Ophthalmic device, control method for ophthalmic device, and program

Abstract

Obtain fundus images with appropriate brightness. [Solution] The ophthalmic device of this disclosure is A light source unit that emits either an observation light for observing the fundus of the eye under examination or a photographic light for photographing the fundus of the eye under examination, An imaging unit that outputs brightness data of the fundus of the eye being examined by photographing the fundus of the eye being examined, A control unit calculates multiple photometric values ​​using multiple luminance data output from the imaging unit, and determines the amount of light emitted from the light source unit using a photometric value selected by analyzing the multiple photometric values. It is equipped with.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an ophthalmologic apparatus, a control method for an ophthalmologic apparatus, and a program.

BACKGROUND ART

[0002] Currently, in the field of ophthalmology, fundus cameras have been put into practical use as apparatuses for capturing a two-dimensional image of the fundus of a subject's eye.

[0003] In fundus cameras, to observe the fundus, a light source (fundus observation light source) such as an LED that outputs near-infrared light or infrared light is used. Further, to photograph the fundus, a light source (fundus photographing light source) such as an arc lamp for emitting flash light or an LED that outputs visible light is used.

[0004] When observing the fundus of a subject's eye, the fundus observation light source is turned on to illuminate the subject's eye, and a fundus observation image is acquired. An examiner can confirm the photographing position and the like of the subject's eye by using this fundus observation image. Further, when photographing the fundus of a subject's eye, the fundus photographing light source is caused to emit light to illuminate the subject's eye, and a fundus photographed image is acquired. The examiner can inspect a disease or the like of the subject's eye by using this fundus photographed image.

[0005] In order to obtain a fundus photographed image that allows appropriate examination, it is necessary to cause the fundus photographing light source to emit light with appropriate brightness according to the state (pupil diameter and the like) of the subject's eye.

[0006] Here, Patent Document 1 discloses a method of changing the light emission amount of a fundus photographing light source based on the pupil diameter of a subject's eye.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0007]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

[0008] In this method, where the amount of light emitted from the fundus imaging light source is changed based on pupil diameter, it may not be possible to obtain fundus images with appropriate brightness depending on the condition of the eye being examined. The condition of the eye being examined refers to, for example, the reflectivity of the fundus. If the reflectivity of the fundus is higher (or lower) than standard due to factors such as race or age, it may not be possible to obtain fundus images with appropriate brightness. Another condition of the eye being examined is, for example, the tendency to constrict the pupil. If the subject is prone to pupillary constriction due to the influence of the surrounding environment, it may not be possible to obtain fundus images with appropriate brightness. As a result, it may not be possible to perform an appropriate examination.

[0009] Therefore, the purpose of this disclosure is to provide an ophthalmic device that can obtain fundus images with appropriate brightness. [Means for solving the problem]

[0010] The ophthalmic device disclosed herein is A light source unit that emits either an observation light for observing the fundus of the eye under examination or a photographic light for photographing the fundus of the eye under examination, An imaging unit that outputs brightness data of the fundus of the eye being examined by photographing the fundus of the eye being examined, A control unit calculates multiple photometric values ​​using multiple luminance data output from the imaging unit, and determines the amount of light emitted from the light source unit using a photometric value selected by analyzing the multiple photometric values. It is equipped with. [Effects of the Invention]

[0011] According to this disclosure, it is possible to obtain fundus images with appropriate brightness. [Brief explanation of the drawing]

[0012] [Figure 1]This is a schematic diagram showing an example of a schematic configuration of the fundus camera according to Embodiment 1. [Figure 2] This is a schematic diagram showing an example of the optical configuration according to Embodiment 1. [Figure 3] This is a schematic diagram showing an example of the control unit according to Embodiment 1. [Figure 4] This is a schematic diagram showing an example of the relationship between illumination of the subject's eye and miosis according to Embodiment 1. [Figure 5] This is a schematic diagram showing an example of a change in a fundus image when the pupil diameter changes due to miosis according to Embodiment 1. [Figure 6] This is a flowchart showing a series of fundus photographing processes according to Embodiment 1. [Figure 7] This is a schematic diagram showing an example of an effective region and an ineffective region of a fundus image according to Embodiment 1. [Figure 8] This is a flowchart showing a series of adjustment value calculation processes according to Embodiment 1. [Figure 9] This is a flowchart showing a series of fundus photographing processes according to Embodiment 2. [Figure 10] This is a schematic diagram showing an example of a change in a fundus image when flare occurs according to Embodiment 2. [Figure 11] This is a flowchart showing a series of adjustment value calculation processes according to Embodiment 2. [Figure 12] This is a graph showing an example of the relationship between pupil diameter change and photometric average value change according to Embodiment 3. [Figure 13] This is a flowchart showing a series of fundus photographing processes according to Embodiment 3. [Figure 14] This is a flowchart showing a series of adjustment value calculation processes according to Embodiment 3. [Description of Embodiments]

[0013] Exemplary embodiments of the present disclosure will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative positions of components, and the like described in the following embodiments are arbitrary, and can be changed according to the configuration of an apparatus to which the present disclosure is applied or various conditions. Further, in the drawings, the same reference numerals are used between the drawings to indicate elements that are identical or functionally similar.

[0014] (Embodiment 1) In Embodiment 1, a fundus camera to which the present disclosure is applied will be described with reference to FIGS. 1 to 8.

[0015] In the present embodiment, the calculation method for calculating the adjustment value of the light amount of observation light and the adjustment value of the light amount of imaging light is changed according to the pupil diameter size. Thereby, the light amount of the observation light and the light amount of the imaging light can be made appropriate. Hereinafter, the present embodiment will be described in detail.

[0016] <Schematic Configuration of Apparatus> First, the schematic configuration of the fundus camera according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of the fundus camera. The fundus camera is provided with an imaging unit 10, a control unit 20, and a display unit 30. The imaging unit 10 is provided with an optical head unit 100, a stage unit 110, a base unit 120 including an operation unit such as a joystick and an imaging button (not illustrated), and a face rest unit 130.

[0017] The optical head unit 100 includes a measurement optical system for irradiating an eye to be examined with light, detecting return light from the eye to be examined, and observing and imaging an anterior eye observation image and a fundus front image. The stage unit 110 is an example of a moving unit capable of moving the optical head unit 100 in the x, y, and z directions in the drawing by using a drive mechanism such as a motor (not illustrated). The face rest unit 130 is a chin rest that can promote fixation of the subject's eye (eye to be examined) by fixing the chin and forehead of the subject. Further, the face rest unit 130 is an example of a moving unit capable of moving the face rest unit 130 in the y direction in the drawing by using a drive mechanism such as a motor (not illustrated).

[0018] The control unit 20 is connected to the imaging unit 10 and the display unit 30, and can control them. The control unit 20 can, for example, align the optical head unit 100 with the eye under examination by controlling the movement of the stage unit 110. The control unit 20 can also generate images for anterior eye observation and frontal fundus images based on the brightness data acquired by the imaging unit 10.

[0019] The control unit 20 can be configured using a general-purpose computer including a processor and memory, but it may also be configured as a dedicated computer for the fundus camera. Furthermore, the control unit 20 may be a separate (external) computer to which the imaging unit 10 is connected for communication, or it may be an internal (built-in) computer of the imaging unit 10. Also, the control unit 20 may be a personal computer, such as a desktop PC, notebook PC, or tablet PC (portable information terminal).

[0020] The display unit 30 is comprised of any monitor. The display unit 30 displays various information such as subject information and various images, according to the control of the control unit 20. The display unit 30 may also be a touch panel display. In this case, the display unit 30 is also used as an operation unit.

[0021] In this embodiment, the imaging unit 10, the control unit 20, and the display unit 30 are configured separately, but they may be configured as a single unit, either partially or entirely. Furthermore, other devices (such as a storage device) may be connected to the control unit 20.

[0022] <Optical configuration of the device> Next, the optical system of the fundus camera according to this embodiment will be described using the schematic diagram in Figure 2. The optical system consists of an observation optical system for observing the eye under examination and an imaging optical system for photographing the eye under examination. The configuration of the optical system will be divided into a plurality of optical axes L1 to L6, where various optical elements are arranged, and each of these will be described in turn. Optical axes L1 to L4 are the optical paths from the observation light illuminating from the fundus observation light source 201 and the imaging light emitted from the fundus imaging light source 203 until they are irradiated onto the eye under examination. The fundus observation light source 201 and the fundus imaging light source 203 are examples of light sources.

[0023] The optical axis L1 is where a light source and related components for observing the fundus are positioned. These components are arranged along the optical path of the light emitted from the light source. A fundus observation light source 201 and a condenser lens 202 are positioned on the optical axis L1. An infrared LED or the like may be used as the fundus observation light source 201.

[0024] The optical axis L2 contains a light source and related components that emit light for photographing the fundus. These components are arranged along the optical path of the light emitted from the light source. On the optical axis L2 are a fundus photography light source 203, a condenser lens 204, and a dichroic mirror 205 for fundus photography. The dichroic mirror 205 has the characteristic of transmitting infrared light and reflecting visible light. A xenon lamp or a white LED may be used as the fundus photography light source 203. In this embodiment, the configuration is branched by the dichroic mirror 205, but this configuration is not required. For example, the fundus observation light source 201 and the fundus photography light source 203 may be placed in the same optical path, and they may be switched within the optical path according to observation and photography.

