumination-side diopter correction optical system is referred to as the illumination-side diopter correction optical system 17, and the light-receiving-side diopter correction optical system is referred to as the light-receiving-side diopter correction optical system 25. The illumination-side diopter correction optical system 17 of this embodiment includes a lens 17A, a lens 17B, and a drive unit (not shown). The light-receiving-side diopter correction optical system 25 of this embodiment includes a lens 25A, a lens 25B, and a drive unit (not shown). In the illumination-side diopter correction optical system 17, the distance between the lens 17A and the lens 17B is changed. In the light-receiving-side diopter correction optical system 25, the distance between the lens 25A and the lens 25B is changed. As a result, diopter correction is performed in each of the illumination optical system 10A and the light-receiving optical system 10B.

[0051] The front photographing optical system 10 further includes a split index projection optical system 50. The split index projection optical system 50 projects two split indices onto the fundus Er as focus indices. The split indices are used for focus detection. For example, the split index projection optical system 50 may include at least an infrared light source 51, an index plate 52, and an angle-deviating prism 53. In this embodiment, the index plate 52 is disposed at a position corresponding to the imaging surface in the light receiving optical system 10B. Similarly, the index plate 52 is disposed at a position corresponding to each of the slit-shaped members 15A and 15B. For example, in detail, the index plate 52 is disposed at a position approximately conjugate with the fundus Er of the emmetropic eye (0D eye) when the diopter correction amount of the irradiation side and the light receiving side is 0D. The angle-deviating prism 53 is disposed closer to the index plate 52 on the examinee's eye side than the index plate 52. In this embodiment, the index plate 52 forms a slit light as an index. The deflection prism 53 splits the index light beam passing through the index plate 52 to form a split index. The split index is projected onto the fundus Er via the irradiation-side diopter correction optical system 17 and the objective lens 22. Therefore, the split index appears in a fundus image (for example, a fundus observation image).

[0052] FIG. 4 illustrates an example of a fundus observation image 60 in which the split indices M1 and M2 are reflected. As described above, in this embodiment, the split indices M1 pass through the light projection area P1 and are projected onto the fundus Er, and the split indices M2 pass through the light projection area P2 and are projected onto the fundus Er. FIG. 4(A) illustrates a case in which the focus state is not properly adjusted and the index plate 52 is displaced from the fundus conjugate position. In this case, the two split indices M1 and M2 are generated at positions separated in the X direction. FIG. 4(B) illustrates a case in which the focus state is properly adjusted and the index plate 52 is disposed at the fundus conjugate position. In this case, the two split indices M1 and M2 are generated at positions that match the X direction. In this embodiment, the conjugate relationship between the fundus Er and the index plate 52 is adjusted by the illumination-side diopter correction optical system 17 disposed between the angle-deviating prism 53 and the fundus Er. Therefore, in this embodiment, defocusing is performed while matching the illumination-side diopter correction amount with the reception-side diopter correction amount. By adjusting the illumination-side and reception-side diopter correction amounts so that the two split indices match, the imaging surface and each of the slit-shaped members 15A and 15B are in a positional relationship conjugate with the fundus Er.

[0053] Also, for example, the wavelength of the infrared light source (infrared light sources 11C and 11D) in the irradiation optical system 10A and the wavelength of the infrared light source (infrared light source 51) in the split index projection optical system 50 may be the same wavelength. In this case, the fundus photographing device 1 can capture the fundus reflected light by the irradiation optical system 10A and the fundus reflected light by the split index projection optical system 50 using one imaging element 28 to obtain a fundus observation image including the split index. Of course, the infrared wavelengths of the infrared light sources may be different. In this case, an imaging element or the like having sensitivity to a predetermined infrared wavelength range may be used.

[0054] In this embodiment, when the pupil of the subject's eye is small, only one of the two split indices M1 and M2 may be projected onto the fundus Er. In this case, instead of the matching state of the two split indices M1 and M2, it is also possible to detect the focus state by detecting the position where one of the split indices is captured. This will be described in detail later.

[0055] In this embodiment, the split index divided into two reaches the fundus Er of the subject's eye by passing through the light projection area P1 and the light projection area P2. However, it is also possible to design the optical system so that the light projection areas of the two split indexes are formed on the inside of the two light projection areas P1 and P2 on the pupil of the subject's eye E. In this case, even if the pupil of the subject's eye E is small, the two split indexes can easily reach the fundus. The light projection areas of the two split indexes and the two light projection areas P1 and P2 may at least partially overlap, or may be completely separated. In this embodiment, the front photographing optical system 10 also serves as a fundus observation optical system that photographs an observation image of the fundus of the subject's eye. However, the fundus photographing device 1 may be provided with a fundus observation optical system separate from the front photographing optical system 10. The fundus observation optical system may capture a fundus observation image by irradiating the fundus Er with illumination light (e.g., infrared light, etc.) from an area closer to the optical axis L than the two light projection areas P1, P2 on the pupil by the front photographing optical system 10. In this case, even if the pupil of the subject's eye E is small, both split indicators are likely to appear in the fundus observation image captured by the fundus observation optical system. Therefore, even if the pupil of the subject's eye is small, it is easy to adjust the focus state using the two split indicators.

[0056] <Anterior segment observation optical system> Referring to FIG. 5, the anterior eye observation optical system 40 will be described. The anterior eye observation optical system 40 images the anterior eye of the eye to be examined E and acquires it as an anterior eye observation image. The anterior eye observation optical system 40 illuminates the anterior eye with infrared light and photographs a frontal image of the anterior eye. The anterior eye observation optical system includes a light source 41, a half mirror 45, an imaging element 47, a dichroic mirror 43, an objective lens 22, and the like. For example, the light source 41 is an infrared light source and illuminates the eye to be examined E. For example, the imaging element 47 is a two-dimensional imaging element and is disposed at a position optically conjugate with the pupil Ep. The dichroic mirror 43 and the objective lens 22 are shared with the frontal imaging optical system 10. As shown in FIG. 5, the fundus imaging apparatus 1 of the present embodiment includes an optical axis alignment unit (dichroic mirror 43 and half mirror 45) that aligns the optical axis of the anterior eye observation optical system 40 with the optical axis L of the apparatus. As a result, the anterior eye of the eye to be examined E is photographed from a direction along the optical axis L of the apparatus that is aligned with the pupil of the eye to be examined E when fundus imaging is performed. Therefore, although details will be described later, information regarding the size of the pupil of the eye to be examined E can be more easily acquired with higher accuracy based on the anterior eye observation image photographed by the anterior eye observation optical system 40. Note that the anterior eye observation optical system 40 may be configured to image the anterior eye in an optical path independent of other optical systems (for example, an optical path whose optical axis is inclined with respect to the optical axis L of the apparatus).

