Fundus photography device

Abstract

To provide an ocular fundus imaging device capable of easily and appropriately imaging the ocular fundus of an eye to be examined whose translucent body is turbid.SOLUTION: An ocular fundus imaging device includes: an imaging unit having a front imaging optical system in which a projection region and a reception region of illumination light are formed side by side in a first direction on the pupils of an eye to be examined for acquiring a two-dimensional reflection image of the ocular fundus by scanning the illumination light on the ocular fundus of the eye to be examined; a driving unit for relatively moving the imaging unit with respect to the eye to be examined; and control means for switching control to guide positional relationships between the eye to be examined and the imaging unit between a first alignment mode and a second alignment mode, the positional relationships in the first alignment mode being guided to a first alignment state, which is predetermined positional relationships and the positional relationships in the second alignment mode being guided to a second alignment state, in which the positional relationships are displaced at least in a direction intersecting with the first direction, as opposed to the first alignment state.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates to a fundus imaging apparatus. [Background technology]

[0002] Fundus cameras, OCT devices, and other fundus imaging devices are widely used in the field of ophthalmology. However, there are cases where the presence of opacity in the optic body of the subject's eye prevents the fundus imaging device from properly capturing images of the fundus.

[0003] In contrast to this, when photographing the fundus of an eye to be examined in which the optical medium is opaque, a method is known in which alignment adjustment is performed to avoid the opacity and a fundus image is acquired.

[0004] For example, Patent Document 1 discloses an apparatus that acquires three-dimensional OCT data of the anterior segment of the eye, determines the distribution of opacities, and then performs alignment adjustment for fundus photography so as to avoid the opacities.

[0005] Furthermore, transillumination is known as a method for obtaining an image of the distribution of opacities in the optic body. Transillumination is a method for observing light that is irradiated through the pupil and then reflected back from the fundus. Patent Document 2 discloses an apparatus for obtaining a transillumination image using an anterior segment observation optical system by providing a dedicated light source.

[0006] Patent Document 2 discloses an optical system for a fundus camera, which is currently widely used in many ophthalmology facilities. The fundus camera simultaneously irradiates the entire fundus imaging area with imaging light and captures a two-dimensional fundus reflection image based on the fundus reflection light. In general, fundus cameras irradiate the subject's pupil with imaging light in a ring shape from the periphery, and the pupil division is set so that the fundus reflection light is extracted from the center of the pupil. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-186930 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-99718 Summary of the Invention [Problem to be solved by the invention]

[0008] In the method of Patent Document 1 for checking the presence or degree of opacity in the subject's eye, the OCT optical system must be adjusted once in advance to photograph the fundus, and then 3D OCT data of the anterior segment must be captured, making it difficult to smoothly obtain a fundus image. Furthermore, the use of retroillumination requires a dedicated light source, etc., which tends to complicate the device configuration.

[0009] Furthermore, in the optical system of the fundus camera disclosed in Patent Document 2, when alignment adjustment is performed to a position away from the center of the subject's eye (e.g., the corneal apex) to avoid opacity, flare is likely to occur due to reflected light from the translucent body, which is a problem.

[0010] The present disclosure has been made based on at least one of the problems of the conventional technology, and has as its technical objective the provision of a fundus photography device that can easily and effectively photograph the fundus of a test eye whose optical body is clouded. [Means for solving the problem]

[0011] A fundus photographing device according to a first aspect of the present disclosure includes a photographing unit including a front photographing optical system in which a light projection area and a light receiving area of ​​illumination light are aligned in a first direction and formed on a pupil of a subject's eye, the front photographing optical system acquiring a two-dimensional reflection image of the fundus by scanning the illumination light on the fundus of the subject's eye, a driving unit that moves the photographing unit relative to the subject's eye, and a control for guiding a positional relationship between the subject's eye and the photographing unit, the control being a first alignment mode. To avoid opacity in the optic media of the subject's eye a control means for switching between a first alignment mode and a second alignment mode, wherein in the first alignment mode, the positional relationship is guided to a first alignment state which is a predetermined positional relationship, and in the second alignment mode, To avoid opacification in the optic media of the subject's eye, and a control means for guiding the alignment state to a second alignment state in which the positional relationship is displaced from the first alignment state in at least a direction intersecting the first direction. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an external view of a fundus imaging device. [Figure 2] FIG. 2 is a schematic diagram of an optical system of the fundus imaging apparatus. [Figure 3] FIG. 2 is a schematic diagram of a front photographing optical system. [Figure 4] FIG. 10 is a diagram showing an example of a fundus observation image on which a split index is projected. [Figure 5] 1 is a schematic diagram of an anterior segment observation optical system; [Figure 6] Schematic diagram of OCT optical system [Figure 7] FIG. 2 is a block diagram showing a control system of the fundus imaging apparatus. [Figure 8] 1 is a flowchart showing the flow of operation of the device in the embodiment. [Figure 9] FIG. 10 is a diagram showing an anterior eye segment observation image. [Figure 10] FIG. 10 is a diagram for explaining a small pupil mode. [Figure 11] 10 is a flowchart showing a second alignment adjustment. [Figure 12] FIG. 10 is a diagram for explaining the second alignment adjustment in normal operation. [Figure 13] FIG. 10 is a diagram for explaining a second alignment adjustment in a small pupil mode. [Figure 14] FIG. 10 is a diagram for explaining a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0013] [overview] An embodiment of a fundus imaging device according to the present disclosure will be described. Each embodiment may be applied to part or all of the other embodiments. For example, the items grouped in < > below may be used independently or in conjunction with each other.

[0014] The fundus imaging device according to each embodiment of the present disclosure performs alignment adjustment for an examinee's eye in which an optical medium is opaque so as to reduce the influence of the opacity, and acquires a photographed image of the fundus.

[0015] A fundus imaging device according to each embodiment of the present disclosure includes at least a photographing unit, a driving section, and a control section.

[0016] First Embodiment First, the fundus imaging apparatus according to the first embodiment will be described.

[0017] <Photography unit> The photographing unit in this embodiment includes at least a photographing optical system and an observation optical system. The photographing unit may include various optical systems in a fundus photographing device. For example, the photographing unit may include at least one of an anterior eye observation optical system and a target projection optical system. The positional relationship between each optical system and the subject's eye may be changed as a whole by a driving unit.

[0018] <Photographing optical system> The photographing optical system is used to project and receive photographing light onto the subject's eye and obtain a photographic image of the fundus.

[0019] <Frontal shooting optical system> The imaging optical system may be, for example, a front imaging optical system. The front imaging optical system acquires a two-dimensional reflected image of the fundus based on the fundus reflected light of the imaging light as a captured image. The imaging optical system may be a scanning optical system or a non-scanning optical system. Examples of the scanning optical system include a spot scan type optical system and a line scan type optical system. In the spot scan type optical system, the spot-shaped imaging light on the fundus is scanned two-dimensionally. In the line scan type optical system, the line-shaped imaging light is scanned in one direction (details will be described later in the second embodiment). Further, examples of the non-scanning optical system include the optical system of a general fundus camera, etc.

[0020] <OCT optical system> The imaging optical system may be, for example, an OCT optical system. The OCT optical system is used to capture OCT data of the fundus based on a principle different from that of the front imaging optical system (specifically, the principle of optical interference). That is, the OCT optical system detects the spectral interference signal between the measurement light guided to the fundus of the subject eye and the reference light. In this case, the measurement light is used as the imaging light. By processing the spectral interference signal, the OCT data of the fundus is imaged.

[0021] The OCT optical system has at least an OCT light source and a detector. The detector detects the interference state between the measurement light and the reference light emitted from the OCT light source. Additionally, it may have an optical scanner for scanning the measurement light on the fundus. The OCT optical system may have a Fourier domain OCT optical system as a basic configuration. For example, the OCT optical system may be a spectral domain OCT (SD-OCT) optical system, a wavelength swept OCT (SS-OCT) optical system, or a time-domain OCT (TD-OCT) optical system.