[0025] On the optical axis L3 in the reflection direction of the dichroic mirror 205, a ring slit 206 with a ring-shaped opening, a lens baffle 207, a split unit 208, a relay lens 209, a corneal baffle 210, and a perforated mirror 211 with a central opening are arranged. The ring slit 206 is positioned approximately optically conjugate to the pupil of the eye E under examination, the lens baffle 207 to the posterior surface of the lens of the eye E under examination, and the corneal baffle 210 to the cornea of ​​the eye E under examination.

[0026] On the optical axis L4 in the direction of reflection of the perforated mirror 211, a dichroic mirror 212 and an objective lens 213 are positioned opposite the eye under examination E. A photographic aperture 225 is positioned in the perforation of the perforated mirror 211, and further behind it, a focus lens 214, a photographic lens 215, and a half mirror 216 are positioned to adjust the focus by moving their position on the optical axis L4. A two-dimensional image sensor 230, which serves both observation and photography, is positioned in front of the half mirror 216.

[0027] An internal fixation target 260 is positioned at the end of the optical axis L5, which is the reflection direction of the half-mirror 216, to indicate the target position of the line of sight of the eye being examined. The target position of the line of sight of the eye being examined can be changed to any position by the examiner's operation or other means.

[0028] A lens 217, aperture 218, prism 219, lens 220, and a two-dimensional image sensor 240 with infrared sensitivity are arranged along the optical axis L6 in the reflection direction of the dichroic mirror 212. These configurations form an anterior segment observation optical system for observing the anterior segment of the eye. Here, light incident on the prism 219 is refracted and separated in opposing left-right directions by the upper and lower halves of the prism 219. Therefore, if the distance between the eye under examination E and the optical head 100 is longer than the proper working distance, the observation image of the anterior segment is imaged closer to the lens 217 than to the prism 219 by the lens 217, and the upper half of the observation image is shifted to the right and the lower half to the left. If the distance between the eye under examination E and the optical head 100 is shorter than the proper working distance, the observation image is shifted vertically in the opposite direction. In addition, the anterior segment of the eye under examination E is illuminated by an infrared anterior segment observation light source 250. The anterior segment observation optical system described above makes it possible to detect the alignment state with the anterior segment of the eye E under examination. This configuration, along with the stage unit 110 and the control unit 20, constitutes an alignment means for controlling the alignment of the imaging optical system with respect to the eye under examination in this embodiment.

[0029] Next, we will describe the configuration of the focusing optical system.

[0030] The split unit 208, positioned on the optical axis L3, includes a focus indicator light source (not shown), a prism, a focus indicator mask, an insertion / removal mechanism, and a unit movement mechanism. The focus indicator light source is used to project the focus indicator. The prism is used to split the light source, projecting the split focus indicator onto the pupil of the eye E under examination. The focus indicator mask is used to form the outline of the focus indicator. The focus indicator mask is positioned approximately optically conjugate to the fundus of the eye E under examination.

[0031] The insertion / removal mechanism includes a split insertion / removal drive motor. The split insertion / removal drive motor inserts the split unit 208 into the optical axis L3. This allows the split indicator to be projected into the fundus image. The split insertion / removal drive motor is also used when removing the split unit 208 from the optical axis L3. This prevents the focus indicator from appearing in the fundus image.

[0032] The unit movement mechanism includes a split-shift motor. The split-shift motor is used to focus the focus indicator by shifting the split unit 208 in the direction of the optical axis.

[0033] The split unit 208 and the focus lens 214 move in conjunction based on control from the control unit 20. The two-dimensional image sensor 230 is optically approximately conjugate to the focus index mask. Therefore, moving the split unit 208 in the optical axis direction moves the split index on the fundus image of the two-dimensional image sensor 230. Simultaneously, the focus lens 214 moves in conjunction in the optical axis direction. When the split focus index projected onto the pupil of the eye E is aligned on the same line, the fundus of the eye E is brought into focus. In manual operation, the examiner operates the unillustrated control unit while confirming the focus index projected onto the fundus image. The control unit 20 moves the split unit 208 and the focus lens 214 in conjunction with the examiner's operation. In automatic operation, the control unit 20 analyzes the fundus image to detect the position of the focus index and automatically moves the split unit 208 and the focus lens 214 in conjunction.

[0034] <Configuration of the control unit> Next, the configuration of the control unit of the fundus camera according to this embodiment will be explained using the schematic diagram in Figure 3. Figure 3 is a block diagram showing an example of the configuration of the control unit 20. The control unit 20 is provided with an acquisition unit 21, an image generation unit 22, an image analysis unit 23, an eye condition detection unit 24, a photometric value calculation unit 25, an eye condition determination unit 26, a light intensity adjustment value calculation unit 27, a drive control unit 28, and a storage unit 29.

[0035] The acquisition unit 21 can acquire various signals (such as brightness data) output from the two-dimensional image sensor 230 and the two-dimensional image sensor 240. The acquisition unit 21 can also acquire instructions from the operator via an operation unit (not shown). Furthermore, the acquisition unit 21 can acquire various information such as subject information stored in the storage unit 29, various images such as fundus images, and various images generated by the image generation unit 22.

[0036] The image generation unit 22 can generate an anterior eye observation image based on the output signal of the two-dimensional image sensor 240 acquired by the acquisition unit 21, and can generate fundus observation images and fundus photography images based on the output signal of the two-dimensional image sensor 230. Note that any known method may be used to generate ophthalmologist-use images such as fundus observation images and fundus photography images from ophthalmological information such as data on the fundus of the eye being examined E. Furthermore, the image generation unit 22 can generate a fundus motion image by sequentially stitching together the generated fundus observation images. In addition, the image generation unit 22 can generate a fundus panoramic image by sequentially stitching together the generated fundus observation images in a spatial order.

[0037] The image analysis unit 23 can calculate information regarding the position of the eye E under examination by analyzing the images generated by the image generation unit 22. Furthermore, by continuously analyzing the images generated by the image generation unit 22, it can detect changes in the position of the eye E under examination.

[0038] The eye condition detection unit 24 can detect the state of the eye E by analyzing the image generated by the image generation unit 22. The state of the eye E includes the state of the surrounding environment (such as the brightness of the surrounding environment). Furthermore, by continuously analyzing the images generated by the image generation unit 22, changes in the state of the eye E can be detected. In this embodiment, the image analysis unit 23 and the eye condition detection unit 24 are shown separately, but this is not limited to this configuration, and the eye condition detection unit 24 may be included in the image analysis unit 23.

[0039] The photometric value calculation unit 25 can calculate photometric value information of the fundus based on the output signal of the two-dimensional image sensor 230 acquired by the acquisition unit 21. Furthermore, by continuously analyzing the output signal of the two-dimensional image sensor 230 acquired by the acquisition unit 21, it can detect time-series changes in the photometric value information. The photometric value is one of the indicators of brightness; the value increases in bright conditions and decreases in dark conditions.

[0040] The eye condition determination unit 26 determines whether to change the calculation method for the adjustment value of the observation light intensity and the adjustment value of the imaging light intensity based on the state of the eye E detected by the eye condition detection unit 24 and any changes in the state of the eye E. The eye condition determination unit 26 also determines whether to change the calculation method for the adjustment value based on information related to the state of the eye E.

[0041] The light intensity adjustment value calculation unit 27 utilizes the photometric value information calculated by the photometric value calculation unit 25, the time-series changes in the photometric value information, and the determination results determined by the eye condition determination unit 26. Using these, the light intensity adjustment value calculation unit 27 can calculate adjustment values ​​to adjust the light intensity of the observation light emitted from the fundus observation light source 201 and the light intensity of the imaging light emitted from the fundus imaging light source 203. In this embodiment, the eye condition determination unit 26 and the light intensity adjustment value calculation unit 27 are shown separately, but this is not limited to this configuration, and the eye condition determination unit 26 may be included in the light intensity adjustment value calculation unit 27.

[0042] The drive control unit 28 controls the driving of various components within the imaging unit 10. Specifically, the drive control unit 28 can control the driving of, for example, the stage unit 110, the face support unit 130, the lens baffle 207, the split unit 208, and the focus lens 214.

[0043] The memory unit 29 can store various types of generated information, images, and videos. It can also store subject identification information, etc. Furthermore, the memory unit 29 can store programs for recording, etc.

[0044] Each component of the control unit 20, other than the storage unit 29, may be composed of software modules executed by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The processor may be, for example, a GPU (Graphical Processing Unit) or an FPGA (Field-Programmable Gate Array). Furthermore, each of these components may be composed of circuits that perform specific functions, such as ASICs. The storage unit 29 may be composed of any storage medium, such as a hard disk, optical disk, or memory.

[0045] <Pupillary constriction and fundus image of the examined eye> Next, we will explain the relationship between pupillary constriction and the fundus image of the eye being examined using schematic diagrams in Figures 4 and 5.

[0046] A corneal baffle image 300, representing the corneal baffle 210, is formed near the cornea Ec in the anterior segment of the eye E under examination. A ring slit image 301, representing the ring slit 206, is formed near the anterior surface (pupil) of the lens El. A lens baffle image 302, representing the lens baffle 207, is formed near the posterior surface of the lens El. The iris Ei is located near the anterior surface of the lens El. These corneal baffle images 300, ring slit image 301, and lens baffle image 302 prevent reflection of illumination light from occurring on the optical surfaces of the eye E under examination (cornea Ec and lens El). The illumination light 310, shown in the shaded area of ​​Figure 4(a), passes through the corneal baffle image 300, ring slit image 301, and lens baffle image 302, illuminating the fundus 303. At this time, a good fundus image like that shown in Figure 5(a) can be obtained.