[0057] <OCT optical system> Referring to FIG. 6, the OCT optical system 200 will be described. As an example, the OCT optical system 200 of the present embodiment will be described as an SD-OCT optical system. The OCT optical system 200 acquires (images) an OCT signal (OCT data) of the fundus Er. The OCT optical system 200 of the present embodiment includes an OCT light source 201, a coupler (optical splitter) 202, a polarizer 203, a measurement optical system 200A, a reference optical system 200B, and a detector 210.

[0058] In SD-OCT, a broadband light source is used for the OCT light source 201. The light from the OCT light source 201 is split by the coupler 202 into measurement light (sample light) and reference light. The measurement light is guided to the fundus Er via the measurement optical system 200A. The reference light is guided to the reference optical system 200B.

[0059] The measurement optical system 200A of this embodiment includes a collimator lens 206, a focus lens 240, a scanning unit 207, a lens 208, and an objective lens 22. The measurement light is guided to the scanning unit 207 via the collimator lens 206 and the focus lens 240. The scanning unit 207 scans the measurement light two-dimensionally on the fundus Er. The scanning unit 207 is disposed at a position substantially conjugate with the pupil of the subject's eye E. As a result, the measurement light is rotated around the pupil of the subject's eye E. In this embodiment, the rotation point of the measurement light on the pupil is located on the optical axis L1 of the OCT optical system 200. As described above, the optical axis L1 of the OCT optical system 200 is aligned with the optical axis L of the fundus imaging device 1. In this embodiment, for example, two galvanometer mirrors are used for the scanning unit 207. The measurement light that has passed through the scanning unit 207 is irradiated onto the fundus Er via the objective lens 22. The measurement light from the fundus Er travels backward through the measurement optical system 200A and is then guided to the detector 210. The focus lens 240 can be moved in the optical axis direction by a drive unit 240A. The focus is adjusted by moving the focus lens 240.

[0060] The reference optical system 200B of this embodiment is a reflective optical system, and includes a reference mirror 231. The reference light makes one round trip between the coupler 202 and the reference mirror 231. The reference light that has made one round trip and is incident on the coupler 202 is guided to the detector 210. The reference mirror 231 can be moved in the optical axis direction by a driving unit 231A. The optical path length of the reference optical system 200B is changed according to the position of the reference mirror 231. As a result, the optical path length difference between the measurement light and the reference light is adjusted. The reference optical system 200B may be formed of a transmission optical system (for example, an optical fiber, etc.).

[0061] In this embodiment, the polarizer 203 is disposed between the coupler 202 and the reference optical system 200B. The polarizer 203 adjusts the polarization state of the reference light. The polarizer 203 is driven by a driving unit 203A to change the polarization state of the reference light. The location of the polarizer 203 is not limited to the example in FIG. 6, and it may be disposed at a position where the polarization state of the measurement light can be adjusted.

[0062] The detector 210 receives interference light between the return light of the measurement light from the fundus Er and the reference light. In SD-OCT, a spectrometer is used for the detector 210. Based on a spectral interference signal from the detector 210, an OCT signal of the fundus Er is generated.

[0063] In general, the required pupil diameter of the OCT optical system 200 can be set to a value sufficiently small relative to the required pupil diameter of an observation optical system in which spatial pupil division is performed. In this embodiment, projection and reception of measurement light from the OCT optical system 200 to the subject's eye E is performed inside the light receiving region R on the pupil of the subject's eye E. Therefore, in this embodiment, if a good fundus observation image is acquired, it is guaranteed that the projection and reception of the OCT measurement light is also performed well at least on the pupil of the subject's eye E.

[0064] <Control system> The control system of the fundus photographing device 1 will be described with reference to FIG. 7. In this embodiment, the control unit 100 controls each part of the fundus photographing device 1. The control unit 100 is a processing device (processor) having an electronic circuit that performs control processing of each part and arithmetic processing. The control unit 100 is realized by a CPU (Central Processing Unit) that is a controller, and a memory, etc. The control unit 100 is electrically connected to a storage unit 101 via a bus, etc. Various control programs and fixed data, etc. are stored in the storage unit (storage device) 101. In this embodiment, a fundus photographing control program, etc. for executing a combo photographing control process (see FIGS. 10 to 12) are stored in the storage unit 101. In addition, temporary data, etc. may be stored in the storage unit 101. Images photographed by the fundus photographing device 1 may be stored in the storage unit 101. However, this is not necessarily limited to this, and photographed images may be stored in an external storage device (for example, a storage device connected to the control unit 100 via a LAN and a WAN).

[0065] The control unit 100 is electrically connected to each of the components, such as the drive unit 8, the front photographing optical system 10, the anterior eye observation optical system 40, the face photographing camera 110, the OCT optical system 200, the monitor 120, and the input interface 130. The control unit 100 can also control each of the above components based on an operation signal output from the input interface 130. The input interface 130 is an example of an operation input unit that accepts an operation by the examiner. The input interface 130 may be, for example, a mouse and a keyboard.

[0066] <Alignment position> With reference to Figs. 8 and 9, an alignment position that can be set by the fundus photographing device 1 of this embodiment will be described. The alignment position is the positional relationship between the subject's eye E and the optical axis L of the fundus photographing device 1, which is set during photographing. As described above, in this embodiment, two light projection areas P1 and P2 are formed as images of two light sources at a position (in this embodiment, positions symmetrical about the optical axis L) different from the optical axis L of the device (in the example shown in Figs. 8 and 9, the center of the light receiving area R) on the pupil conjugate plane. In addition, on the pupil conjugate plane, a light receiving area R is formed between the two light projection areas P1 and P2 (in this embodiment, the position through which the optical axis L of the device passes). Note that in Figs. 8 and 9, the light projection areas P1 and P2 and the light receiving area R are merely described for convenience of explanation.

[0067] Here, as shown in FIG. 8, when the pupil of the subject's eye E (a region indicated by the pupil diameter Pd) is sufficiently large and the total width PR of the light projection regions P1, P2 and the light receiving region R falls within the pupil diameter Pd, it is possible to irradiate the fundus Er with both the lights passing through the two light projection regions P1, P2. Therefore, when the size of the pupil is equal to or larger than a threshold value, the fundus photographing device 1 sets the alignment position between the subject's eye E and the optical axis L of the device to a first position that assumes that the two light projection regions P1, P2 and one light receiving region R of the front photographing optical system 10 all fall within the pupil region of the subject's eye E. As an example, in this embodiment, the fundus photographing device 1 sets the alignment position where the pupil center and the optical axis L of the device approximately coincide with each other as the target first position. However, the details of the first position can also be changed. For example, the fundus photographing device 1 may set the alignment position where the corneal center of the subject's eye E and the optical axis L of the device approximately coincide with each other as the target first position. Details of this will be provided later.