[0022] Further, the fundus imaging device may be provided with both a front imaging optical system and an OCT optical system as imaging optical systems.

[0023] <Observation optical system> The observation optical system (also referred to as the fundus observation optical system) is used to project and receive observation light, which is infrared light and is different from the photographing light, onto the fundus of the subject's eye, and to acquire a fundus observation image, which is a two-dimensional reflection image based on the observation light. The observation light and the photographing light may, for example, have different wavelengths. The fundus observation image is acquired at any time in approximately real time. The fundus observation image is used, for example, to adjust various photographing conditions. In this embodiment, the observation optical system is also used to adjust (and guide) the positional relationship between the subject's eye and the photographing unit (details will be described later). The observation optical system may be a scanning optical system or a non-scanning optical system, similar to the front photographing optical system described above.

[0024] When the photographing optical system is a front photographing optical system, part or all of the photographing optical system may be used as both the photographing optical system and the observation optical system.

[0025] <Target projection optical system> The target projection optical system projects a target light beam onto the fundus to adjust the photographing conditions of the photographing optical system. The target light beam is captured by the observation optical system. As a result, the target image is reflected in the observed image. The control unit adjusts the photographing conditions based on the target image. Furthermore, the target image may be used to adjust the positional relationship between the subject's eye and the photographing unit (details will be described later).

[0026] The target projection optical system may project, for example, a target light beam for focus adjustment. The target light beam for focus adjustment may be a split target. In this case, at least two target light beams constituting the split target pass through different positions in the anterior segment of the subject's eye and are projected onto the fundus. The focus state is detected as the separation / alignment state of the split target. Diopter correction is performed in the photographing optical system and the observation optical system based on the focus state.

[0027] <Anterior segment observation optical system> The fundus imaging device of the first embodiment may have an anterior eye observation optical system and may be able to acquire an anterior eye observation image through the anterior eye observation optical system. The anterior eye observation optical system may have at least an imaging element. The anterior eye observation image is used to adjust the positional relationship between the subject's eye and the imaging unit (i.e., for alignment, tracking, etc.). The anterior eye observation image may be, for example, a front image of the anterior eye or an image from an oblique direction. During alignment, the anterior eye observation image may be displayed on a monitor. This allows the examiner to grasp the alignment state in real time.

[0028] The anterior-segment observation image may be captured by an imaging element of the imaging optical system or an imaging element separate from the detector. In addition to this imaging element, the anterior-segment observation optical system may also include various optical elements such as a light source.

[0029] Furthermore, the fundus imaging device may have an alignment target projection optical system that projects an alignment target onto the subject's eye, and alignment may be guided based on the alignment target formed on the observed image of the anterior segment or the fundus.

[0030] <Drive unit> The drive unit is a mechanism for moving the photographing unit relative to the subject's eye. In this case, the drive unit can change the relative position of the photographing unit with respect to the subject's eye at least in the XY directions (up, down, left, and right directions). It is more preferable that the relative position can also be changed in the Z direction. The drive unit is driven to adjust the positional relationship between the subject's eye and the photographing unit.

[0031] The driving unit may have an actuator that changes the positional relationship between the subject's eye and the photographing unit based on a signal from the control unit. The driving unit may displace the photographing unit, or may displace a face support unit (e.g., a chin rest) that supports the subject's face, or may be a combination of both.

[0032] <Control unit> The control unit is a processor that controls various control operations and arithmetic processing in the fundus imaging apparatus.

[0033] For example, the control unit performs alignment control. In the first embodiment, the control unit guides the positional relationship between the subject's eye and the photographing unit at least in the X and Y directions based on the fundus observation image. In this case, the positional relationship may be guided so that the optical axis of the photographing unit does not coincide with the center of the anterior segment (for example, the center of the pupil or the corneal apex). Note that the alignment control based on the fundus observation image according to the first embodiment may be performed at a stage when the system transitions to an alignment state in which the fundus observation image can be acquired.

[0034] In this embodiment, the alignment guidance may be a so-called automatic alignment method or a manual alignment method. In the automatic alignment method, the control unit may drive and control the drive unit based on a fundus observation image. In the manual alignment method, the control unit may display an anterior eye observation image on the monitor and also display a guide (e.g., an electronic reticle) that guides operation to the target position based on the fundus observation image. In this case, the ophthalmologic imaging apparatus may include an operation input unit that receives an operation from the examiner and drives the drive unit in response to the operation to adjust the positional relationship between the subject's eye and the imaging unit. The operation input unit may be an input interface that inputs an operation for driving an actuator of the drive unit, or may directly act on a mechanical drive unit.

[0035] For example, if opacity occurs in the optic body of the subject's eye and at least a portion of the observation light is blocked by the opacity, the observation image will be affected by the opacity. For example, the influence of the opacity may cause a decrease in brightness, uneven brightness, a decrease in contrast, and shadows due to vignetting in the observation image. By evaluating the influence of the opacity in the observation image, for example, it is possible to estimate the presence or absence of opacity or the degree of opacity at a position on the pupil of the subject's eye that is used to project and receive the observation light, given the positional relationship between the subject's eye and the imaging unit at that time. In this case, the evaluation may be based on at least one of the brightness and contrast in the observation image. Specifically, the influence of opacity in the observation image may be evaluated based on the degree of decrease in either the brightness or the contrast in the observation image.

[0036] However, this is not necessarily limited to this. For example, when an observation image is acquired with an index light beam from the index projection optical system projected onto the fundus, the influence of opacity in the observation image may be evaluated based on the detection result of the index image. In this case, the presence or absence of opacity or the degree of opacity at the position on the pupil of the subject's eye where the index light beam is projected and received is estimated based on the detection result of the index image. The influence of opacity in the observation image may be evaluated based on at least one of the presence or absence of an index image, the brightness of the index image, and the contrast of the index image.

[0037] When the control unit evaluates the influence of opacity in the observation image, the evaluation may be performed based on a partial region of the observation image. For example, the evaluation is preferably performed based on the central portion of the observation image. The central portion of the image is less susceptible to uneven brightness even if the optical axis of the photographing unit is displaced from the center of the anterior segment, making it easier to properly evaluate the influence of opacity in the observation image. Furthermore, even if flare occurs due to the translucent body, the central portion of the observation image is less susceptible to flare, making it easier to properly evaluate the influence of opacity in the observation image.

[0038] In the first embodiment, the positional relationship between the subject's eye and the photographing unit is guided at least in the X and Y directions based on the fundus observation image, so that even when photographing a subject's eye in which opacity has occurred in the optically transparent body, for example, the influence of the opacity can be reduced based on the fundus observation image, and the alignment state can be adjusted. That is, when photographing a subject's eye in which opacity has occurred in the optically transparent body, the control unit may guide the positional relationship between the subject's eye and the photographing unit so as to avoid the opacity.

[0039] When guiding the positional relationship between the subject's eye and the photographing unit based on a fundus observation image, the control unit may search for a positional relationship between the subject's eye and the photographing unit that will allow a better observation image to be acquired. In this case, the control unit may acquire multiple fundus observation images at multiple positional relationships that are different from each other at least in the X and Y directions, and guide the positional relationship between the subject's eye and the photographing unit based on the multiple fundus observation images. In this case, the positional relationship between the subject's eye and the photographing unit can be induced so that the effects of opacity are more effectively suppressed. For example, multiple fundus observation images may be acquired in association with the current alignment state (the positional relationship between the subject's eye and the photographing unit). After multiple fundus observation images are acquired at multiple positional relationships, the positional relationship may be re-guided to a positional relationship that more effectively suppresses the effects of opacity, and then photographing may be performed. Note that the multiple positional relationships at which multiple fundus observation images are acquired during the search may transition in a predetermined pattern or a random pattern. The timing at which the search is terminated may be determined as appropriate. For example, the search may be terminated when the observation images acquired at any time satisfy a predetermined condition.

