Fundus imaging 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 an imaging optical system for projecting and receiving imaging light to and from the ocular fundus of an eye to be examined, and acquiring a captured image of the ocular fundus, and an observation optical system for projecting and receiving observation light by infrared light, which is observation light different from the imaging light, to and from the ocular fundus of the eye to be examined, and acquiring an ocular fundus observation image, which is a two-dimensional reflection image based on the observation light; a driving unit for relatively moving the imaging unit with respect to the eye to be examined; and control means for guiding positional relationships between the eye to be examined and the imaging unit at least with respect to an XY direction on the basis of the ocular fundus observation image.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present disclosure relates to a fundus imaging device.

Background Art

[0002] Fundus imaging devices such as fundus cameras and OCT devices are widely used in the field of ophthalmology. When there is turbidity in the transparent body of the eye to be examined and the transmission and reception of imaging light by the fundus imaging device are obstructed by the turbidity, it may not be possible to capture a good fundus image.

[0003] On the other hand, when imaging the fundus of an eye to be examined with a turbid transparent body, a method of performing alignment adjustment to avoid turbidity and obtaining a fundus image is known.

[0004] For example, in Patent Document 1, an apparatus is disclosed that performs alignment adjustment for fundus imaging so as to avoid turbidity after capturing three-dimensional OCT data of the anterior segment of the eye to obtain the distribution of turbidity.

[0005] In addition, as a method of obtaining the distribution of turbidity of the transparent body as an image, the transillumination method is known. The transillumination method is a method of observing the light that is irradiated from the pupil and then reflected back from the fundus. Patent Document 2 discloses an apparatus that obtains a transillumination image using an anterior segment observation optical system by providing a dedicated light source.

[0006] Patent Document 2 discloses the optical system of a fundus camera that is currently widespread in many ophthalmic facilities. A fundus camera irradiates imaging light simultaneously over the entire imaging range of the fundus and captures a two-dimensional reflected image of the fundus based on the fundus reflected light. Generally, in a fundus camera, imaging light is irradiated in a ring shape from the peripheral part of the pupil of the eye to be examined, and pupil division is set so that the fundus reflected light is extracted from the center of the pupil.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008] In the method described in Patent Document 1 for confirming the presence or degree of opacity in the eye under examination, it is necessary to adjust the OCT optical system for the anterior segment beforehand and then acquire 3D OCT data of the anterior segment, making it difficult to smoothly acquire fundus images. Furthermore, using the transillumination method requires a dedicated light source, etc., which tends to complicate the equipment configuration.

[0009] Furthermore, in the optical system of the fundus camera disclosed in Patent Document 2, when the alignment is adjusted to a position away from the center of the eye under examination (for example, the corneal apex) in order to avoid opacity, flare due to reflected light from the transparent material is likely to occur, which is problematic.

[0010] This disclosure is based on at least one of the problems of the prior art, and aims to provide a fundus imaging device that can easily capture good images of the fundus of an eye with a cloudy transparent body. [Means for solving the problem]

[0011] A fundus imaging apparatus according to a first aspect of this disclosure includes: an imaging optical system that emits and receives imaging light onto the fundus of an eye under examination and acquires an image of the fundus; an observation optical system that emits and receives observation light, which is infrared light and different from the imaging light, onto the fundus of an eye under examination and acquires a fundus observation image, which is a two-dimensional reflected image based on the observation light; and an indicator projection optical system that projects an indicator beam onto the fundus of the eye for adjusting the imaging conditions of the imaging optical system, A photographic unit including a drive unit for moving the photographic unit relative to the eye being examined, and a control means for guiding the positional relationship between the eye being examined and the photographic unit, at least in the XY direction, based on the fundus observation image. a control means that detects an index image formed on the fundus observation image based on the index light beam and guides the positional relationship based on the index image. It is equipped with the following. [Brief explanation of the drawing]

[0012] [Figure 1] It is an external view of a fundus imaging device. [Figure 2] It is a schematic diagram of the optical system of a fundus imaging device. [Figure 3] It is a schematic diagram of the front imaging optical system. [Figure 4] It is a diagram showing an example of a fundus observation image on which a split index is projected. [Figure 5] It is a schematic diagram of the anterior eye observation optical system [Figure 6] It is a schematic diagram of an OCT optical system [Figure 7] It is a block diagram showing the control system of a fundus imaging device. [Figure 8] It is a flowchart showing the operation flow of the device in the embodiment. [Figure 9] It is a diagram showing an anterior eye observation image. [Figure 10] It is a diagram for explaining the small pupil mode. [Figure 11] It is a flowchart showing the flow of the second alignment adjustment. [Figure 12] It is a diagram for explaining the second alignment adjustment in normal times. [Figure 13] It is a diagram for explaining the second alignment adjustment in the small pupil mode. [Figure 14] It is a diagram for explaining a modification example. [Embodiments for Carrying Out the Invention]

[0013] [Summary] Embodiments of a fundus imaging device according to the present disclosure will be described. The items classified in the following <> can be used independently or in combination.

[0014] The fundus imaging device according to each embodiment of the present disclosure performs alignment adjustment on an eye to be examined with a turbid light-transmitting body so that the influence of turbidity is reduced, and acquires a fundus imaging image.

[0015] Each embodiment of the fundus imaging apparatus in this disclosure comprises at least an imaging unit, a drive unit, and a control unit.

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

[0017] <Photography Unit> The imaging unit in this embodiment comprises at least an imaging optical system and an observation optical system. The imaging unit may also include various optical systems in a fundus imaging device. For example, the imaging unit may include at least one of an anterior segment observation optical system and an index projection optical system. The positional relationship of each optical system with respect to the eye under examination may be changed integrally by a drive unit.

[0018] <Filming optics> The imaging optical system is used to project and receive imaging light onto the eye under examination and to acquire images of the fundus.

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

[0020] The imaging optical system may be, for example, an OCT optical system. An OCT optical system is used to acquire OCT data of the fundus based on a different principle (specifically, the principle of optical interference) than that of a frontal imaging optical system. That is, the OCT optical system detects the spectral interference signal between a measurement light guided to the fundus of the eye under examination and a reference light. In this case, the measurement light is used as the imaging light. By processing the spectral interference signal, OCT data of the fundus is acquired.

[0021] The OCT optical system includes at least an OCT light source and a detector. The detector detects the interference state between the measurement light emitted from the OCT light source and a reference light. Additionally, it may have an optical scanner for scanning the measurement light over the fundus. The OCT optical system may be based on a Fourier domain OCT optical system. 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] Furthermore, the fundus imaging device may be equipped with both a frontal imaging optical system and an OCT optical system as its imaging optical system.

[0023] <Observation Optical System> The observation optical system (also called the fundus observation optical system) is used to project and receive observation light, which is infrared light different from the imaging light, onto the fundus of the eye under examination, and to acquire a fundus observation image, which is a two-dimensional reflected image based on the observation light. The observation light and the imaging light may have different wavelengths, for example. The fundus observation image is acquired as it progresses, almost in real time. The fundus observation image is used, for example, to adjust various imaging conditions. In this embodiment, it is also used to adjust (and guide) the positional relationship between the eye under examination and the imaging 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 frontal imaging optical system described above.