[0068] Also, as shown in FIG. 9(A), if the pupil of the subject's eye E (the area indicated by the pupil diameter Pd) is small, the total width PR of the light projection areas P1, P2 and the light receiving area R may not fit within the pupil diameter Pd. In this case, as shown in FIG. 9(A), if the alignment position is set so that the optical axis L of the device (which coincides with the center of the light receiving area R in this embodiment) coincides with the center of the pupil or the center of the cornea, the light projected through the light projection areas P1, P2 is vignetted by the iris, and the fundus Er may not be photographed properly. Therefore, as shown in FIG. 9(B), when the size of the pupil is less than the threshold, the fundus photographing device 1 sets the alignment position between the subject's eye E and the optical axis L of the device to a second position shifted from the first position. As a result, one of the two light projection areas P1, P2 is placed within the pupil area, and the fundus Er is photographed properly.

[0069] The second position in this embodiment is a position where at least a part of the light projection regions P1, P2 and the light receiving region R of the front photographing optical system 10 is assumed to be outside the pupil region of the subject's eye. In detail, the second position in this embodiment is a position where one of the two light projection regions P1, P2 and the light receiving region R of the front photographing optical system 10 is within the pupil region, and the other of the two light projection regions P1, P2 is outside the pupil region. By intentionally locating one of the two light projection regions P1, P2 outside the pupil region, it becomes easier to locate the other light projection region and light receiving region within the pupil region.

[0070] As described above, the front photographing optical system 10 forms the light projection areas P1 and P2 in two areas symmetrical (e.g., bilaterally symmetrical) with respect to the optical axis L of the device on the pupil of the subject's eye E, and forms the light receiving area R in an area through which the optical axis L of the device passes. The second position of this embodiment is a position where one of the two light projection areas P1 and P2, the light receiving area R, and the pupil image by the OCT optical system 200 are assumed to be at least within the pupil area of ​​the subject's eye E. Therefore, the second position of this embodiment is a position that is decentered (offset) to the left or right with respect to the first position. The offset amount of the second reference position with respect to the first reference position may be set according to the pupil diameter Pd of the subject's eye E. Furthermore, the fundus photographing device 1 may search for an alignment position where one of the two light projection regions P1, P2, the light receiving region R, and the pupil image by the OCT optical system 200 are at least within the pupil region of the subject's eye E based on a fundus observation image or the like, and set the searched position as the second reference position. The offset amount of the second reference position relative to the first reference position may be a fixed value. Furthermore, when setting the alignment position to the second position, the fundus photographing device 1 may turn off a light source for irradiating light onto one of the two light projection regions P1, P2 that is expected to be outside the pupil region.

[0071] First Embodiment The combo photography control process executed by the fundus photography apparatus 1 of the first embodiment will be described with reference to Fig. 10 etc. The combo photography control process illustrated in Fig. 10 is executed by the control unit 100 of the fundus photography apparatus 1 according to a fundus photography control program stored in the storage unit 101. In the combo photography control process, the photography operation of the combo photography is controlled. The combo photography is a photography method in which the OCT signal of the fundus Er of the subject's eye E is acquired by the OCT optical system 200, and the front image of the fundus Er is photographed by the front photography optical system 10 in succession.

[0072] As described above, the front photographing optical system 10 of the fundus photographing device 1 of this embodiment photographs a front image of the fundus Er by irradiating the fundus Er of the subject's eye E with illumination light, which is visible light. By using visible light, a color front image of the fundus Er, etc., is appropriately photographed. On the other hand, when photographing a front image using visible light, the pupil of the subject's eye E may contract, and the light for photographing may then be difficult to pass through the pupil. In addition, in the acquisition process of the OCT signal by the OCT optical system 200 of this embodiment, a measurement light having a central wavelength longer than that of visible light and less dazzling than visible light is used. Therefore, in the combo photographing of this embodiment, after the acquisition process of the OCT signal by the OCT optical system is performed, the photographing process of the front image by the front photographing optical system 10 is performed continuously. As a result, the combo photographing is performed in a state where the influence of the miosis of the subject's eye E caused by the illumination light is appropriately suppressed. However, the acquisition process of the OCT signal by the OCT optical system can also be performed after the photographing process of the front image by the front photographing optical system 10.

[0073] Furthermore, in the combo photography of this embodiment, the fundus photography device 1 automatically adjusts the alignment position between the subject's eye E and the optical axis L of the fundus photography device 1 by controlling the drive unit 8. As a result, the combo photography can be performed more easily. However, the fundus photography device 1 may also perform a process of outputting guidance for guiding the alignment position (for example, displaying guidance for the alignment position on the monitor 120, etc.). In this case, the user (examiner, etc.) can check the output guidance and perform combo photography in a state where the alignment position has been adjusted to an appropriate position by the user.

[0074] 10, the control unit 100 executes an initial alignment adjustment for adjusting the alignment position between the subject's eye E and the optical axis L of the device to a position where a fundus observation image can be acquired (S1). In the initial alignment adjustment, the control unit 100 controls the drive unit 8 based on a face image acquired by the face photographing camera 110 and an anterior eye observation image acquired by the anterior eye observation optical system 40 to adjust the position of the photographing unit 3 relative to the subject's eye E (i.e., the position of the optical axis L of the device relative to the subject's eye E).

[0075] For example, the control unit 100 acquires a face image by the face photographing camera 110. The control unit 100 detects the position of at least one of the left and right eyes E based on the face image. The control unit 100 adjusts the position of the photographing unit 3 to a position where an anterior eye observation image can be photographed based on the detected position information of the eye E.