[0040] In the first embodiment, the positional relationship between the subject's eye and the photographing unit is determined based on a fundus observation image, which reduces the complexity of the device configuration. Furthermore, in a device equipped with an OCT optical system, it is possible to align the subject's eye to avoid opacity using OCT data acquired through the OCT optical system. In comparison with this case, determining the positional relationship between the subject's eye and the photographing unit based on a fundus observation image is considered to facilitate a smoother process from alignment to photographing. That is, compared with an OCT optical system, a fundus observation optical system is more likely to shorten the time required for various adjustments leading up to photographing. Furthermore, the observation optical system generally has a larger area on the pupil of the subject's eye used for light projection and reception than an OCT optical system, which improves the efficiency of determining the positional relationship between the subject's eye and the photographing unit. Furthermore, compared with using OCT data, determining the positional relationship between the subject's eye and the photographing unit based on a fundus observation image is more suitable for obtaining not only OCT data but also two-dimensional reflection images as photographed images.

[0041] Furthermore, although details will be described later in the second embodiment, when the photographing optical system acquires a two-dimensional reflected image as a photographed image, the photographing optical system is preferably a scan-type optical system. By using the scan-type optical system, the positional relationship between the subject's eye and the photographing unit is induced so as to avoid opacity due to the optically transparent body, and as a result, even if photographing is performed with the optical axis of the photographing unit displaced from the center of the anterior segment, it becomes easier to acquire a photographed image in which flare due to the optically transparent body is suppressed.

[0042] The control unit may also acquire pupil information of the subject's eye. The pupil information is information about the pupil region, and may be information that specifies at least one of the position, shape, size, etc. of the pupil in the subject's eye. The pupil information is acquired, for example, based on an anterior eye observation image. When pupil size (for example, pupil diameter) is acquired as pupil information, the pupil information may be acquired from an external device or based on operational input by the examiner. In this case, the fundus imaging device may have an input interface.

[0043] The control unit may guide the positional relationship between the subject's eye and the photographing unit in consideration of pupil information. Note that the pupil information may be acquired in real time based on an anterior-segment observation image, and the real-time pupil information may be used to control the guidance of the positional relationship.

[0044] The range of movement in the X and Y directions of the relative positions of the subject's eye and the photographing unit, which is effective for finding a positional relationship that allows the observation light to be properly projected and received relative to the fundus, can be specified based on the pupil information. Therefore, by taking the pupil information into consideration, alignment adjustment based on the observation image can be performed more smoothly.

[0045] Furthermore, when information on the pupil size of the subject's eye is acquired as the pupil information, the control unit may change the guidance control of the positional relationship between the subject's eye and the photographing unit based on the fundus observation image according to the pupil size. For example, at least one of the movement range, movement direction, movement pattern, etc. when changing the relative position between the subject's eye and the photographing unit based on the observation image may be changed between different pupil sizes.

[0046] For example, if the pupil division of the photographing optical system and the observation optical system is set so that the light-projecting area and the light-receiving area of ​​the observation light on the pupil of the test eye are aligned in one direction, in an eye with a small pupil, moving the relative position between the test eye and the photographing unit in the one direction will likely result in vignetting of the photographing light and the observation light by the iris. In this case, for example, if the pupil size is larger than a threshold, the direction of movement when changing the relative position between the test eye and the photographing unit based on the observation image is not limited, and if the pupil size is equal to or smaller than the threshold, the relative position between the test eye and the photographing unit is limited to a direction intersecting the one direction based on the observation image, which will make it easier to appropriately adjust to an alignment state in which the effects of opacity are suppressed.

[0047] In general, the required pupil diameter of the OCT optical system is smaller than that of the observation optical system. Therefore, for example, when the imaging optical system is an OCT optical system, if the pupil size is larger than a threshold, the relative position between the subject's eye and the imaging unit may be changed based on the observation image, and if the pupil size is equal to or smaller than the threshold, the relative position between the subject's eye and the imaging unit may be changed based on OCT data acquired via the OCT optical system.

[0048] <Reuse of search results> When the control unit searches for the positional relationship between the subject's eye and the photographing unit and photographs the subject's eye, the search results for the photographs may be reused thereafter. For example, the search results may be used for alignment guidance during follow-up photographs. Furthermore, when photographs are taken while changing the presentation position of fixation or the like between a first position and a second position, alignment guidance at the second position may be performed based on the search results performed at the first position. Since the positional relationship between the optical axis of the photographing unit and the pupil of the subject's eye changes depending on the presentation position of fixation or the like, the search results performed at the first position may be saved together with position information of the pupil of the subject's eye at that time. For example, the adjustment results of the positional relationship between the subject's eye and the photographing unit at the first position may be saved based on the pupil center position. During alignment adjustment at the second position, the positional relationship between the subject's eye and the photographing unit may be induced based on the pupil position acquired from the anterior eye observation image and the adjustment results acquired in advance at the first position. For example, the first position may be a presentation position such as fixation that allows a captured image to be obtained at the center of the macula, and the second position may be a presentation position such as fixation that allows a captured image to be obtained at the center of the macula (or centered between the macula and the macula).

[0049] <Starting conditions for alignment control based on fundus observation images> In the fundus imaging apparatus of the first embodiment, it may be possible to switch whether or not alignment control based on a fundus observation image is started.

[0050] For example, whether or not to perform alignment control based on a fundus observation image may be set in advance by an operation input from the examiner.

[0051] Furthermore, for example, after the alignment state is appropriately adjusted to a state where a fundus observation image can be acquired, the control unit may determine whether or not to start the alignment control by estimating the influence of opacity based on the fundus observation image. Depending on the determination result, the alignment control based on the fundus observation image may be started automatically, or an instruction to start the alignment control based on the fundus observation image may be requested from the examiner via a user interface.

[0052] Furthermore, for example, if information indicating that the subject's eye has cataracts is associated with the subject's ID in a previous examination, alignment control based on the fundus observation image may be started automatically in accordance with the information associated with the subject's ID, or an instruction to start alignment control based on the fundus observation image may be requested from the examiner via a user interface. Furthermore, if information indicating that the subject's eye has an IOL inserted is associated with the subject's eye, there is a high possibility that the problem of opacity will not occur, and therefore alignment adjustment may be completed without performing alignment control based on the fundus observation image.

[0053] Second Embodiment Next, a second embodiment of the present disclosure will be described.

[0054] <Scanning type front imaging optical system> In the second embodiment, the photographing unit has at least a scanning-type front photographing optical system. The front photographing optical system may be a spot scan type optical system or a line scan type optical system. In the following description, unless otherwise specified, the front photographing optical system in the second embodiment is also used as the observation optical system. For convenience of explanation, the photographing light and the observation light are collectively referred to as "illumination light."

[0055] In the second embodiment, the front imaging optical system has at least an irradiation optical system, a light receiving optical system, a scanning unit, and a harmful light removing unit.

[0056] The illumination optical system illuminates the fundus of the subject's eye with illumination light via the objective optical system. Additionally, the illumination optical system may have a light source (illumination light source) that emits illumination light. The light-receiving optical system has a light-receiving element that receives the fundus reflection light of the illumination light. A signal from the light-receiving element is input to an image processing unit. The image processing unit acquires a two-dimensional reflection image of the fundus of the subject's eye based on the signal from the light-receiving element. Note that the light-receiving element may be any of a point light-receiving element, a line sensor, a two-dimensional light-receiving element (imaging element), etc., and may be appropriately adopted depending on the optical system.

[0057] The illumination optical system and the light-receiving optical system may share some optical elements. For example, the objective optical system and the light-path combining unit may be shared. The light-path combining unit combines and separates the projection light path of the illumination light and the reception light path of the fundus reflected light. In this case, the objective optical system is disposed on the common light path formed by the projection light path and the reception light path by the light-path combining unit.

[0058] In the second embodiment, the illumination optical system forms a local illumination area in a part of the imaging range of the fundus. That is, the illumination optical system irradiates the fundus with local illumination light. The illumination optical system typically forms a slit-shaped or spot-shaped illumination area.

[0059] The harmful light removing unit may be disposed at a position conjugate with the fundus on the optical path of the light receiving optical system.