[0047] In this type of illumination, if the subject experiences glare, the iris Ei of the subject's eye E constricts, reducing the pupil diameter. When the pupil diameter decreases, a light-blocking area 311, as shown in Figure 4(b), is created in the illumination light 310, reducing the amount of light reaching the fundus 303 (incident light amount). A decrease in incident light amount also reduces the amount of light reflected from the fundus 303 (reflected light amount), which can result in a generally dark fundus image as shown in Figure 5(b). The area indicated by 351 in Figure 5(b) is darker than the area indicated by 350 in Figure 5(a). Furthermore, if illumination unevenness occurs due to the creation of the light-blocking area 311, the resulting fundus image may be a dark image with uneven brightness as shown in Figure 5(c). The area indicated by 352 in Figure 5(c) is darker than the area indicated by 350 in Figure 5(a). The location indicated by 353 in Figure 5(c) is darker than the location indicated by 352 in Figure 5(c). The location indicated by 354 in Figure 5(c) is darker than the location indicated by 352, and brighter than the location indicated by 353.

[0048] In particular, in fundus images with uneven brightness as shown in Figure 5(c), conventional automatic exposure may not be able to obtain good fundus observation and fundus photography images, so countermeasures are necessary.

[0049] <Fundus Photography Flowchart> Next, the fundus imaging flow according to this embodiment will be explained using Figure 6. Figure 6 is a flowchart showing a series of fundus imaging processes according to this embodiment.

[0050] First, in step S401, the examiner inputs the subject's information into the control unit 20 using the input unit. Here, the examination is initiated by this operation. Once the examination is started, the control unit 20 turns on the anterior segment observation light source 250 to illuminate the anterior segment of the subject's eye. The control unit 20 also turns on the fundus observation light source 201 to illuminate the fundus of the subject's eye.

[0051] Next, in step S402, the image generation unit 22 generates an image for anterior eye observation. More specifically, the acquisition unit 21 acquires the signal output from the two-dimensional image sensor 240, and the image generation unit 22 generates an image for anterior eye observation based on the acquired signal. The generated image for anterior eye observation is displayed on the display unit 30 and stored in the storage unit 29.

[0052] Next, in step S403, the examiner moves the face support unit 130 and the optical head unit 100 to a predetermined position using the input unit and operation unit while viewing the anterior eye observation image displayed on the display unit 30. Alternatively, the image analysis unit 23 and the drive control unit 28 may automatically move them to the predetermined position. Specifically, the image analysis unit 23 calculates information regarding the position of the eye under examination E and its positional relationship with the optical head unit 100 based on the anterior eye observation image generated by the image generation unit 22. Then, the drive control unit 28 automatically moves the face support unit 130 and the optical head unit 100 to the predetermined position. Furthermore, the examiner may then make fine adjustments to the position using the input unit and operation unit.

[0053] Next, in step S404, the condition of the eye under examination is acquired. More specifically, the eye condition detection unit 24 detects the pupil size using the anterior eye observation image generated in step S402. Any known method may be used to detect the pupil size. A method that extracts the edge of the pupil to detect the size may be used, or a method that detects the size by approximating the pupil as an ellipse may be used. A method that detects the pupil size approximately, rather than the exact pupil size, may also be used. Note that the pupil size is just one example of information regarding the pupil of the eye under examination.

[0054] Next, in step S405, the image generation unit 22 generates a fundus observation image. More specifically, the acquisition unit 21 acquires the signal output from the two-dimensional image sensor 230, and the image generation unit 22 generates a fundus observation image based on the acquired signal. The generated fundus observation image is displayed on the display unit 30 and stored in the storage unit 29.

[0055] Next, in step S406, the photometric value calculation unit 25 acquires the photometric values ​​of the fundus image. More specifically, the photometric value calculation unit 25 acquires signals (luminance data) output from the two-dimensional image sensor 230 and calculates photometric value information of the fundus image based on the acquired signals. More specifically, first, the fundus image is divided into multiple regions as shown in Figure 7. Then, the photometric value is calculated using the set of signals (signal group) corresponding to one of the divided regions. This calculation is performed for all regions. The set of photometric values ​​calculated in this way is called photometric value information. In this embodiment, the photometric value is calculated using signals output from the two-dimensional image sensor 230, but this is not the only method. For example, the photometric value may be calculated using a fundus observation image generated by the image generation unit 22. It is sufficient that photometric value information for the fundus image can be calculated.

[0056] Next, in step S407, the light intensity adjustment value calculation unit 27 calculates the adjustment values ​​for the light intensity of the observation light and the light intensity of the imaging light. More specifically, the light intensity adjustment value calculation unit 27 calculates the adjustment values ​​for the light intensity of the observation light and the light intensity of the imaging light based on the photometric value information calculated by the photometric value calculation unit 25. A more detailed method for calculating the adjustment values ​​will be described below.

[0057] Next, in step S408, the control unit 20 adjusts the amount of light used for fundus observation. More specifically, the control unit 20 adjusts the illumination light intensity of the fundus observation light source 201 based on the adjustment value of the observation light intensity calculated by the light intensity adjustment value calculation unit 27.

[0058] Next, in step S409, the examiner decides whether to start fundus photography. The examiner checks the anterior eye observation image and fundus observation image displayed on the display unit 30, and if they decide to perform fundus photography, they start fundus photography using the input unit or operation unit. The control unit 20 detects that an operation to start fundus photography has been performed and proceeds to step S410. If the examiner decides not to perform fundus photography yet, they do not perform an operation to start fundus photography and return to step S405. The decision of whether or not to perform fundus photography can also be made automatically. In the case of automatic shooting, the control unit 20 analyzes the anterior eye observation image and fundus observation image, etc., and determines whether the alignment position is appropriate, whether the brightness of the fundus is appropriate, etc. If it is decided to perform fundus photography, it automatically proceeds to step S410. In this embodiment, if it is decided not to perform fundus photography, it returns to step S405, but this is not limited to that. For example, it may return to step S404. You may return to step S404, detect the latest pupil size from the most recent anterior eye observation image, and update the information.

[0059] Next, in step S410, the control unit 20 illuminates the fundus imaging light source 203 in order to perform fundus imaging. At this time, the amount of light emitted from the fundus imaging light source 203 is adjusted based on the adjustment value of the light intensity of the imaging light calculated by the light intensity adjustment value calculation unit 27.

[0060] Next, in step S411, the image generation unit 22 generates a fundus image. More specifically, the acquisition unit 21 acquires the signal output from the two-dimensional image sensor 230, and the image generation unit 22 generates a fundus image based on the acquired signal. The generated fundus image is displayed on the display unit 30 and stored in the storage unit 29. Once fundus photography is complete, the process proceeds to step S412 and terminates.

[0061] In this embodiment, pupil diameter size was detected using an anterior eye observation image, but this is not limited to this method. For example, the way in which pupil diameter size changes may be detected using an anterior eye observation image. More specifically, the ease with which the pupil constricts may be detected by comparing the pupil diameter size before illumination with the pupil diameter size after illumination. In this case, strictly speaking, it is not detection of pupil diameter size, but rather an indicator of the ease with which the pupil constricts. Alternatively, the ease with which the pupil constricts may be detected by detecting the brightness of the environment surrounding the eye under examination using an anterior eye observation image. In examinations in bright environments, the pupil is smaller from the start compared to examinations in dark environments, the pupil diameter becomes even smaller when light is irradiated, and the recovery of the pupil diameter tends to be slower. Therefore, if the ambient brightness is brighter than a predetermined value, it can be said that the surrounding environment is conducive to pupil constriction. The ease with which the pupil constricts is one example of information regarding the pupil of the eye under examination.

[0062] Furthermore, although this embodiment describes a fundus imaging flow for only one eye, a flow for imaging both eyes consecutively may also be used. In that case, the above flow should be performed for the right eye and the left eye separately.

[0063] Furthermore, in this embodiment, the input of subject information in step S401 also serves to indicate the start of the examination. However, the method of starting the examination is not limited to this; for example, turning on the power of the device may be considered as the start of the examination. Alternatively, providing a dedicated input indicating the start of the examination, different from the subject information, via the input unit may be considered as the start of the examination. Also, the completion of the previous examination may be considered as the start of the next examination.

[0064] <Light intensity adjustment value calculation flow> Next, the flow of the light intensity adjustment value according to this embodiment will be explained using Figure 8. Figure 8 is a flowchart showing a series of processes for calculating the light intensity adjustment value according to this embodiment.

[0065] First, in step S501, the control unit 20 determines whether the photometric values ​​used to calculate the adjustment value are valid or invalid. Each photometric value included in the photometric value information calculated by the photometric value calculation unit 25 is associated with information about the corresponding region. The light intensity adjustment value calculation unit 27 can use this information to determine the photometric value for any location in the fundus image. Furthermore, not all regions of the fundus image are used to calculate the adjustment value; it is divided into valid and invalid regions. Region 601 shown in Figure 7 is the region used to calculate the adjustment value (valid region). Region 602 is the region not used to calculate the adjustment value (invalid region). The central part, which is likely to be of interest to the examiner, is set as the valid region, while the peripheral parts of the fundus, where optical illumination light is difficult to reach, and the peripheral parts of the fundus image, which are easily affected by reflected light from the cornea Ec and lens El, are set as invalid regions. Information on the locations of the valid and invalid regions is stored in the storage unit 29. The light intensity adjustment value calculation unit 27 uses information about the region associated with the photometric value and information about the locations of the valid and invalid regions to determine whether each photometric value is valid or invalid.