[0076] When the position of the photographing unit 3 is adjusted to a position where the anterior eye observation image can be photographed, the anterior eye observation optical system 40 photographs an anterior eye observation image as shown in FIG. 8 and FIG. 9. The control unit 100 adjusts the positional relationship between the subject's eye E and the photographing unit 3 (the optical axis L of the device) based on the anterior eye observation image. In this embodiment, the control unit 100 sets a first position where the center of the pupil and the center of the anterior eye observation image where the optical axis L of the device is located approximately coincide with each other as a target initial alignment position. For example, the control unit 100 may detect the position of the center of the pupil by performing known image processing (e.g., edge detection, etc.) on the anterior eye observation image. The control unit 100 detects a deviation in alignment with respect to the initial alignment position (first position) and moves the photographing unit 3 in the XY direction so as to eliminate the detected deviation in alignment. The deviation in alignment may be detected as a deviation amount between the center of the pupil on the anterior eye observation image and the optical axis L of the device. If the fundus photographing device 1 has a configuration capable of detecting another reference position such as the corneal apex (for example, an optical system that projects an alignment index onto the corneal apex), the control unit may set an alignment position where the optical axis L of the device and another reference position approximately coincide as the initial alignment position (first position). As described above, in this embodiment, initial alignment adjustment is performed, and the positional relationship in the XY directions between the subject's eye E and the photographing unit 3 is adjusted to the first position where the center of the light receiving region R (which coincides with the optical axis L of the device in this embodiment) and the pupil center (which may be the corneal apex, etc.) coincide.

[0077] Furthermore, the control unit 100 adjusts the position of the photographing unit 3 in the Z direction so that the distance between the subject's eye E and the photographing unit 3 is a predetermined distance. For example, the control unit 100 may adjust the position of the photographing unit 3 in the Z direction so that the anterior eye observation image is focused on the pupil. Furthermore, the position of the photographing unit 3 in the Z direction may be adjusted by using various alignment indices.

[0078] Next, the control unit 100 acquires information on the size of the pupil of the subject's eye E (S2). The control unit 100 judges whether the size of the pupil of the subject's eye E is equal to or larger than a threshold value (S3). If the size of the pupil of the subject's eye E acquired in S2 is equal to or larger than the threshold value (S3: YES), the control unit 100 maintains the alignment position between the subject's eye E and the optical axis L of the fundus photographing device 1 at the first position set in S1, and the process proceeds directly to S6. As described above, the first position is an alignment position that assumes that the two light projection regions P1 and P2 and the one light receiving region R of the front photographing optical system 10 are all within the pupil region of the subject's eye E.

[0079] On the other hand, if the size of the pupil of the subject's eye E acquired in S2 is less than the threshold value (S3: NO), the control unit 100 sets the alignment position between the subject's eye E and the optical axis L of the fundus imaging device 1 to the second position (S4). As described above, the second position is an alignment position shifted from the first position. In this embodiment, the second position is an alignment position that assumes that one of the two light projection regions P1, P2 and the light receiving region R of the front imaging optical system 10 is within the pupil region, and the other of the two light projection regions P1, P2 is outside the pupil region.

[0080] The method of acquiring information on the size of the pupil of the eye E (S2) and the method of judging whether the size of the pupil of the eye E is equal to or larger than a threshold (S3) can be appropriately selected. For example, in S2, the control unit 100 can acquire information on the size of the pupil of the eye E based on an anterior eye observation image (see Figs. 8 and 9) captured by the anterior eye observation optical system 40. In this case, the size of the pupil of the eye actually captured is more appropriately grasped. In this embodiment, the control unit 100 detects the pupil area from the anterior eye observation image by performing known image processing (e.g. edge detection, etc.) on the anterior eye observation image, and can acquire the pupil diameter Pd of the detected pupil area as information on the size of the pupil. The pupil diameter Pd may be acquired by a device different from the fundus photographing device 1, or may be manually input by the examiner. In addition, in S3, the control unit 100 compares the pupil diameter Pd acquired in S2 with a threshold value. The threshold value may be approximately the same as the overall width PR of the light projection regions P1, P2 and the light reception region R (the width in the X direction in this embodiment, as shown in FIGS. 8 and 9).

[0081] In addition, in S2, the control unit 100 can also obtain information about the size of the pupil of the subject's eye E based on the state of the split indices M1 and M2 (see FIG. 4) that appear in the observation image of the fundus Er photographed by the front photographing optical system 10. As described above, in this embodiment, the two split indices M1 and M2 are projected and received through the light projection areas P1 and P2 and the light reception area R. Therefore, the split indices M1 and M2 that are irradiated into the pupil area without being vignetted by the iris are considered to be projected on the fundus observation image unless the projection and reception are hindered by opacity. In other words, if the size of the pupil is sufficiently large, the two split indices M1 and M2 are projected, and if the size of the pupil is small, at least a part of the split indices M1 and M2 is considered to be missing. The control unit 100 can detect these split indices M1 and M2 by performing arithmetic processing, and obtain information about the size of the pupil based on the detection result. In this case, the split indices M1 and M2 for acquiring the focus state are used to appropriately acquire information on the size of the pupil. In S3, the control unit 100 may determine that the size of the pupil is less than the threshold value when the ratio of the split indices M1 and M2 that are partially missing is greater than the threshold value. The control unit 100 may determine that the size of the pupil is equal to or greater than the threshold value when the ratio of the split indices M1 and M2 that are partially missing is equal to or less than the threshold value. In addition, in this embodiment, when the pupil of the subject's eye E is very small, the light for photographing the fundus observation image is vignetted by the iris, and as a result, the fundus observation image may not be photographed or may be dark. Therefore, the control unit 100 may determine that the size of the pupil is less than the threshold value when the fundus observation image is not photographed or is dark.

[0082] When the control unit 100 determines that the alignment position needs to be changed from the first position to the second position, it executes at least one of a notification process and a storage process to the effect that the alignment position needs to be changed. As a result, the examiner or the subject can accurately grasp that the alignment position will be changed to the second position, and can proceed with imaging while recognizing that the alignment position will be changed or that it is necessary to change the alignment position.

[0083] In addition, in this embodiment, if the size of the pupil is less than the threshold, it may not be possible to detect the focus state using both of the two split indexes M1 and M2 (see FIG. 4). Therefore, the determination in S3 in this embodiment also serves as a determination of whether or not it is possible to detect the focus state using the two split indexes M1 and M2.

[0084] Next, the control unit 100 executes focus adjustment (S6). In this embodiment, when the size of the pupil is equal to or larger than the threshold (that is, when the alignment position is set to the first position) (S3: YES), the two split indices M1 and M2 are reflected on the fundus observation image. In this case, the control unit 100 detects the separation state of the split indices M1 and M2 from the fundus observation image, drives the diopter correction unit (diopter correction optical systems 17 and 25) so that the split indices M1 and M2 match, and defocuses the front photographing optical system 10. The control unit 100 drives the focus lens 240 of the OCT optical system 200 in conjunction with the diopter correction unit (diopter correction optical systems 17 and 25) of the front photographing optical system 10. This allows focus adjustment of the OCT optical system 200. Note that the focus adjustment of the OCT optical system 200 may be performed independently by a method described later.