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

[0025] <Target projection optical system> The indicator projection optical system projects an indicator beam onto the fundus of the eye to adjust the imaging conditions of the imaging optical system. The indicator beam is imaged by the observation optical system. As a result, the indicator image is captured in the observation image. The control unit adjusts the imaging conditions based on the indicator image. Furthermore, the indicator image may be used to adjust the positional relationship between the eye under examination and the imaging unit (details will be described later).

[0026] The indicator projection optical system may, for example, project an indicator beam for focus adjustment. The indicator beam for focus adjustment may be a split indicator. In this case, at least two indicator beams constituting the split indicator are projected onto the fundus, passing through different positions in the anterior segment of the eye under examination. The focus state is detected as the separation / matching state of the split indicator. Based on the focus state, diopter correction is performed in the imaging optical system and the observation optical system.

[0027] <Anterior segment observation optical system> The fundus imaging device of the first embodiment may have an anterior segment observation optical system and may be capable of acquiring an anterior segment observation image via the anterior segment observation optical system. The anterior segment observation optical system may have at least an image sensor. The anterior segment observation image is used to adjust the positional relationship between the eye under examination and the imaging unit (i.e., for alignment, tracking, etc.). The anterior segment observation image may be, for example, a frontal image of the anterior segment or an image from an oblique direction. During alignment, the anterior segment observation image may be displayed on a monitor. This allows the examiner to grasp the alignment status in real time.

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

[0029] Furthermore, the fundus imaging device may have an alignment index projection optical system that projects alignment indices onto the eye under examination. Alignment may then be induced based on the alignment indices formed on the observational image of the anterior segment or fundus.

[0030] <Drive Unit> The drive unit is a mechanism that moves the imaging unit relative to the eye under examination. In this case, the drive unit can change the relative position of the imaging unit with respect to the eye under examination, at least in the XY direction (up, down, left, and right directions). Furthermore, 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 eye under examination and the imaging unit.

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

[0032] <Department Head> The control unit is a processor that is responsible for various control operations and calculation processing in the fundus imaging device.

[0033] For example, the control unit performs alignment control. In the first embodiment, the control unit guides the positional relationship between the eye under examination and the imaging unit based on the fundus observation image, at least in the XY direction. In this case, the positional relationship may be guided to such that the optical axis of the imaging unit is misaligned with the center of the anterior segment (e.g., the center of the pupil or the apex of the cornea). Note that the alignment control based on the fundus observation image according to the first embodiment may be performed when the system transitions to an alignment state in which the fundus observation image can be acquired.

[0034] In this embodiment, alignment guidance may be a so-called auto-alignment method or a manual alignment method. In the auto-alignment method, the control unit may drive the drive unit based on the fundus observation image. In the manual alignment method, the control unit may display the anterior segment observation image on the monitor and also display a guide (e.g., an electronic reticle) that guides the operation to the target position based on the fundus observation image. In this case, the ophthalmic imaging device may be equipped with an operation input unit that receives operations from the examiner and drives the drive unit in response to the operations to adjust the positional relationship between the eye under examination and the imaging unit. The operation input unit may be an input interface for inputting operations to drive the actuator of the drive unit, or it may directly act on the mechanical drive unit.

[0035] For example, if opacity occurs in the transparent media of the eye under examination, and at least a portion of the transmitted and received light of the observation light is blocked by the opacity, the observed image will be affected by the opacity. For example, the effects of opacity may result in a decrease in brightness, uneven brightness, a decrease in contrast, and shadows due to vignetting caused by the opacity in the observed image. By evaluating the effect of opacity on the observed image, it is possible to estimate, for example, the presence or degree of opacity at the position on the pupil of the eye used for transmitting and receiving the observation light, given the positional relationship between the eye under examination and the imaging unit at that time. In this case, the evaluation may be based on at least one of the brightness and contrast of the observed image. More specifically, the effect of opacity on the observed image may be evaluated based on the degree of decrease in either the brightness or contrast of the observed image.

[0036] However, this is not necessarily the only way. For example, when an observation image is acquired with an indicator beam projected onto the fundus from an indicator projection optical system, the effect of opacity in the observation image may be evaluated based on the detection result of the indicator image. In this case, the presence or absence of opacity, or the degree of opacity, at the position on the pupil of the eye being examined where the indicator beam is projected and received is estimated based on the detection result of the indicator image. The effect of opacity in the observation image may also be evaluated based on the presence or absence of an indicator image, or at least one of the brightness or contrast of the indicator image.

[0037] Furthermore, when the control unit evaluates the effect of turbidity in the observed image, the evaluation may be performed based on a portion of the observed image. For example, it is preferable to evaluate based on the central part of the observed image. The central part of the image is less affected by uneven brightness even if the optical axis of the imaging unit is displaced from the center of the anterior segment, making it easier to appropriately evaluate the effect of turbidity in the observed image. In addition, even if flare occurs due to the transparent material, the central part of the observed image is less affected by the flare, making it easier to appropriately evaluate the effect of turbidity in the observed image.

[0038] In the first embodiment, the positional relationship between the eye under examination and the imaging unit is guided at least in the XY direction based on the fundus observation image. For example, even when imaging an eye under examination in which opacity has occurred in the transparent media, the alignment state can be adjusted based on the fundus observation image to minimize the effect of the opacity. That is, when imaging an eye under examination in which opacity has occurred in the transparent media, the control unit may guide the positional relationship between the eye under examination and the imaging unit to avoid the opacity.

[0039] When guiding the positional relationship between the eye under examination and the imaging unit based on fundus observation images, the control unit may search for a positional relationship between the eye under examination and the imaging unit that allows for the acquisition of better observation images. In this case, the control unit may acquire multiple fundus observation images in multiple positional relationships that are different from each other in at least the XY direction, and guide the positional relationship between the eye under examination and the imaging unit based on these multiple fundus observation images. In this case, the positional relationship between the eye under examination and the imaging unit can be guided so that the effect of opacity is more effectively suppressed. For example, multiple fundus observation images may be acquired in correspondence with the alignment state (positional relationship between the eye under examination and the imaging unit) at that time. After multiple fundus observation images have been acquired in multiple positional relationships, the control unit may be guided again to a positional relationship in which the effect of opacity is more preferably suppressed, and imaging may be performed. The multiple positional relationships in which multiple fundus observation images are acquired during the search may transition in a predetermined pattern or in a random pattern. The timing for the end of the search can be determined as appropriate. For example, the search may be completed when the observation images acquired as needed satisfy predetermined conditions.

[0040] In the first embodiment, the positional relationship between the eye under examination and the imaging unit is guided based on the fundus observation image, so the device configuration is less likely to become complicated. In addition, in a device equipped with an OCT optical system, it is also conceivable to use OCT data acquired via the OCT optical system to align in order to avoid opacity. Compared to that case, guiding the positional relationship between the eye under examination and the imaging unit based on the fundus observation image is considered to make the flow from alignment to imaging smoother. In other words, the fundus observation optical system is more likely to shorten the time required for various adjustments leading up to imaging compared to the OCT optical system. Also, generally, the area used for light projection and reception on the pupil of the eye under examination is wider in the observation optical system than in the OCT optical system, so it is more efficient when searching for the positional relationship between the eye under examination and the imaging unit. Furthermore, compared to using OCT data, guiding the positional relationship between the eye under examination and the imaging unit based on the fundus observation image is more suitable not only for acquiring OCT data but also for acquiring 2D reflection images as imaging images.

