ophthalmic devices

Abstract

This invention provides a new technology for optimally achieving small pupil imaging without complicating control and avoiding loss of intraocular information. [Solution] The ophthalmic device includes an objective lens, an illumination optical system, an optical scanner, an imaging optical system, and a pupil-splitting member. The illumination optical system includes an illumination diaphragm positioned approximately optically conjugate to the pupil of the eye under examination and having one or more illumination apertures, and emits slit-shaped illumination light. The optical scanner is positioned approximately optically conjugate to the pupil and deflects the illumination light, guiding it to the eye under examination via the objective lens. The imaging optical system guides the reflected light of the illumination light that has passed through the objective lens to an image sensor. The pupil-splitting member includes a imaging diaphragm positioned approximately optically conjugate to the pupil and having one or more imaging apertures, and spatially separates the optical paths of the illumination optical system and the imaging optical system. The illumination aperture and the imaging aperture are formed such that the pupil separation amount is greater than a predetermined central ghost generation suppression threshold.

Description

[Technical Field]

[0001] This invention relates to an ophthalmic device. [Background technology]

[0002] In recent years, screening tests using ophthalmic devices have been performed. Such ophthalmic devices are also expected to be used for self-examination, and further miniaturization and weight reduction are desired.

[0003] For example, Patent Documents 1 and 2 disclose an ophthalmic device configured to pattern-illuminate the fundus of the eye under examination using a slit-shaped illumination light and to detect the reflected light with an image sensor. This ophthalmic device can acquire a clear image of the fundus with a simple configuration by adjusting the illumination pattern and the timing of light reception by the image sensor.

[0004] In such ophthalmic devices, it is necessary to introduce illumination light into the eye through the pupil of the eye being examined, and to emit reflected light (backlight, fundus reflection) from the fundus through the pupil. Therefore, in ophthalmic devices, the image of the illumination aperture through which the illumination light passes and the image of the imaging aperture (photoreceiving aperture) through which the reflected light passes are separated at the pupillary conjugate plane, which is optically approximately conjugate to the pupil of the eye being examined.

[0005] For example, Patent Document 3 discloses an ophthalmic device configured to illuminate the fundus with slit-shaped illumination light that has passed through two illumination apertures, and to receive reflected light from the fundus that has passed through a single imaging aperture. In this ophthalmic device, slit-shaped illumination light is generated by irradiating illumination light into a slit that is formed to suppress the generation of flare.

[0006] For example, Patent Document 4 discloses an ophthalmic device configured to position both the image of the illumination aperture and the image of the imaging aperture within the pupil of the eye being photographed by shifting the alignment reference position relative to the eye being examined according to the size of the pupil diameter. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent No. 7831106 [Patent Document 2] U.S. Patent No. 8,237,835 [Patent Document 3] International Publication No. 2021 / 205965 [Patent Document 4] Japanese Patent Publication No. 2020-6172 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, the ophthalmic devices disclosed in Patent Documents 1 to 3 have a problem in that when photographing eyes with small pupil diameters, central ghosting (objective lens surface flare) or black spot shadows caused by a black spot plate placed to suppress the occurrence of central ghosting occurs.

[0009] Figures 14A to 14C show schematic diagrams illustrating the operation of conventional ophthalmic equipment when photographing the fundus of an eye under examination. Figure 14A schematically represents the illumination beam and imaging beam when photographing the fundus of an eye under examination. Figure 14B shows an example of a fundus image in which a central ghost as an artifact is depicted. Figure 14C shows an example of a fundus image in which a black spot shadow as an artifact is depicted. Note that Figures 14B and 14C show examples of fundus images formed based on the reception results of imaging light that passed through a single imaging aperture, after the fundus was illuminated with illumination light that passed through two illumination apertures.

[0010] As shown in Figure 14A, the illumination beam IL that illuminates the fundus of the eye under examination passes through the objective lens OBJ positioned on the optical axis O and is guided to the fundus through the pupil of the eye under examination. The imaging beam SL, which is the reflected light beam of the illumination beam IL reflected from the fundus, exits the eye through the pupil, passes through the objective lens OBJ, and is guided to the receiving light path (imaging light path).

[0011] At a position approximately conjugate to the pupil of the eye under examination, the illumination beam IL and the imaging beam SL are separated from each other. However, if the eye under examination has a small pupil, the illumination beam IL and the imaging beam SL entering the eye through the pupil are close together near the optical axis. As a result, reflected light from the lens surface SF (the lens surface near the apex) on the optical axis O of the objective lens OBJ is more likely to enter the light-receiving optical path, which can cause central ghosting as an artifact. In this case, as shown in Figure 14B, the fundus image IMG10 of the eye under examination shows central ghosts CG1 and CG2 corresponding to the two illumination apertures. Each of the regions of central ghosts CG1 and CG2 is a region where fundus information is completely lost.

[0012] Therefore, in order to prevent reflected light, which is a cause of central ghosting, from being guided into the light-receiving path, ophthalmic equipment generally places a black spot plate in the illumination path at a position that is approximately optically conjugate to the apex of the objective lens OBJ, thereby blocking reflected light from the lens surface SF of the objective lens OBJ. However, if the eye under examination is highly myopic, the position that is optically conjugate to the fundus shifts, and black spot shadows as artifacts may occur due to the black spot plate. In this case, as shown in Figure 14C, the fundus image IMG11 of the eye under examination shows black spot shadows BS1 and BS2 corresponding to the two illumination apertures. Each of the regions of black spot shadows BS1 and BS2 is in a black-crushed state, and is a region where fundus information is completely lost.