[0066] Next, in step S502, the control unit 20 calculates the distribution of photometric values. More specifically, the light intensity adjustment value calculation unit 27 calculates the standard deviation by analyzing the photometric values ​​that were determined to be effective in step S501. For example, if the brightness of the fundus image is relatively uniform, the standard deviation will be low. Conversely, if there is unevenness in the brightness of the fundus image, the standard deviation will be high. In this embodiment, the standard deviation was calculated, but this is not the only method; variance or other indicators may also be calculated. The important thing is that the distribution of photometric values ​​of the fundus image can be calculated.

[0067] Next, in step S503, the control unit 20 determines the pupil diameter size. The pupil diameter size used is the value detected by the eye condition detection unit 24 in step S404. The eye condition determination unit 26 determines whether the pupil diameter size is above a threshold. If the pupil diameter size is above the threshold, it can be determined that sufficient illumination light reaches the fundus (the iris Ei is not constricted, or the iris Ei is constricted but does not significantly affect the brightness of the fundus). If the pupil diameter size is below the threshold, it can be determined that illumination light does not easily reach the fundus (the iris Ei is constricted, or the iris Ei is constricted and affects the brightness of the fundus). The determination threshold for pupil diameter size is set based on optical characteristics, etc. The determination threshold for pupil diameter size is also stored in the memory unit 29. Of course, in some eyes, the pupil diameter size may be small even if the pupil is not constricted, but the same applies to how easily illumination light reaches the eye as described above.

[0068] The eye condition determination unit 26 proceeds to step S505 if the pupil diameter size is greater than or equal to the threshold. The eye condition determination unit 26 proceeds to step S504 if the pupil diameter size is less than the threshold. The pupil diameter size determination threshold may be a fixed value or a variable value. The pupil diameter size determination threshold may be changed depending on the shooting mode. Since the effect of miosis on the brightness of the fundus and the examiner's points of focus differ depending on the shooting mode, it is sufficient to set an appropriate threshold.

[0069] One example of an imaging mode is one in which the macula is centered in the image. Another example is one in which the optic disc is centered in the image. Yet another example is one in which the posterior pole is centered in the image. Each of these imaging modes has a different fixation lamp position. Therefore, imaging modes with different fixation lamp positions may be distinguished as different imaging modes. Note that a different fixation lamp position changes the relative position of the eye being examined and the incident light, thus changing the brightness of the fundus. For this reason, it is advisable to set a threshold for each imaging mode with a different fixation lamp position.

[0070] Furthermore, one example of an imaging mode is the mode for imaging the first eye when continuously imaging the eyes under examination. Another example of an imaging mode is the mode for imaging the second eye when continuously imaging the eyes under examination. When continuously imaging the eyes under examination, the second eye tends to be more constricted than the first eye. Therefore, it is advisable to set different thresholds for imaging the first and second eyes. Another example of an imaging mode is OCT imaging in a device capable of both OCT imaging and fundus imaging. Another example of an imaging mode is fundus imaging in a device capable of both OCT imaging and fundus imaging. In OCT imaging, brightness adjustment is performed when observing the fundus. Therefore, it is advisable to set different thresholds for OCT imaging and fundus imaging.

[0071] Next, in step S504, the control unit 20 determines the distribution of photometric values. More specifically, the eye condition determination unit 26 determines whether the standard deviation calculated in step S502 is below a threshold. If the standard deviation is below a threshold, the brightness of the fundus image is relatively uniform, so it can be assumed that changing the amount of light will change the brightness of the entire fundus.

[0072] For example, as shown in Figure 5(b), if the entire fundus is dark, increasing the light intensity of the fundus observation light source will increase the overall brightness of the fundus. On the other hand, if the standard deviation exceeds the threshold, it can be assumed that the brightness of the entire image will not change even if the light intensity is changed, because there is unevenness in the brightness of the fundus image. For example, as shown in Figure 5(c), if the entire fundus is dark and also uneven, increasing the light intensity of the fundus observation light source at the location indicated by 352 will increase the brightness accordingly. However, in the area indicated by 353, which is dark due to the strong effect of pupillary constriction, increasing the light intensity of the fundus observation light source will not increase the brightness. The standard deviation threshold is stored in the memory unit 29. The eye condition determination unit 26 transitions to step S505 if the standard deviation is below the threshold. The eye condition determination unit 26 transitions to step S506 if the standard deviation is greater than the threshold.

[0073] Next, in step S505, the control unit 20 calculates the adjustment value using the photometric values ​​of the effective area. First, the light intensity adjustment value calculation unit 27 calculates the average value of the photometric values ​​of the effective area. If the average value of the photometric values ​​is P, the photometric value of each in the effective area is p(i), and the number of effective areas is N, the calculation is performed using the following formula.

[0074]

number

[0075] Next, the observation light intensity adjustment value is calculated. If the target observation photometric value is Pto and the observation light intensity adjustment value is Ato, the calculation is performed using the following formula. The target observation photometric value Pto is the photometric value at which the fundus observation image achieves the expected brightness. The target observation photometric value Pto is a pre-set fixed value. However, the target observation photometric value Pto may be a value that the operator can change. Ato=Pto-P ···Formula 2

[0076] The observation light intensity adjustment value Ato is the value obtained by subtracting the average photometric value P from the target observation photometric value Pto. For example, if the observation light intensity adjustment value Ato is zero, the target observation photometric value Pto and the current average photometric value P are the same (= the current brightness is appropriate), so the light intensity of the fundus observation light source is not changed. If the observation light intensity adjustment value Ato is a positive value, the current average photometric value P is lower than the target observation photometric value Pto (= the current brightness is too dark), so the light intensity of the fundus observation light source is increased by the observation light intensity adjustment value Ato. If the observation light intensity adjustment value Ato is a negative value, the current average photometric value P is higher than the target observation photometric value Pto (= the current brightness is too bright), so the light intensity of the fundus observation light source is decreased by the observation light intensity adjustment value Ato. In this way, the light intensity of the fundus observation light source is adjusted so that the average photometric value P approaches the target observation photometric value Pto.

[0077] Next, we calculate the amount of light intensity adjustment needed for fundus observation. If Ato(i) is the current light intensity adjustment value and Atos is the current value, the calculation is performed using the following formula.

[0078]

number

[0079] By accumulating the observation light intensity adjustment value Ato(i) up to the present, the amount by which the observation light intensity has been adjusted compared to the starting point can be calculated. For example, if the current observation light intensity adjustment value Atos is zero, the current light intensity of the fundus observation light source is the same as the initial light intensity. If the current observation light intensity adjustment value Atos is 1, the current light intensity of the fundus observation light source has been increased by 1 compared to the initial light intensity. If the current observation light intensity adjustment value Atos is -1, the current light intensity of the fundus observation light source has been decreased by 1 compared to the initial light intensity.

[0080] Next, the exposure light adjustment value is calculated. If the target exposure light metering value is Pco and the exposure light adjustment value is Aco, the calculation is performed using the following formula. The target exposure light metering value Pco is the value at which the fundus image achieves the expected brightness. The target exposure light metering value Pco is a fixed value set in advance. However, the target exposure light metering value Pco may be a value that the operator can change. Aco = Pco - Pto + Atos ... Equation 4

[0081] For example, if the target photographic metering value Pco and the target observational metering value Pto are the same, it means that if the fundus imaging light source is emitted at the same light intensity as the fundus observation light source that produces the expected photometric value for the fundus image, a fundus image with the expected brightness can be obtained. If the target photographic metering value Pco is higher than the target observational metering value Pto, emitting the fundus imaging light source at the same light intensity as the fundus observation light source that produces the expected photometric value for the fundus image will result in a fundus image that is darker than expected. Therefore, it is necessary to emit the light source at a higher intensity by the difference between the target photographic metering value Pco and the target observational metering value Pto. If the target photographic metering value Pco is lower than the target observational metering value Pto, emitting the fundus imaging light source at the same light intensity as the fundus observation light source that produces the expected photometric value for the fundus image will result in a fundus image that is brighter than expected. Therefore, it is necessary to emit the light source at a lower intensity by the difference between the target photographic metering value Pco and the target observational metering value Pto. Furthermore, in order to obtain the fundus image with the expected brightness photometric value, the light intensity of the fundus observation light source is adjusted by the current observation light intensity adjustment value Atos. This adjustment is also taken into consideration when calculating the shooting light intensity adjustment value Aco. For example, if the target shooting light intensity Pco and the target observation light intensity Pto are the same and the current observation light intensity adjustment value Atos is zero, the shooting light intensity adjustment value Aco will be zero. In this case, the photometric value of the fundus image is the expected value without correction, so if the fundus shooting light source emits light at the same intensity as the expected fundus observation light source, a fundus image with the expected brightness can be obtained. If the target shooting light intensity Pco and the target observation light intensity Pto are the same and the current observation light intensity adjustment value Atos is 1, the shooting light intensity adjustment value Aco will be 1. In this case, in order to obtain the photometric value of the fundus image with the expected value, the light intensity of the fundus observation light source is increased by 1. Therefore, in order to obtain a fundus image with the expected brightness, the emitted light intensity of the fundus shooting light source is also increased by 1. If the target imaging photometric value Pco and the target observation photometric value Pto are the same and the current observation light intensity adjustment value Atos is -1, then the imaging light intensity adjustment value Aco will be -1. At this time, since the light intensity of the fundus observation light source has been reduced by 1 in order to make the photometric value of the fundus image the expected value, the light emission intensity of the fundus photography light source is also reduced by 1 in order to obtain a fundus photographic image with the expected brightness.