[0041] Furthermore, although details will be described later in the second embodiment, when the imaging optical system acquires a two-dimensional reflected image as the captured image, it is preferable that the imaging optical system be a scan-type optical system. By having a scan-type optical system, the positional relationship between the eye under examination and the imaging unit is guided to avoid turbidity of the transparent material, and as a result, even if imaging is performed with the optical axis of the imaging unit displaced from the center of the anterior segment, it becomes easier to obtain a captured image with suppressed flare due to the transparent material.

[0042] The control unit may also acquire pupil information of the eye under examination. Pupil information is information relating to the pupil region and may include, for example, information that identifies at least one of the following: the position, shape, or size of the pupil in the eye under examination. Pupil information is acquired, for example, based on anterior segment observation images. When pupil size (e.g., pupil diameter) is acquired as pupil information, the pupil information may be acquired from an external device or based on operator input from the examiner. In that case, the fundus imaging device may have an input interface.

[0043] The control unit may guide the positional relationship between the eye under examination and the imaging unit, taking pupil information into consideration. Furthermore, pupil information may be acquired in real time based on anterior segment observation images, and this real-time pupil information may be used for guiding and controlling the positional relationship.

[0044] Based on pupil information, the effective range of movement in the XY direction of the relative position between the eye under examination and the imaging unit, which is necessary for finding a positional relationship in which observation light is best projected onto and received by the fundus, can be identified. Therefore, by considering pupil information, alignment adjustments based on the observed image can be performed more smoothly.

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

[0046] For example, if the pupil division of the imaging optical system and the observation optical system is set so that the light-emitting area and the light-receiving area of ​​the observation light on the pupil of the eye being examined are aligned in one direction, then in eyes with small pupils, moving the relative position of the eye being examined and the imaging unit in the aforementioned one direction will easily cause vignetting of the imaging light and observation light due to the iris. In this case, for example, if the pupil size is larger than the threshold, the direction of movement when changing the relative position of the eye being examined and the imaging unit based on the observation image is not limited, and if the pupil size is below the threshold, limiting the relative position of the eye being examined and the imaging unit to a direction intersecting the one direction based on the observation image will make it easier to appropriately adjust to an alignment state in which the effects of opacity are suppressed.

[0047] Incidentally, OCT optical systems generally require a smaller pupil diameter than observation optical systems. 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 eye under examination and the imaging unit may be changed based on the observation image, and if the pupil size is below the threshold, the relative position between the eye under examination and the imaging unit may be changed based on the OCT data acquired via the OCT optical system.

[0048] <Reusing search results> When the control unit searches for the positional relationship between the eye under examination and the imaging unit and imaging is performed, the results of the search for that imaging may be reused afterward. For example, they may be used to guide alignment during follow-up imaging. Also, when imaging is performed by changing the presentation position, such as fixation, between a first position and a second position, alignment guidance at the second position may be performed based on the results of the search performed at the first position. Since the positional relationship between the optical axis of the imaging unit and the pupil of the eye under examination changes depending on the presentation position, such as fixation, the results of the search performed at the first position may be saved along with the position information of the pupil of the eye under examination at that time. For example, the adjustment result of the positional relationship between the eye under examination and the imaging unit at the first position may be saved with the pupil center position as the reference. When adjusting alignment at the second position, the positional relationship between the eye under examination and the imaging unit may be guided based on the pupil position obtained from the anterior segment observation image and the adjustment result at the first position obtained in advance. For example, the first position may be a presentation position such as fixation where an image can be acquired at the center of the macula, and the second position may be a presentation position such as fixation where an image can be acquired at the center of the papilloma (or centered between the macula and the papilloma).

[0049] <Initiation conditions for alignment control based on fundus observation images> In the fundus imaging device of the first embodiment, it may be possible to switch whether or not to start alignment control based on fundus observation images.

[0050] For example, whether or not to perform alignment control based on fundus observation images may be pre-configurable through input from the examiner.

[0051] Furthermore, for example, after the alignment has been appropriately adjusted to a state in which fundus observation images can be acquired, the control unit may determine whether or not to start the alignment control described above by estimating the effect of opacity based on the fundus observation images. Depending on the determination result, the alignment control based on the fundus observation images may be started automatically, or the examiner may be requested to start the alignment control based on the fundus observation images via the user interface.

[0052] Furthermore, for example, if information indicating that the eye under examination is a cataract eye has been associated with the subject's ID in a past examination, the system may automatically initiate alignment control based on fundus observation images according to the information associated with the subject's ID, or the system may request the examiner to initiate alignment control based on fundus observation images via the user interface. Also, if information indicating that the eye under examination is an IOL-implanted eye has been associated with it, the problem of opacity is unlikely to occur, so the alignment adjustment may be completed without performing alignment control based on fundus observation images.

[0053] <Second Embodiment> Next, a second embodiment of this disclosure will be described.

[0054] <Scanning-type frontal imaging optical system> In the second embodiment, the imaging unit has at least a scanning-type front imaging optical system. The front imaging 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 imaging optical system in the second embodiment is assumed to also serve as the observation optical system. Also, for the sake of convenience in the explanation, the imaging light and the observation light will be collectively referred to as "illumination light".

[0055] In the second embodiment, the front imaging optical system includes at least an illumination optical system, a light-receiving optical system, a scanning unit, and a harmful light removal unit.

[0056] The illumination optical system illuminates the fundus of the eye under examination with illumination light via the objective optical system. Additionally, the illumination optical system may have a light source that emits illumination light. The light-receiving optical system has a light-receiving element that receives the light reflected from the fundus of the eye under examination. The signal from the light-receiving element is input to the image processing unit. In the image processing unit, a two-dimensional reflected image of the fundus of the eye under examination is acquired based on the signal from the light-receiving element. Note that, depending on the optical system, any of the following may be used as the light-receiving element: a point light-receiving element, a line sensor, a two-dimensional light-receiving element (imaging element), etc.

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

[0058] In the second embodiment, the illumination optical system forms a local illumination area in a portion of the imaging range in the fundus. That is, it irradiates the fundus with local illumination light. Typically, the illumination optical system forms the illumination area in the shape of a slit or spot.

[0059] The harmful light removal unit may be positioned in a location conjugate to the fundus of the eye on the optical path of the light-receiving optical system.

[0060] The harmful light removal unit causes the photodetector to receive the fundus reflected light from a localized imaging area (hereinafter referred to as the "effective area") which is part of the imaging range. 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 scan type device is a pinhole, and a typical aperture in a slit scan type device is a slit. In this case, the fundus reflected light from the effective area corresponding to the aperture opening within the entire imaging range of the fundus is selectively guided to the photodetector and acquired as an effective image. In particular, in a slit scan type device, the photodetector may also serve as the harmful light removal unit. In this case, a line sensor with a slit shape may be used as the photodetector, or a CMOS sensor that performs line exposure on a two-dimensional imaging surface (in other words, has a rolling shutter function) may be used. In this case, the fundus reflected light from the effective area corresponding to the line-shaped effective pixels within the entire imaging range of the fundus is selectively guided to the photodetector and the effective area is imaged.

[0061] The scanning unit synchronously scans the fundus of the eye between a local illumination area and an effective area (local imaging area). The scanning unit may be, for example, an optical scanner shared between the illumination optical system and the photodetector optical system. In this case, the optical scanner is positioned on the common optical path between the illumination optical system and the photodetector optical system.