[0060] The harmful light removal unit receives fundus reflected light from a localized imaging area (hereinafter referred to as the "effective area"), which is a part of the imaging range, at the light receiving element. The harmful light removal unit also removes light from areas other than the effective area. The harmful light removal unit may be, for example, an aperture. A typical aperture in a spot scanning device is a pinhole, and a typical aperture in a slit scanning device is a slit. In this case, fundus reflected light from an effective area corresponding to the aperture opening within the entire imaging range of the fundus is selectively guided to the light receiving element to obtain an effective image. In particular, in slit scanning devices, the light receiving element may also serve as the harmful light removal unit. In this case, a line sensor having a slit shape may be used as the light receiving element, or a CMOS that performs line exposure on a two-dimensional imaging surface (in other words, with a rolling shutter function) may be used. In this case, fundus reflected light from an effective area corresponding to a line-shaped effective pixel within the entire imaging range of the fundus is selectively guided to the light receiving element to image the effective area.

[0061] The scanning unit synchronously scans the local illumination area and the effective area (local photographing area) on the fundus. The scanning unit may be, for example, an optical scanner shared between the illumination optical system and the light-receiving optical system. In this case, the optical scanner is disposed on a common optical path between the illumination optical system and the light-receiving optical system.

[0062] The scanning unit may also include a first scanning unit provided in the irradiation optical system and a second scanning unit separate from the first scanning unit and provided in the light receiving optical system. In this case, in an example of a slit scan type device, a first slit-shaped member may be disposed on the optical path of the irradiation optical system to form a localized illumination area in a slit shape. The first scanning unit may include a first slit-shaped member and a driving unit that moves the first slit-shaped member in a direction intersecting with the optical axis. Furthermore, when a second slit-shaped member is used as the harmful light removal unit, the second scanning unit may include a second slit-shaped member and a driving unit that moves the second slit-shaped member in a direction intersecting with the optical axis. The driving units of the first scanning unit and the second scanning unit may be separate devices or may be a common device.

[0063] Furthermore, in a slit-scan type device, when a CMOS is used as the light-receiving element, the CMOS can also serve as the second scanning unit. That is, the line exposure using the rolling shutter function described above may be controlled in synchronization with the first scanning unit. In this case, the CMOS light-receiving element serves both as the harmful light removal unit and the second scanning unit. This reduces the number of components in the optical system.

[0064] In a line scan type optical system, a line of illumination light is scanned in one direction. The line of illumination light may be scanned linearly on the fundus, or may be scanned in a rotational manner on the fundus. In the case of a rotational scan, the center of rotation may be the optical axis of the front imaging optical system.

[0065] <Pupil division in a frontal imaging optical system> In this disclosure, of the pupil image of the front imaging optical system formed on the pupil of the subject's eye, the area through which light passes from the device toward the fundus is referred to as the light projection area, and the area through which fundus reflected light passes is referred to as the light receiving area.

[0066] In the front imaging optical system according to the second embodiment, at least a light-projecting region and a light-receiving region are formed on the pupil of the subject's eye, aligned in a first direction. The light-projecting region and the light-receiving region aligned in the first direction are arranged in a line and non-concentrically. That is, unlike a general fundus camera optical system in which pupil division is performed using a ring slit and a hole mirror, the light-projecting region and the light-receiving region are arranged without a gap between one of the light-projecting region and the light-receiving region and the other. Furthermore, the light-projecting region and the light-receiving region may be arranged on the pupil of the subject's eye so that the other of the light-projecting region and the light-receiving region is not arranged in a direction intersecting the first direction relative to the other.

[0067] At least one of the light-projecting region and the light-receiving region may be formed in a plurality of positions different from each other in the first direction. In order to suppress flare of the light-transmitting body, it is desirable that the first direction coincides with the scanning direction of the illumination light on the fundus in a slit-scan type device.

[0068] <Alignment control mode switching> In the second embodiment, the control for guiding the positional relationship between the subject's eye and the photographing unit (front photographing optical system) is switched between a first alignment mode and a second alignment mode by the control unit. The first alignment mode and the second alignment mode may be set based on, for example, information about opacity in the optical medium of the subject's eye (hereinafter referred to as opacity information of the subject's eye). Alternatively, they may be set based on a mode switching operation by the examiner.

[0069] In the first alignment mode, the positional relationship between the subject's eye and the photographing unit is guided to a first alignment state, which is a predetermined positional relationship. In the second alignment mode, the positional relationship between the subject's eye and the photographing unit is guided to a second alignment state, in which the positional relationship between the subject's eye and the photographing unit is displaced from the first alignment state. In the second embodiment, one light-projecting area and one light-receiving area are aligned in a first direction on the pupil of the subject's eye, so there is little room (space) to move the light-projecting area and the light-receiving area in the first direction within the pupil area. Therefore, it is difficult to avoid opacity even if the light-projecting area and the light-receiving area are moved in the first direction within the pupil area.

[0070] In contrast, in the second embodiment, in the second alignment mode, the control unit guides the eye to the second alignment state by at least displacing the positional relationship between the subject's eye and the photographing unit in a direction intersecting with the first direction relative to the first alignment state. In the front photographing optical system, it is easy to ensure a margin (space) for moving the light-projecting area and the light-receiving area within the pupil area in a direction intersecting with the first direction, so it is thought that guiding the positional relationship in a direction intersecting with the first direction makes it easier to avoid opacity.

[0071] The direction intersecting the first direction may be a direction perpendicular to the first direction or a direction intersecting the first direction obliquely.

[0072] Furthermore, even if the optical axis of the front imaging optical system is displaced from the center of the anterior segment as a result of guiding the positional relationship between the subject's eye and the imaging unit so as to avoid opacification of the optically transparent body, flare due to the optically transparent body can be suppressed by using the scanning optical system as described above. That is, in a scanning optical system, local illumination light is irradiated onto the fundus over the entire imaging range. Therefore, compared to a general fundus camera in which illumination light is irradiated onto the entire imaging range simultaneously, separation of the projected and received light at the optically transparent body is more easily achieved, and flare is less likely to occur. Thus, in the second embodiment, the fundus of a subject's eye with an opacified optically transparent body can be well imaged in the second alignment mode.

[0073] <Obfucation information acquisition> The control unit may acquire opacity information of the subject's eye. The opacity information may be information indicating at least one of the presence or absence of opacity, the degree of opacity, and the distribution of opacity. In the first embodiment, it was shown that the presence or absence of opacity or the degree of opacity at a certain position on the pupil of the subject's eye can be estimated based on a fundus observation image. Therefore, the opacity information may be acquired based on the fundus observation image. However, in the second embodiment, the opacity information is not necessarily limited to this. For example, the opacity information may be acquired based on at least one of a transillumination image, OCT data of the anterior segment, and OCT data of the fundus. The opacity information may also be acquired based on the test results of a previous test. In this case, the subject's ID and the opacity information may be stored in memory in a pre-associated state.

[0074] As described above, the control unit may select whether to execute alignment control in the first alignment mode or the second alignment mode based on the opacity information.

[0075] Furthermore, the opacity information may be used to predict the positional relationship between the subject's eye and the photographing unit that can avoid opacity in the second alignment mode, or to evaluate the influence of opacity.

[0076] Furthermore, similarly to the first embodiment, the control unit may acquire pupil information as information relating to the pupil region of the subject's eye, and may guide the positional relationship between the subject's eye and the photographing unit in consideration of the pupil information. In this case, for example, the control unit may acquire information relating to the pupil size of the subject's eye as the pupil information, and may change the guidance control of the positional relationship based on the fundus observation image in accordance with the pupil size.

[0077] In the second embodiment, the photographing unit may further include the above-described OCT optical system. The OCT optical system is used to photograph OCT data of the fundus based on the principle of optical interference. In the second alignment mode, the control unit may capture OCT data and a two-dimensional reflected image of the fundus in the second alignment state. That is, after the positional relationship between the subject's eye and the photographing unit is guided to the second alignment state in the second alignment mode, the control unit may control the OCT optical system to acquire OCT data of the fundus and control the front photographing optical system to photograph a two-dimensional reflected image of the fundus. In this case, the two-dimensional reflected image of the fundus may be a color fundus image.