[0082] Next, in step S506, the control unit 20 calculates adjustment values ​​by excluding photometric values ​​from unnecessary areas (selecting photometric values ​​from necessary areas). First, the light intensity adjustment value calculation unit 27 calculates the average value P of the photometric values ​​in the effective area. The average value P is calculated using the calculation formula in Equation 1. Next, the light intensity adjustment value calculation unit 27 calculates the ratio between each photometric value p(i) in the effective area and the average value P of the photometric values. If the photometric value p(i) is smaller than the average value P of the photometric values ​​and the ratio is below a threshold, the light intensity adjustment value calculation unit 27 changes that area into an invalid area as an outlier. The threshold value for the ratio is stored in the storage unit 29. In this way, the photometric values ​​of the effective area are checked and areas below the threshold are excluded as invalid areas. Next, adjustment values ​​(Ato, Aco) are calculated using the photometric values ​​of the effective area, excluding the aforementioned invalid areas. The method for calculating adjustment values ​​is the same as in step S505, so a detailed explanation is omitted here. By performing the method described above, darker areas of the fundus image can be excluded from the calculation of the adjustment value, and the adjustment value can be calculated. In this embodiment, outliers were identified using a ratio, but this is not the only method; for example, a fixed threshold could be used. The important thing is that the dark areas can be appropriately excluded from the calculation of the adjustment value. The threshold used to identify outliers in this embodiment is an example of a first threshold.

[0083] For example, let P1 be the average photometric value of the fundus image shown in Figure 5(b), Ato1 be the observation light intensity adjustment value, and Aco1 be the shooting light intensity adjustment value. Furthermore, let P2 be the average photometric value of the fundus image shown in Figure 5(c), Ato2 be the observation light intensity adjustment value, and Aco2 be the shooting light intensity adjustment value. Furthermore, if the photometric values ​​at the location indicated by 351 and the location indicated by 352 are the same, then when the adjustment values ​​are calculated using the method in step S505 for both, the following relationship is obtained. P1 > P2 Ato1 <Ato2 Aco1 <Aco2 When the light intensity of the fundus observation light source is adjusted based on the observation light intensity adjustment value Ato1 for a fundus image like the one shown in Figure 5(b), the area indicated by 351 (the entire fundus) is illuminated with the expected amount of light, resulting in a fundus image with the expected brightness. Therefore, a good fundus observation image can be obtained. Similarly, a good fundus photographic image can be obtained.

[0084] On the other hand, in the fundus image shown in Figure 5(c), there is unevenness in brightness, and the photometric value is particularly affected by the darker area shown at 353, so the average photometric value P2 is smaller than the average photometric value P1. Therefore, the observation light intensity adjustment value Ato1 and the shooting light intensity adjustment value Aco2 are larger than the observation light intensity adjustment value Ato1 and the shooting light intensity adjustment value Aco1. When the light intensity of the fundus observation light source is adjusted based on this observation light intensity adjustment value Ato2, the area shown at 352 is illuminated with an unnecessarily high amount of light (excessive light emission), resulting in a fundus image that is brighter than expected. Also, the area shown at 353 is dark due to the strong effect of pupillary constriction, so even if the light intensity of the fundus observation light source is adjusted to a higher level, the fundus image will not be as bright as expected and will remain dark. Overall, it is not possible to obtain good fundus observation images. Similarly, it is not possible to obtain good fundus photography images.

[0085] However, following this flow, the adjustment values ​​for the fundus image shown in Figure 5(c) are calculated using the method in step S506. If the photometric mean of the fundus image is P2', the observation light intensity adjustment value is Ato2', and the shooting light intensity adjustment value is Aco2', then calculating the adjustment values ​​using the method in step S506 results in the following relationship. P2 <P2′ Ato2>Ato2′ Aco2>Aco2′ By excluding the photometric values ​​from the darker area indicated by 353 in the fundus image, the average photometric value P2' becomes larger than the average photometric value P2. Therefore, the observation light intensity adjustment value Ato2' and the shooting light intensity adjustment value Aco2' become smaller than the observation light intensity adjustment value Ato2 and the shooting light intensity adjustment value Aco2. When the light intensity of the fundus observation light source is adjusted based on this observation light intensity adjustment value Ato2', the area indicated by 352 is illuminated with the expected amount of light (without excessive light emission), resulting in a fundus image with the expected brightness. However, the area indicated by 353 is darkened due to the strong effect of pupillary constriction, so even if the light intensity of the fundus observation light source is adjusted, the fundus image will not have the expected brightness. However, it is possible to accept this due to the pupillary constriction and observe other parts. Overall, it is possible to obtain better fundus observation images. Similarly, it is possible to obtain better fundus photography images.

[0086] In this embodiment, the average photometric value was calculated to identify outliers and calculate adjustment values, but this is not the only method. For example, the median of the photometric values ​​may be calculated and used, or other calculation methods may be used. Any calculation method that shows the trend of the photometric values ​​is acceptable. The individual photometric values ​​for the fundus image may vary greatly depending on the condition of the fundus and the degree to which the incident light is blocked. When the variation is large, the method using the average value may not be able to properly grasp the trend of the photometric values ​​if there are extremely large or small values. In contrast, the method using the median value can properly grasp the trend of the photometric values ​​even when there are extremely large or small values.

[0087] Furthermore, although the method for calculating the adjustment value in step S505 and the method for calculating the adjustment value in S506 are the same in this embodiment, it is not limited to this, and for example, the target observation photometric value Pto and the target photographic photometric value Pco may be changed to different values ​​for calculation. Depending on the pupillary constriction of the eye being examined, the light may not reach the fundus easily even when irradiated, and the fundus image may not become bright. In such cases, the values ​​of the target observation photometric value Pto and the target photographic photometric value Pco may be increased to make it easier for the adjustment value to be larger than usual.

[0088] Furthermore, while this embodiment uses a method to exclude dark outliers, it is not limited to this. For example, when calculating the average value, a method may be used in which the photometric values ​​of dark outliers are weighted before calculation. The important thing is that the average value is not lowered by the influence of outliers.

[0089] Furthermore, while this embodiment uses a method that excludes only dark outliers, it is not limited to this. Due to the pupillary constriction of the eye being examined, excluding only dark outliers may, in some cases, make the brightness of the optic nerve head of the eye being examined more prominent. The photometric value of the optic nerve head is sufficiently large compared to the photometric values ​​of other parts of the fundus. If the optic nerve head has a prominent brightness in a dark fundus image due to pupillary constriction, the average photometric value P will increase, and the observation light intensity adjustment value Ato and the shooting light intensity adjustment value Aco will decrease. As a result, the fundus image will be darker than expected. Therefore, by excluding not only dark outliers but also the bright parts of the optic nerve head, it is possible to calculate the average photometric value, observation light intensity adjustment value, and shooting light intensity adjustment value that are not affected by the bright parts of the optic nerve head. Alternatively, a method may be used in which the bright parts of the optic nerve head are weighted before calculation, rather than being excluded.

[0090] Finally, the process ends in step S507. The control unit 20 reflects the calculated observation light intensity adjustment value Ato in the light intensity of the fundus observation light source and determines the light intensity of the fundus observation light source. The control unit 20 also reflects the shooting light intensity adjustment value Aco in the light intensity of the fundus shooting light source and determines the light intensity of the fundus shooting light source. More specifically, in step S408, the control unit 20 adjusts the light intensity of the fundus observation light source by the observation light intensity adjustment value Ato and illuminates the fundus. Then, in step S410, the control unit 20 adjusts the light intensity of the fundus shooting light source by the shooting light intensity adjustment value Aco and emits light.

[0091] In this embodiment, the distribution of photometric values ​​is determined after determining the pupil diameter size, but this is not the only way to proceed. For example, assuming that there is a high possibility of uneven brightness when the pupil diameter size is below a threshold, the process may proceed to step S506 without determining the distribution of photometric values.

[0092] (Embodiment 2) Embodiment 1 described a method for changing the calculation method of the adjustment value when the eye under examination constricts, reducing the pupil diameter and causing uneven brightness in the fundus image. In contrast, Embodiment 2 describes another example of changing the calculation method of the adjustment value, specifically when flare occurs in the eye under examination, using Figures 9 to 11.

[0093] The general configuration of the device, the optical configuration of the device, and the configuration of the control unit are the same as in Embodiment 1, so a detailed description is omitted here.

[0094] <Fundus Photography Flowchart> First, the fundus imaging flow according to this embodiment will be explained using Figure 9. Figure 9 is a flowchart showing a series of fundus imaging processes according to this embodiment.

[0095] First, in step S601, the examiner inputs subject information to the control unit 20 using the input unit, thereby starting the examination. Step S601 is the same as step S401 described in Embodiment 1, so a detailed description is omitted here.