[0062] Furthermore, the scanning unit may include a first scanning unit provided in the illumination 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 arranged on the optical path of the illumination optical system in order to form a local illumination area in the shape of a slit. The first scanning unit may have a first slit-shaped member and a drive unit that moves the first slit-shaped member in a direction intersecting the optical axis. Furthermore, if a second slit-shaped member is used as a harmful light removal unit, the second scanning unit may have a second slit-shaped member and a drive unit that moves the second slit-shaped member in a direction intersecting the optical axis. The drive unit of the first scanning unit and the drive unit of the second scanning unit may be separate devices or may be a common device.

[0063] Furthermore, in a slit-scan type device, if a CMOS sensor is used as the photodetector, the CMOS sensor can also function 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 sensor, which is the photodetector, 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 line-scan type optical systems, a line of illumination light is scanned in one direction. The line of illumination light may be scanned linearly over the fundus, for example, or it may be scanned in a rotational manner over the fundus. In the case of rotational scanning, the center of rotation may be the optical axis of the frontal imaging optical system.

[0065] <Pupil division pattern in frontal imaging optical system> In this disclosure, of the pupil image formed on the pupil of the eye being examined by a frontal imaging optical system, the area through which light passes from the device toward the fundus is referred to as the light-emitting area, and the area through which the fundus-reflected light passes is referred to as the light-receiving area.

[0066] In the frontal imaging optical system of the second embodiment, at least a light-emitting region and a light-receiving region are formed on the pupil of the eye under examination, aligned in a first direction. The light-emitting region and the light-receiving region aligned in the first direction are arranged in a line and not concentrically. Multiple light-emitting regions and light-receiving regions may be formed at positions different from each other with respect to the first direction. In order to suppress flare of the light-transmitting material, it is desirable that the first direction coincides with the scanning direction of the illumination light in the fundus in a slit-scan type device.

[0067] <Alignment control mode switching> In the second embodiment, the control for guiding the positional relationship between the eye under examination and the imaging unit (frontal imaging optical system) is switched by the control unit between a first alignment mode and a second alignment mode. The first alignment mode and the second alignment mode may be set, for example, based on information regarding turbidity in the transparent material of the eye under examination (hereinafter referred to as turbidity information of the eye under examination). Alternatively, they may be set based on a mode switching operation by the examiner.

[0068] In the first alignment mode, the positional relationship between the eye under examination and the imaging unit is guided to a predetermined first alignment state. In the second alignment mode, the positional relationship between the eye under examination and the imaging unit is shifted from the first alignment state to a second alignment state. In the second embodiment, since each of the light-emitting and light-receiving regions is aligned in a first direction on the pupil of the eye under examination, there is little room (space) to move the light-emitting and light-receiving regions in the first direction within the pupillary region. Therefore, even if the light-emitting and light-receiving regions are moved in the first direction within the pupillary region, it is difficult to avoid opacity.

[0069] In contrast, in the second embodiment, the control unit, in the second alignment mode, guides the eye under examination and the imaging unit to the second alignment state by at least displacing the positional relationship in a direction intersecting the first direction relative to the first alignment state. In the above frontal imaging optical system, it is easy to secure space for moving the light-emitting area and light-receiving area within the pupil region in a direction intersecting the first direction, so it is considered that guiding the positional relationship in a direction intersecting the first direction makes it easier to avoid opacity.

[0070] Furthermore, even if the optical axis of the frontal imaging optical system is displaced from the center of the anterior segment as a result of guiding the positional relationship between the eye under examination and the imaging unit to avoid turbidity of the transparent media, the fact that the frontal imaging optical system is a scanning type optical system as described above suppresses flare caused by the transparent media. As a result, in the second alignment mode, the fundus of the eye under examination with turbidity of the transparent media is captured in good condition.

[0071] <Acquisition of turbidity information> The control unit may acquire opacity information of the eye under examination. The opacity information may indicate at least one of the following: 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 eye under examination can be estimated based on fundus observation images. Therefore, opacity information may be acquired based on fundus observation images. However, in the second embodiment, the opacity information is not necessarily limited to this. For example, opacity information may be acquired based on at least one of the following: a transillumination image, anterior segment OCT data, or fundus OCT data. In addition, opacity information may be acquired based on the results of past examinations. In this case, the subject's ID and opacity information may be stored in memory in a pre-associated state.

[0072] As described above, the control unit may select which of the first alignment mode and the second alignment mode to perform based on the turbidity information.

[0073] Furthermore, opacity information may be used to predict the positional relationship between the eye under examination and the imaging unit that can avoid opacity in the second alignment mode, or to evaluate the effects of opacity.

[0074] Furthermore, similar to the first embodiment, the control unit may acquire pupil information as information regarding the pupil region of the eye under examination, and guide the positional relationship between the eye under examination and the imaging unit taking the pupil information into consideration. In this case, for example, the control unit may acquire information regarding the pupil size of the eye under examination as pupil information, and change the guidance control of the positional relationship based on the fundus observation image according to the pupil size.

[0075] [First Embodiment] An embodiment of the fundus imaging device according to the first and second embodiments will be described.

[0076] The fundus imaging device 1 captures a color fundus image as a two-dimensional reflection image of the fundus erin. Furthermore, it acquires OCT data of the eye being examined.

[0077] Figure 1 is an external view of the fundus imaging device 1. The fundus imaging device 1 has an imaging unit 3. The imaging unit 3 mainly comprises the optical system shown in Figure 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 eye under examination E and the imaging unit 3.

[0078] The drive unit 8 moves the imaging unit 3 on the drive unit 8 in the XYZ directions relative to the eye E being examined. The drive unit 8 has actuators for moving the imaging unit 3 in each movable direction and is driven based on control signals 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.

[0079] The face-capturing camera 110 captures the subject's face. The control unit 100 identifies the position of the subject's eye E from the captured face image and controls the drive unit 8 to align the imaging unit 3 with the identified position of the subject's eye E.

[0080] Furthermore, the imaging device 1 also has a monitor 120. Various captured images, observed images, etc., are displayed on the monitor 120.

[0081] <Photography Unit> Figure 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 frontal imaging optical system 10, an anterior segment observation optical system 40, and an OCT optical system 200. In this embodiment, the objective lens 22 is shared among the optical systems. In this embodiment, the frontal imaging optical system 10 also serves as the fundus observation optical system. These optical systems are provided in the imaging unit 3.

[0082] In this embodiment, the optical axis of the anterior segment observation optical system 40 and the optical axis 200 of the OCT optical system are coaxial by a half mirror 45. Furthermore, in this embodiment, the optical axes of the anterior segment observation optical system 10 and the OCT optical system 200, which are coaxial by the half mirror 45, and the optical axis of the frontal imaging optical system 10 are coaxial by a dichroic mirror 43. For example, light from the optical system is guided to the eye under examination via the objective lens 22. Details of each optical system are described below.

[0083] <Frontal imaging optical system> Figure 3 is a schematic diagram of the frontal imaging optical system 10. In Figure 3, the pupil-conjugate position, which is conjugate to the pupil of the eye being examined, is indicated by a '△' on the optical axis, and the fundus-conjugate position is indicated by an '×' on the optical axis.

[0084] 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, an objective lens 22, etc. The light-receiving optical system 10b includes an objective lens 22, a perforated mirror 20, lenses 25a and 25b, a slit-shaped member 15b, an image sensor 28, etc.

