Ophthalmologic apparatus, method for controlling ophthalmologic apparatus, program and recording medium

Abstract

To provide a method for performing a Van Herick method by using ophthalmologic apparatus that scans an anterior ocular segment by moving a Scheimpflug optical system using slit light as illumination light.SOLUTION: An illumination system 21 of a Scheimpflug optical system 2 of ophthalmologic apparatus 1 projects slit light to an anterior ocular segment of a subject's eye E from a front direction. Imaging systems 22L and 22R image the anterior ocular segment from a direction that forms a first angle in a width direction of the slit light with respect to the front direction. A moving mechanism 6 moves the Scheimpflug optical system 2 in the width direction of the slit light. A control unit 7 controls the Scheimpflug optical system 2 and the moving mechanism 6 in order to collect a set of anterior ocular segment images. An image processing unit 81 generates a virtual image of the anterior ocular segment, viewed from a virtual viewpoint in the front direction, on which virtual slit light is projected from a direction that forms a second angle in the width direction of the slit light with respect to the front direction, on the basis of the set of anterior ocular segment images.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an ophthalmic device, a method for controlling the ophthalmic device, a program, and a recording medium.

Background Art

[0002] In the field of ophthalmology, image diagnosis plays an important role. In ophthalmic image diagnosis, various types of ophthalmic devices (ophthalmic imaging devices) such as a slit lamp microscope, a fundus camera, a scanning laser ophthalmoscope (SLO), and an optical coherence tomography (OCT) are used. The ophthalmic device having an imaging function is not limited to these ophthalmic imaging devices, and imaging functions are also installed in ophthalmic examination devices and ophthalmic measurement devices such as a refractometer, a keratometer, a tonometer, a specular microscope, a wavefront analyzer, and a microperimeter.

[0003] One of the image diagnostic methods is the Van Herick method (see Patent Documents 1 and 2). The Van Herick method is a screening method for the anterior chamber depth using a slit lamp microscope, and is widely used for the diagnosis of angle-closure glaucoma because of its simplicity. The Van Herick method is a method for estimating the width of the angle by comparing the corneal thickness and the anterior chamber depth in the vicinity of the limbus (referred to as the peripheral part), which is the boundary between the cornea and the conjunctiva. Specifically, the angle between the slit light of the slit lamp microscope and the observation system (imaging system) is set to 60 degrees, the slit light is projected perpendicularly to the limbus, and an image from the front (0 degrees) is acquired, and the width of the angle is estimated by comparing the corneal thickness and the anterior chamber depth in the peripheral part.

[0004] In the Van Herick method, the status of the corner is classified into the following four grades: the cornea and the iris are in contact and the corner is blocked (grade 0); the anterior chamber depth is less than one-fourth of the corneal thickness and the corner is likely to be blocked (grade 1); the anterior chamber depth is one-fourth of the corneal thickness and there is a possibility of corner blockage (grade 2); the anterior chamber depth is between one-fourth and one-half of the corneal thickness and corner blockage is unlikely to occur (grade 3); the anterior chamber depth is greater than or equal to the corneal thickness and corner blockage does not occur (grade 4).

[0005] In the observation of the anterior segment of the eye, a slit lamp microscope has been mainly used, but other modalities have also been proposed. For example, Patent Document 3 discloses an ophthalmic device configured to scan the anterior segment of the eye by moving a shine-proof optical system using slit light as illumination light. Although such an ophthalmic device has a remarkable effect of being able to image a wide range of the anterior segment of the eye with a deep depth of field, there is a problem that it cannot be used for the Van Herick method.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] One object of the present disclosure is to provide a method for implementing the Van Herick method using an ophthalmic device that scans the anterior segment of the eye by moving a shine-proof optical system using slit light as illumination light.

Means for Solving the Problems

[0008] One exemplary aspect of an embodiment is an ophthalmic device including an illumination system that projects slit light from the front direction onto the anterior eye segment of an eye to be examined, an imaging system that images the anterior eye segment from a first oblique direction forming a first angle with respect to the front direction in the width direction of the slit light, a shine-proof optical system in which the illumination system and the imaging system satisfy shine-proof conditions, a moving mechanism that moves the shine-proof optical system in the width direction, a control unit that controls the shine-proof optical system and the moving mechanism to collect a set of anterior eye segment images, and an image processing unit that generates a virtual anterior eye segment image of the anterior eye segment onto which virtual slit light is projected from a virtual position in a second oblique direction forming a second angle with respect to the front direction in the width direction as seen from a virtual viewpoint in the front direction based on the set of anterior eye segment images.

[0009] Another exemplary aspect of an embodiment is a method for controlling an ophthalmic device for imaging the anterior eye segment of an eye to be examined, the ophthalmic device including an illumination system that projects slit light from the front direction onto the anterior eye segment, an imaging system that images the anterior eye segment from a first oblique direction forming a first angle with respect to the front direction in the width direction of the slit light, a shine-proof optical system in which the illumination system and the imaging system satisfy shine-proof conditions, a moving mechanism that moves the shine-proof optical system in the width direction, and a processor, the method including causing the processor to execute a process of controlling the shine-proof optical system and the moving mechanism to collect a set of anterior eye segment images, and a process of generating, based on the set of anterior eye segment images, a virtual anterior eye segment image of the anterior eye segment onto which virtual slit light is projected from a virtual position in a second oblique direction forming a second angle with respect to the front direction in the width direction as seen from a virtual viewpoint in the front direction.

[0010] Yet another exemplary aspect of an embodiment is a program that causes a computer to execute the method according to the exemplary aspect.

[0011] Yet another exemplary aspect of an embodiment is a computer-readable non-transitory recording medium on which the program according to the exemplary aspect is recorded.

Advantages of the Invention

[0012] According to an embodiment, it becomes possible to provide a method for performing the Van Herick method using an ophthalmic apparatus that moves a shine-proof optical system using slit light as illumination light to perform an anterior eye scan.

Brief Description of the Drawings

[0013]

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Modes for Carrying Out the Invention

[0014] A non-limiting embodiment according to the present disclosure will be described.

[0015] Any known technology can be combined with the embodiments. For example, any matter described in the documents cited in the present disclosure can be combined with any aspect of the embodiments. Further, at least one of any known document related to the technical field of the present disclosure, any known technology in a technical field similar to the technical field of the present disclosure, and any known technology in a technical field different from the technical field of the present disclosure can be combined with any aspect of the embodiments.

[0016] For example, the matters disclosed in Patent Document 3 (Japanese Patent Application Laid-Open No. 2023-49320) can be incorporated into the present disclosure by reference. More generally, any technical matter (matters disclosed in patent applications, papers, etc.) disclosed by the applicant of the present application regarding the technology related to the present disclosure can be incorporated into the present disclosure by reference.

[0017] Any two or more of the various non-limiting aspects according to the embodiments can be at least partially combined.

[0018] At least a part of the functions of any of the aspects described in the present disclosure is implemented using circuitry or processing circuitry. The circuitry or processing circuitry includes a general-purpose processor, a dedicated processor, an integrated circuit, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), a programmable logic device (e.g., SPLD (Simple Programmable Logic Device), CPLD (Complex Programmable Logic Device), FPGA (Field Programmable Gate Array)), a conventional circuitry, and any combination thereof, configured and / or programmed to execute at least a part of the disclosed functions. A processor is regarded as a processing circuitry or circuitry including transistors and / or other circuitry. In the present disclosure, terms such as circuitry, unit, means, or the like refer to hardware that executes at least a part of the disclosed functions, or hardware programmed to execute at least a part of the disclosed functions. The hardware may be the hardware disclosed herein, or may be known hardware programmed and / or configured to execute at least a part of the described functions. When the hardware is a processor that can be regarded as a certain type of circuitry, the terms circuitry, unit, means, or the like refer to a combination of hardware and software, and this software is used to configure the hardware and / or the processor.

[0019] <Summary of Embodiments> Embodiments according to the present disclosure aim to provide a method for implementing the Van Herick method using an ophthalmic device that moves a shine-proof optical system using slit light as illumination light to perform anterior eye segment scanning. By achieving this objective, the effect of expanding the application range of such types of ophthalmic devices is achieved. Conversely, the effect of expanding the types of ophthalmic devices capable of implementing the Van Herick method is also achieved. As a result, a remarkable effect of being able to more widely perform a simple examination for angle-closure glaucoma is achieved.

[0020] Note that the effects of the embodiments according to the present disclosure are not limited to those described above. Some non-limiting aspects of the embodiments will be described below, but it should be understandable to those skilled in the art that each aspect exhibits effects corresponding to its features (configuration, operation, action, use, etc.).

[0021] A first aspect of the embodiment is an ophthalmic device including a shine-proof optical system, a moving mechanism, a control unit, and an image processing unit.

[0022] The shine-proof optical system includes an illumination system and a photographing system. The illumination system is configured to project slit light onto the anterior eye segment of the eye to be examined from the front direction. The photographing system is configured to photograph the anterior eye segment from a first oblique direction forming a first angle in the width direction of the slit light with respect to the front direction. The illumination system and the photographing system are configured to satisfy the conditions of shine-proof.

[0023] The moving mechanism is configured to move the shine-proof optical system in the width direction of the slit light.

[0024] The control unit is configured to control the shine-proof optical system and the moving mechanism to collect a set of anterior eye segment images. In other words, the control unit is configured to cause the shine-proof optical system (photographing unit) to collect a set of anterior eye segment images by controlling the shine-proof optical system and the moving mechanism.

[0025] The image processing unit is configured to generate a virtual anterior eye image of the anterior eye on which virtual slit light is projected from a virtual position in a second oblique direction forming a second angle with respect to the width direction of the slit light in the front direction, as viewed from a virtual viewpoint in the front direction, based on the collected set of anterior eye images.

[0026] The ophthalmic device according to this aspect is configured to perform an anterior eye scan by moving a Schlein-proof optical system using slit light as illumination light, and can generate a pseudo-image (virtual anterior eye image) similar to the image used in the Van Herick method based on the set of anterior eye images collected in the anterior eye scan. Therefore, according to this aspect, it becomes possible to perform an examination based on the Van Herick method using an ophthalmic device that performs an anterior eye scan by moving a Schlein-proof optical system using slit light as illumination light.

[0027] In addition, the illumination system and the imaging system of the ophthalmic device according to the present aspect are configured to satisfy the conditions of a Scheimpflug camera. Generally, the conditions of a Scheimpflug camera are conditions related to an optical system (illumination system) that projects illumination light onto an object and an optical system (imaging system) that images the object, and define that the illumination system and the imaging system are configured such that the object plane, the lens principal plane, and the film plane (imaging plane) intersect on the same straight line. An optical system that satisfies the conditions of a Scheimpflug camera has an object plane that is not arranged parallel to the lens principal plane. A camera using such a Scheimpflug optical system (Scheimpflug camera) can perform imaging while simultaneously focusing over a wide depth range from a nearby object to a distant object. In the anterior eye scan of the present aspect, for example, a series of images can be taken with the entire anterior eye in focus over a wide depth range from the anterior surface of the cornea to the posterior surface of the lens. Therefore, according to the present aspect, there is an effect that an image that highly accurately represents the entire main observation range of the anterior eye can be obtained. Further, according to the present aspect, in which a virtual anterior eye image can be generated from such a high-quality image, there is also an effect that an examination based on the Van Herick method can be performed with high quality. Furthermore, according to the present aspect, in which a high-definition image of a wide three-dimensional region of the anterior eye can be obtained, there is also an effect that an examination based on the Van Herick method can be performed by focusing on a desired position of the anterior eye.