[0096] Next, in step S602, the image generation unit 22 generates an image for anterior eye observation. Step S602 is the same as step S402 described in Embodiment 1, so a detailed description is omitted here.

[0097] Next, in step S603, the examiner moves the face support unit 130 and the optical head unit 100 to a predetermined position using the input unit and operation unit while viewing the anterior eye observation image displayed on the display unit 30. Alternatively, the drive control unit 28 may automatically move the face support unit 130 and the optical head unit 100 to a predetermined position. Furthermore, the examiner may then make fine adjustments to the position using the input unit and operation unit.

[0098] Next, in step S604, the image generation unit 22 generates a fundus observation image. Step S604 is the same as step S405 described in Embodiment 1, so a detailed description is omitted here.

[0099] Next, in step S605, the condition of the eye under examination is acquired. More specifically, the eye condition detection unit 24 detects the presence or absence of flare using the fundus observation image generated in step S604. Flare refers to the area that becomes brighter due to the reflected light from the light irradiated onto the eye under examination, which is reflected by the cornea or lens. Normally, if the alignment position of the optical head unit 100 is appropriate, a good fundus image without flare can be obtained as shown in Figure 10(a). However, depending on the shape of the cornea or lens of the eye under examination E, or factors such as contact lenses, flare may appear in the fundus image as shown in Figure 10(b). In addition, even if the alignment position is appropriate, flare may occur if the fixation position of the eye under examination is misaligned. Furthermore, flare may occur if the examiner makes fine adjustments to the position to avoid opacity in the eye under examination. Moreover, if the pupil of the eye under examination is small, there is a method of intentionally shifting the alignment position to allow as much light as possible to reach the fundus, but this method may also cause flare. The position and extent to which flares appear in the fundus image vary, and in some cases, flares may appear prominently in the fundus image, as shown in Figure 10(c). Furthermore, in the fundus image, the brightness value of the flared area is higher than that of the non-flared area. Therefore, if an area with a brightness value above a certain threshold and an area exceeding that threshold is present, it can be determined to be a flare. In this way, the presence or absence of flares is detected using the fundus observation image. The threshold values ​​for flare detection and area are stored in the memory unit 29. While this embodiment uses brightness value and area to detect the presence or absence of flares, it is not limited to this; edge detection may be used, or other methods may be employed. The goal is simply to detect the presence or absence of flares.

[0100] Next, in step S606, the control unit 20 acquires the photometric values ​​of the fundus image. Step S606 is the same as step S406 described in Embodiment 1, so a detailed description is omitted here.

[0101] Next, in step S607, the control unit 20 calculates the adjustment values ​​for the light intensity of the observation light and the light intensity of the imaging light. The light intensity adjustment value calculation unit 27 calculates the adjustment values ​​for the light intensity of the observation light and the light intensity of the imaging light based on the photometric value information calculated by the photometric value calculation unit 25. A more detailed method for calculating the adjustment values ​​will be described below.

[0102] Next, in step S608, the control unit 20 adjusts the amount of light for fundus observation. Step S608 is the same as step S408 described in Embodiment 1, so a detailed description is omitted here.

[0103] Next, in step S609, the control unit 20 determines whether to start fundus photography. If the control unit 20 detects that fundus photography should be started, it proceeds to step S610. If the control unit 20 does not detect that fundus photography should be started, it returns to step S604.

[0104] Next, in step S610, the control unit 20 illuminates the fundus photography light source 203 in order to perform fundus photography. Step S610 is the same as step S410 described in Embodiment 1, so a detailed description is omitted here.

[0105] Next, in step S611, the image generation unit 22 generates a fundus image. Step S611 is the same as step S411 described in Embodiment 1, so a detailed description is omitted here. Once fundus photography is complete, the process proceeds to step S612 and terminates.

[0106] In this embodiment, the presence or absence of flare was detected using fundus observation images, but this is not the only method. For example, the alignment state may be detected using anterior eye observation images and alignment information to determine whether the eye is prone to flare. In this case, strictly speaking, the indicator would be the likelihood of flare occurring, rather than the presence or absence of flare. Alternatively, the direction of the gaze of the eye being examined may be detected using anterior eye observation images to determine the likelihood of flare occurring. For example, if the actual gaze position / direction deviates from the expected gaze position / direction, the balance of the positional relationship with the device is disrupted. In this case, it can be determined that the eye is prone to flare.

[0107] The assumed line of sight position / direction may be the position of the fixation light. If the actual line of sight position / direction deviates from the position of the fixation light, the positional balance with the device is disrupted. In this case, it can be determined that flare is likely to occur.

[0108] <Light intensity adjustment value calculation flow> Next, the flow of the light intensity adjustment value according to this embodiment will be explained using Figure 11. Figure 11 is a flowchart showing a series of processes for calculating the light intensity adjustment value according to this embodiment.

[0109] First, in step 701, the control unit 20 determines whether the photometric value used to calculate the adjustment value is valid or invalid. Step S701 is the same as step S501 described in Embodiment 1, so a detailed description is omitted here.

[0110] Next, in step S702, the control unit 20 determines whether or not there is a flare. The information on the presence or absence of a flare is the result detected in step S605. The eye condition determination unit 26 determines whether or not there is a flare, and if there is no flare, it proceeds to step S703. If there is a flare, the eye condition determination unit 26 proceeds to step S704.

[0111] Next, in step S703, the control unit 20 calculates an adjustment value using the photometric value of the effective area. Step S703 is the same as step S505 described in Embodiment 1, so a detailed description is omitted here.

[0112] Next, in step S704, the control unit 20 calculates an adjustment value by excluding the photometric values ​​of unnecessary areas (selecting the photometric values ​​of necessary areas). First, the light intensity adjustment value calculation unit 27 analyzes the photometric value p(i) of each area in the effective area and calculates whether the photometric value is greater than or equal to the flare threshold. The flare threshold is the photometric value corresponding to the luminance threshold used to detect the presence or absence of flare in step S605. If the photometric value p(i) is greater than or equal to the flare threshold, the light intensity adjustment value calculation unit 27 changes that area into an invalid area as an outlier. Next, it calculates an adjustment value using the photometric values ​​of the effective area, excluding the aforementioned invalid area. The method for calculating the adjustment value is the same as in step S505 described in Embodiment 1, so a detailed explanation is omitted here. By performing the above method, the flare portion of the fundus image can be excluded from the adjustment value calculation target and the adjustment value can be calculated. In this embodiment, the photometric value corresponding to the luminance threshold used in step S605 was used as the flare threshold, but this is not the only option, and a flare threshold set based on other information may be used. The goal is to appropriately exclude the flare portion from the calculation of the adjustment value. Note that the threshold for identifying outliers in this embodiment is an example of a second threshold.

[0113] For example, let P3 be the average photometric value of the fundus image shown in Figure 10(a), Ato3 be the observation light intensity adjustment value, and Aco3 be the imaging light intensity adjustment value. Furthermore, let P4 be the average photometric value of the fundus image shown in Figure 10(c), Ato4 be the observation light intensity adjustment value, and Aco4 be the imaging light intensity adjustment value. Furthermore, if the photometric value at location 354 and location 357 are the same, then calculating the adjustment values ​​for both using the method in step S703 results in the following relationship. P3 <P4 Ato3>Ato4 Aco3 > Aco4 When the light intensity of the fundus observation light source is adjusted based on the observation light intensity adjustment values ​​A to 3 for a fundus image like the one shown in Figure 10(a), the area indicated by 354 (the entire fundus) is illuminated with the expected amount of light, resulting in a fundus image with the expected brightness. Therefore, a good fundus observation image can be obtained. Similarly, a good fundus photographic image can be obtained.

[0114] On the other hand, in the fundus image shown in Figure 10(c), there is significant flare, and the photometric value is particularly affected by the brighter area shown at 358, resulting in a higher average photometric value P4 compared to the average photometric value P3. Therefore, the observation light intensity adjustment value Ato4 and the shooting light intensity adjustment value Aco4 are smaller than the observation light intensity adjustment value Ato3 and the shooting light intensity adjustment value Aco3. When the light intensity of the fundus observation light source is adjusted based on this observation light intensity adjustment value Ato4, the area shown at 357 is illuminated with an insufficient amount of light (under-luminescence), resulting in a fundus image that is darker than expected. Also, in the area shown at 358, the flare is strong and makes it bright, so even if the light intensity of the fundus observation light source is adjusted to a lower level, the fundus image does not become bright as expected and remains bright. Overall, it is not possible to obtain good fundus observation images. Similarly, it is not possible to obtain good fundus photography images.

[0115] However, following this flow, the adjustment values ​​for the fundus image shown in Figure 10(c) are calculated using the method in step S704. If the photometric mean of the fundus image is P4′, the observation light intensity adjustment value is Ato4′, and the imaging light intensity adjustment value is Aco4′, then calculating the adjustment values ​​using the method in step S704 results in the following relationship. P4 > P4' Ato4 <Ato4′ Aco4 <Aco4′ By excluding the photometric values ​​from the brighter area indicated by 358 in the fundus image, the average photometric value P4′ becomes smaller than the average photometric value P4. Therefore, the observation light intensity adjustment value Ato4′ and the shooting light intensity adjustment value Aco4′ become larger than the observation light intensity adjustment value Ato4 and the shooting light intensity adjustment value Aco4. When the light intensity of the fundus observation light source is adjusted based on this observation light intensity adjustment value Ato4′, the area indicated by 357 is illuminated with the expected amount of light (not under-illuminated), resulting in a fundus image with the expected brightness. However, the area indicated by 358 is brightened by flare, so even if the light intensity of the fundus observation light source is adjusted, the fundus image will not have the expected brightness. However, it is possible to accept this due to the flare factor and observe other parts. Overall, it is possible to obtain better fundus observation images. Similarly, it is possible to obtain better fundus photography images.