[0085] Also, when the size of the pupil is less than the threshold (S3: NO), the alignment position is set to the second position (S4), so that it is highly likely that only one of the two split indices M1 and M2 is reflected on the fundus observation image. Therefore, the control unit 100 defocuses the front photographing optical system 10 so that the position of one of the two split indices M1 and M2 that is expected to be reflected on the fundus observation image is located at a preset matching position (that is, if both the two split indices M1 and M2 are reflected on the fundus observation image, the position will match the other split indices when the focus is adjusted). In other words, when the control unit 100 determines that it is impossible to detect the focus state using the two split indices M1 and M2 (in this embodiment, when it determines that the size of the pupil is less than the threshold), it detects the focus state by decentering the position of the optical axis L of the device relative to the subject's eye E compared to when it is possible to detect it. As a result, even if the pupil of the subject's eye E is small, the focus state is appropriately detected. In addition, adjustment of the OCT optical system 200 (for example, at least one of focus adjustment and photographing position adjustment) may be performed in conjunction with the focus state detected by one split index in the fundus observation image.

[0086] As described above, in this embodiment, the front photographing optical system 10 also serves as an observation image photographing optical system for photographing a fundus observation image. Therefore, if the alignment position is set to the first position, the fundus observation image may not be properly taken, and as a result, adjustment of the OCT optical system 200 based on the fundus observation image (e.g., focus adjustment, etc.) may not be properly performed. However, in this embodiment, even if the size of the pupil is less than the threshold, the alignment position is set to the second position, so that the fundus observation image is properly photographed. Therefore, even if the size of the pupil is less than the threshold, the adjustment of the OCT optical system 200 based on the fundus observation image is easily performed properly.

[0087] It is also possible to change the method of detecting the focus state when it is determined that it is impossible to detect the focus state using the two split indices M1 and M2. For example, the control unit 100 may detect and adjust the focus state of the subject's eye E by searching for the OCT focus after completing the adjustment of the optical path length of the OCT optical system 200. The detection result of the OCT focus may be reflected in the focus adjustment of the front imaging optical system 10.

[0088] As described above, even if the pupil of the subject's eye E is small, it is possible to adopt a configuration in which the two split indices M1 and M2 are reflected in the fundus observation image. For example, by adopting at least one of a configuration in which the light projection areas of the two split indices M1 and M2 are formed inside the two light projection areas P1 and P2, and a configuration in which the fundus observation optical system irradiates the fundus Er with illumination light from an area closer to the optical axis L than the two light projection areas P1 and P2 on the pupil by the front photographing optical system 10 to photograph the fundus observation image, the two split indices M1 and M2 are likely to be reflected in the fundus observation image even if the pupil of the subject's eye E is small. In this case, in S6, the focus state may be detected based on the two split indices M1 and M2 reflected in the fundus observation image regardless of the size of the pupil.

[0089] Next, the control unit 100 performs various adjustments of the OCT optical system 200 (S7). For example, the control unit 100 performs fine adjustment of the focus, adjustment of the optical path length, adjustment of the polarization state (polarizer adjustment), and the like while acquiring OCT data via the OCT optical system 200. For details of the adjustments, see, for example, Japanese Patent Application Laid-Open No. 2015-195876 by the present applicant. As a result of adjusting the OCT optical system 200, it becomes possible to acquire an OCT signal of the fundus Er with high sensitivity and high resolution.

[0090] The control unit 100 acquires an OCT signal of the fundus Er of the subject's eye E by the OCT optical system 200 (S8). After that, the control unit 100 captures a front image of the fundus Er of the subject's eye E by the front photographing optical system 10 using visible light (S9). That is, when the size of the pupil of the subject's eye E is equal to or larger than a threshold value, the fundus photographing device 1 can appropriately photograph a front image with all of the light projection areas P1, P2 and the light receiving area R of the front photographing optical system 10 being within the pupil area of ​​the subject's eye E by setting the alignment position to the first position. In addition, the OCT signal is also appropriately acquired. On the other hand, when the size of the pupil of the subject's eye E is less than the threshold value, the fundus photographing device 1 sets the alignment position at least during front image photographing (in the first embodiment, both during OCT signal acquisition and front image photographing) to the second position. As a result, when photographing a front image, by intentionally placing parts of the light projection areas P1, P2 and the light receiving area R outside the pupil area, the other parts are likely to be located inside the pupil area. Therefore, the fundus photographing device 1 can appropriately continuously perform the process of acquiring the OCT signal and the process of photographing the front image of the fundus Er according to the size of the pupil of the subject's eye E.

[0091] In the first embodiment, when the size of the pupil of the subject's eye E is less than a threshold value, the control unit 100 executes combo imaging with both the alignment positions set to the second position when acquiring an OCT signal by the OCT optical system 200 and when photographing by the front photographing optical system 10. This makes it possible to omit the operation for adjusting the alignment position between acquiring an OCT signal and photographing a front image. This makes it easier to execute combo imaging more smoothly. It also reduces the possibility that the subject may feel uncomfortable due to the device moving during combo imaging.

[0092] <Second embodiment> The combo photography control process executed by the fundus photography apparatus 1 of the second embodiment will be described with reference to Fig. 11 etc. The combo photography control process illustrated in Fig. 11 is executed by the control unit 100 of the fundus photography apparatus 1 in accordance with a fundus photography control program stored in the storage unit 101. Note that, among the configuration and processing of the fundus photography apparatus 1 of the second embodiment, explanations of those parts that can adopt the same configuration and processing as in the first embodiment will be omitted or simplified.

[0093] As an example, in the second embodiment, similarly to the first embodiment, after the OCT signal acquisition process is performed by the OCT optical system 200, the front image capturing process is continuously performed by the front imaging optical system 10. As a result, combo imaging is performed in a state where the influence of miosis of the subject's eye E caused by the illumination light is appropriately suppressed. Also, in the combo imaging of the second embodiment, the fundus imaging device 1 automatically adjusts the alignment position between the subject's eye E and the optical axis L of the fundus imaging device 1 by controlling the drive unit 8.

[0094] 11, the control unit 100 executes an initial alignment adjustment for adjusting the alignment position between the subject's eye E and the optical axis L of the device to a position where a fundus observation image can be acquired (S11). In the initial alignment adjustment, the control unit 100 sets a first position where the center of the pupil and the center of the anterior eye observation image where the optical axis L of the device is located approximately coincide with each other as a target initial alignment position. The process of S11 can be the same as the process of S1 in the first embodiment.