[0028] A second aspect of the embodiment is the ophthalmic device of the first aspect, wherein the image processing unit may be configured to generate a virtual anterior eye image according to at least the following first to third steps.

[0029] In the first step, the image processing unit of the present aspect constructs a three-dimensional image from the set of anterior eye images collected under the control executed by the control unit. The three-dimensional image may be any type of image defined by a three-dimensional coordinate system. For example, the three-dimensional image may be stack data obtained by embedding a plurality of anterior eye images included in the set of anterior eye images in one three-dimensional coordinate system, or voxel data (volume data) obtained by image interpolation and voxelization.

[0030] In the second step, the image processing unit of this embodiment extracts an image (referred to as a partial image) corresponding to a plane along the second oblique direction from the three-dimensional image constructed in the first step. As defined in the first aspect, the second oblique direction is a direction forming a second angle with respect to the front direction, which is the direction in which the slit light is projected by the illumination light, in the width direction of the slit light, and is also the direction in which the virtual slit light is projected from the virtual position.

[0031] In the third step, the image processing unit of this embodiment generates a virtual anterior eye image by applying an orthographic projection in the direction of the complementary angle formed by the front direction and the second oblique direction to the partial image extracted from the three-dimensional image in the second step. Here, the angle formed by the front direction and the second oblique direction is the second angle described above. Therefore, the angle of the "complementary angle" of this embodiment is a value obtained by subtracting the second angle from 90 degrees (the difference between 90 degrees and the second angle).

[0032] The ophthalmic apparatus according to the second aspect can generate a virtual anterior eye image simulating an image obtained by combining the projection of slit light from the second oblique direction and the imaging from the front, based on the three-dimensional image constructed from the anterior eye image set collected by the anterior eye scan combining the projection of slit light from the front direction and the imaging from the first oblique direction by executing the first to third steps. Therefore, according to this embodiment, it is possible to provide a specific method for performing an examination based on the Van Herick method using an ophthalmic apparatus that moves a Scheimpflug optical system using slit light as illumination light to perform an anterior eye scan.

[0033] A third aspect of the embodiment is the ophthalmic device of the second aspect, wherein the image processing unit applies correction processing including at least one of distortion correction and aspect correction to the anterior eye image set collected under the control executed by the control unit, and constructs a three-dimensional image from the anterior eye image set to which this correction processing has been applied. That is, the image processing unit of this aspect executes the first to third steps of the second aspect after executing correction processing including at least one of distortion correction and aspect correction. This correction processing is applied to each anterior eye image included in the anterior eye image set.

[0034] Correction processing including at least one of distortion correction and aspect correction may be performed between the first step and the second step. The correction processing in this case is applied to the three-dimensional image constructed from the anterior eye image set collected under the control executed by the control unit.

[0035] Alternatively, correction processing may be performed as a sub-step of the first step. For example, the first step may include a sub-step of constructing stack data, a sub-step of applying correction processing to this stack data, and a sub-step of constructing volume data from the stack data to which the correction processing has been applied.

[0036] Also, when the correction processing includes a plurality of sub-correction processes, the timing for performing these sub-correction processes may be arbitrary. For example, when the correction processing includes a first sub-correction process and a second sub-correction process, the image processing unit may be configured to execute the first sub-correction process, the first step, the second sub-correction process, the second step, and the third step in this order.

[0037] At any stage of the correction process (for example, the second or third step), by performing image processing to generate an image taking into account the effect of optical refraction by the eye to be examined, a virtual anterior eye segment image that more faithfully reproduces the actually observed image can be generated. This image processing includes, for example, image distortion correction considering the effect of optical refraction exerted by the human eye on the virtual slit light when the virtual slit light is incident from a virtual position in a second oblique direction forming a second angle (for example, 60 degrees) in the width direction of the slit light with respect to the front direction. This image distortion correction can be performed using, for example, a projective transformation formula determined by an operation such as ray tracing using a predetermined model and / or a projective transformation formula determined from parameters obtained by analyzing an image obtained in actual imaging. Alternatively, in the evaluation process described later, evaluation may be performed taking into account the effect of optical refraction in the human eye, or the evaluation result obtained in the evaluation process described later may be corrected based on the effect of optical refraction in the human eye.

[0038] As several examples have been given above, the temporal arrangement of the correction process and the three-dimensional image construction (the first step) may be arbitrary. This aspect is intended to include various modifications regarding the correction process and the three-dimensional image construction.

[0039] The method of the correction process of this aspect may be arbitrary. For example, the method of distortion correction may be any method described in Japanese Patent Application Laid-Open No. 2019-213733 by the present applicant, and the method of aspect ratio correction may be any method described in Japanese Patent Application Laid-Open No. 2023-003456 by the present applicant.

[0040] The ophthalmic device according to the third aspect can correct the form of the anterior eye segment represented in the image by a correction process including at least one of distortion correction and aspect correction, so that it is possible to provide a virtual anterior eye segment image representing the actual form of the anterior eye segment or a form close thereto. Therefore, according to this aspect, it becomes possible to improve the quality of the examination based on the Van Herick method.

[0041] A fourth aspect of the embodiment is an ophthalmic apparatus according to any one of the first to third aspects, further including an evaluation processing unit. The evaluation processing unit is configured to generate evaluation information of the eye to be examined based on the virtual anterior eye image generated by the image processing unit.

[0042] According to the ophthalmic apparatus according to the fourth aspect, it is possible to automatically perform an evaluation of the eye to be examined based on the virtual anterior eye image and provide the result.

[0043] A fifth aspect of the embodiment is the ophthalmic apparatus according to the fourth aspect, in which a second angle, which is the angle formed by the projection direction of the virtual slit light with respect to the anterior eye and the direction of the virtual viewpoint with respect to the anterior eye, is 60 degrees. The second angle is set to 60 degrees by the image processing unit or is set to 60 degrees in advance.

[0044] Also, the virtual slit light in this aspect is projected onto the corneal limbus of the anterior eye. The target position onto which the virtual slit light is projected is set with respect to the corneal limbus by the image processing unit or is set with respect to the corneal limbus in advance. Note that the corneal limbus is the boundary portion between the cornea and the conjunctiva.

[0045] Furthermore, the evaluation processing unit in this aspect is configured to calculate the ratio of the corneal thickness to the anterior chamber depth in the vicinity of the corneal limbus of the anterior eye and generate evaluation information based on the result.

[0046] The evaluation information obtained in this way corresponds to the evaluation information obtained by an examination based on the Van Herick method. The evaluation information in this aspect may include, for example, the value of the ratio of the corneal thickness to the anterior chamber depth and / or the grade (grades 0 to 4) indicating the state of the anterior chamber angle. Thus, according to the fifth aspect, it is possible to automatically perform an evaluation corresponding to the examination based on the Van Herick method and provide the result.

[0047] The sixth aspect of the embodiment is an ophthalmic apparatus according to any one of the first to fifth aspects. First, the imaging system includes a pair of imaging systems arranged at first angles in opposite directions across the front direction with respect to the anterior eye of the eye to be examined. In other words, the pair of imaging systems in this aspect are arranged at equal angles in opposite directions with respect to the illumination system. For example, one of the pair of imaging systems is arranged at a predetermined angle to the left with respect to the illumination system, and the other imaging system is arranged at the same predetermined angle to the right with respect to the illumination system.

[0048] Furthermore, in this aspect, each of the illumination system and the pair of imaging systems is configured as a shine-proof optical system that satisfies the shine-proof condition. That is, in this aspect, the combination of the illumination system and one of the pair of imaging systems is configured as one shine-proof optical system, and the combination of the illumination system and the other imaging system is also configured as another shine-proof optical system.

[0049] The control unit of this aspect executes an anterior eye scan by combining the control of such a shine-proof optical system of this aspect with the control of the moving mechanism. In this anterior eye scan, each of the pair of imaging systems collects a set of anterior eye images. As a result, a pair of sets of anterior eye images are collected.

[0050] The image processing unit of this aspect is configured to generate a virtual anterior eye image based on the pair of sets of anterior eye images collected under the control of the control unit of this aspect.

[0051] The ophthalmic device according to this aspect includes a shine-proof optical system including the illumination system and a pair of imaging systems configured as described above. Therefore, the region of the anterior eye (object plane) onto which the slit light from the illumination system is projected can be imaged from two positions inclined by equal angles in opposite directions to each other, and a pair of anterior eye image sets can be acquired. Moreover, each anterior eye image set to be acquired can be a series of images that depict a wide three-dimensional region of the anterior eye with high definition. Further, the ophthalmic device according to this aspect can generate a high-quality virtual anterior eye image from such a pair of anterior eye image sets. For example, when strong corneal reflections of slit light are mixed in one of a pair of anterior eye images acquired at a certain point in time (a certain scan position), the other anterior eye image can be used to generate the virtual anterior eye image.

[0052] The seventh aspect of the embodiment is the ophthalmic device of the sixth aspect, wherein the image processing unit is configured to generate a first virtual anterior eye image and a second virtual anterior eye image respectively based on a first anterior eye image and a second anterior eye image that are substantially simultaneously acquired by the pair of imaging systems among the pair of anterior eye image sets. That is, the image processing unit of this aspect is configured to generate a first virtual anterior eye image from the first anterior eye image and to generate a second virtual anterior eye image from the second anterior eye image.

[0053] Moreover, the ophthalmic device of this aspect includes an evaluation processing unit. The evaluation processing unit of this aspect is configured to obtain a first corneal thickness and a first anterior chamber depth based on the first virtual anterior eye image, and to obtain a second corneal thickness and a second anterior chamber depth based on the second virtual anterior eye image. Further, the evaluation processing unit of this aspect is configured to obtain an average corneal thickness between the first corneal thickness and the second corneal thickness, and to obtain an average anterior chamber depth between the first anterior chamber depth and the second anterior chamber depth. In addition, the evaluation processing unit of this aspect is configured to generate evaluation information by calculating a ratio between the average corneal thickness and the average anterior chamber depth.

[0054] The ophthalmic apparatus according to the seventh aspect is configured to obtain the average values (average corneal thickness, average anterior chamber depth) of two measured values (two corneal thicknesses, two anterior chamber depths) measured from two anterior eye images obtained substantially simultaneously by two imaging systems. Therefore, it is possible to reduce the influence of errors caused by the refractive power of the cornea and the like on the evaluation result.

[0055] In addition, in order to obtain the true values of the corneal thickness and the anterior chamber depth, it is necessary to perform precise and complicated refractive correction processing to remove the influence of factors such as the refractive power of the cornea. However, the ophthalmic apparatus according to this aspect is configured to calculate the ratio of two values (average corneal thickness and average anterior chamber depth) that contain similar errors caused by the refractive power of the cornea. Therefore, it is possible to obtain an evaluation result with reduced influence of errors caused by the refractive power of the cornea.