[0085] 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. Thus, the light source unit 11 of this embodiment is provided with two light sources for each wavelength. Two light sources of the same wavelength are arranged on the pupil conjugate plane, away from the optical axis L. The two light sources are arranged side by side along the X direction, which is the scanning direction in Figure 3, and are arranged axially symmetric with respect to the optical axis L. As shown in Figure 3, the outer shape of the two light sources may be a rectangle in which the direction intersecting the scanning direction is longer than the scanning direction.

[0086] Light from the two light sources passes through the lens 13 and irradiates the slit-shaped member 15a. In this embodiment, the slit-shaped member 15a has a translucent portion (opening) formed to be elongated along the Y direction. As a result, the illumination light is formed in a slit shape on the fundus conjugate surface (the region illuminated in a slit shape on the fundus Er is shown as indicated by the symbol B).

[0087] The slit-shaped member 15a is displaced by a drive unit (not shown) such that the light-transmitting portion crosses the optical axis L in the X direction. This enables scanning of the illumination light in this embodiment. 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 by a single drive 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, please refer to, for example, "Japanese Patent Application Publication No. 2019-118721" by the present applicant.

[0088] In the illumination optical system 10a, the images from each light source are relayed by the optical system from lens 13 to objective lens 22 and formed on the pupil conjugate plane. In other words, pupil images from the two light sources are formed on the pupil conjugate plane at positions separated with respect to the scanning direction. In this way, in this embodiment, two light-emitting regions P1 and P2 on the pupil conjugate plane are formed as images of the two light sources.

[0089] Furthermore, the slit-shaped light passing through the slit-shaped member 15a is relayed by the optical system from lens 17a to objective lens 22 and formed as an image on the fundus Er. This creates a slit-shaped illumination light on the fundus Er. The illumination light is reflected on the fundus Er and extracted from the pupil Ep.

[0090] The perforated mirror 20 is an optical path coupling unit that connects the optical paths of the illumination optical system 10a and the light-receiving optical system 10b. The perforated mirror 20 reflects the illumination light from the light source unit 11 toward the eye E under examination, and allows a portion of the fundus reflected light from the eye E under examination, after passing through the aperture, to pass 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 reflective parts 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 placed on the reflective side of the mirror, and the independent optical path of the illumination optical system 10a is placed on the transmissive side of the mirror. Furthermore, the perforated mirror and the mirror used as a substitute can each be replaced with a combination of a half mirror and a light-shielding part.

[0091] Since the aperture of the perforated mirror 20 is conjugate to the pupil of the eye being examined, 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 eye being examined. For this reason, the image of the aperture on the pupil of the eye being examined becomes the light-receiving region R in this embodiment. The light-receiving region R is formed sandwiched between two light-emitting regions P1 and P2 (images of two light sources). Furthermore, as a result of appropriately setting the imaging magnification of each image, the diameter of the aperture, and the spacing between the two light sources, the light-receiving region R and the two light-emitting regions P1 and P2 are formed so that they do not overlap on the pupil.

[0092] The retinal reflected light that has passed through the aperture of the objective lens 22 and the perforated mirror 20 forms an image of the slit-shaped region of the retinal erythrocyte at the retinal conjugate position via lenses 25a and 25b. At this time, harmful light is removed because the light-transmitting portion of the slit-shaped member 15b is positioned at the imaging position.

[0093] The image sensor 28 is positioned in a conjugate location in the fundus. In this embodiment, a relay optical system 27 is provided between the slit-shaped member 15b and the image sensor 28, thereby creating a conjugate relationship between the slit-shaped member 15b and the image sensor 28 in the fundus. As a result, both the removal of harmful light and image formation are performed well. 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 placed in close proximity. In this embodiment, a device with a two-dimensional light-receiving surface is used as the image sensor 28. For example, a CMOS, a two-dimensional CCD, etc., may be used. The image of the slit-shaped region of the fundus Er, which is imaged in 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 and visible light.

[0094] In this embodiment, as the slit-shaped illumination light scans the fundus Er, an image of the scanning position on the fundus Er (a slit-shaped image) is sequentially projected for each scan line of the image sensor 28. In this way, the entire image of the scanning range is projected onto the image sensor 28 in a time-division manner. As a result, a frontal image of the fundus (a two-dimensional reflected image) is captured as the entire image of the scanning range.

[0095] In this embodiment, the scanning unit in the light-receiving optical system 10b was a device that mechanically scans the slit, but it 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, the slit scanning may be realized by the rolling shutter function of the CMOS. In this case, by displacing the area exposed on the imaging surface in synchronization with the scanning unit in the illumination optical system 10a, harmful light can be removed while efficiently taking images. Furthermore, a liquid crystal shutter or the like can be used as a scanning unit that electronically scans the slit.

[0096] The front imaging 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 path of the illumination optical system 10a and the independent optical path of the light-receiving optical system 10b, respectively. However, the diopter correction unit may be provided in the common optical path of the illumination optical system 10a and the light-receiving optical system 10b.

[0097] In the following, for convenience, the diopter correction optical system on the illumination side will be referred to as the illumination-side diopter correction optical system 17, and the diopter correction optical system on the light-receiving side will be referred to as the light-receiving-side diopter correction optical system 25. The illumination-side diopter correction optical system 17 of this embodiment includes lens 17a, lens 17b, and a drive unit (not shown). The light-receiving-side diopter correction optical system 25 of this embodiment also includes lens 25a, lens 25b, and a drive unit (not shown). In the illumination-side diopter correction optical system 17, the distance between lens 17a and lens 17b is changed, and in the light-receiving-side diopter correction optical system 25, the distance between lens 25a and lens 25b is changed. As a result, diopter correction is performed in both the illumination optical system 10a and the light-receiving optical system 10b.

[0098] The frontal 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.

[0099] For example, the indicator projection optical system 50 may include at least an infrared light source 51, an indicator plate 52, and a declination prism 53. In this embodiment, the indicator plate 52 is positioned at a location corresponding to the imaging surface in the light-receiving optical system 10b. Similarly, the indicator plate 52 is positioned at a location corresponding to each of the slit-shaped members 15a and 15b. For example, in detail, the indicator plate 52 is positioned at a location approximately conjugate to the fundus Er of an emmetropic eye (0D eye) when the diopter correction amount on the irradiating and receiving sides is 0D. The declination prism 53 is positioned closer to the indicator plate 52, on the side of the eye being examined.

[0100] For example, the indicator plate 52 is formed using the slit light as an indicator. The declination prism 53 separates the indicator light beam through the indicator plate 52 to form a split indicator. The separated split indicator is projected onto the fundus Er via the illumination-side diopter correction optical system 17 to the objective lens 22. As a result, the split indicator is captured in the fundus image (e.g., fundus observation image). In this embodiment, the two separated split indicators reach the fundus Er of the eye under examination, with one passing through the projection area P1 and the other through the projection area P2.

[0101] Figure 4 illustrates a fundus observation image 60 in which split indicators M1 and M2 are reflected. In this embodiment, split indicator M1 is projected onto the fundus Er by passing through the projection area P1, and split indicator M2 is projected onto the fundus Er by passing through the projection area P2. Figure 4(a) shows the case where the focus state is not properly adjusted and the indicator plate 52 is misaligned from the fundus conjugate position. In this case, the two split indicators M1 and M2 appear at positions separated in the X direction. Figure 4(b) shows the case where the focus state is properly adjusted and the indicator plate 52 is positioned at the fundus conjugate position. In this case, the two split indicators M1 and M2 appear at positions aligned in the X direction. In this embodiment, the conjugate relationship between the fundus Er and the indicator plate 52 is adjusted by the illumination-side diopter correction optical system 17 placed between the declination prism 53 and the fundus Er. Therefore, in this embodiment, defocusing is performed while matching the diopter correction amount on the irradiating side and the diopter correction amount on the receiving side. By adjusting the diopter correction amounts on the irradiating and receiving sides so that the two split indicators match, the imaging surface and the slit-shaped members 15a and 15b each achieve a positional relationship conjugate to the fundus Er.