[0095] Next, the control unit 100 judges whether or not it is possible to detect the focus state using both of the two split indices M1 and M2 projected toward the fundus Er by the split indices projection optical system 50 (see FIG. 3) (S12). In this embodiment, the control unit 100 judges that it is impossible to detect the focus state using both of the two split indices M1 and M2 when the size of the pupil of the subject's eye E (pupil diameter Ed in this embodiment) is less than the focus judgment threshold. The focus judgment threshold may be a value different from or the same as a threshold for judging the alignment position when photographing a front image (for example, a threshold used in the judgment in S20 described later). In this embodiment, the focus judgment threshold is set to a value larger than the threshold for judging the alignment position when photographing a front image.

[0096] In addition, the control unit 100 may project two split indices M1 and M2 with the optical axis L of the device positioned in a normal position (e.g., the corneal apex or the center of the pupil) relative to the subject eye E, and determine whether or not both split indices M1 and M2 are captured in the fundus observation image with an area larger than the allowable area, thereby determining whether or not it is possible to detect the focus state using the two split indices M1 and M2.

[0097] When it is determined that it is possible to detect the focus state using both the two split indices M1 and M2 (S12: YES), the control unit 100 performs normal focus state detection and focus adjustment using both the two split indices M1 and M2 with the alignment position set to the first position (S13). In detail, the control unit 100 detects the separation state of the split indices M1 and M2 from the fundus observation image, drives the diopter correction unit (diopter correction optical systems 17 and 25) so that the split indices M1 and M2 match, and defocuses the front photographing optical system 10. The control unit 100 drives the focus lens 240 of the OCT optical system 200 in conjunction with the diopter correction unit (diopter correction optical systems 17 and 25) of the front photographing optical system 10. This allows the focus adjustment of the OCT optical system 200 to be performed. The focus adjustment of the OCT optical system 200 may be performed independently by a method described later.

[0098] On the other hand, if it is determined that it is impossible to detect the focus state using both split indicators M1, M2 (S12: NO), the control unit 100 executes a process for detecting the focus state when the test eye E has a small pupil and a process for adjusting the focus (S14).

[0099] In S14, the control unit 100 may set the alignment position to a focus detection position shifted (eccentric) from the first position so that only one of the two split indices M1 and M2 appears on the fundus observation image. In this embodiment, the amount of shift of the focus detection position from the first position is smaller than the amount of shift of the second position from the first position. The control unit 100 may defocus the front photographing optical system 10 so that, with the alignment position adjusted to the focus detection position, one of the two split indices M1 and M2 that is to appear on the fundus observation image is located at a preset matching position (that is, if both the two split indices M1 and M2 appear on the fundus observation image, the position will match the other split indices when the focus is adjusted). That is, when the control unit 100 determines that it is impossible to detect the focus state using both of the two split indices M1 and M2, the control unit 100 may detect the focus state by decentering the position of the optical axis L of the device with respect to the subject's eye E compared to when the focus state can be detected. In this case, the focus state is appropriately detected even if the pupil of the subject's eye E is small. Also, the focus adjustment of the OCT optical system 200 may be performed in conjunction with the focus state detected by one split indices.

[0100] Furthermore, in S14, the control unit 100 may detect and adjust the focus state of the subject's eye E by searching for the OCT focus in a state in which adjustment of the optical path length of the OCT optical system 200 has been completed. The detection result of the OCT focus may be reflected in the focus adjustment of the front imaging optical system 10.

[0101] Next, the control unit 100 performs various adjustments of the OCT optical system 200 (S16). For example, the control unit 100 performs fine adjustment of the focus, adjustment of the optical path length, adjustment of the polarization state (polarizer adjustment), etc. while acquiring OCT data through the OCT optical system 200. The control unit 100 acquires an OCT signal of the fundus Er of the subject's eye E by the OCT optical system 200 with the alignment position set to the first position or the focus detection position (S17). Even if the alignment position is adjusted to the focus detection position, the OCT signal is acquired as it is, thereby reducing the number of operations for adjusting the alignment position. Therefore, the possibility that the subject may feel uncomfortable due to the movement of the device during combo shooting is also reduced.

[0102] Next, the control unit 100 acquires information on the size of the pupil of the subject's eye E (S18). The control unit 100 judges whether the size of the pupil of the subject's eye E is equal to or larger than a threshold value (S20). That is, in the second embodiment, the alignment position is set to the first position or a focus detection position having a smaller eccentricity than the second position, and then the OCT signal is acquired by the OCT optical system 200, and information on the size of the pupil of the subject's eye E is acquired. The size of the pupil of the subject's eye E is likely to change depending on various influences (for example, the amount of light entering the subject's eye E, etc.). Therefore, by acquiring information on the size of the pupil of the subject's eye E after performing an acquisition process of the OCT signal with the alignment position set to the first position or the focus detection position, information on the size of the pupil of the subject's eye E immediately before capturing a front image of the fundus is acquired. As a result, information on the size of the pupil is more easily acquired appropriately. Furthermore, when the amount of change in the alignment position from the first position or the focus detection position to the second position is varied according to the size of the pupil, the amount of change in the alignment position can be easily set appropriately. The method of acquiring information on the size of the pupil of the subject's eye E (S18) can be the same as S2 in the first embodiment. The method of determining whether the size of the pupil of the subject's eye E is equal to or larger than a threshold (S20) can be the same as S3 in the first embodiment.

[0103] If the size of the pupil of the test eye E obtained in S18 is equal to or larger than the threshold value (S20: YES), the control unit 100 maintains the alignment position between the test eye E and the optical axis L of the fundus photography device 1 at the first position set in S11 or the focus detection position set in S14, and performs photographing of a front image of the fundus Er of the test eye E using the front photography optical system 10 (S22).

[0104] On the other hand, if the size of the pupil of the subject's eye E acquired in S18 is less than the threshold value (S20: NO), the control unit 100 sets the alignment position between the subject's eye E and the optical axis L of the fundus photographing device 1 to the second position (S21). As described above, the second position is an alignment position shifted from the second position. In this embodiment, the second position is an alignment position assuming that one of the two light projection regions P1, P2 and the light receiving region R of the front photographing optical system 10 is within the pupil region, and the other of the two light projection regions P1, P2 is outside the pupil region. After that, the control unit 100 executes photographing a front image of the fundus Er of the subject's eye E by the front photographing optical system 10 (S22).

[0105] As described above, when the size of the pupil of the subject's eye E is equal to or larger than the threshold value, the fundus photographing device 1 of the second embodiment can appropriately photograph a front image by setting the alignment position to the first position or the focus detection position. In addition, the OCT signal is also appropriately acquired. On the other hand, when the size of the pupil of the subject's eye E is smaller than the threshold value, the fundus photographing device 1 sets the alignment position at the time of photographing the front image to the second position. As a result, when photographing the front image, by intentionally placing a part of the light projection areas P1, P2 and the light receiving area R outside the pupil area, the other parts are easily positioned within the pupil area. Therefore, the fundus photographing device 1 can appropriately perform the process of acquiring the OCT signal and the process of photographing the front image of the fundus Er successively according to the size of the pupil of the subject's eye E.