[0056] Thus, according to the ophthalmic apparatus according to this aspect, it is possible to generate high-quality evaluation information.

[0057] The eighth aspect of the embodiment is the ophthalmic apparatus of the sixth aspect, further including an evaluation processing unit. The evaluation processing unit is configured to generate evaluation information of the eye to be examined based on the virtual anterior eye image generated from a pair of anterior eye image sets by the image processing unit.

[0058] According to the ophthalmic apparatus according to the eighth aspect, it is possible to automatically perform an evaluation of the eye to be examined based on a high-quality virtual anterior eye image generated from a pair of anterior eye image sets collected by a shine-proof optical system including an illumination system and a pair of imaging systems, and provide the result.

[0059] The ninth aspect of the embodiment is the ophthalmic apparatus of the eighth aspect, wherein the second angle, which is the angle formed by the projection direction of the virtual slit light on the anterior eye and the direction of the virtual viewpoint on the anterior eye, is 60 degrees. The second angle is set to 60 degrees by the image processing unit, or is set to 60 degrees in advance.

[0060] Also, the virtual slit light of this aspect is projected onto the corneal limbus of the anterior eye segment. The target position onto which the virtual slit light is projected is set for the corneal limbus by the image processing unit, or is set in advance for the corneal limbus.

[0061] Furthermore, the evaluation processing unit of this aspect is configured to calculate the ratio of the corneal thickness to the anterior chamber depth in the vicinity of the corneal limbus of the anterior eye segment, and generate evaluation information based on the result.

[0062] The evaluation information obtained in this way corresponds to the evaluation information obtained by the examination based on the Van Herick method. The evaluation information of this aspect may include, for example, the value of the ratio of the corneal thickness to the anterior chamber depth, and / or the grade (grades 0 to 4) indicating the state of the angle. Thus, according to the ninth aspect, it is possible to automatically perform an evaluation corresponding to the examination based on the Van Herick method and provide the result.

[0063] Also, in this aspect, a virtual anterior eye segment image is generated from each of a pair of anterior eye segment image sets collected by a shine-proof optical system including an illumination system and a pair of imaging systems, and an evaluation corresponding to the examination based on the Van Herick method is automatically performed based on each of the pair of virtual anterior eye segment images generated from the pair of anterior eye segment image sets, and it is possible to statistically process the pair of evaluation results obtained by this pair of evaluations to generate evaluation information. For example, evaluation information can be generated based on the average of the pair of evaluation information.

[0064] The tenth aspect of the embodiment is an ophthalmic apparatus according to any one of the first to ninth aspects, wherein the image processing unit generates a virtual anterior eye segment image for each of a plurality of combinations of a virtual position and a virtual viewpoint set with different positions in the width direction of the slit light. The generation process of the virtual anterior eye segment image of this aspect will be described in more detail below.

[0065] As described above, the virtual position is the projection position of the virtual slit light (the position in the second oblique direction), and the virtual viewpoint is the position of a virtual camera for virtually photographing the anterior eye segment onto which the virtual slit light is projected from the front direction.

[0066] In this aspect, a plurality of combinations of a virtual position and a virtual viewpoint are set. Let any two combinations among these plurality of combinations be a first combination and a second combination. The first combination is a pair of a first virtual position and a first virtual viewpoint, and the second combination is a pair of a second virtual position and a second virtual viewpoint.

[0067] At this time, the first virtual position and the second virtual position are different positions from each other in the width direction of the slit light. Similarly, the first virtual viewpoint and the second virtual viewpoint are different positions from each other in the width direction of the slit light.

[0068] Note that the distance between the first virtual position and the second virtual position in the width direction of the slit light is assumed to be equal to the distance between the first virtual viewpoint and the second virtual viewpoint in the width direction of the slit light. Further, the coordinates of the first virtual position and the coordinates of the second virtual position in the direction perpendicular to the width direction of the slit light are assumed to be equal, and the coordinates of the first virtual viewpoint and the coordinates of the second virtual viewpoint in the direction perpendicular to the width direction of the slit light are assumed to be equal.

[0069] Therefore, the plurality of combinations including the first combination (the pair of the first virtual position and the first virtual viewpoint) and the second combination (the pair of the second virtual position and the second virtual viewpoint) correspond to the parallel movement of the virtual position and the virtual viewpoint in the width direction of the slit light. This corresponds to the anterior eye scan performed while moving the Scheimpflug optical system in the width direction of the slit light.

[0070] In this way, the image processing unit of this aspect can be considered to perform a virtual anterior eye scan by integrally moving a virtual illumination system that projects virtual slit light onto the anterior eye from a second oblique direction and a virtual imaging system that virtually images the anterior eye from the front direction in the width direction of the slit light. By this virtual anterior eye scan, the image processing unit of this aspect can generate a plurality of virtual anterior eye images corresponding to a plurality of different positions in the width direction of the slit light.

[0071] Note that the virtual anterior eye scan of this aspect combines illumination from a second oblique direction, imaging from the front direction, and translational movement of the illumination position and the imaging position, whereas it should be noted that the anterior eye scan actually applied by the ophthalmic device of this aspect to the eye to be examined combines illumination from the front direction, imaging from a first oblique direction, and translational movement of the illumination position and the imaging position.

[0072] According to the ophthalmic device according to the tenth aspect, it is possible to generate and provide a plurality of images (a plurality of virtual anterior eye images) obtained by the above-described virtual anterior eye scan from the set of anterior eye images collected by the above-described actual anterior eye scan.

[0073] The eleventh aspect of the embodiment is the ophthalmic device of the tenth aspect, which further includes an evaluation processing unit. The evaluation processing unit of this aspect is configured to generate evaluation information of the eye to be examined based on a plurality of virtual anterior eye images generated by the above-described virtual anterior eye scan.

[0074] According to the ophthalmic device according to the eleventh aspect, it is possible to automatically perform an evaluation of the eye to be examined based on a plurality of virtual anterior eye images and provide the result. For example, in this aspect, it is possible to obtain evaluation results at a plurality of positions, obtain the distribution of the evaluation results, perform statistical processing of the evaluation results, and selectively obtain the evaluation results at desired positions.

[0075] A twelfth aspect of the embodiment is the ophthalmic device of the eleventh aspect, wherein a second angle, which is an angle formed by a projection direction of virtual slit light onto the anterior eye segment and a direction of a virtual viewpoint onto the anterior eye segment, is 60 degrees. The second angle is set to 60 degrees by the image processing unit or is set to 60 degrees in advance.

[0076] Also, the virtual slit light of this aspect is projected onto a plurality of different positions on the corneal limbus of the anterior eye segment. The plurality of target positions onto which the virtual slit light is projected are set with respect to the corneal limbus by the image processing unit or are set with respect to the corneal limbus in advance.

[0077] Furthermore, the evaluation processing unit of this aspect is configured to calculate, for each of a plurality of positions on the corneal limbus of the anterior eye segment, a ratio of a corneal thickness to an anterior chamber depth in the vicinity of the position and generate evaluation information based on the result. As a result, a plurality of pieces of evaluation information corresponding to a plurality of positions on the corneal limbus of the anterior eye segment are generated.

[0078] Each of the plurality of pieces of evaluation information thus obtained corresponds to the evaluation information obtained by an examination based on the Van Herick method. The evaluation information of this aspect may include, for example, a value of a ratio of a corneal thickness to an anterior chamber depth and / or a grade (grades 0 to 4) indicating a state of a corneal angle. Thus, according to the twelfth aspect, it is possible to automatically perform an evaluation corresponding to an examination based on the Van Herick method for a plurality of positions on the corneal limbus of the anterior eye segment and provide the result.

[0079] Furthermore, the evaluation processing unit of this aspect applies a predetermined statistical process to a plurality of pieces of evaluation information generated for a plurality of positions of the corneal limbus region of the anterior eye part to generate statistical evaluation information. For example, in this aspect, statistical evaluation information can be generated based on any statistic that can be calculated from the plurality of pieces of evaluation information. Examples of such statistics include the mean, median, mode, variance, standard deviation, and the like. Also, in this aspect, the final evaluation information can be generated based on the trends exhibited by the plurality of pieces of evaluation information. For example, the final evaluation information can be generated by obtaining the trends obtained by dividing the corneal limbus region into a plurality of partial regions (e.g., upper region, lower region, temporal region, nasal region, etc.).

[0080] A 13th aspect of the embodiment is an ophthalmic apparatus according to any one of the 1st to 12th aspects, further including a corneal angle parameter calculation unit. The corneal angle parameter calculation unit is configured to calculate a value of a predetermined corneal angle parameter based on at least one of the anterior eye part image set and the virtual anterior eye part image.

[0081] The corneal angle parameter is numerical information representing the state of the corneal angle. Examples of the corneal angle parameter include AOD (angle opening distance), ACA (anterior chamber angle), TIA (trabecular iris angle), TISA (trabecular iris space area), ARA (angle recess area), AtA (angle-to-angle distance), and the like. Known methods can be used for the calculation of the corneal angle parameter. Typically, the corneal angle parameter calculation includes a process for specifying the position of the corneal angle and / or a predetermined position near the corneal angle (e.g., segmentation, feature point detection, etc.), and a measurement process for obtaining the value of the corneal angle parameter based on the specified position (e.g., distance measurement, ratio calculation, angle calculation, etc.).

[0082] The parameters calculated by the ophthalmic device of this aspect are not limited to the corneal angle parameters. For example, the ophthalmic device of this aspect may be able to calculate any anterior eye segment parameter. The anterior eye segment parameter is numerical information representing the form and state of the anterior eye segment. Examples of anterior eye segment parameters include the anterior corneal curvature radius, the posterior corneal curvature radius, the anterior lens curvature radius, the posterior lens curvature radius, the corneal diameter (vertical diameter, horizontal diameter (White-to-White)), the corneal thickness (central thickness, peripheral thickness), the lens thickness, the anterior chamber depth, the anterior chamber volume, the pupil diameter, the pupil center (eccentricity), etc. Also, the anterior eye segment parameter may be shape distribution data, for example, various corneal shape maps such as an axial curvature map (axial curvature map), a tangential curvature map (tangential curvature map), an elevation map (elevation map), a refractive power map, a thickness map (pachymetry map), a wavefront aberration map, etc. Known methods can be used for the calculation of anterior eye segment parameters. Typically, the anterior eye segment parameter calculation includes processing for specifying the site and / or position to be measured (for example, segmentation, feature point detection, etc.), and measurement processing for obtaining the value of the anterior eye segment parameter based on the specified site and / or position (for example, distance measurement, ratio calculation, angle calculation, etc.). For the corneal angle parameters and anterior eye segment parameters, for example, refer to Japanese Patent Application Laid-Open No. 2022-007433 by the present applicant.

[0083] According to the ophthalmic device according to the 13th aspect, in addition to the virtual anterior eye segment image, it is possible to provide the measured value of the corneal angle parameter and the measured value of the anterior eye segment parameter.

[0084] The 14th aspect of the embodiment is an ophthalmic device including the ophthalmic device of the 4th or 5th aspect or its configuration, and further includes a corneal angle parameter calculation unit and a display unit. The corneal angle parameter calculation unit is configured to calculate the value of a predetermined corneal angle parameter based on at least one of the anterior eye segment image set and the virtual anterior eye segment image, similar to that of the 13th aspect. The display unit is configured to display the evaluation information and the value of the corneal angle parameter.