[0116] In this embodiment, a method for excluding bright outliers was used, but this is not the only method. For example, a method could be used in which the photometric values ​​of bright outliers are weighted when calculating the average value. The important thing is that the average value is calculated in a way that does not become excessively high due to the influence of outliers.

[0117] Finally, the process ends in step S705. The observation light intensity adjustment value Ato and the shooting light intensity adjustment value Aco, calculated in this way, are reflected in the light intensity of the fundus observation light source and the light intensity of the fundus shooting light source. More specifically, in step S608, the control unit 20 adjusts the light intensity of the fundus observation light source by the observation light intensity adjustment value Ato and illuminates the fundus. Also, in step S610, the control unit 20 adjusts the light intensity of the fundus shooting light source by the shooting light intensity adjustment value Aco and emits light.

[0118] In this embodiment, the presence or absence of flare is determined, but this is not the only method. For example, the location and size of the flare may also be included as criteria for determination. Furthermore, the distribution of photometric values ​​may also be included as criteria for determination.

[0119] Furthermore, in this embodiment, the validity or invalidity of each photometric value is initially determined using the information on the locations of the valid and invalid regions stored in the memory unit 29, but this is not the only method. For example, if information such as the location and size of the flare is also detected when detecting the presence or absence of flare, that information can be reflected in the information on the locations of the valid and invalid regions. Therefore, the locations of the valid and invalid regions are changed based on information such as the location and size of the flare. More specifically, the size, location, and shape of the region are changed so that the location where the flare occurs becomes the invalid region. The number of divisions may also be changed so that the location where the flare occurs becomes the invalid region appropriately. By doing this, flares can be appropriately excluded without having to determine each photometric value.

[0120] (Embodiment 3) Embodiment 1 described a method for changing the calculation method of the adjustment value when the eye under examination constricts, reducing the pupil diameter and causing uneven brightness in the fundus image. Embodiment 2 described a method for changing the calculation method of the adjustment value when flare occurs in the fundus image due to the alignment state of the eye under examination, etc. In contrast, Embodiment 3 describes another example of changing the calculation method of the adjustment value, specifically when the eye under examination is pulsating, using Figures 12 to 14.

[0121] The general configuration of the device, the optical configuration of the device, and the configuration of the control unit are the same as in Embodiment 1, so a detailed description is omitted here.

[0122] <Changes in the pulsation and photometric values ​​of the eye being examined> First, we will explain the relationship between the pulsation of the eye under examination and the change in photometric values ​​using the graph in Figure 12. The left vertical axis shows the pupil diameter size, and the right vertical axis shows the average photometric value. The horizontal axis is time, and time progresses from left to right. 1001 shows the change in pupil diameter size, and 1002 shows the change in the average photometric value. Pulsation is the phenomenon in which the pupil unconsciously expands and contracts regularly. The degree of pulsation varies depending on the eye under examination. It also changes depending on the surrounding environment. As shown in 1001, when the eye under examination is pulsating, when the pupil diameter size decreases, the amount of incident light decreases and the fundus image becomes darker. Therefore, the overall photometric value of the fundus image decreases, and the average photometric value also decreases. Conversely, when the pupil diameter size increases, the amount of incident light increases, and the fundus image becomes brighter. Therefore, the overall photometric value of the fundus image increases, and the average photometric value also increases. If the change (variation) in pupil diameter size is large, the change (variation) in the average photometric value will also be large. If the change (variation) in pupil diameter size is small, the change (variation) in the average photometric value will also be small. In this embodiment, a method for selecting the photometric value used to calculate the adjustment value for observed light intensity at an appropriate timing by analyzing the period of pupil diameter variation is described.

[0123] <Fundus Photography Flowchart> Next, the fundus imaging flow according to this embodiment will be explained using Figure 13. Figure 13 is a flowchart showing a series of fundus imaging processes according to this embodiment.

[0124] Steps S801, S802, and S803 are the same as steps S401, S402, and S403 described in Embodiment 1, so a detailed description is omitted here.

[0125] Next, in step S804, the control unit 20 acquires the state of the eye under examination. More specifically, the eye state detection unit 24 detects the pupil size using the anterior eye observation image generated in step S802. The detected pupil size is stored in the memory unit 29. The eye state detection unit 24 continuously performs this pupil size detection. Then, based on the continuous pupil size stored in the memory unit 29, the eye state detection unit 24 detects the time-series change in pupil size and detects whether the eye under examination is pulsating.

[0126] Steps S805 and S806 are the same as steps S405 and S406 described in Embodiment 1, so a detailed description is omitted here.

[0127] Next, in step S807, the control unit 20 calculates the adjustment values ​​for the light intensity of the observation light and the light intensity of the imaging light. The light intensity adjustment value calculation unit 27 calculates the adjustment values ​​for the light intensity of the observation light and the light intensity of the imaging light based on the photometric value information calculated by the photometric value calculation unit 25. A more specific method for calculating the adjustment values ​​will be described in detail below.

[0128] Step S808 is the same as step S408 described in Embodiment 1, so a detailed description is omitted here.

[0129] Next, in step S809, the control unit 20 determines whether to start fundus photography. If the control unit 20 detects that fundus photography should be started, it proceeds to step S810. If the control unit 20 does not detect that fundus photography should be started, it returns to step S804.

[0130] Steps S810, S811, and S812 are the same as steps S410, S411, and S412 described in Embodiment 1, so a detailed description is omitted here.

[0131] <Light intensity adjustment value calculation flow> Next, the flow of the light intensity adjustment value according to this embodiment will be explained using Figure 14. Figure 14 is a flowchart showing a series of processes for calculating the light intensity adjustment value according to this embodiment.

[0132] Step S901 is the same as step S501 described in Embodiment 1, so a detailed description is omitted here.

[0133] Next, in step S902, the control unit 20 determines the pulsation state by analyzing the pupil diameter of the eye being examined. The pulsation state is determined using the value detected by the eye condition detection unit 24 in step S804. The eye condition determination unit 26 determines whether the magnitude of the pulsation is below a threshold. Since there are no eyes that are completely free of pulsation, it determines whether the magnitude of the pulsation affects the brightness of the fundus observation image and fundus photography image. If the magnitude of the pulsation is below the threshold, the eye condition determination unit 26 proceeds to step S904. If the magnitude of the pulsation exceeds the threshold, the eye condition determination unit 26 proceeds to step S903.

[0134] Next, in step S903, the control unit 20 changes the timing of the adjustment value calculation. More specifically, it determines the pupil diameter fluctuation period by analyzing the pupil diameter of the eye being examined. The determined fluctuation period represents the pulse period. The control unit 20 changes the timing of the adjustment value calculation to match the pulse period.

[0135] Next, in step S904, the control unit 20 determines whether to calculate the adjustment value. If the light intensity adjustment value calculation unit 27 determines that it is time to calculate the adjustment value, it proceeds to step S905. If the light intensity adjustment value calculation unit 27 determines that it is not time to calculate the adjustment value, it proceeds to step S906 and terminates. If it is not time to calculate the adjustment value, the observation light intensity adjustment value Ato does not change. Therefore, the light intensity of the fundus observation light source does not change.

[0136] Next, in step S905, the control unit 20 calculates an adjustment value using the photometric value of the effective area. Step S905 is the same as step S505 described in Embodiment 1, so a detailed description is omitted here.

[0137] For example, if there is a pulsation as shown in Figure 12, the average photometric value at the point where the pupil diameter size is in a valley is set to P5, and the observed light intensity adjustment value is set to Ato5. Furthermore, if the average photometric value at the point where the pupil diameter size is in a peak is set to P6, and the observed light intensity adjustment value is set to Ato6, then when the adjustment values ​​are calculated in step S905, the following relationship is obtained.

[0138] P5 <P6 Ato5>Ato6 When the light intensity of the fundus observation light source is adjusted based on the calculated observation light intensity adjustment values ​​Ato5 and Ato6, the light intensity increases when the pupil diameter is at a trough and decreases when the pupil diameter is at a peak. Because these changes in light intensity occur continuously, the brightness of the fundus image is not stable. Furthermore, the subject may experience discomfort because the light illuminating their eyes repeatedly becomes brighter and dimer.

[0139] However, by aligning the timing of the pulse with the timing of the adjustment value calculation according to this flow, the adjustment value can be calculated at the trough of the pupil diameter size. Alternatively, it can be calculated at the peak of the pupil diameter size. Or, it can be calculated at an intermediate size (i.e., at approximately the same pupil diameter size). If the adjustment value can be calculated at the same pupil diameter size, the average photometric value can be stabilized, and the observation light intensity adjustment value will also be stable. If the observation light intensity adjustment value is stable, the light intensity of the fundus observation light source will also be stable, so the brightness of the fundus image will be stable, and a good fundus observation image can be obtained.

[0140] This flow terminates at step S906.