[0106] In the second embodiment, when the size of the pupil of the subject's eye E is less than a threshold value, the control unit 100 executes combo imaging in a state in which the alignment position when the OCT signal is acquired by the OCT optical system 200 is set to the first position or the focus detection position, and the alignment position when imaging by the front imaging optical system 10 is set to the second position. As described above, the amount of eccentricity of the focus detection position relative to the first position is smaller than the amount of eccentricity of the second position relative to the first position. Therefore, in the second embodiment, the tilt of the image acquired by the OCT optical system 200 is appropriately suppressed, making it easier to acquire an OCT signal with higher accuracy.

[0107] <Third embodiment> The combo photography control process executed by the fundus photography apparatus 1 of the third embodiment will be described with reference to Fig. 12. The combo photography control process illustrated in Fig. 12 is executed by the control unit 100 of the fundus photography apparatus 1 in accordance with a fundus photography control program stored in the storage unit 101. Note that, among the configuration and processing of the fundus photography apparatus 1 of the third embodiment, descriptions of those parts that can adopt the same configuration and processing as the first and second embodiments will be omitted or simplified.

[0108] The fundus photographing device 1 of the third embodiment has a configuration in which the two split indices M1 and M2 are reflected in the fundus observation image even if the pupil of the subject's eye E is small. For example, the split indices projection optical system of the fundus photographing device 1 of the third embodiment forms the light projection areas of the two split indices M1 and M2 on the pupil of the subject's eye E inside the two light projection areas P1 and P2 for fundus photography. Therefore, even if the pupil of the subject's eye E is small, the two split indices M1 and M2 can easily reach the fundus Er. The light projection areas of the two split indices M1 and M2 and the two light projection areas P1 and P2 for fundus photography may at least partially overlap or may be completely separated. The fundus photographing device 1 of the third embodiment also has a fundus observation optical system in addition to the front photography optical system 10. The fundus observation optical system of the third embodiment captures a fundus observation image by irradiating the fundus Er with illumination light (e.g., infrared light, etc.) from an area closer to the optical axis L than the two light projection areas P1, P2 on the pupil by the front photographing optical system 10. Therefore, even if the pupil of the subject's eye E is small, both split indices M1, M2 are likely to appear in the fundus observation image captured by the fundus observation optical system. Therefore, even if the pupil of the subject's eye E is small, it is easy to adjust the focus state using the two split indices M1, M2.

[0109] As an example, in the third embodiment as well, after the OCT signal acquisition process is performed by the OCT optical system 200, the front image capturing process is continuously performed by the front imaging optical system 10. As a result, the combo imaging is performed in a state where the influence of miosis of the subject's eye E caused by the illumination light is appropriately suppressed. Also, in the combo imaging of the third embodiment as well, the fundus imaging device 1 automatically adjusts the alignment position between the subject's eye E and the optical axis L of the fundus imaging device 1 by controlling the drive unit 8.

[0110] 12, the control unit 100 executes an initial alignment adjustment for adjusting the alignment position between the subject's eye E and the optical axis L of the device to a position where a fundus observation image can be acquired (S31). In the initial alignment adjustment, the control unit 100 sets a first position where the center of the pupil and the center of the anterior eye observation image where the optical axis L of the device is located approximately coincide with each other as a target initial alignment position. The process of S31 can be the same as the process of S1 in the first embodiment and the process of S11 in the second embodiment.

[0111] Next, the control unit 100 performs focus state detection and focus adjustment using both of the two split indices M1 and M2 with the alignment position set to the first position (S32). As described above, in the third embodiment, even if the pupil of the subject's eye E is small, the focus state can be detected using both of the two split indices M1 and M2. In detail, the control unit 100 detects the separation state of the split indices M1 and M2 from the fundus observation image, drives the diopter correction unit (diopter correction optical systems 17 and 25) so that the split indices M1 and M2 match, and defocuses the front photographing optical system 10. The control unit 100 drives the focus lens 240 of the OCT optical system 200 in conjunction with the diopter correction unit (diopter correction optical systems 17 and 25) of the front photographing optical system 10. This allows the focus adjustment of the OCT optical system 200 to be performed.

[0112] Next, the control unit 100 performs various adjustments of the OCT optical system 200 (S33). For example, the control unit 100 performs fine adjustment of the focus, adjustment of the optical path length, adjustment of the polarization state (polarizer adjustment), etc. while acquiring OCT data via the OCT optical system 200. With the alignment position set to the first position, the control unit 100 acquires an OCT signal of the fundus Er of the subject's eye E by the OCT optical system 200 (S34).

[0113] Next, the control unit 100 acquires information on the size of the pupil of the subject's eye E (S35). The control unit 100 judges whether the size of the pupil of the subject's eye E is equal to or larger than a threshold value (S36). That is, in the third embodiment, with the alignment position set to the first position, the OCT optical system 200 acquires an OCT signal, and then information on the size of the pupil of the subject's eye E is acquired. The size of the pupil of the subject's eye E is likely to change depending on various influences (for example, the amount of light entering the subject's eye E, etc.). Therefore, with the alignment position set to the first position, information on the size of the pupil of the subject's eye E is acquired after performing an acquisition process of the OCT signal, thereby acquiring information on the size of the pupil immediately before capturing a front image of the fundus Er. As a result, information on the size of the pupil is more easily acquired appropriately. In addition, when the change amount of the alignment position from the first position to the second position is changed depending on the size of the pupil, the change amount of the alignment position is also more easily set appropriately. The method for acquiring information on the size of the pupil of the subject's eye E (S35) may be the same as S2 in the first embodiment and S18 in the second embodiment. The method for determining whether the size of the pupil of the subject's eye E is equal to or larger than a threshold (S36) may be the same as S3 in the first embodiment and S20 in the second embodiment.

[0114] If the size of the pupil of the test eye E obtained in S35 is equal to or larger than the threshold value (S36: YES), the control unit 100 maintains the alignment position between the test eye E and the optical axis L of the fundus photography device 1 at the first position set in S31, and performs photography of a front image of the fundus Er of the test eye E using the front photography optical system 10 (S38).