[0085] According to the ophthalmic device according to the 14th aspect, in addition to the evaluation information, it is possible to display the measured values of the corner parameters and the measured values of the anterior eye segment parameters. It is also possible to display images included in the anterior eye segment image set, rendering images of the anterior eye segment image set, virtual anterior eye segment images, and the like.

[0086] Any two or more matters related to the 1st to 14th aspects can be at least partially combined. Also, any matter described in the present disclosure can be at least partially combined with the 1st to 14th aspects. The ophthalmic device of the aspect obtained by such a combination exhibits the operational effects based on each combined matter, and also exhibits the synergistic operational effects of two or more combined matters.

[0087] The 15th aspect of the embodiment provides an invention of a method corresponding to the ophthalmic device of the 1st aspect. The method of this aspect is a method for controlling an ophthalmic device for photographing the anterior eye segment of an eye to be examined. The ophthalmic device controlled by the method of this aspect includes a shine-proof optical system, a moving mechanism, and a processor. The shine-proof optical system includes an illumination system and a photographing system. The illumination system is configured to project slit light from the front direction onto the anterior eye segment of the eye to be examined. The photographing system is configured to photograph the anterior eye segment from a first oblique direction forming a first angle in the width direction of the slit light with respect to the front direction. The illumination system and the photographing system are configured to satisfy the shine-proof conditions. The moving mechanism is configured to move the shine-proof optical system in the width direction of the slit light.

[0088] The method of this aspect causes the processor to execute a process of controlling the shine-proof optical system and the moving mechanism to collect an anterior eye segment image set.

[0089] Furthermore, the method of this aspect causes the processor to execute a process of generating a virtual anterior eye segment image of the anterior eye segment on which virtual slit light is projected from a virtual position in a second oblique direction forming a second angle in the width direction of the slit light with respect to the front direction as viewed from a virtual viewpoint in the front direction based on the collected anterior eye segment image set.

[0090] The method according to the 15th aspect has the same effect as the ophthalmic device according to the 1st aspect.

[0091] Any matter regarding the 1st to 14th aspects can be at least partially combined with the 15th aspect. Also, any matter described in the present disclosure can be at least partially combined with the 15th aspect. The method of the aspect obtained by such a combination exhibits the operational effects based on each combined matter, and also exhibits the synergistic operational effects of two or more combined matters.

[0092] The 16th aspect of the embodiment is a program for causing a computer to execute the method of the 15th aspect. The computer of the 16th aspect includes the processor of the 15th aspect.

[0093] The program according to the 16th aspect has the same effect as the ophthalmic device according to the 1st aspect.

[0094] Any matter regarding the 1st to 14th aspects can be at least partially combined with the 16th aspect. Also, any matter described in the present disclosure can be at least partially combined with the 16th aspect. The program of the aspect obtained by such a combination exhibits the operational effects based on each combined matter, and also exhibits the synergistic operational effects of two or more combined matters.

[0095] The 17th aspect of the embodiment is a computer-readable non-transitory recording medium on which the program of the 16th aspect is recorded.

[0096] The recording medium according to the 17th aspect has the same effect as the ophthalmic device according to the 1st aspect.

[0097] Any matter related to the first to the fourteenth aspects can be at least partially combined with the seventeenth aspect. Also, any matter described in the present disclosure can be at least partially combined with the seventeenth aspect. The recording medium of the aspect obtained by such a combination exhibits the effects based on each combined matter and also exhibits the synergistic effects of two or more combined matters.

[0098] In the present disclosure, various non-limiting aspects including the first to the seventeenth aspects are described. In the present disclosure, exemplary aspects of an ophthalmic device, an exemplary aspect of a method for controlling an ophthalmic device, an exemplary aspect of a program, and an exemplary aspect of a recording medium are mainly described. However, the category of the aspects of the embodiments is not limited to these. For example, those skilled in the art will be able to understand that the embodiments according to the present disclosure can provide various aspects of medical methods, various aspects of imaging methods, various aspects of data processing methods, and the like.

[0099] <Ophthalmic device> Some non-limiting exemplary aspects of the ophthalmic device according to the embodiment will be described. The ophthalmic device according to the embodiment may include any type of anterior eye scanner. In the present disclosure, some examples of a slit lamp microscope configured to enable anterior eye scanning will be described in detail, but the method of anterior eye scanning and the applicable configurations are not limited to these examples.

[0100] FIG. 1 shows a configuration example of an ophthalmic device according to one aspect. The ophthalmic device 1 of this aspect is used for anterior eye imaging of the eye to be examined E, and includes a shine-proof optical system 2, a fixation optical system 3, a moving mechanism 6, a control unit 7, a data processing unit 8, a communication unit 9, and a user interface (UI) 10. The cornea of the eye to be examined E is denoted by the reference symbol Co, the corneal limbus (the boundary portion between the cornea Co and the conjunctiva) is denoted by the reference symbol Li, the iris is denoted by the reference symbol Ir, and the lens is denoted by the reference symbol Cr.

[0101] According to the convention in the field of ophthalmology, the direction along the axis of the subject's eye E is defined as the Z direction (Z axis), and the plane perpendicular to the Z direction is defined as the XY plane. The left-right direction (horizontal direction) for the subject is defined as the X direction (X axis), and the direction perpendicular to both the X and Z directions (up-down direction, body axis direction) is defined as the Y direction (Y axis).

[0102] Reference symbol 2a denotes the optical axis of the optical system included in the Scheimpflug optical system 2. The optical axis 2a of the Scheimpflug optical system 2 is arranged parallel to the Z axis. Reference symbol 3a denotes the optical axis of the fixation optical system 3 (referred to as the fixation optical axis). The fixation optical axis 3a is arranged so as to be inclined at an angle θ in the Y direction with respect to the Z axis (illumination optical axis 21a). In other words, the Scheimpflug optical system 2 and the fixation optical system 3 are arranged in a positional relationship such that the optical axis 2a and the fixation optical axis 3a form an angle θ in the Y direction. The inclination direction of the fixation optical axis 3a with respect to the optical axis 2a may be upward or downward. Furthermore, this inclination angle may be variable.

[0103] In another embodiment, the Scheimpflug optical system and the fixation optical system may be arranged so that the optical axis of the Scheimpflug optical system coincides with the optical axis of the fixation optical system, in which case, for example, the optical path of the Scheimpflug optical system and the optical path of the fixation optical system are coaxially coupled by an optical path coupling element (e.g., a half mirror).

[0104] The communication unit 9 performs data communication between the ophthalmologic apparatus 1 and other devices. That is, the communication unit 9 transmits data to other devices and receives data transmitted from other devices. The communication unit 9 may perform any data communication method. For example, the communication unit 9 includes one or more of various communication interfaces, such as a communication interface conforming to the Internet, a communication interface conforming to a dedicated line, a communication interface conforming to a LAN, and a communication interface conforming to short-range communication. The data communication may be wired communication or wireless communication.

[0105] The data transmitted or received by the communication unit 9 may be encrypted data. The control unit 7 and / or the data processing unit 8 may include either or both of an encryption processing unit that encrypts the data transmitted by the communication unit 9 and a decryption processing unit that decrypts the data received by the communication unit 9.

[0106] The user interface 10 includes any user interface device such as a display device and an operation device. Users such as doctors, examinees, and assistants can operate the ophthalmic apparatus 1 and input information into the ophthalmic apparatus 1 by using the user interface 10. At least a part of the user interface 10 may be a peripheral device of the ophthalmic apparatus 1.

[0107] The display device displays various information under the control of the control unit 7. The display device may include a flat panel display such as a liquid crystal display (LCD). The user interface 10 includes the display device 11 shown in FIG. 3. The operation device includes a device for operating the ophthalmic apparatus 1 and a device for inputting information. The operation device includes, for example, buttons, switches, levers, dials, handles, knobs, mice, keyboards, trackballs, operation panels, and the like. A device in which the display device and the operation device are integrated, such as a touch screen, may be used.

[0108] The shine-proof optical system 2 includes an illumination system and a photographing system that satisfy the shine-proof conditions, and is used to apply an anterior eye scan to the eye to be examined E to collect a plurality of anterior eye images (anterior eye image set, anterior eye image group). The illumination light used for the anterior eye scan in this embodiment is slit light, typically visible illumination light (visible slit light), but the type of illumination light is not limited to this.

[0109] One example of the shine-proof optical system 2 is shown in FIG. 2. FIG. 2 is a view (top view) of the shine-proof optical system 2 as seen from above. The shine-proof optical system 2 in this example includes an illumination system 21 and a pair of imaging systems 22L and 22R. The illumination system 21 projects visible illumination light onto the anterior eye part of the eye E to be examined. The imaging system 22L images the anterior eye part onto which the visible illumination light is projected. Similarly, the imaging system 22R images the anterior eye part onto which the visible illumination light is projected. The illumination system 21 and the pair of imaging systems 22L and 22R are moved by a moving mechanism 6. In the anterior eye part scan, the illumination system 21 and the pair of imaging systems 22L and 22R are integrally moved in the X direction by the moving mechanism 6.

[0110] The optical axis (illumination optical axis) 21a of the illumination system 21 is arranged parallel to the Z axis. Thereby, the illumination system 21 can project slit light onto the anterior eye part of the eye E to be examined from the front direction.

[0111] The optical axis (imaging optical axis) 22La of the imaging system 22L is inclined by an angle θL in a first direction (+X direction or -X direction) defined by the X axis with respect to the illumination optical axis 21a. Thereby, the imaging system 22L can image the anterior eye part of the eye E to be examined from a first oblique direction forming a first angle (θL) in the width direction (X direction) of the slit light with respect to the front direction (Z direction). Also, the illumination system 21 and the imaging system 22L form one shine-proof optical system that satisfies the shine-proof condition.

[0112] The optical axis (imaging optical axis) 22Ra of the imaging system 22R is inclined by an angle θR in a second direction (-X direction or +X direction) opposite to the first direction with respect to the illumination optical axis 21a. The angle θL and the angle θR may be equal to each other or different from each other. Thereby, the imaging system 22R can image the anterior eye part of the eye E to be examined from a first oblique direction forming a first angle (θR) in the width direction (X direction) of the slit light with respect to the front direction (Z direction). Also, the illumination system 21 and the imaging system 22R form one shine-proof optical system that satisfies the shine-proof condition.

[0113] The illumination optical axis 21a and the two imaging optical axes 22La and 22Ra are all arranged on the ZX plane. The shine-proof optical system 2 is shown as a side view in FIG. 1 and as a top view in FIG. 2, respectively. The optical axis 2a in FIG. 1 corresponds to the illumination optical axis 21a and the two imaging optical axes 22La and 22Ra in FIG. 2. The fixation optical axis 3a in FIG. 1 is arranged at an angle θ in the Y direction with respect to each of the illumination optical axis 21a and the two imaging optical axes 22La and 22Ra.

[0114] One non-limiting example of the configuration described above is described in Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2023-49320) by the applicant of the present application. The shine-proof optical system 2 and the fixation optical system 3 of this aspect may have the same configuration as the slit lamp microscope described in Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2023-49320). In that case, the shine-proof optical system 2 has the following configuration.