[0078] [First Example] An example of the fundus imaging apparatus according to the first and second embodiments will be described.

[0079] The fundus photographing device 1 photographs a color fundus image as a two-dimensional reflection image of the fundus Er, and further photographs OCT data of the subject's eye.

[0080] Fig. 1 is an external view of a fundus imaging device 1. The fundus imaging device 1 has a photographing unit 3. The photographing unit 3 mainly includes the optical system shown in Fig. 2. The fundus imaging device 1 has a base 7, a drive unit 8, a face support unit 9, and a face imaging camera 110. These are used to adjust the positional relationship between the subject's eye E and the photographing unit 3.

[0081] The drive unit 8 moves the photographing unit 3 on the drive unit 8 in each of the X, Y and Z directions relative to the subject's eye E. The drive unit 8 has an actuator for moving the photographing unit 3 in each movable direction, and 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.

[0082] 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 controls the driving of the driving unit 8 to align the photographing unit 3 with the identified position of the subject's eye E.

[0083] The photographing device 1 further includes a monitor 120. The monitor 120 displays various photographed images, observed images, and the like.

[0084] <Photography unit> 2 is a schematic diagram of the optical system of the fundus imaging device 1. In this embodiment, the fundus imaging device 1 has a front imaging optical system 10, an anterior eye observation optical system 40, and an OCT optical system 200. In this embodiment, each optical system shares an objective lens 22. In this embodiment, the front imaging optical system 10 also serves as the fundus observation optical system. These optical systems are provided in the imaging unit 3.

[0085] In this embodiment, the optical axis of the anterior eye observation optical system 40 and the optical axis 200 of the OCT optical system are made coaxial by a half mirror 45. In this embodiment, the optical axes of the anterior eye observation optical system 10 and the OCT optical system 200, which are made coaxial by the half mirror 45, and the optical axis of the front imaging optical system 10 are made coaxial by a dichroic mirror 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.

[0086] <Frontal shooting optical system> Fig. 3 is a schematic diagram of the front imaging optical system 10. In Fig. 3, the pupil conjugate position conjugate with the pupil of the subject's eye is indicated by a "△" on the optical axis, and the fundus conjugate position is indicated by an "X" on the optical axis.

[0087] The front imaging optical system includes an illumination optical system 10a and a light-receiving optical system 10b. The illumination 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 perforated mirror 20, and an objective lens 22. The light-receiving optical system 10b includes an objective lens 22, a perforated mirror 20, lenses 25a and 25b, a slit-shaped member 15b, and an image sensor 28.

[0088] The light source unit 11 has multiple types of light sources with different wavelength bands. For example, the light source unit 11 has visible light sources 11a and 11b and infrared light sources 11c and 11d. As such, the light source unit 11 of this embodiment is provided with two light sources for each wavelength. The two light sources of the same wavelength are arranged apart from the optical axis L on the pupil conjugate plane. The two light sources 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 whose length in a direction intersecting the scanning direction is longer than that in the scanning direction.

[0089] Light from the two light sources 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 slit-shaped illuminated area on the fundus Er is shown as symbol B).

[0090] 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. This realizes scanning of the illumination light in this embodiment. Note that 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 on the light-emitting side and the light-receiving side are driven in conjunction with each other by a single 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 an optical system employing an optical chopper, see, for example, Japanese Patent Application Laid-Open No. 2019-118721 filed by the present applicant.

[0091] 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 formed on the pupil conjugate plane. That is, pupil images by the two light sources are formed at positions separated in the scanning direction on the pupil conjugate plane. In this way, in this embodiment, two light-projected areas P1 and P2 on the pupil conjugate plane are formed as images of the two light sources.

[0092] The slit-shaped light that has passed 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 through the pupil Ep.

[0093] The perforated mirror 20 is an optical path coupling unit that couples the optical paths of the irradiation optical system 10a and the light-receiving optical system 10b. The perforated mirror 20 reflects 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 passes through the aperture toward the image sensor 28. 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 and reflecting portions are reversed may be used as the optical path coupling unit. However, in this case, the independent optical path of the light-receiving optical system 10b is located on the reflecting side of the mirror, and the independent optical path of the irradiation optical system 10a is located on the transmitting side of the mirror. The perforated mirror and the mirrors that serve as its alternatives can each be further replaced with a combination of a half mirror and a light-blocking portion.

[0094] Because 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 perforated mirror aperture (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 region R in this embodiment. The light-receiving region R is formed between two light-projecting regions P1 and P2 (images of the two light sources). Furthermore, as a result of appropriately setting the imaging magnification of each image, the diameter of the aperture, and the arrangement distance between the two light sources, the light-receiving region R and the two light-projecting regions P1 and P2 are formed so as not to overlap each other on the pupil.

[0095] 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 lenses 25a and 25b. At this time, harmful light is removed by arranging the light-transmitting portion of the slit-shaped member 15b at the position of image formation.

[0096] The image sensor 28 is positioned at a conjugate position with the fundus. In this embodiment, a relay optical system 27 is provided between the slit-shaped member 15b and the image sensor 28, thereby establishing a conjugate relationship between the slit-shaped member 15b and the image sensor 28. As a result, both removal of harmful light and image formation are performed effectively. Alternatively, the relay optical system 27 between the image sensor 28 and the slit-shaped member 15b may be omitted, and the two may be positioned closely together. In this embodiment, a device with a two-dimensional light-receiving surface is used as the image sensor 28. For example, it may be a CMOS, a two-dimensional CCD, or the like. An image of the slit-shaped region of the fundus Er formed by the light-transmitting portion of the slit-shaped member 15b is projected onto the image sensor 28. The image sensor 28 is sensitive to both infrared light and visible light.

[0097] In this embodiment, as the slit-shaped illumination light is scanned on the fundus Er, images (slit-shaped images) of the scanning positions on the fundus Er are sequentially projected for each scanning line of the image sensor 28. In this way, the entire image of the scanning range is projected on the image sensor 28 in a time-division manner. As a result, a front image (two-dimensional reflection image) of the fundus is captured as the entire image of the scanning range.

[0098] 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, if the image sensor 28 is a CMOS, slit scanning may be achieved by the rolling shutter function of the CMOS. In this case, by displacing the area to be exposed on the imaging surface in synchronization with the scanning unit in the irradiation optical system 10a, it is possible to efficiently capture images while eliminating harmful light. Also, a liquid crystal shutter or the like may be used as a scanning unit that electronically scans the slit.

[0099] 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 irradiating optical system 10a and the receiving optical system 10b, respectively. However, the diopter correction units may be provided in the common optical path of the irradiating optical system 10a and the receiving optical system 10b.

[0100] For convenience, the illumination-side diopter correction optical system will be referred to as the illumination-side diopter correction optical system 17, and the light-receiving-side diopter correction optical system will be referred to as the light-receiving-side diopter correction optical system 25. The illumination-side diopter correction optical system 17 in this embodiment includes lenses 17a, 17b, and a drive unit (not shown). The light-receiving-side diopter correction optical system 25 in this embodiment includes lenses 25a, 25b, and a drive unit (not shown). The distance between lenses 17a and 17b in the illumination-side diopter correction optical system 17 is changed, and the distance between lenses 25a and 25b in the light-receiving-side diopter correction optical system 25 is changed. This allows diopter correction to be performed in both the illumination optical system 10a and the light-receiving optical system 10b.

[0101] The front imaging optical system 10 further includes an index projection optical system 50. The index projection optical system 50 projects two split indices onto the fundus Er as focus indices. The split indices are used for focus detection.

[0102] For example, the index projection optical system 50 may include at least an infrared light source 51, an index plate 52, and a deflection prism 53. In this embodiment, the index plate 52 is disposed at a position corresponding to the imaging plane of 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, when the diopter correction amount on the illumination side and the light receiving side is 0D, the index plate 52 is disposed at a position approximately conjugate with the fundus Er of an emmetropic eye (0D eye). The deflection prism 53 is disposed closer to the index plate 52 and closer to the eye to be examined.