[0102] Further, 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. Accordingly, in the present 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 one 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. In this case, an imaging element having sensitivity in a predetermined infrared wavelength range or the like may be used.

[0103] <Anterior eye observation optical system> FIG. 5 is a schematic diagram of the anterior eye observation optical system 40.

[0104] 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, and the like. 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 disposed 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.

[0105] <OCT optical system> 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.

[0106] 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.

[0107] In SD-OCT, a broadband light source is used as the OCT light source 201. The light from the OCT light source 201 is split into measurement light (sample light) and reference light by the coupler 202. The measurement light is guided to the fundus Er via the measurement optical system 200a. The reference light is guided to the reference optical system 200b.

[0108] In this embodiment, the measuring optical system 200a includes a collimator lens 206, a focusing lens 240, a scanning unit 207, a lens 208, and an objective lens 22.

[0109] The measurement light is guided to the scanning unit 207 via the collimator lens 206 and the focus lens 240. The scanning unit 207 scans the measurement light two-dimensionally over the fundus Er. The scanning unit 207 is positioned approximately conjugate to the pupil of the eye being examined E. As a result, the measurement light is rotated around the pupil of the eye being examined 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 is then guided to the detector 210 after retracing the steps of the measurement optical system 200a.

[0110] In this embodiment, the reference optical system 200b is a reflective optical system mainly comprising a reference mirror 231. The reference light makes one round trip between the coupler 202 and the reference mirror 231. The reference light that has made one round trip and entered the coupler 202 is guided to the detector 210.

[0111] In this embodiment, the reference mirror 231 is movable in the optical axis direction by the drive unit 231a. The optical path length of the reference optical system 200b is changed according to the position of the reference mirror 231. As a result, the difference in optical path length between the measurement light and the reference light is adjusted.

[0112] In this embodiment, the reference optical system 200b is shown to be formed by a reflective optical system, but the reference optical system 200b may also be formed by a transmissive optical system (e.g., an optical fiber).

[0113] In this embodiment, the polarizer 203 is positioned 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 the drive unit 203a to change the polarization state of the reference light. Note that the arrangement of the polarizer 203 is not limited to the example in Figure 6, and it may be positioned to adjust the polarization state of the measurement light.

[0114] The detector 210 receives interference light from the reflected light of the measurement light from the fundus Er and the reference light. In SD-OCT, a spectrometer is used as the detector 210. Based on the spectral interference signal from the detector 210, OCT data of the fundus Er is generated.

[0115] Generally, the required pupil diameter for an OCT optical system can be set to a value sufficiently smaller than the required pupil diameter for an observation optical system where spatial pupil division is performed. In this embodiment, the transmission and reception of measurement light from the OCT optical system 200 to the eye E under examination occurs within the light-receiving area R on the pupil of the eye E under examination. Therefore, in this embodiment, if a good fundus observation image is obtained, it is guaranteed that the transmission and reception of measurement light will also be good, at least on the pupil of the eye E under examination.

[0116] <Department Head> Figure 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 unit (processor) that performs control processing for each part and calculation processing. The control unit 100 is equipped with a CPU, RAM, ROM, etc. Also, for convenience, the control unit 100 is assumed to perform image processing for various images obtained by the fundus imaging device 1. In other words, the control unit 100 also serves as the image processing unit.

[0117] The control unit 100 is electrically connected to various components such as the drive unit 8, the frontal imaging optical system 10, the anterior segment observation optical system 40, the face imaging camera 110, the OCT optical system 200, the monitor 120, the input interface 130, and the memory unit 101.

[0118] The control unit 100 controls each of the above components based on the operation signals output from the input interface 130. The input interface 130 is an operation input unit that accepts operations from the examiner. For example, it may be a mouse, keyboard, etc.

[0119] The storage unit 101 may be a non-transient storage medium that can retain its contents even when the power supply is interrupted. For example, the storage unit 101 may be a hard disk drive, flash ROM, USB memory, etc. For example, the storage unit 101 may store various control programs, fixed data, etc. Also, for example, the storage unit 101 may store 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 LAN and WAN).

[0120] <Operation Description> Next, the operation of the fundus imaging device 1 in this embodiment will be explained with reference to Figures 8 to 13.

[0121] In this embodiment, even if the intermediate transparent media of the eye E under examination is cloudy, the alignment state is automatically adjusted so that a two-dimensional reflection image (color fundus image) and OCT data of the fundus Er can be acquired while avoiding the cloudiness. This embodiment shows an example of when auto-alignment is performed.

[0122] Figure 8 is a flowchart showing the operation flow of the ophthalmic imaging device 1.

[0123] The operation begins with the subject's face positioned relative to the face support unit 9. First, the position of the imaging unit 3 is adjusted relative to the subject's eye E to a position where fundus observation images can be acquired. The position of the imaging unit 3 is adjusted based on the face image acquired via the face imaging camera 110 and the anterior segment observation image acquired via the anterior segment observation optical system 40.

[0124] 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 or right eyes of the subject included in the facial image. Based on the detected position information, the control unit 3 adjusts its position to a position where anterior segment observation is possible.

[0125] Once alignment adjustment is performed based on the facial image, an anterior segment observation image, as shown in Figure 9, is acquired via the anterior segment observation optical system 40. Note that in Figure 9, the projection areas P1, P2 and the light-receiving area R are shown only for explanatory purposes. The control unit 100 adjusts the positional relationship between the eye under examination E and the imaging 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 where the pupil center and the image center (in this embodiment, the position of the imaging optical axis L) are approximately coincident. An alignment deviation from the reference position is detected, and the imaging unit 3 is moved in the XY direction in a direction that eliminates the alignment deviation. The alignment deviation may be detected as the amount of deviation between the pupil center and the imaging optical axis on the anterior segment observation image. Alternatively, if the fundus imaging device 1 has, for example, an alignment projection optical system that projects an alignment index onto the corneal apex, the alignment deviation may be detected as the amount of deviation between the alignment index and the imaging optical axis.

[0126] Thus, in this embodiment, as a result of the first alignment adjustment, the positional relationship between the eye E under examination and the imaging unit 3 in the XY direction is adjusted so that the center of the light-receiving area R (i.e., the imaging optical axis) coincides with the center of the pupil.

[0127] Furthermore, the control unit 100 adjusts the positional relationship in the Z direction so that the distance between the eye E under examination and the imaging unit 3 is a predetermined distance. For example, the imaging unit 3 may be moved in the anterior-posterior direction so that the anterior segment observation image is in focus on the pupil Ep. Alternatively, the positional relationship in the Z direction may be adjusted using various alignment indicators.

[0128] Next, the control unit 100 acquires the pupil diameter Pd (see Figure 9) as pupil size (pupil information in this embodiment) based on the anterior segment observation image and compares it with a threshold. For example, the control unit 100 detects the pupil region from the anterior segment observation image using a method such as edge detection and further 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 it may be manually entered by the examiner.