[0115] The illumination system 21 includes an illumination light source that generates visible light, a slit forming portion that forms a slit opening for converting the generated visible light into slit light, an objective lens that projects the formed slit light onto the anterior eye part of the eye to be examined E, and the like.

[0116] The imaging system 22L includes an optical system including an objective lens, a zoom optical system, an imaging lens, etc., and an imaging element that detects the light guided by this optical system. The imaging element is an area sensor such as a charge-coupled device (CCD) image sensor or a complementary metal-oxide-semiconductor (CMOS) image sensor. The imaging system 22R has the same configuration as the imaging system 22L.

[0117] The illumination system 21 and the imaging system 22L form a shine-proof optical system. That is, the illumination system 21 and the imaging system 22L are configured such that the object plane including the illumination optical axis 2Ia, the principal plane of the above optical system of the imaging system 22L, and the imaging plane of the above imaging element intersect on the same straight line. The same applies to the combination of the illumination system 21 and the imaging system 22R.

[0118] The shape of the slit light projected onto the anterior segment by the illumination system 21 is a thin strip with the Y direction as the longitudinal direction (length direction of the slit light) and the X direction as the lateral direction (width direction of the slit light). The movement mechanism 6 moves the illumination system 21 and the imaging systems 22L and 22R integrally in the X direction. The movement mechanism 6 includes an actuator such as a motor and a mechanism for moving the illumination system 21 and the imaging systems 22L and 22R by the driving force generated by the actuator.

[0119] The Scheimpflug optical system 2 performs an anterior segment scan using slit light by combining projection of slit light by the illumination system 21, multiple photographing (time-series photographing, video photographing, repeated photographing) by the photographing systems 22L and 22R, and integral movement of the illumination system 21 and the photographing systems 22L and 22R by the movement mechanism 6. This allows multiple photographing from oblique directions by the photographing systems 22L and 22R while moving the projection area (object plane) of the slit light projected from the front direction onto the anterior segment in the X direction, thereby collecting a series of anterior segment images (anterior segment image set). Each anterior segment image included in the collected anterior segment image set depicts a cross section corresponding to the slit light projection area at the time of photographing.

[0120] When the configuration of Patent Document 3 (JP Patent Publication No. 2023-49320) is adopted, the fixation optical system 3 includes a fixation light source, a diffuser, a pinhole member, a first lens, a cross reticle plate, and a second lens in order to project fixation light onto the subject's eye E (fundus) from a direction inclined at an angle θ in the Y direction (upward or downward) with respect to the optical axis 2a of the Scheimpflug optical system 2.

[0121] The fixation light source generates green light as visible light. The generated visible light is diffused by a diffuser plate and then projected onto a pinhole member. The visible light that passes through an opening (pinhole) formed in the pinhole member is projected onto a cross reticle plate via a first lens. The visible light that passes through a cross-shaped light-transmitting portion formed on the cross reticle plate is guided to the subject's eye E via a second lens. The subject can visually recognize the cross-shaped fixation light (fixation target).

[0122] Return to the reference of FIG. 1. The moving mechanism 6 moves the shine-proof optical system 2 and the fixation optical system 3. The moving mechanism 6 may be capable of moving the shine-proof optical system 2 and the fixation optical system 3 three-dimensionally (i.e., in the X direction, Y direction, and Z direction), and is used for alignment, tracking, etc.

[0123] The control unit 7 controls each part of the ophthalmic apparatus 1. For example, the control unit 7 controls elements of the illumination system 21 (such as an illumination light source, optical elements, mechanisms, etc.), elements of the imaging systems 22L and 22R (such as an image sensor, optical elements, mechanisms, etc.), the moving mechanism 6, the data processing unit 8, the communication unit 9, the user interface 10, and the like.

[0124] The control unit 7 includes a processor, a main storage device, an auxiliary storage device, and the like. Various computer programs such as various control programs are stored in the auxiliary storage device. These computer programs may be stored in a computer or storage device accessible to the ophthalmic apparatus 1. The functions of the control unit 7 are realized by the cooperation of software such as control programs and hardware such as a processor.

[0125] The data processing unit 8 executes various data processing. The data to be processed may be either data acquired by the ophthalmic apparatus 1 or data input from the outside.

[0126] The data processing unit 8 includes a processor, a main storage device, an auxiliary storage device, and the like. Various computer programs such as various data processing programs are stored in the auxiliary storage device. These computer programs may be stored in a computer or storage device accessible to the ophthalmic apparatus 1. The functions of the data processing unit 8 are realized by the cooperation of software such as data processing programs and hardware such as a processor.

[0127] One non-limiting example of the data processing unit 8 is shown in FIG. 3. The data processing unit 8 in this example includes an image processing unit 81, an evaluation processing unit 82, and a corner parameter calculation unit 83. In another example, the data processing unit 8 may include only the image processing unit 81 among the image processing unit 81, the evaluation processing unit 82, and the corner parameter calculation unit 83, or may include only the image processing unit 81 and the evaluation processing unit, or may include only the image processing unit 81 and the corner parameter calculation unit 83. In still another example, the data processing unit 8 may include the image processing unit 81 and any other arbitrary processing unit.

[0128] The image processing unit 81 generates a virtual anterior eye image based on the set of anterior eye images collected from the subject eye E by the anterior eye scan. The virtual anterior eye image is an image viewed from a virtual viewpoint different from the viewpoints (imaging positions) in the collection of the set of anterior eye images.

[0129] In the anterior eye scan of this aspect, the imaging system 3 performs imaging from a viewpoint located obliquely (first oblique direction) with respect to the anterior eye of the subject eye E, whereas the virtual viewpoint is arranged in the front direction with respect to the anterior eye of the subject eye E. Thus, the virtual anterior eye image generation process of this aspect includes a viewpoint conversion from the imaging position in the anterior eye scan to the virtual viewpoint.

[0130] In addition to this viewpoint conversion, the virtual anterior eye image generation process of this aspect also includes a process of converting the projection direction of the illumination light (slit light) (referred to as illumination direction conversion). In the anterior eye scan of this aspect, the illumination unit 2 projects slit light onto the anterior eye from the front direction (Z direction) with respect to the anterior eye of the subject eye E, whereas the position (virtual position) set by the illumination direction conversion is arranged obliquely with respect to the anterior eye of the subject eye E. More specifically, this virtual position is arranged in an oblique direction (second oblique direction) forming a predetermined angle (second angle) in the width direction (X direction) of the slit light with respect to the front direction (Z direction) with respect to the anterior eye of the subject eye E.

[0131] As described above, the virtual anterior-eye-segment image generation process executed by the image processing unit 81 of this embodiment is a process that combines an illumination direction conversion that converts the projection direction of the slit light from the front direction to the second oblique direction (virtual position) and a viewpoint conversion that converts the viewpoint from the photographing position (first oblique direction) in the anterior-eye-segment scan to a virtual viewpoint (front direction). In other words, the virtual anterior-eye-segment image generation process of this embodiment is a novel process that differs from general viewpoint conversion.

[0132] The virtual anterior eye image generated by the virtual anterior eye image generation process of this embodiment corresponds to an image obtained by photographing the anterior eye in a state in which virtual slit light (virtual slit light) is projected from a second oblique direction with a virtual camera positioned at a virtual viewpoint located in the front direction.

[0133] In other words, the virtual anterior eye image generation process of this embodiment is a process of generating a virtual anterior eye image obtained by combining projection of virtual slit light from a second oblique direction and virtual photography from a frontal direction from a set of anterior eye images collected by an anterior eye scan performed by combining projection of slit light from a frontal direction and photography from a first oblique direction.

[0134] Fig. 4 shows the virtual anterior eye image generation process when the Scheimpflug optical system 2 in Fig. 2 is used. Fig. 5 shows the image conversion process performed by the virtual anterior eye image generation process in this example.

[0135] The left diagram in Figure 4 shows an illumination system 21 that projects slit light from the front direction onto the anterior segment of the subject's eye E, an imaging system 22L that has a photographing optical axis 22La that is inclined by an angle θ1 to the left (a first direction in the X direction) with respect to the illumination optical axis 21a, and an imaging system 22R that has a photographing optical axis 22Ra that is inclined by the same angle θ1 to the right (a second direction that is the opposite direction to the first direction in the X direction) with respect to the illumination optical axis 21a.

[0136] The process of generating a virtual anterior-segment image based on the set of anterior-segment images acquired by the illumination system 21 and the imaging systems 22L and 22R means converting the optical arrangement shown in the left diagram of FIG. 4 into the virtual optical arrangement shown in the right diagram. The right diagram of FIG. 4 shows a virtual illumination system 23 and a virtual imaging system 24. The virtual imaging system 24 is a virtual element that virtually images the anterior segment of the subject's eye E from the front direction. The virtual illumination system 23 is a virtual element that projects virtual slit light onto the anterior segment. A virtual illumination optical axis 23a of the virtual illumination system 23 is inclined by an angle θ2 in the X direction (rightward or leftward) with respect to a virtual imaging optical axis 24a of the virtual imaging system 24.

[0137] An example of an anterior eye image obtained using the optical arrangement shown in the left diagram of Fig. 4 is shown in the left diagram of Fig. 5. With the optical arrangement shown in the left diagram of Fig. 4, the anterior eye is photographed from an oblique direction, and therefore the subject's eye E (anterior eye) is depicted at an angle in the resulting anterior eye image 30. Reference numeral 31 denotes an image of the cornea Co that is brightly depicted by a slit light projected from the front direction. Reference numeral 32 denotes an image of the iris Ir that is brightly depicted by a slit light projected from the front direction. In other words, the cornea image 31 corresponds to the intersection region between the slit light and the cornea Co, and the iris image 32 corresponds to the intersection region between the slit light and the iris Ir.

[0138] On the other hand, an example of a virtual anterior-segment image obtained by the virtual optical arrangement shown in the right diagram of Fig. 4 is shown in the right diagram of Fig. 5. With the optical arrangement shown in the right diagram of Fig. 4, the anterior segment is photographed from the front, so the subject's eye E (anterior segment) is depicted in a frontally facing state in the resulting virtual anterior-segment image 40. Reference numeral 41 denotes a virtual image of the cornea Co that is depicted brightly by a slit light projected from an oblique direction. Reference numeral 42 denotes a virtual image of the iris Ir that is depicted brightly by a slit light projected from an oblique direction. In other words, the virtual cornea image 41 corresponds to the intersection region between the virtual slit light and the cornea Co, and the virtual iris image 42 corresponds to the intersection region between the virtual slit light and the iris Ir.

[0139] An example of the steps executed in the virtual anterior eye image generation process will be described. As shown in FIG. 6, the ophthalmic apparatus 1 of this embodiment collects an anterior eye image set 50 by applying an anterior eye scan to the subject eye E before the virtual anterior eye image generation process. The anterior eye scan is performed by the control unit 7 controlling the Scheimpflug optical system 2 and the moving mechanism 6 so as to perform a plurality of shootings while moving the slit light 50 projected from the front direction to the anterior eye of the subject eye E in the X direction. The collected anterior eye image set 50 is sent to the image processing unit 81.