[0103] For example, the index plate 52 forms a slit light as an index. The deflection prism 53 splits the index light beam that passes through the index plate 52 to form a split index. The split index is projected onto the fundus Er via the illumination-side diopter correction optical system 17 and the objective lens 22. Therefore, the split index is captured in a fundus image (for example, a fundus observation image). In this embodiment, one of the split indexes split into two passes through the light projection area P1, and the other passes through the light projection area P2 before reaching the fundus Er of the subject's eye.

[0104] FIG. 4 illustrates an example of a fundus observation image 60 in which split indices M1 and M2 are projected. 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 appear 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 positioned at the fundus conjugate position. In this case, the two split indices M1 and M2 appear at positions aligned in 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, which is 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 light-receiving-side diopter correction amount. By adjusting the illumination-side and light-receiving-side diopter correction amounts so that the two split indices match, the imaging plane and the slit-shaped members 15a and 15b each have a positional relationship conjugate with the fundus Er.

[0105] Also, for example, the infrared light sources (infrared light sources 11c and 11d) in the irradiation optical system 10a and the infrared light source (infrared light source 51) in the indicator projection optical system 50 may have the same infrared wavelength. Thus, in this embodiment, the fundus reflected light by the irradiation optical system 10a and the fundus reflected light by the indicator projection optical system 50 can be imaged by a single imaging element 28, and a fundus observation image including a split indicator can be obtained. Of course, the infrared wavelengths of the respective infrared light sources may be different, and in this case, an imaging element having sensitivity in a predetermined infrared wavelength range or the like may be used.

[0106] <Anterior eye observation optical system> FIG. 5 is a schematic diagram of the anterior eye observation optical system 40.

[0107] The anterior eye observation optical system 40 images the anterior eye of the subject eye 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 front 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, etc. For example, the light source 41 is an infrared light source and illuminates the subject eye E. For example, the imaging element 47 is a two-dimensional imaging element and is arranged at a position optically conjugate with the pupil Ep. The dichroic mirror 43 and the objective lens 22 are shared with the front imaging optical system. 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.

[0108] <OCT optical system>[[ID=I5]] FIG. 6 shows a schematic configuration of the OCT optical system 200. As an example, the OCT optical system 200 will be described as an SD - OCT optical system.

[0109] The OCT optical system 200 images the OCT data of the fundus Er. The OCT optical system 200 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.

[0110] In SD-OCT, a broadband light source is used as the OCT light source 201. Light from the OCT light source 201 is split into measurement light (sample light) and reference light by a coupler 202. The measurement light is guided to the fundus Er via a measurement optical system 200a. The reference light is guided to a reference optical system 200b.

[0111] In this embodiment, the measurement optical system 200 a includes a collimator lens 206 , a focus lens 240 , a scanning unit 207 , a lens 208 , and an objective lens 22 .

[0112] The measurement light is guided to the scanning unit 207 via a collimator lens 206 and a 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 approximately conjugate with the pupil of the subject's eye E. This causes the measurement light to rotate around the pupil of the subject's eye E. 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 back through the measurement optical system 200a and is then guided to the detector 210.

[0113] In this embodiment, the reference optical system 200b is a reflective optical system and mainly includes a reference mirror 231. The reference light makes one round trip between the coupler 202 and the reference mirror 231. After making one round trip, the reference light is incident on the coupler 202 and guided to the detector 210.

[0114] In this embodiment, the reference mirror 231 can be moved in the optical axis direction by a drive unit 231a. The optical path length of the reference optical system 200b is changed depending on the position of the reference mirror 231. As a result, the difference in optical path length between the measurement light and the reference light is adjusted.

[0115] In this embodiment, the reference optical system 200b is formed by a reflective optical system, but the reference optical system 200b may be formed by a transmissive optical system (for example, optical fiber).

[0116] 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 driver 203a to change the polarization state of the reference light. Note that the location of the polarizer 203 is not limited to the example in FIG. 6, and it may be disposed at a position that adjusts the polarization state of the measurement light.

[0117] The detector 210 receives interference light between the reference light and the measurement light returned from the fundus Er. In SD-OCT, a spectrometer is used as the detector 210. OCT data of the fundus Er is generated based on the spectral interference signal from the detector 210.

[0118] In general, the required pupil diameter of the OCT optical system can be set to a value sufficiently small compared 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, as long as a good fundus observation image is acquired, it is guaranteed that projection and reception of measurement light will also be performed well at least on the pupil of the subject's eye E.

[0119] <Control unit> FIG. 7 shows the control system of the fundus imaging device 1. The fundus imaging device 1 has a control unit 100. The control unit 100 is a processing device (processor) that controls each unit and performs calculations. The control unit 100 includes a CPU, RAM, ROM, etc. For convenience, the control unit 100 is also assumed to perform image processing of various images obtained by the fundus imaging device 1. In other words, the control unit 100 also functions as an image processing unit.

[0120] The control unit 100 is electrically connected to each part 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, the input interface 130, and the memory unit 101.

[0121] The control unit 100 controls the above-mentioned components based on operation signals output from the input interface 130. The input interface 130 is an operation input unit that accepts operations by the examiner. For example, the input interface 130 may be a mouse, a keyboard, or the like.

[0122] The storage unit 101 may be a non-transitory storage medium that can retain its contents even when the power supply is cut off. For example, the storage unit 101 may be a hard disk drive, a flash ROM, a USB memory, etc. For example, the storage unit 101 stores various control programs, fixed data, etc. Furthermore, for example, the storage unit 101 stores images captured by the fundus imaging device 1. The captured images may be stored in an external storage device (for example, a storage device connected to the control unit 100 via a LAN or WAN).

[0123] <Operation description> Next, the operation of the fundus photographing apparatus 1 in this embodiment will be described with reference to FIGS.

[0124] In this embodiment, even if the optically transparent intermediate body of the subject's eye E is opaque, the alignment state is automatically adjusted so that the opacity can be avoided and a two-dimensional reflection image (color fundus image) of the fundus Er and OCT data can be captured. In this embodiment, a case where auto-alignment is performed is shown as an example.

[0125] FIG. 8 is a flowchart showing the flow of operations in the ophthalmologic photographing apparatus 1.

[0126] The operation is started with the subject's face placed against the face support part 9. First, the position of the photographing unit 3 is adjusted with respect to the subject's eye E to a position where a fundus observation image can be acquired. The position of the photographing unit 3 is adjusted based on the face image acquired via the face photographing camera 110 and the anterior eye observation image acquired via the anterior eye observation optical system 40.

[0127] For example, the control unit 100 acquires a facial image via the facial imaging camera 110. The control unit 100 detects the position of at least one of the left and right eyes to be examined included in the facial image. Based on the detected position information, the control unit 100 adjusts the position of the photographing unit 3 to a position where the anterior segment of the eye can be observed.

[0128] After the alignment adjustment is performed based on the facial image, an anterior-segment observation image as shown in FIG. 9 is acquired via the anterior-segment observation optical system 40. Note that the light-projecting regions P1 and P2 and the light-receiving region R are shown in FIG. 9 merely for convenience of explanation. The control unit 100 adjusts the positional relationship between the subject's eye E and the photographing unit 3 based on the anterior-segment observation image. In this embodiment, the control unit 100 sets a reference position for alignment, aiming for a positional relationship in which the pupil center and the image center (in this embodiment, the position of the photographing optical axis L) approximately coincide with each other. An alignment deviation from the reference position is detected, and the photographing unit 3 is moved in the X and Y directions toward eliminating the alignment deviation. The alignment deviation may be detected as the amount of deviation between the pupil center and the photographing optical axis on the anterior-segment observation image. Furthermore, if the fundus photographing device 1 has an alignment projection optical system that projects an alignment index onto the corneal vertex, for example, the alignment deviation may be detected as the amount of deviation between the alignment index and the photographing optical axis.