[0141] In this embodiment, pupil size is detected using an anterior eye observation image to determine whether or not it is pulsating, but this is not the only method. As shown in Figure 12, since there is a relationship between changes in pupil size and changes in photometric values, it is also possible to detect whether or not it is pulsating by detecting the time-series change in the average photometric value. More specifically, the light intensity adjustment value calculation unit 27 stores the average photometric value in the storage unit 29 and then detects whether or not the eye under examination is pulsating based on the calculated continuous average photometric value.

[0142] This embodiment includes the following configurations, methods, and programs.

[0143] (Composition 1) A light source unit that emits either an observation light for observing the fundus of the eye under examination or a photographic light for photographing the fundus of the eye under examination, An imaging unit that outputs brightness data of the fundus of the eye being examined by photographing the fundus of the eye being examined, A control unit calculates multiple photometric values ​​using multiple luminance data output from the imaging unit, and determines the amount of light emitted from the light source unit using a photometric value selected by analyzing the multiple photometric values. An ophthalmic device equipped with the following features.

[0144] (Configuration 2) The aforementioned plurality of photometric values ​​are photometric values ​​corresponding to multiple regions in the fundus of the eye being examined, The control unit, An ophthalmic apparatus according to Configuration 1, which determines the amount of light emitted from the light source using a photometric value selected from among the plurality of photometric values ​​based on the results of analyzing the distribution of the plurality of photometric values.

[0145] (Composition 3) A first threshold lower than the average value of the plurality of photometric values ​​and a second threshold higher than the average value of the plurality of photometric values, The control unit, The ophthalmic apparatus according to configuration 2, wherein the amount of light emitted from the light source is determined using a photometric value from the plurality of photometric values ​​that is greater than the first threshold, or the amount of light emitted from the light source is determined using a photometric value from the plurality of photometric values ​​that is less than the second threshold, or the amount of light emitted from the light source is determined using a photometric value between the first threshold and the second threshold.

[0146] (Composition 4) The ophthalmic apparatus according to configuration 3, wherein the photometric values ​​used to determine the amount of light emitted from the light source do not include photometric values ​​corresponding to the optic nerve head of the eye being examined.

[0147] (Composition 5) The control unit, The system further includes a detection unit for detecting information regarding the pupil of the eye being examined, An ophthalmic device according to any one of configurations 1 to 4, which determines the amount of light emitted from the light source unit using a photometric value selected from among the plurality of photometric values ​​by analyzing the plurality of photometric values ​​based on detected information about the pupil.

[0148] (Composition 6) The aforementioned information regarding the pupil is the pupil diameter. The ophthalmic apparatus according to configuration 5, which, when the pupil diameter is smaller than a threshold, determines the amount of light emitted from the light source using a photometric value selected from among the plurality of photometric values ​​by analyzing the plurality of photometric values.

[0149] (Composition 7) The information relating to the pupil is the brightness around the eye being examined. The ophthalmic apparatus according to configuration 5 or 6, which, when the ambient brightness is greater than a predetermined value, determines the amount of light emitted from the light source using a photometric value selected from among the plurality of photometric values ​​by analyzing the plurality of photometric values.

[0150] (Composition 8) The aforementioned multiple photometric values ​​are photometric values ​​calculated using luminance data acquired at different times. The control unit, An ophthalmic device according to any one of configurations 1 to 7, which determines the amount of light emitted from the light source using a photometric value selected from the plurality of photometric values ​​based on the results of analyzing the period of fluctuation of the pupil diameter of the eye being examined.

[0151] (Composition 9) The control unit, By analyzing the aforementioned multiple photometric values, the selected photometric value is used to adjust the amount of light in the observation light so that the photometric value approaches a predetermined value. An ophthalmic apparatus according to any one of configurations 1 to 8, which determines the amount of light of the photographic light based on the amount of light of the adjusted observation light.

[0152] (Composition 10) The aforementioned plurality of photometric values ​​are photometric values ​​corresponding to multiple regions in the fundus of the eye being examined, The control unit, An ophthalmic apparatus according to any one of configurations 1 to 9, which determines the amount of light emitted from the light source using the multiple photometric values ​​that have been weighted based on the results of analyzing the distribution of the multiple photometric values.

[0153] (Method 1) A light source unit that emits either an observation light for observing the fundus of the eye under examination or a photographic light for photographing the fundus of the eye under examination, An imaging unit that photographs the fundus of the eye under examination and outputs brightness data related to the fundus of the eye under examination, A control method for an ophthalmic device comprising, A control method for an ophthalmic device, comprising the steps of calculating multiple photometric values ​​using multiple luminance data output from the imaging unit, and determining the amount of light emitted from the light source unit using a photometric value selected from the multiple photometric values ​​by analyzing them.

[0154] (Program 1) A program that causes a computer to execute the control method described in Method 1.

[0155] (Other embodiments) Furthermore, the disclosed technology can also be realized by performing the following process: that is, the disclosed technology can also be realized by supplying software (programs) that implement one or more functions of the various embodiments described above to a system or device via a network or storage medium, and the computer (or CPU, MPU, etc.) of that system or device reads and executes the program. The computer may have one or more processors or circuits and may include a network of separate computers or separate processors or circuits for reading and executing computer executable instructions. In this case, the processor or circuit may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), or a field-programmable gateway (FPGA). The processor or circuit may also include a digital signal processor (DSP), a dataflow processor (DFP), or a neural processing unit (NPU). [Explanation of symbols]

[0156] 10. Photography Department 20 Control Unit 30 Display section 100 Optical head section 110 Stage Section 120 Base section 130 Face support section

Claims

1. A light source unit that emits either an observation light for observing the fundus of the eye under examination or a photographic light for photographing the fundus of the eye under examination, An imaging unit that outputs brightness data of the fundus of the eye being examined by photographing the fundus of the eye being examined, A control unit calculates multiple photometric values ​​using multiple luminance data output from the imaging unit, and determines the amount of light emitted from the light source unit using a photometric value selected by analyzing the multiple photometric values. An ophthalmic device equipped with the following features.

2. The aforementioned plurality of photometric values ​​are photometric values ​​corresponding to multiple regions in the fundus of the eye being examined, The control unit, The ophthalmic apparatus according to claim 1, which determines the amount of light emitted from the light source using a photometric value selected from among the plurality of photometric values ​​based on the results of analyzing the distribution of the plurality of photometric values.

3. A first threshold lower than the average value of the plurality of photometric values ​​and a second threshold higher than the average value of the plurality of photometric values, The control unit, The ophthalmic apparatus according to claim 2, wherein the amount of light emitted from the light source is determined using a photometric value from the plurality of photometric values ​​that is greater than the first threshold, or the amount of light emitted from the light source is determined using a photometric value from the plurality of photometric values ​​that is less than the second threshold, or the amount of light emitted from the light source is determined using a photometric value between the first threshold and the second threshold.

4. The ophthalmic apparatus according to claim 3, wherein the photometric values ​​used to determine the amount of light emitted from the light source unit do not include photometric values ​​corresponding to the optic nerve head of the eye under examination.

5. The control unit, The system further includes a detection unit for detecting information regarding the pupil of the eye being examined, The ophthalmic apparatus according to claim 1, which determines the amount of light emitted from the light source unit using a photometric value selected from among the plurality of photometric values ​​by analyzing the plurality of photometric values ​​based on the detected pupil information.

6. The aforementioned information regarding the pupil is the pupil diameter. The ophthalmic apparatus according to claim 5, wherein, when the pupil diameter is smaller than a threshold, the amount of light emitted from the light source is determined using a photometric value selected from among the plurality of photometric values ​​by analyzing the plurality of photometric values.

7. The information relating to the pupil is the brightness around the eye being examined. The ophthalmic apparatus according to claim 5, wherein, when the ambient brightness is greater than a predetermined value, the amount of light emitted from the light source is determined using a photometric value selected from among the plurality of photometric values ​​by analyzing the plurality of photometric values.

8. The aforementioned multiple photometric values ​​are photometric values ​​calculated using luminance data acquired at different times. The control unit, The ophthalmic apparatus according to claim 1, which determines the amount of light emitted from the light source using a photometric value selected from the plurality of photometric values ​​based on the results of analyzing the period of fluctuation of the pupil diameter of the eye being examined.

9. The control unit, By analyzing the aforementioned multiple photometric values, the selected photometric value is used to adjust the amount of light in the observation light so that the photometric value approaches a predetermined value. The ophthalmic apparatus according to claim 1, which determines the amount of light of the photographic light based on the amount of light of the adjusted observation light.

10. The aforementioned plurality of photometric values ​​are photometric values ​​corresponding to multiple regions in the fundus of the eye being examined, The control unit, The ophthalmic apparatus according to claim 1, which determines the amount of light emitted from the light source using the plurality of photometric values ​​that have been weighted based on the results of analyzing the distribution of the plurality of photometric values.

11. A light source unit that emits either an observation light for observing the fundus of the eye under examination or a photographic light for photographing the fundus of the eye under examination, An imaging unit that photographs the fundus of the eye under examination and outputs brightness data related to the fundus of the eye under examination, A control method for an ophthalmic device comprising, A control method for an ophthalmic device, comprising the steps of calculating multiple photometric values ​​using multiple luminance data output from the imaging unit, and determining the amount of light emitted from the light source unit using a photometric value selected from the multiple photometric values ​​by analyzing them.

12. A program that causes a computer to execute the control method described in claim 11.

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