[0140] The image processing unit 81 constructs a three-dimensional image 51 (for example, volume data) from the anterior eye image set 50 (see FIG. 6). Note that the image processing unit 81 may apply a predetermined correction process (distortion correction and / or aspect correction) to the anterior eye image set 50 and construct a three-dimensional image 51 from the anterior eye image set 50 to which the correction process has been applied.

[0141] Next, as shown in FIGS. 7 and 8, the image processing unit 81 extracts a partial image 52 corresponding to a plane along a predetermined direction (second oblique direction) from the constructed three-dimensional image 51.

[0142] The orientation of the second direction (partial image 52) may be arbitrary. However, when performing an evaluation based on the Van Herick method, the second direction is set to an orientation forming an angle of 60 degrees (second angle) with respect to the Z direction. Further, the partial image 52 is set at a position passing through the corneal limbus Li. The partial image 52 set in this way corresponds to the projection area of the slit light used in the Van Herick method. When the coordinates along the second direction are the L coordinates (L axis, L direction), the partial image 52 is expressed as an image defined in the LY coordinate system (see FIG. 8).

[0143] Note that the partial image 52 is not limited to an image representing a two-dimensional region and may be an image representing a three-dimensional region. For example, the partial image 52 may be a flat plate-shaped region having a thickness corresponding to the slit width.

[0144] Next, the image processing unit 81 applies orthogonal projection to the partial image 52 in the direction of the complementary angle of the angle between the front direction (Z direction) and the second oblique direction (L direction). Here, the magnitude of the angle between the Z direction and the L direction is the second angle described above. If the second angle is θ2 according to the example of FIG. 4, the magnitude of the complementary angle is 90-θ2 degrees. When performing evaluation based on the Van Herick method, the second angle θ2 is set to 60 degrees, so the complementary angle is 30 degrees. The orthogonal projection performed by the image processing unit 81 is a process of converting the partial image 52 defined in the LY coordinate system into an image viewed from the front direction (Z direction).

[0145] An example of image transformation by orthogonal projection is shown in Figure 9. This example shows how an image 53 defined in the LY coordinate system for evaluation based on the Van Herick method is transformed into an image 54 (virtual anterior eye image) defined in the XY coordinate system obtained from a viewpoint located in the front direction.

[0146] The control unit 7 can display on the display device 11 images included in the anterior segment image set collected in the anterior segment scan, images constructed based on the anterior segment image set, virtual anterior segment images generated by the image processing unit 81, etc.

[0147] The evaluation processing unit 82 is configured to generate evaluation information of the subject's eye E based on the virtual anterior-segment image generated by the image processing unit 81. The type of evaluation information to be generated may be arbitrary. That is, the disease to be evaluated may be arbitrary, and the evaluation method may also be arbitrary.

[0148] The evaluation processing unit 82 may be configured to execute processing according to an algorithm (program) created in advance according to the type of evaluation information to be generated, for example. Alternatively, the evaluation processing unit 82 may be configured to execute processing using a machine learning model that has been subjected to machine learning in advance according to the type of evaluation information to be generated.

[0149] When performing an evaluation based on the Van Herick method, as described above, the image processing unit 81 generates a virtual anterior eye image under the conditions that the second angle is set to 60 degrees and the virtual slit light is projected onto the corneal limbus Li. The evaluation processing unit 82 analyzes this virtual anterior eye image to calculate the corneal thickness and the anterior chamber depth in the vicinity of the corneal limbus Li, and calculates the ratio of the obtained corneal thickness to the anterior chamber depth. The evaluation processing unit 82 can determine a grade (any one of the four grades 0 to 4 defined in the Van Herick method) indicating the state of the angle from the calculated ratio value. The evaluation processing unit 82 generates evaluation information including at least the ratio value of the corneal thickness to the anterior chamber depth and / or the grade based thereon.

[0150] As shown in FIGS. 2 and 4, when the Shine-proof optical system 2 includes a pair of imaging systems 22L and 22R and a pair of anterior eye image sets are collected from the subject eye E by anterior eye scanning, the image processing unit 81 generates a single or a pair of virtual anterior eye images from the pair of anterior eye image sets, and the evaluation processing unit 82 can generate evaluation information of the subject eye E based on the generated single or pair of virtual anterior eye images.

[0151] For example, the image processing unit 81 can select an anterior eye image without corneal reflection from a pair of anterior eye image sets to form a single anterior eye image set, and generate a single virtual anterior eye image from this single anterior eye image set. The evaluation processing unit 82 can generate evaluation information of the subject eye E based on this single virtual anterior eye image.

[0152] In another example, the image processing unit 81 can generate a pair of virtual anterior eye images by generating virtual anterior eye images from each of a pair of anterior eye image sets. The evaluation processing unit 82 can obtain a pair of evaluation results by performing evaluations based on each of this pair of virtual anterior eye images, and generate evaluation information based on this pair of evaluation results. For example, the evaluation processing unit 82 can generate evaluation information by applying a statistical operation such as an average operation to the pair of evaluation results.

[0153] When the image processing unit 81 performs the virtual anterior eye scan described above and generates a plurality of virtual anterior eye images corresponding to a plurality of positions in the X direction, the evaluation processing unit 82 can generate evaluation information of the eye to be examined E based on the plurality of generated virtual anterior eye images. The evaluation processing unit 82 can generate a plurality of pieces of evaluation information corresponding to a plurality of positions in the X direction by applying the above-described processing to each of the plurality of virtual anterior eye images. Further, the evaluation processing unit 82 can perform a predetermined process on these plurality of pieces of evaluation information. For example, the evaluation processing unit 82 can generate information representing the relationship between the position and the evaluation result (distribution of the evaluation results) based on the plurality of pieces of evaluation information. Also, the evaluation processing unit 82 can generate statistical information by applying a predetermined statistical process to the plurality of pieces of evaluation information. The information generated from the plurality of pieces of evaluation information by the evaluation processing unit 82 corresponds to the above-described statistical evaluation information.

[0154] The control unit 7 can cause the display device 11 to display the information (evaluation information, statistical evaluation information, etc.) generated by the evaluation processing unit 82.

[0155] The corner parameter calculation unit 83 is configured to calculate a value of a predetermined corner parameter based on either or both of the anterior eye image set collected by the anterior eye scan and the virtual anterior eye image generated by the image processing unit 81. The type of the corner parameter to be calculated may be arbitrary, and for example, it may be any one of AOD, ACA, TIA, TISA, ARA, and AtA.

[0156] The control unit 7 can cause the display device 11 to display the value of the corner parameter calculated by the corner parameter calculation unit 83, the evaluation result based on this value, and the like. Further, the control unit 7 can cause the display device 11 to display the value of the corner parameter calculated by the corner parameter calculation unit 83, the evaluation result based on this value, and the like together with the information (evaluation information, statistical evaluation information, etc.) generated by the evaluation processing unit 82.

[0157] The processes executable by the data processing unit 8 are not limited to the above-described aspects. The data processing unit 8 may execute a process according to any one of several exemplary aspects described below.

[0158] A first exemplary aspect will be described. In recent years, the Van Herick Plus method, which is a modified method of the Van Herick method, has been proposed: Ramanjit Sihota et al., ‘Van Herick Plus’: a modified grading scheme for the assessment of peripheral anterior chambler depth and angle. British Journal of Ophthalmology, 2019, Jul; 103(7): 960-965. doi: 10.1136 / bjophthalmol-2018-312132.

[0159] While the conventional Van Herick method performs observation from the front direction while projecting slit illumination onto the anterior eye part from a direction inclined 60 degrees in the temporal direction with respect to the front direction, in the Van Herick Plus method, observation is performed from a direction inclined 30 degrees while projecting slit illumination onto the anterior eye part from the front direction.

[0160] In terms of hardware, the Van Herick Plus method is similar to the ophthalmic device 1 of this aspect in terms of the illumination system that projects slit illumination from the front direction and the imaging system that performs imaging from an oblique direction. However, the Van Herick Plus method is different from the method according to this aspect in that, at least, it does not use a shine-proof optical system, does not have a moving mechanism for anterior eye part scanning, and does not have a processor for generating a virtual anterior eye part image.

[0161] Also, although they are common in that the imaging systems are arranged in a direction inclined with respect to the front direction, the inclination angles θL and θR of the imaging systems 22L and 22R of the ophthalmic apparatus 1 of this embodiment are determined in the design of the shine-proof optical system 2 based on the shine-proof conditions, and may be 30 degrees or may be another angle, whereas the inclination angle in the Van Herick Plus method is 30 degrees.

[0162] The ophthalmic apparatus 1 of this embodiment can generate a virtual anterior eye image imitating an image obtained by the Van Herick Plus method and perform an evaluation based thereon.

[0163] For example, the image processing unit 81 first constructs a three-dimensional image 55 from the set of anterior eye images collected from the subject eye E by anterior eye scanning (see FIG. 10). Next, the image processing unit 81 extracts a partial image 56 corresponding to a plane along the front direction, which is the slit light projection direction in the Van Herick Plus method, from the constructed three-dimensional image 55. Next, the image processing unit 81 applies an orthographic projection onto a plane 58 perpendicular to the inclined 30-degree direction 57, which is the imaging direction in the Van Herick Plus method, to the extracted partial image 56. Thereby, a virtual anterior eye image imitating an image obtained by the Van Herick Plus method is obtained.

[0164] The evaluation processing unit 82 can generate evaluation information of the subject eye E based on this virtual anterior eye image. This evaluation information is considered to be usable in place of the evaluation result obtained by the Van Herick Plus method. The method for generating the evaluation information may be the same as the method for the Van Herick method or may be a method referring to the matters described in the literature regarding the Van Herick Plus method.

[0165] Also, any matters in the aspect regarding the Van Herick method can be combined with the aspect regarding the Van Herick Plus method.

[0166] A second exemplary embodiment will be described. The ophthalmic apparatus 1 according to this embodiment includes a shine-proof optical system 2 having a pair of imaging systems 22L and 22R, and collects a pair of anterior eye images from the eye to be examined E by anterior eye scanning. The data processing unit 8 according to this embodiment processes a pair of anterior eye images that are substantially simultaneously acquired by the pair of imaging systems 22L and 22R among the pair of anterior eye image sets collected by the anterior eye scanning. This pair of anterior eye images consists of two images acquired by the pair of imaging systems 22L and 22R when slit light from the illumination system 21 is projected onto a certain position of the eye to be examined E, and can be regarded as depicting the same cross-section of the anterior eye of the eye to be examined E. In this embodiment, one of this pair of anterior eye images is referred to as the first anterior eye image, and the other is referred to as the second anterior eye image.

[0167] The image processing unit 81 generates a first virtual anterior eye image based on the first anterior eye image, and generates a second virtual anterior eye image based on the second anterior eye image. The processing method for generating a virtual anterior eye image from an anterior eye image may be arbitrary, and may be any of the processing methods described in the present disclosure.