[0129] The control unit 100 compares the acquired pupil diameter Pd with a threshold. For example, the threshold may be approximately the same as the overall width PR (width in the X direction, see Figure 9) in the light-emitting areas P1, P2 and the light-receiving area R.

[0130] If the pupil diameter Pd is above the threshold, the acquisition of fundus observation images is initiated (S4).

[0131] Figure 10 shows an anterior segment observation image acquired when the pupil diameter Pd is smaller than the threshold. As shown in Figure 10(a), when the pupil diameter Pd is smaller than the threshold (S3: No), in this embodiment, the light projected through the projection areas P1 and P2 is vignetted by the iris. In this case, the fundus Er cannot be properly captured. Therefore, in this case, the small pupil mode is set (S10), and the acquisition of fundus observation images is started in small pupil mode (S4).

[0132] As shown in Figure 10(b), in the small pupil mode of this embodiment, the alignment reference position is offset (eccentric) in the X direction so that one of the light-emitting areas P1 and P2, along with the light-receiving area R, is preferentially positioned within the pupil area relative to the other. Furthermore, the positional relationship between the eye under examination E and the imaging unit 3 is adjusted according to the offset of the reference position. The amount of offset of the reference position may be set according to the pupil diameter Pd or it may be a fixed value. As shown in Figure 10(b), in this embodiment, the light-emitting area P1 is preferentially positioned. In addition, in the small pupil mode, the control unit 100 may light only the light-emitting area P1 of the two observation light sources 11c and 11d, and turn off the other.

[0133] After the acquisition of fundus observation images is started (S4), the control unit 100 determines whether or not the clouding of the transparent media has an effect on the fundus observation images (whether or not the effect is at an acceptable level) (S5).

[0134] In this embodiment, the presence or absence of turbidity is determined using split indices M1 and M2. The control unit 100 projects the split indices from the indice projection optical system 50.

[0135] As described above, in this embodiment, the two split indicators are projected and received via the projection areas P1 and P2 and the receiving area R. Therefore, it is thought that the split indicators projected into the pupil area without being obscured by the iris will be visible in the fundus observation image, provided that the projection and reception are not obstructed by turbidity. In other words, if the pupil size is sufficient, both split indicators M1 and M2 will be visible, and in the small pupil mode, it is thought that at least one of the split indicators M1 and M2 will be visible. The control unit 100 detects these split indicators and determines whether or not there is an effect of turbidity in the transparent material based on the detection results.

[0136] For example, if one or two desired indicator images are not properly detected, it may be determined that the fundus observation image is affected by opacity of the transparent media. Alternatively, if the brightness of the detected split indicator is lower than the threshold, it may be determined that the fundus observation image is affected by opacity of the transparent media. If it is determined that the fundus observation image is affected by opacity of the transparent media (S5: Yes), a second alignment adjustment (S20) is performed, and further alignment adjustments are made to avoid opacity. Details of the second alignment adjustment (S20) will be described later.

[0137] If it is determined that there is no effect from the opacity of the transparent media in the fundus observation image (S5: No), and after the second alignment adjustment (S20) is performed, focus adjustment is performed (S6).

[0138] For example, the control unit 100 detects the separation state of split indices M1 and M2 from the fundus observation image, drives the diopter correction unit (diopter correction optical systems 17 and 25) so that the split indices M1 and M2 match, and defocuses the frontal 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 frontal imaging optical system 10. This adjusts the force of the OCT optical system 200.

[0139] In small pupil mode, only at least one of the split indicators M1 and M2 is visible in the fundus observation image. Therefore, the focus adjustment described above is performed so that the desired indicator image from the two indicator images M1 and M2 is positioned at a pre-set matching position. The matching position here may be, for example, the matching position assuming that both split indicators M1 and M2 are visible.

[0140] Next, various adjustments are made to the OCT optical system 200 (S7). The control unit 100 acquires OCT data through the OCT optical system 100 and performs fine adjustments to the focus, optical path length, polarization state (polarizer adjustment), etc. For details of the adjustments, please refer to, for example, Japanese Patent Application Publication No. 2015-195876 by the present applicant. As a result of the adjustment of the OCT optical system 200, OCT data of the fundus Er can be acquired with high sensitivity and high resolution.

[0141] Next, the control unit 100 performs the imaging (S8). For example, the control unit 100 controls the OCT optical system 200 to acquire OCT data. Then, it controls the frontal imaging optical system 10 to acquire a color fundus image. The control unit 100 may perform each imaging based on the operation input that triggers the imaging, or it may perform each imaging automatically. The imaging results are stored in the storage unit 101. The imaging results may also be displayed on the monitor 120.

[0142] <Second alignment adjustment> Next, we will explain the details of the second alignment adjustment by referring to the flowchart in Figure 11.

[0143] In the second alignment adjustment, the control unit 100 searches for an alignment state in which one or two desired target images can be detected well, while transitioning (changing) the positional relationship between the eye E under examination and the imaging unit 3.

[0144] In this embodiment, we describe how to evaluate the effect of opacity of the transparent media by continuously detecting split indicators on fundus observation images acquired in near real-time during the search, using the same method as in S5.

[0145] In this embodiment, the pattern for transitioning the positional relationship (referred to as the search pattern) differs depending on whether or not the pupil is in small pupil mode.

[0146] First, referring to Figure 12, we will explain the first search pattern that is executed under normal circumstances (when S21: No). In this case, an alignment state in which both split indices M1 and M2 are detected is searched for.

[0147] The control unit 100 moves the imaging unit 3 within a range where the light-emitting areas P1, P2 and the light-receiving area R do not extend beyond the pupil. The movement range may be set, for example, based on the pupil diameter Pd.

[0148] In the first search pattern, the control unit 100 randomly moves the imaging unit 3 in the XY direction within a range where the light-emitting areas P1, P2 and the light-receiving area R do not extend beyond the pupil (Figure 12(a) ⇒ Figure 12(b)), and acquires fundus observation images at each position. Note that the first search pattern does not necessarily have to be random; it may be a predetermined pattern. For example, it may be a pattern in which the unit is first moved in the Y direction and then in the X direction, or it may be any other pattern.

[0149] Furthermore, the control unit 200 may, at any time, determine the direction and amount of movement of the imaging unit 3 based on the observation images obtained during the search. For example, during the search, there may be cases where only one of the two split indicators M1 and M2 is detected even though they are illuminated within the pupil region. In this case, it is presumed that there is no opacity in the light-emitting regions P1 and P2 corresponding to the detected indicator image, and in the light-receiving region R. This can be used to narrow down the positional relationships in which there is still a possibility of obtaining a good fundus observation image while performing the search, and then transition to the narrowed-down positional relationships.

[0150] During the search, the control unit 100 acquires information indicating the alignment state at the time each observation image was acquired, in association with each observation image. The control unit evaluates the effect of opacity in each observation image (S23) and changes the alignment reference position based on the alignment state of the observation image with no (or less) effect of opacity. Furthermore, it adjusts the positional relationship between the eye under examination E and the imaging unit 3 according to the changed alignment reference position (S24).

[0151] Next, with reference to Figure 13, a second search pattern performed in small pupil mode (S21: Yes) will be described. For example, if the light-emitting area P1 is preferentially located within the pupil area, an alignment state is searched in which the split indicator M1, which is emitted and received via the light-emitting area P1 and the light-receiving area R, is properly detected.