[0115] On the other hand, if the size of the pupil of the subject's eye E acquired in S35 is less than the threshold value (S36: NO), the control unit 100 sets the alignment position between the subject's eye E and the optical axis L of the fundus photographing device 1 to the second position (S37). As described above, the second position is an alignment position shifted from the second position. In this embodiment, the second position is an alignment position assuming that one of the two light projection regions P1, P2 and the light receiving region R of the front photographing optical system 10 is within the pupil region, and the other of the two light projection regions P1, P2 is outside the pupil region. Thereafter, the control unit 100 executes photographing a front image of the fundus Er of the subject's eye E by the front photographing optical system 10 (S38).

[0116] As described above, according to the third embodiment, similarly to the first and second embodiments, the process of acquiring the OCT signal and the process of photographing the front image of the fundus Er are appropriately performed consecutively according to the size of the pupil of the test eye E. In addition, in the third embodiment, when the size of the pupil of the test eye E is less than a threshold value, the control unit 100 performs combo photographing in a state in which the alignment position at the time of acquiring the OCT signal by the OCT optical system 200 is set to the first position, and the alignment position at the time of photographing by the front photographing optical system 10 is set to the second position. Therefore, in the third embodiment, the tilt of the image acquired by the OCT optical system 200 is appropriately suppressed, so that the OCT signal can be easily acquired with higher accuracy.

[0117] The techniques disclosed in the above embodiments are merely examples. Therefore, the techniques exemplified in the above embodiments can be modified. For example, some of the processes exemplified in Figs. 10 to 12 can be omitted. [Explanation of symbols]

[0118] 1 Fundus photography device 8 Drive unit 10 Frontal Shooting Optical System 28 Imaging element 40 Anterior segment imaging optical system 50 Split target projection optical system 100 Control section 101 Storage section 200 OCT optics P1, P2 Light projection area R light receiving area M1,M2 split indicator

Claims

1. A fundus photographing device that photographs an image of a fundus of a subject's eye with an optical axis of the device aligned with a pupil of the subject's eye, a front photographing optical system that forms a light projection area, through which illumination light passes, and a light receiving area, from which fundus reflected light of the illumination light is extracted, in different areas on the pupil of the subject's eye, forms the illumination light that passes through the light projection area and irradiates the fundus in a slit shape, and photographs a front image of the fundus by scanning the slit-shaped illumination light in a direction intersecting the elongation direction; an OCT optical system that splits light emitted from an OCT light source into measurement light and reference light, and acquires an OCT signal by receiving interference light between the measurement light reflected by tissue and the reference light; an optical axis alignment unit that aligns the optical axis of the front imaging optical system and the optical axis of the OCT optical system on the optical axis of the device; a driving unit for adjusting the positional relationship between the eye to be examined and the optical axis of the device; A control unit; Equipped with The control unit an alignment position between the subject's eye and the optical axis of the device can be selectively set to either a first position where the light projection area and the light reception area of ​​the front photographing optical system are all within the pupil area of ​​the subject's eye, or a second position shifted from the first position; When combo imaging is performed for the same subject's eye, in which acquisition of an OCT signal by the OCT optical system and capture of a front image by the front imaging optical system are performed consecutively, Obtaining information about the pupil size of the subject's eye; When the size of the pupil of the subject's eye is equal to or larger than a threshold value, the combo photographing is performed with the alignment position set to the first position; A fundus photography device characterized in that, when the size of the pupil of the test eye is less than a threshold value, the combo photography is performed with the alignment position during photography using at least the front photography optical system set to the second position.

2. 2. The fundus imaging apparatus according to claim 1, the front imaging optical system captures the front image of the fundus by irradiating the illumination light, which is visible light, onto the fundus; In the combo photography, the fundus photography device is characterized in that after the OCT signal is acquired by the OCT optical system, a front image is continuously photographed by the front photographing optical system.

3. 2. The fundus imaging apparatus according to claim 1, an anterior ocular segment observation optical system for capturing an anterior ocular segment observation image of the subject's eye; The control unit acquires information about the size of the pupil of the subject's eye based on an anterior-segment observation image captured by the anterior-segment observation optical system.

4. 2. The fundus imaging apparatus according to claim 1, The optical system further includes a split target projection optical system that projects two split targets, the separation state of which changes depending on the focus state, onto the fundus of the subject's eye, The control unit acquires information about the size of the pupil of the subject's eye based on the state of the split target reflected in the observation image of the fundus.

5. 2. The fundus imaging apparatus according to claim 1, The optical system further includes a split target projection optical system that projects two split targets, the separation state of which changes depending on the focus state, onto the fundus of the subject's eye, The control unit determining whether or not a focus state of the subject's eye can be detected using the two split targets based on the captured image of the subject's eye; A fundus photography device characterized by, when it is determined that it is impossible to detect the focus state of the test eye using the two split indicators, performing a process of detecting the focus state by decentering the position of the optical axis of the device relative to the test eye compared to when detection is possible, or a process of acquiring the focus state detected by the OCT optical system.

6. A fundus photography control program executed in a fundus photography device that photographs an image of a fundus of a subject's eye while aligning an optical axis of the device with a pupil of the subject's eye, comprising: The fundus photographing device is a front photographing optical system that forms a light projection area, through which illumination light passes, and a light receiving area, from which fundus reflected light of the illumination light is extracted, in different areas on the pupil of the subject's eye, forms the illumination light that passes through the light projection area and irradiates the fundus in a slit shape, and photographs a front image of the fundus by scanning the slit-shaped illumination light in a direction intersecting the elongation direction; an OCT optical system that splits light emitted from an OCT light source into measurement light and reference light, and acquires an OCT signal by receiving interference light between the measurement light reflected by tissue and the reference light; an optical axis alignment unit that aligns the optical axis of the front imaging optical system and the optical axis of the OCT optical system on the optical axis of the device; a driving unit for adjusting the positional relationship between the eye to be examined and the optical axis of the device; A control unit; Equipped with an alignment position between the subject's eye and the optical axis of the device can be selectively set to either a first position where the light projection area and the light reception area of ​​the front photographing optical system are all within the pupil area of ​​the subject's eye, or a second position shifted from the first position; The fundus photography control program is executed by the control unit, When combo imaging is performed for the same subject's eye, in which acquisition of an OCT signal by the OCT optical system and capture of a front image by the front imaging optical system are performed consecutively, a pupil information acquiring step of acquiring information about the size of the pupil of the subject's eye; a first photographing step of performing the combo photographing with the alignment position set to the first position when the size of the pupil of the subject's eye is equal to or larger than a threshold value; a second photographing step, in which, when the size of the pupil of the subject's eye is less than a threshold, the combo photographing is performed with at least the alignment position during photographing by the front photographing optical system set to the second position; a fundus photographing control program for causing the fundus photographing device to execute the above;

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