[0168] The evaluation processing unit 82 of this embodiment obtains the corneal thickness and the anterior chamber depth based on the first virtual anterior eye image, and obtains the corneal thickness and the anterior chamber depth based on the second virtual anterior eye image. The processing method for obtaining the corneal thickness and the anterior chamber depth from the virtual anterior eye image may be arbitrary, and may be any of the processing methods described in the present disclosure. The corneal thickness and the anterior chamber depth obtained from the first virtual anterior eye image are referred to as the first corneal thickness and the first anterior chamber depth, respectively. Also, the corneal thickness and the anterior chamber depth obtained from the second virtual anterior eye image are referred to as the second corneal thickness and the second anterior chamber depth, respectively.

[0169] Furthermore, the evaluation processing unit 82 of this embodiment obtains the average value (average corneal thickness) of the first corneal thickness obtained from the first virtual anterior eye image and the second corneal thickness obtained from the second virtual anterior eye image. Similarly, the evaluation processing unit 82 of this embodiment obtains the average value (average anterior chamber depth) of the first anterior chamber depth obtained from the first virtual anterior eye image and the second anterior chamber depth obtained from the second virtual anterior eye image.

[0170] Furthermore, the evaluation processing unit 82 of this embodiment generates evaluation information by calculating the ratio between the average corneal thickness and the average anterior chamber depth.

[0171] In one example of this embodiment, the evaluation processing unit 82 can analyze a first virtual anterior segment image to calculate a first corneal thickness and a first anterior chamber depth at (or near) the limbus, and analyze a second virtual anterior segment image to calculate a second corneal thickness and a second anterior chamber depth at (or near) the limbus.

[0172] Furthermore, the evaluation processing unit 82 of this example can determine the average corneal thickness (average value of the first corneal thickness and the second corneal thickness) at (or near) the limbus and the average anterior chamber depth (average value of the first anterior chamber depth and the second anterior chamber depth) at (or near) the limbus, and calculate the ratio between the average corneal thickness at (or near) the limbus and the average anterior chamber depth.

[0173] Furthermore, the evaluation processing unit 82 of this example can determine a grade indicating the condition of the iridocorneal angle based on the ratio of the average corneal thickness to the average anterior chamber depth. This grade may be based on the Van Herick method or the Van Herick Plus method.

[0174] In addition, the evaluation processing unit 82 in this example may obtain the ratio between the first corneal thickness and the first anterior chamber depth (first ratio), a grade based on the first ratio (first grade), the ratio between the second corneal thickness and the second anterior chamber depth (second ratio), a grade based on the second ratio (second grade), a comparison result between the first corneal thickness and the second corneal thickness (e.g., difference, ratio), a comparison result between the first anterior chamber depth and the second anterior chamber depth (e.g., difference, ratio), etc.

[0175] The evaluation processing unit 82 of this example can generate evaluation information including at least the value of the ratio between the average corneal thickness and the average anterior chamber depth and / or a grade based thereon. This evaluation information may further include a first ratio, a first grade, a second ratio, a second grade, a comparison result between the first corneal thickness and the second corneal thickness, a comparison result between the first anterior chamber depth and the second anterior chamber depth, etc.

[0176] The ophthalmologic apparatus 1 according to the second exemplary embodiment is configured to measure a pair of corneal thicknesses (first corneal thickness and second corneal thickness) and a pair of anterior chamber depths (first anterior chamber depth and second anterior chamber depth) based on a pair of anterior eye images obtained substantially simultaneously by a pair of imaging systems 22L and 22R, and to calculate the average value of the obtained pair of corneal thicknesses (average corneal thickness) and the average value of the pair of anterior chamber depths (average anterior chamber depth). This makes it possible to reduce the influence of errors due to the refractive power of the cornea, etc., on the evaluation results.

[0177] For more information on this effect, see, for example, the following document: Melanie Corbett et. al., Corneal Topography Principles and Applications, (Second Edition, Springer International Publishing (2019), pp. 46-47, "Dual Scheimpflug Imaging." The ophthalmic apparatus described in this document is an ophthalmic apparatus that performs scanning by rotating a pair of imaging systems that are arranged symmetrically with respect to the illumination system around the illumination optical axis, and the object of correction is an error in the corneal thickness measurement when the projection position of the illumination light (i.e., the focal plane of Scheimpflug imaging) is deviated from the corneal apex. Therefore, both the type of ophthalmic apparatus and the object of correction are different from those of this embodiment. However, it would be understandable to a person skilled in the art that the effect of this embodiment can be obtained from the perspective of correcting the influence of the refractive power of the cornea.

[0178] Strictly speaking, in order to obtain the true values of corneal thickness and anterior chamber depth, for example, it is necessary to perform refractive correction using ray tracing described in the following literature: Wolfgang Fink, Refractive correction method for digital charge-coupled device-recorded Scheimpflug photographs by means of ray tracing, Journal of Biomedical Optics 10(2), 024003 (March / April 2005).

[0179] In contrast, the ophthalmic device 1 according to the second exemplary aspect is configured to calculate the ratio of the average corneal thickness and the average anterior chamber depth that are both affected by the same error caused by the refractive power of the cornea, so that an evaluation result in which the influence of this error is canceled out can be obtained. Moreover, there is no need to perform complicated ray tracing calculations.

[0180] As described above, according to the ophthalmic device 1 according to the second exemplary aspect, it is possible to generate high-quality evaluation information without performing complicated arithmetic processing. Note that the ophthalmic device 1 according to another aspect may be configured to perform ray tracing calculations to obtain the true values of corneal thickness and anterior chamber depth and generate high-quality evaluation information.

[0181] A third exemplary aspect will be described. In the data processing unit 8 according to this aspect, the evaluation processing unit 82 is configured to generate evaluation information using a mathematical model (machine learning model, inference model) trained and constructed using machine learning technology.

[0182] The data input to this machine learning model may be, for example, one or more anterior eye segment images acquired by the imaging system 22L or 22R, one or more anterior eye segment image pairs acquired substantially simultaneously by the left and right imaging systems 22L and 22R, and any of the virtual anterior eye segment images generated by the image processing unit 81.

[0183] In addition, the output data from the machine learning model may be any information that can be included in the evaluation information, such as the result of narrow angle assessment, the grade of the Van Herick method, the grade of the Van Herick Plus method, the value of the angle parameter, etc.

[0184] The machine learning model includes a neural network such as a convolutional neural network. The neural network may be constructed using, for example, a known open-source neural network architecture. The convolutional neural network may have a known structure including, for example, an input layer, a convolutional layer, a pooling layer, a fully connected layer, and an output layer. The neural network may include a support vector machine, a recurrent neural network, etc.

[0185] The machine learning model in this example is constructed by applying machine learning to a neural network using training data, which includes, for example, a large number of pairs of training anterior eye images and training evaluation information.

[0186] The training anterior segment images may be images of the anterior segment of the eye produced by any modality, including a slit lamp microscope, a Scheimpflug camera, an optical coherence tomography (OCT), a gonioscope, or an ultrasound scanner.

[0187] The type of information included in the training evaluation information is selected depending on the type of information included in the evaluation information generated by the evaluation processing unit 82. For example, the training evaluation information may include the result of narrow angle assessment, the grade of the Van Herick method, the grade of the Van Herick Plus method, and the values of the angle parameters. The training evaluation information is generated, for example, by a doctor or a computer based on training anterior segment images. This computer-generated information may be generated based on machine learning or non-machine learning.

[0188] The machine learning method used to build the machine learning model may be any, such as supervised learning, semi-supervised learning, unsupervised learning, and reinforcement learning, or at least a partial combination of two or more of them. Typically, the machine learning model is built using supervised learning (or semi-supervised learning) using training data in which input images are labeled with the final output, as described above. Furthermore, the machine learning model may be built using a support vector machine, a Bayesian classifier, boosting, k-means, kernel density estimation, principal component analysis, independent component analysis, self-organizing maps, random forests, generative adversarial networks, etc.

[0189] The machine learning model constructed in this manner functions to receive input of one or more anterior segment images of the subject's eye E (e.g., an anterior segment image of the subject's eye E obtained by the imaging system 22L or 22R, a pair of anterior segment images of the subject's eye E obtained by the left and right imaging systems 22L and 22R, a virtual anterior segment image of the subject's eye E generated by the image processing unit 81, etc.) and output information used to generate evaluation information (e.g., the result of narrow angle assessment, the grade of the Van Herick method, the grade of the Van Herick Plus method, the value of the angle parameter, etc.).

[0190] An example of the operation of the ophthalmologic apparatus 1 of this embodiment will be described with further reference to FIG.

[0191] In preparation for the examination, the subject's head is placed on a holding portion (forehead rest, chin rest) not shown of the ophthalmic apparatus 1. In response to an instruction operation performed using, for example, the user interface 10, the ophthalmic apparatus 1 starts projecting fixation light onto the subject's eye E, which is the target of an anterior eye scan, aligns the Scheimpflug optical system 2 with the subject's eye E, and starts tracking to make the Scheimpflug optical system 2 follow the movement of the subject's eye E.

[0192] The ophthalmic device 1 executes an anterior segment scan of the eye to be examined E in response to a predetermined imaging trigger (S1). The imaging trigger may be, for example, an instruction operation using the user interface 10, completion of alignment, or start of tracking.

[0193] The set of anterior segment images collected in the anterior segment scan in step S1 is sent to the image processing unit 81. The image processing unit 81 applies correction processing such as distortion correction and aspect correction to the anterior segment images included in the set of anterior segment images (S2).

[0194] As shown in FIG. 6, the image processing unit 81 constructs a three-dimensional image based on the set of anterior segment images obtained by the correction processing in step S3 (S3).

[0195] As shown in FIGS. 7 and 8, the image processing unit 81 extracts a partial image corresponding to a region (such as a planar region or a flat plate region inclined by 60 degrees with respect to the front direction) where slit light is projected in the Van Herick method from the three-dimensional image constructed in step S3 (S4).

[0196] As shown in FIG. 9, the image processing unit 81 orthogonally projects the partial image of the three-dimensional image extracted in step S4 onto the XY plane (S5). Thereby, a virtual anterior segment image based on the set of anterior segment images collected in the anterior segment scan in step S1 is generated.

[0197] The evaluation processing unit 82 generates evaluation information based on the virtual anterior segment image generated in step S5 (S6).

[0198] In this example, the evaluation processing unit 82 calculates the value of the corneal thickness and the value of the anterior chamber depth in the peripheral part by applying the grading algorithm of the Van Herick method to the virtual anterior eye image. Further, the evaluation processing unit 82 determines a grade (any one of grades 0 to 4) indicating the width of the anterior chamber angle by comparing the calculated corneal thickness value and anterior chamber depth value according to the grading of the Van Herick method. The evaluation processing unit 82 generates evaluation information including the grade obtained in this way.

[0199] Based on the anterior eye image set acquired in step S1 and / or the virtual anterior eye image generated in step S5, the anterior chamber angle parameter calculation unit 83 calculates the value of a predetermined anterior chamber angle parameter (S7).

[0200] The control unit 7 causes the display device 11 to display the evaluation information generated in step S6 and the value of the anterior chamber angle parameter obtained in step S7 (S8).

[0201] The ophthalmic device 1 can output any information generated in this operation example in any manner. Examples of the output method include display, storage, transmission, printing, and the like. Thus, the process of this operation example is completed (end).

[0202] According to this aspect, it is possible to perform an examination based on the Van Herick method using the ophthalmic device 1 that moves the Shine-proof optical system 2 using slit light as illumination light to perform anterior eye scanning.