[0152] In this case, the control unit 100 primarily moves the imaging unit 3 in the Y direction to perform the search, under the condition that the light-emitting area P1 and the light-receiving area R do not extend beyond the pupil (Figure 13(a) ⇒ Figure 13(b)). In other words, it is preferable to move preferentially in the Y direction out of the XY directions. In this embodiment, since the light-emitting area P1 and the light-receiving area R are arranged side by side in the X direction, it is thought that in the case of a small pupil, it may be difficult to secure space to move in the X direction within the pupil area.

[0153] Furthermore, the transition of the positional relationship between the eye E under examination and the imaging unit 3 in the second search pattern may be random, predetermined, or determined sequentially during the search, similar to the first search pattern.

[0154] Furthermore, for example, the control unit 100 may, during the search, switch which of the two light projection areas P1 and P2 is preferentially positioned within the pupil region. As shown in Figure 10(b), the control unit may switch from a state in which light projection area P1 is eccentric so that it is included in the pupil region to a state in which light projection area P2 is eccentric so that it is included in the pupil region. This increases the possibility of obtaining a good fundus observation image.

[0155] In this embodiment, even if there is opacity in the transparent media of the eye E under examination, the alignment is adjusted to a state in which a suitable fundus observation image can be obtained.

[0156] As mentioned above, in this embodiment, focus adjustment is performed afterward. Since the focus adjustment is performed with the split indicator clearly visible in the fundus observation image as a result of the alignment adjustment, the failure of focus adjustment is less likely in this embodiment.

[0157] Furthermore, in this embodiment, since the optical system for capturing both the fundus observation image and the color fundus image is the same, a good color fundus image is captured in this alignment state. Also, in this embodiment, the transmission and reception of measurement light from the OCT optical system 200 to the eye E under examination occurs inside the light-receiving area R on the pupil of the eye E under examination. Therefore, good quality OCT data can also be captured.

[0158] Furthermore, in this embodiment, the frontal imaging 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 frontal imaging optical system 10 is displaced from the center of the anterior segment to suppress the effects of turbidity, noise light from the transparent body is suitably removed by the slit-shaped member 15. Thus, good color fundus images can be captured.

[0159] [Examples of transformation] The technologies disclosed in the above embodiments are merely examples. Therefore, it is possible to modify the technologies exemplified in the above embodiments. For example, it is possible to implement only some of the technologies exemplified in the above embodiments.

[0160] For example, in the first embodiment, the case of searching for a positional relationship in which both of the two split indices M1 and M2 are appropriately detected was described. However, it is not necessarily limited to this, and a positional relationship in which one of the two split indices M1 and M2 is appropriately detected may also be searched. In this case, it becomes easier to perform appropriate alignment adjustments for the eye being examined with severe opacity.

[0161] Furthermore, although the above embodiment describes a case where focus adjustment is performed after alignment adjustment, alignment adjustment and focus adjustment may be performed in parallel. That is, while the positional relationship between the eye under examination and the imaging unit is changed based on the fundus observation image, focus adjustment may be started when at least one of the split indices M1 and M2 is detected. In this case, the time required for various adjustments leading up to imaging is shortened.

[0162] Furthermore, in the above embodiment, once alignment based on the anterior segment observation image is completed, the examiner may be asked to select whether or not to set the small pupil mode via the input interface 130. In that case, for example, the anterior segment observation image of the eye under examination may be displayed on the monitor 120, allowing the examiner to confirm the positional relationship between the pupil of the eye under examination and the light-emitting and light-receiving areas.

[0163] Furthermore, for example, when acquiring multiple fundus observation images at different positions in the XY direction, the transition of the positional relationship between the eye under examination and the imaging unit may be performed based on the examiner's operation. For example, the examiner may adjust the positional relationship by operating a joystick. In addition, the control unit 100 may limit the range of transitions possible in the XY direction, taking pupil information into consideration. Regardless of the examiner's operation, the control unit 100 may control the positional relationship so that the pupil image of the optical system does not extend beyond the pupil.

[0164] In the above embodiment, the case in which a split indicator is detected as a result of the search was described. However, there may be cases in which no split indicator is detected even after performing the search. In this case, the control unit 100 may perform the imaging while maintaining the alignment reference position based on the alignment based on the anterior segment observation image.

[0165] Furthermore, the front imaging optical system 10 in the above embodiment is a slit-scan type optical system in which the light-receiving area R and the two light-emitting areas P1 and P2 are all formed in a single row. In contrast, in a spot-scan type optical system, for example, the light-emitting area and the light-receiving area may be formed in a single row, or in addition to the light-emitting area and light-receiving area formed in a single row, at least one more light-emitting area and light-receiving area may be formed that are arranged in a direction intersecting the row.

[0166] For example, Figure 14 shows pupil images (each region (each pupil image) P11, P12, P13, P14, R) on an anterior segment observation image in an optical system where a light-receiving region R and light-emitting regions P11, P12 are formed in a row in the X direction, and a light-receiving region R and light-emitting regions P13, P14 are formed in a row in the Y direction. Illumination light may be emitted simultaneously or selectively from multiple light-emitting regions P11, P12, P13, P14.

[0167] In such a device, in the second alignment mode, the control unit selects one of the multiple light-emitting regions P11, P12, P13, and P14, and sets the direction of arrangement of the selected light-emitting region and the light-receiving region R as the first direction. The control unit then displaces the positional relationship between the eye under examination and the imaging unit in a direction that intersects the first direction with respect to the predetermined positional relationship guided by the first alignment. For example, if light-emitting region P11 is selected, the position is displaced in the Y direction. This may guide the system into the second alignment state.

[0168] In the example shown in Figure 14, multiple (four in the figure) light-emitting regions are formed for a single light-receiving region R, but the number of light-receiving and light-emitting regions can be changed as appropriate. [Explanation of symbols]

[0169] 3. Shooting Unit 8 Drive unit 10 Frontal imaging optical system 70 Control means 200 OCT optics

Claims

1. A photographic unit including: a photographic optical system that projects and receives photographic light onto the fundus of the eye under examination and acquires a photographic image of the fundus; an observation optical system that projects and receives observation light, which is different from the photographic light and is infrared light, onto the fundus of the eye under examination and acquires a fundus observation image, which is a two-dimensional reflected image based on the observation light; and an indicator projection optical system that projects an indicator light beam onto the fundus to adjust the photographic conditions of the photographic optical system; A drive unit that moves the imaging unit relative to the eye being examined, A control means for guiding the positional relationship between the eye under examination and the imaging unit, at least in the XY direction, based on the fundus observation image, comprising: a control means for detecting an index image formed on the fundus observation image based on the index light beam, and guiding the positional relationship based on the index image; A fundus imaging device equipped with the following features.

2. The fundus imaging apparatus according to claim 1, wherein the control means acquires a plurality of fundus observation images in a plurality of positional relationships that are different from each other in at least the XY direction, and guides the positional relationships based on the plurality of fundus observation images.

3. The fundus imaging apparatus according to claim 1 or 2, wherein the control means acquires pupil information as information relating to the pupil region of the eye to be examined, and guides the positional relationship taking into consideration the pupil information.

4. The fundus imaging apparatus according to claim 3, wherein the control means acquires information regarding the pupil size of the eye under examination as pupil information, and changes the guidance control of the positional relationship based on the fundus observation image according to the pupil size. A fundus imaging device.

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