[0129] As described above, in this embodiment, as a result of the first alignment adjustment, the positional relationship in the XY directions between the subject's eye E and the photographing unit 3 is adjusted so that the center of the light-receiving region R (i.e., the photographing optical axis) coincides with the center of the pupil. If the reference for the first alignment adjustment is set to the corneal vertex, it may be adjusted to coincide with the corneal vertex.

[0130] The control unit 100 also adjusts the positional relationship 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 photographing unit 3 may be moved in the front-to-back direction so that the anterior-segment observation image is focused on the pupil Ep. The positional relationship in the Z direction may also be adjusted using various alignment indicators.

[0131] Next, the control unit 100 acquires a pupil diameter Pd (see FIG. 9) as the pupil size (pupil information in this embodiment) based on the anterior eye observation image, and compares it with a threshold. For example, the control unit 100 detects the pupil region from the anterior eye observation image using a technique such as edge detection, and then acquires the pupil diameter Pd. The pupil diameter Pd may be acquired as a measurement result from a device other than the fundus imaging device 1, or may be manually input by the examiner.

[0132] The control unit 100 compares the acquired pupil diameter Pd with a threshold value. As an example, the threshold value may be approximately the same as the overall width PR (width in the X direction, see FIG. 9) of the light projection regions P1, P2 and the light reception region R.

[0133] If the pupil diameter Pd is equal to or greater than the threshold, acquisition of fundus observation images is started (S4).

[0134] FIG. 10 shows an anterior segment observation image acquired when the pupil diameter Pd is smaller than the threshold value. As shown in FIG. 10(a), when the pupil diameter Pd is smaller than the threshold value (S3: No), in this embodiment, the light projected through the light projection areas P1 and P2 is blocked by the iris. In this case, the fundus Er cannot be properly photographed. Therefore, in this case, the small pupil mode is set (S10), and acquisition of the fundus observation image is started in the small pupil mode (S4).

[0135] As shown in FIG. 10(b), in the small pupil mode of this embodiment, the alignment reference position is offset (decentered) in the X direction so that one of the light-receiving region R and the light-projection region P1, P2 is preferentially positioned within the pupil region relative to the remaining one. Furthermore, the positional relationship between the subject's eye E and the photographing unit 3 is adjusted according to the offset of the reference position. The offset amount of the reference position may be set according to the pupil diameter Pd or may be a fixed value. As shown in FIG. 10(b), in this embodiment, the light-projection region P1 is preferentially positioned. Furthermore, in the small pupil mode, the control unit 100 may turn on only the light-projection region P1 of the two observation light sources 11c, 11d and turn off the other two.

[0136] After acquisition of a fundus observation image is started (S4), the control unit 100 determines whether or not there is an influence of opacity of the optically transparent body on the fundus observation image (whether or not the influence is at an acceptable level) (S5).

[0137] In this embodiment, the presence or absence of the influence of opacity is determined using split indices M1 and M2. The control unit 100 controls the indices projection optical system 50 to project split indices.

[0138] As described above, in this embodiment, the two split indices project and receive light through the light projection areas P1 and P2 and the light reception area R. Therefore, the split indices projected into the pupil area without being vignetted by the iris are considered to be reflected in the fundus observation image if the projection and reception are not hindered by opacity. In other words, if the pupil size is sufficient, the two split indices M1 and M2 are considered to be reflected, and in the small pupil mode, at least one of the split indices M1 and M2 is considered to be reflected. The control unit 100 detects these split indices and determines whether or not there is an effect of opacity of the transparent body based on the detection results.

[0139] For example, if two or one of the intended target images are not properly detected, it may be determined that the fundus observation image is affected by opacity of the optically transparent body. Alternatively, if the brightness of the detected split target is lower than a threshold, it may be determined that the fundus observation image is affected by opacity of the optically transparent body. If it is determined that the fundus observation image is affected by opacity of the optically transparent body (S5: Yes), a second alignment adjustment (S20) is performed, and further alignment adjustment is performed to avoid the opacity. Details of the second alignment adjustment (S20) will be described later.

[0140] If it is determined that there is no influence of opacity of the optically transparent body in the fundus observation image (S5: No), and after the second alignment adjustment (S20) is performed, a focus adjustment is performed (S6).

[0141] For example, 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 coincide with each other, and defocuses the front imaging optical system 10. The control unit 100 drives the focusing 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 imaging optical system 10. This allows force adjustment of the OCT optical system 200.

[0142] In the small pupil mode, since only one of the split indices M1 and M2 is reflected in the fundus observation image, the focus adjustment is performed so that the desired one of the two indices M1 and M2 is positioned at a predetermined matching position. The matching position here may be, for example, the matching position when it is assumed that the two split indices M1 and M2 are reflected.

[0143] Next, various adjustments are made to the OCT optical system 200 (S7). The control unit 100 performs fine adjustments of the focus, adjustments of the optical path length, adjustments of the polarization state (polarizer adjustment), and the like while acquiring OCT data via the OCT optical system 100. For details of the adjustments, see, for example, Japanese Patent Application Laid-Open No. 2015-195876 filed by the present applicant. As a result of adjusting the OCT optical system 200, OCT data of the fundus Er can be acquired with high sensitivity and high resolution.

[0144] Next, the control unit 100 executes photography (S8). For example, the control unit 100 controls the OCT optical system 200 to capture OCT data. Thereafter, the control unit 100 controls the front imaging optical system 10 to capture a color fundus image. The control unit 100 may execute each photography based on an operation input that triggers photography, or may execute each photography automatically. The photography results are stored in the storage unit 101. The photography results may also be displayed on the monitor 120.

[0145] <Second alignment adjustment> Next, the second alignment adjustment will be described in detail with reference to the flowchart of FIG.

[0146] In the second alignment adjustment, the control unit 100 searches for an alignment state in which two or one desired target images can be favorably detected while shifting (changing) the positional relationship between the eye E and the photographing unit 3.

[0147] In this embodiment, split indices are detected as needed during the search for fundus observation images acquired in substantially real time, and the influence of opacity of the optic medium is evaluated using a method similar to that in S5.

[0148] In this embodiment, the pattern for transitioning the positional relationship (called a search pattern) differs depending on whether the mode is the small pupil mode or not.

[0149] First, the first search pattern executed normally (S21: No) will be described with reference to Fig. 12. In this case, an alignment state in which both split indicators M1 and M2 are detected is searched for.

[0150] The control unit 100 moves the photographing unit 3 within a range in which the light projection areas P1, P2 and the light reception area R do not extend beyond the pupil. The movement range may be set based on the pupil diameter Pd, for example.

[0151] In the first search pattern, the control unit 100 moves the photographing unit 3 randomly in the X and Y directions within a range in which the light projection areas P1, P2 and the light reception area R do not extend beyond the pupil (FIG. 12(a) ⇒ FIG. 12(b)), and acquires a fundus observation image at each position. Note that the first search pattern does not necessarily have to be a random pattern, and may be a predetermined pattern. For example, it may be a pattern in which the photographing unit 3 is first moved in the Y direction and then moved in the X direction, or may be another pattern.

[0152] Furthermore, the control unit 200 may determine the direction and amount of movement of the photographing unit 3 as needed based on the observation image obtained during the search. For example, during the search, even though two split indices M1 and M2 are projected into the pupil area, only one of them may be detected. In this case, it is estimated that there is no opacity in the light-projecting areas P1 and P2 that correspond to the detected indices and in the light-receiving area R. By utilizing this, while performing the search, the positional relationship that still has the possibility of obtaining a good fundus observation image may be narrowed down, and the search may be transitioned to the narrowed positional relationship.

[0153] During the search, the control unit 100 acquires information indicating the alignment state when each observation image was acquired, in association with each observation image. The control unit evaluates the influence of opacity in each observation image (S23), and changes the alignment reference position based on the alignment state of an observation image that is not (or is less) affected by opacity. Furthermore, the control unit adjusts the positional relationship between the subject's eye E and the photographing unit 3 according to the changed alignment reference position (S24).