[0203] Since the illumination system 21 and the imaging systems 22L and 22R of this aspect are configured to satisfy the Shine-proof conditions, for example, a series of in-focus anterior eye images can be collected over a wide depth range from the anterior corneal surface to the posterior lens surface to generate an anterior eye image set. Therefore, according to this aspect, it is possible to acquire an image that highly precisely represents the entire main observation range of the anterior eye.

[0204] According to this aspect, since it is possible to generate a virtual anterior eye segment image from such a high-quality image, an examination based on the Van Herick method can be carried out with high quality.

[0205] According to this aspect, since a high-definition image of a wide three-dimensional region of the anterior eye segment can be acquired, it is possible to perform an examination based on the Van Herick method while focusing on a desired position of the anterior eye segment.

[0206] According to this aspect, various effects according to the above-described various aspects can be achieved.

[0207] For example, since this aspect can correct the form of the anterior eye segment represented in the image by distortion correction and aspect correction, it is possible to generate a virtual anterior eye segment image representing the actual form of the anterior eye segment or a form close thereto, and it is also possible to improve the quality of the examination based on the Van Herick method.

[0208] In addition, this aspect can automatically perform an evaluation of the eye to be examined based on the virtual anterior eye segment image and provide the result, and in particular, it is possible to generate evaluation information obtained by an examination based on the Van Herick method and evaluation information obtained by an examination based on the Van Herick Plus method.

[0209] In addition, since the ophthalmic apparatus 1 according to this aspect includes a shine-proof optical system 2 including an illumination system 21 and imaging systems 22L and 22R, it is possible to photograph the region of the anterior eye segment on which slit light from the illumination system 21 is projected from two separate oblique directions to generate a pair of anterior eye segment image sets, and moreover, each generated anterior eye segment image set depicts a wide three-dimensional region of the anterior eye segment in high definition. Therefore, according to the ophthalmic apparatus 1, a high-quality virtual anterior eye segment image can be generated, and furthermore, a high-quality evaluation can be performed.

[0210] In addition, the ophthalmic device 1 according to the present aspect can generate a plurality of images (a plurality of virtual anterior eye images) obtained by the aforementioned virtual anterior eye scan from a set of anterior eye images actually collected by scanning the anterior segment of the subject eye E, and further, it is also possible to generate evaluation information such as statistical evaluation information based on the plurality of virtual anterior eye images.

[0211] In addition, the ophthalmic device 1 according to the present aspect can calculate the limbus parameter value of the subject eye E, and further, can display this limbus parameter value together with the evaluation information.

[0212] As described above, some non-limiting aspects of the ophthalmic device according to the embodiment have been described. It is possible to at least partially combine any two or more aspects.

[0213] <Other aspects> The embodiments according to the present disclosure are not limited to ophthalmic devices. As embodiments other than ophthalmic devices, there are a method of controlling an ophthalmic device, a method of photographing the anterior segment of the eye, a program, a recording medium, and the like. Similar to the embodiments of the ophthalmic device, these embodiments can also provide a method for implementing the Van Herick method using an ophthalmic device that moves a Scheimpflug optical system using slit light as illumination light to perform an anterior eye scan.

[0214] Some embodiments provide a method for controlling an ophthalmic device. The ophthalmic device includes a shine-proof optical system, a moving mechanism, and a processor. The shine-proof optical system includes an illumination system configured to project slit light from a front direction onto the anterior eye part of an eye to be examined, and an imaging system configured to image the anterior eye part from a first oblique direction forming a first angle with respect to the front direction in the width direction of the slit light. The illumination system and the imaging system are configured to satisfy the conditions of shine-proof. The moving mechanism is configured to move the shine-proof optical system in the width direction of the slit light. The method according to the present embodiment causes the processor to perform a process of controlling the shine-proof optical system and the moving mechanism to collect a set of anterior eye part images, and a process of generating a virtual anterior eye part image of the anterior eye part onto which virtual slit light is projected from a virtual position in a second oblique direction forming a second angle with respect to the front direction in the width direction of the slit light as seen from a virtual viewpoint in the front direction based on the collected set of anterior eye part images.

[0215] Any matter described in the present disclosure can be combined with the method according to the embodiment.

[0216] Some embodiments provide a program. The program according to the embodiment causes a computer including a processor and a memory to execute the method according to the above-described embodiment. Any matter described in the present disclosure can be combined with the program according to the embodiment.

[0217] Some embodiments provide a computer-readable non-transitory recording medium. A program for causing a computer to execute the method according to the above-described embodiment is recorded on the recording medium according to the embodiment. Any matter described in the present disclosure can be combined with the recording medium according to the embodiment.

[0218] The computer-readable non-transitory recording medium that can be used as the recording medium according to the present embodiment may be any form of recording medium, for example, any one of a magnetic disk, an optical disk, a magneto-optical disk, and a semiconductor memory.

[0219] The embodiments and aspects described in this disclosure are merely examples. Any modifications (such as omissions, substitutions, additions, etc.) within the scope of the gist of the present invention can be applied to the embodiments and aspects of this disclosure.

Explanation of Reference Numerals

[0220] 1 Ophthalmic device 2 Anti-glare optical system 21 Lighting system 22L, 22R Imaging system 4 Observation system 6 Moving mechanism 7 Control unit 8 Data processing unit 81 Image processing unit 82 Evaluation processing unit 83 Corner parameter calculation unit 11 Display device

Claims

1. An illumination system that projects slit light from the front direction onto the anterior segment of the eye to be examined, and an imaging system that images the anterior segment from a first oblique direction that forms a first angle with respect to the front direction in the width direction of the slit light, wherein the illumination system and the imaging system are configured as a shine-proof optical system that satisfies the shine-proof condition, a moving mechanism that moves the shine-proof optical system in the width direction, a control unit that controls the shine-proof optical system and the moving mechanism in order to collect a set of anterior segment images, an image processing unit that generates a virtual anterior segment image of the anterior segment of the eye as seen from a virtual viewpoint in the front direction, with virtual slit light projected from a virtual position in a second oblique direction that forms a second angle with respect to the front direction in the width direction, based on the set of anterior segment images, comprising an ophthalmic device.

2. The image processing unit constructs a three-dimensional image from the set of anterior segment images, extracts a partial image corresponding to a plane along the second oblique direction from the three-dimensional image, and generates the virtual anterior segment image by applying an orthographic projection in the direction of the complementary angle of the angle formed by the front direction and the second oblique direction to the partial image. The ophthalmic device according to Claim 1.

3. The image processing unit applies correction processing including at least one of distortion correction and aspect correction to the set of anterior segment images, and constructs the three-dimensional image from the set of anterior segment images to which the correction processing has been applied. The ophthalmic device according to Claim 2.

4. further comprising an evaluation processing unit that generates evaluation information of the eye to be examined based on the virtual anterior segment image. The ophthalmic device according to Claim 1.

5. The second angle is 60 degrees, the virtual slit light is projected onto the corneal limbus of the anterior segment of the eye, and the evaluation processing unit generates the evaluation information by calculating the ratio of the corneal thickness to the anterior chamber depth in the vicinity of the corneal limbus. The ophthalmic device according to Claim 4.

6. The imaging system includes a pair of imaging systems arranged in directions that form the first angle with respect to each other in opposite directions across the front direction, the illumination system and each of the pair of imaging systems are configured as a shine-proof optical system that satisfies the shine-proof condition, the control unit controls the shine-proof optical system and the moving mechanism in order to collect a pair of sets of anterior segment images, and the image processing unit generates the virtual anterior segment image based on the pair of sets of anterior segment images. The ophthalmic device according to Claim 1.

7. The image processing unit generates a first virtual anterior eye image and a second virtual anterior eye image based on a first anterior eye image and a second anterior eye image that are substantially simultaneously acquired by the pair of imaging systems from the pair of anterior eye image sets, determines a first corneal thickness and a first anterior chamber depth based on the first virtual anterior eye image, determines a second corneal thickness and a second anterior chamber depth based on the second virtual anterior eye image, determines an average corneal thickness between the first corneal thickness and the second corneal thickness, determines an average anterior chamber depth between the first anterior chamber depth and the second anterior chamber depth, and further includes an evaluation processing unit that generates evaluation information by calculating a ratio between the average corneal thickness and the average anterior chamber depth, The ophthalmic apparatus according to claim 6.

8. further includes an evaluation processing unit that generates evaluation information of the eye to be examined based on the virtual anterior eye image generated from the pair of anterior eye image sets by the image processing unit, The ophthalmic apparatus according to claim 6.

9. The second angle is 60 degrees, the virtual slit light is projected onto the corneal limbus of the anterior eye, the evaluation processing unit generates the evaluation information by calculating a ratio between the corneal thickness and the anterior chamber depth in the vicinity of the corneal limbus, The ophthalmic apparatus according to claim 8.

10. The image processing unit generates a plurality of virtual anterior eye images corresponding to different positions in the width direction by generating the virtual anterior eye image for each of a plurality of combinations of the virtual position and the virtual viewpoint that are set with different positions in the width direction, The ophthalmic apparatus according to claim 1.

11. further includes an evaluation processing unit that generates evaluation information of the eye to be examined based on the plurality of virtual anterior eye images, The ophthalmic apparatus according to claim 10.

12. The second angle is 60 degrees, the virtual slit light is projected onto a plurality of different positions on the corneal limbus of the anterior eye, the evaluation processing unit, for each of the plurality of positions of the corneal limbus, calculates a ratio between the corneal thickness and the anterior chamber depth in the vicinity of the position to generate the evaluation information, thereby generating a plurality of evaluation information corresponding to the plurality of positions, applies a predetermined statistical process to the plurality of evaluation information to generate statistical evaluation information, The ophthalmic apparatus according to claim 11.

13. further includes a corner parameter calculation unit that calculates a value of a predetermined corner parameter based on at least one of the anterior eye image set and the virtual anterior eye image, The ophthalmic apparatus according to claim 1.

14. A corner parameter calculation unit that calculates a value of a predetermined corner parameter based on at least one of the anterior eye image set and the virtual anterior eye image; A display unit that displays the evaluation information and the value of the corner parameter; further comprising The ophthalmic apparatus according to claim 4.

15. A method for controlling an ophthalmic apparatus for photographing the anterior eye of an eye to be examined, the ophthalmic apparatus comprising: an illumination system that projects slit light from a front direction onto the anterior eye, and an imaging system that images the anterior eye from a first oblique direction that forms a first angle with respect to the front direction in the width direction of the slit light, wherein the illumination system and the imaging system are a shine-proof optical system that satisfies the shine-proof condition; a moving mechanism that moves the shine-proof optical system in the width direction; a processor comprising causing the processor to control the shine-proof optical system and the moving mechanism to collect an anterior eye image set; generate a virtual anterior eye image of the anterior eye as seen from a virtual viewpoint in the front direction, where the virtual slit light is projected from a virtual position in a second oblique direction that forms a second angle with respect to the front direction in the width direction, based on the anterior eye image set. execute A method.

16. A program for causing a computer to execute the method according to claim 15.

17. A computer-readable non-transitory recording medium on which the program according to claim 16 is recorded. ​

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