[0154] Next, the second search pattern executed in the small pupil mode (S21: Yes) will be described with reference to Fig. 13. For example, when the light projection area P1 is preferentially arranged within the pupil area, an alignment state in which the split index M1, which is projected and received via the light projection area P1 and the light receiving area R, is properly detected is searched for.

[0155] In this case, the control unit 100 performs the search by moving the photographing unit 3 mainly in the Y direction, on the condition that the light projection area P1 and the light receiving area R do not protrude from the pupil (FIG. 13(a) ⇒ FIG. 13(b)). In other words, it is preferable to give priority to movement in the Y direction out of the X and Y directions. In this embodiment, since the light projection area P1 and the light receiving area R are arranged side by side in the X direction, in the case of a small pupil, it may be difficult to secure space within the pupil area for movement in the X direction.

[0156] In addition, the transition of the positional relationship between the test eye E and the photographing unit 3 in the second search pattern may be random, predetermined, or determined sequentially during the search, as in the first search pattern.

[0157] Furthermore, for example, the control unit 100 may switch between the two light projection areas P1 and P2, which one is preferentially positioned within the pupil region, during the search. As shown in FIG. 10(b), the control unit 100 may switch from a state in which the light projection area P1 is decentered so that it is included in the pupil region to a state in which the light projection area P2 is decentered so that it is included in the pupil region. This increases the possibility of acquiring a good fundus observation image.

[0158] In this embodiment, as described above, even if the optically transparent body of the subject's eye E is opaque, the alignment state is adjusted so that a fundus observation image can be appropriately acquired.

[0159] As described above, in this embodiment, focus adjustment is then performed. As a result of the alignment adjustment, focus adjustment is performed in a state where the split indicator is clearly reflected in the fundus observation image, so in this embodiment, focus adjustment is less likely to fail.

[0160] In this embodiment, since the optical system for capturing the fundus observation image and the color fundus image is the same, the color fundus image can be captured well in this alignment state. In this embodiment, the measurement light from the OCT optical system 200 to the subject's eye E is projected and received inside the light-receiving region R on the pupil of the subject's eye E. Therefore, the OCT data can also be captured well.

[0161] In this embodiment, the front photographing optical system 10 is a slit scan type optical system, and harmful light is removed by the slit-shaped member 15. Therefore, even if the optical axis of the front photographing optical system 10 is displaced from the center of the anterior segment to suppress the influence of opacity, noise light from the transparent body is suitably removed by the slit-shaped member 15. Therefore, good color fundus images can be taken.

[0162] [Example of transformation] The techniques disclosed in the above embodiments are merely examples. Therefore, the techniques exemplified in the above embodiments may be modified. For example, it is possible to implement only some of the techniques exemplified in the above embodiments.

[0163] For example, in the first embodiment, a positional relationship where both of the split indices M1 and M2 are appropriately detected is searched for. However, this is not necessarily limited to this, and a positional relationship where only one of the split indices M1 and M2 is appropriately detected may be searched for. In this case, it becomes easier to perform appropriate alignment adjustment for a highly opaque eye.

[0164] In the above embodiment, the focus adjustment is performed after the alignment adjustment. However, the alignment adjustment and the focus adjustment may be performed in parallel. That is, the focus adjustment may be started when at least one of the split indicators M1 and M2 is detected while the positional relationship between the subject's eye and the photographing unit is being changed based on the fundus observation image. In this case, the time required for various adjustments before photographing is shortened.

[0165] Furthermore, in the above embodiment, when alignment based on the anterior-segment observation image is completed, the examiner may be prompted to select whether to set the small pupil mode via the input interface 130. In this case, for example, the anterior-segment observation image of the subject's eye may be displayed on the monitor 120, and the examiner may be prompted to confirm the positional relationship between the pupil of the subject's eye and the light-projecting and light-receiving areas.

[0166] Furthermore, for example, when acquiring a plurality of fundus observation images at different positions in the X and Y directions, the transition of the positional relationship between the subject's eye and the photographing unit may be performed based on the examiner's operation. For example, the examiner may adjust the positional relationship by operating a joystick. Furthermore, the control unit 100 may limit the range of transition in the X and Y directions in consideration of pupil information. The control unit 100 may control the positional relationship so that the pupil image of the optical system does not protrude beyond the pupil, regardless of the examiner's operation.

[0167] In the above embodiment, the split index is detected as a result of the search. However, there may be a case where the split index is not detected even after the search. In this case, the control unit 100 may perform imaging while maintaining the alignment reference position based on the alignment based on the anterior eye observation image.

[0168] Furthermore, the front photographing optical system 10 of the above embodiment is a slit scan type optical system, in which the light receiving region R and the two light projecting regions P1, P2 are all formed in a line. In contrast to this, in a spot scan type optical system, for example, the light projecting region and the light receiving region may be formed in a line, or further, in addition to the light projecting region and the light receiving region formed in a line, at least one more light projecting region and light receiving region may be formed in a direction intersecting the line.

[0169] 14 shows pupil images (each region (each pupil image) P11, P12, P13, P14, R) in an optical system in which the light-receiving region R and the light-projecting regions P11, P12 are formed in a line in the X direction and the light-receiving region R and the light-projecting regions P13, P14 are formed in a line in the Y direction, on an anterior-segment observation image. Illumination light may be emitted from the multiple light-projecting regions P11, P12, P13, P14 simultaneously or selectively.

[0170] In such an apparatus, in the second alignment mode, the control unit selects one of the plurality of light-projecting regions P11, P12, P13, and P14, and, with the direction of arrangement of any selected light-projecting region and light-receiving region R as a first direction, displaces the positional relationship between the subject's eye and the photographing unit at least in a direction intersecting with the first direction relative to the predetermined positional relationship induced by the first alignment. For example, when light-projecting region P11 is selected, the positional relationship is displaced at least in the Y direction. This may lead to the second alignment state.

[0171] In the example of FIG. 14, a plurality of (four in the figure) light-projecting regions are formed for one light-receiving region R, but the number of light-receiving regions and light-projecting regions can be changed as appropriate. [Explanation of symbols]

[0172] 3 Filming Unit 8 Drive unit 10 Frontal imaging optical system 70 Control Means 200 OCT optics

Claims

1. an imaging unit including a front imaging optical system in which a light-projecting region and a light-receiving region of illumination light are aligned in a first direction and formed on a pupil of a subject's eye, the front imaging optical system acquiring a two-dimensional reflection image of the fundus by scanning the illumination light on the fundus of the subject's eye; a driving unit that moves the photographing unit relatively to the eye to be examined; a control means for switching control for guiding a positional relationship between the subject's eye and the photographing unit between a first alignment mode and a second alignment mode for avoiding opacity in an optically transparent body of the subject's eye, In the first alignment mode, the positional relationship is guided to a first alignment state, which is a predetermined positional relationship; a control means for guiding the subject's eye to a second alignment state in which the positional relationship is displaced from the first alignment state in at least a direction intersecting with the first direction in order to avoid opacity in the optically transparent body of the subject's eye in the second alignment mode; A fundus photography device comprising:

2. A fundus imaging device as described in claim 1, wherein the light-emitting area and the light-receiving area formed side by side in the first direction are arranged in a line and non-concentrically.

3. 3. The fundus imaging device according to claim 1, wherein the control means acquires opacity information, which is information regarding opacity in the optical medium of the subject's eye, and selectively sets either the first alignment mode or the second alignment mode based on the opacity information.

4. A determination means for determining whether the subject's eye has a small pupil, A fundus photography device as described in any one of claims 1 to 3, wherein when it is determined that the pupil is small, in the second alignment mode, the control means first displaces the positional relationship in the first direction relative to the first alignment state, and then further displaces the positional relationship in a direction intersecting the first direction to guide the device to the second alignment state.

5. the photographing unit further includes an OCT optical system that photographs OCT data of the fundus based on the principle of optical interference; 5. The fundus imaging apparatus according to claim 1, wherein the control means, in the second alignment mode, captures the OCT data of the fundus and the two-dimensional reflection image in the second alignment state.

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