[0013] On the other hand, the method disclosed in Patent Document 4 may allow for a configuration that does not require a black spot plate. However, if the eye being examined has a small pupil, it is necessary to change the alignment reference position, which complicates the control process.

[0014] As described above, conventional methods have problems such as the loss of fundus information in at least part of the imaging area due to the deterioration of fundus image quality caused by the depiction of central ghosting or black spot shadows when the eye under examination has a small pupil, or the control becoming complicated in order to eliminate the need for a black spot plate. These problems are not limited to when the imaging site is the fundus, but are also the same when imaging the inside of the eye under examination.

[0015] The present invention has been made in view of the above circumstances, and one of its objects is to provide a new technology for suitably realizing small pupil imaging while avoiding loss of intraocular information without complicating control.

Means for Solving the Problems

[0016] One aspect of some embodiments includes an objective lens, an illumination diaphragm disposed at a position optically substantially conjugate with the pupil of the eye to be examined and having one or more illumination apertures formed therein, and an illumination optical system that irradiates slit-shaped illumination light; an optical scanner disposed at a position optically substantially conjugate with the pupil, that deflects the illumination light, and that guides the illumination light to the eye to be examined through the objective lens; an imaging optical system that guides return light of the illumination light from the eye to be examined that has passed through the objective lens to an image sensor disposed at a position optically substantially conjugate with the imaging site of the eye to be examined; and a pupil splitting member that includes an imaging diaphragm disposed at a position optically substantially conjugate with the pupil and having one or more imaging apertures formed therein, and that spatially separates the optical path of the illumination optical system and the optical path of the imaging optical system. The illumination aperture and the imaging aperture are formed such that a pupil separation amount, which is the shortest distance in the arrangement direction between the image of the illumination aperture and the image of the imaging aperture on a pupil conjugate plane at a position optically substantially conjugate with the pupil, is greater than a predetermined center ghost generation suppression threshold value. The present invention relates to an ophthalmic device.

Advantages of the Invention

[0017] According to this invention, it is possible to provide a new technology for suitably realizing small pupil imaging while avoiding loss of intraocular information without complicating control.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram showing a configuration example of an optical system of an ophthalmic device according to an embodiment. [Figure 2] It is a schematic diagram showing a configuration example of an optical system of an ophthalmic device according to an embodiment. [Figure 3] It is a schematic diagram showing a configuration example of an optical system of an ophthalmic device according to an embodiment. [Figure 4] This is a schematic diagram illustrating the configuration of the optical system of the ophthalmic apparatus according to the embodiment. [Figure 5] This is an explanatory diagram of the operation of an ophthalmic device according to an embodiment. [Figure 6] This is an explanatory diagram of the operation of an ophthalmic device according to an embodiment. [Figure 7] This is an explanatory diagram of the operation of an ophthalmic device according to an embodiment. [Figure 8] This is a schematic diagram illustrating the configuration of the optical system of the ophthalmic apparatus according to the embodiment. [Figure 9] This is a schematic diagram illustrating the configuration of the optical system of the ophthalmic apparatus according to the embodiment. [Figure 10] This is a schematic diagram illustrating the configuration of the optical system of the ophthalmic apparatus according to the embodiment. [Figure 11] This is a schematic diagram showing an example of the configuration of the processing system of an ophthalmic device according to the embodiment. [Figure 12] This is a flowchart showing an example of operation of the ophthalmic device according to the embodiment. [Figure 13A] This is an explanatory diagram of the operation of an ophthalmic device according to an embodiment. [Figure 13B] This is an explanatory diagram of the operation of an ophthalmic device according to an embodiment. [Figure 14A] This is a schematic diagram illustrating conventional ophthalmic equipment. [Figure 14B] This is a schematic diagram illustrating conventional ophthalmic equipment. [Figure 14C] This is a schematic diagram illustrating conventional ophthalmic equipment. [Modes for carrying out the invention]

[0019] An example of an embodiment of the ophthalmic apparatus according to this invention will be described in detail with reference to the drawings. It is possible to appropriately refer to the contents of the documents cited in this specification as the contents of the following embodiments.

[0020] The ophthalmic apparatus according to this embodiment illuminates a predetermined shooting range (illumination area) in the shooting area of ​​the eye under examination by moving the irradiation position (illumination area, irradiation range) of a slit-shaped illumination light through the objective lens, and receives the reflected light from the shooting area using an image sensor. The result of receiving the reflected light is read out from a light-receiving element at the reflected light receiving position corresponding to the irradiation position of the illumination light, in synchronization with the timing of the movement of the irradiation position of the illumination light.

[0021] In such ophthalmic devices, pupil separation is performed by spatially separating the image of the illumination aperture through which illumination light passes and the image of the imaging aperture (photoreceiving aperture) through which the reflected light passes, at the pupil conjugate plane located at a position optically conjugate to the pupil of the eye being examined. In this embodiment, attention is paid to the pupil separation amount, which is the shortest distance in the alignment direction (separation direction) between the image of the illumination aperture and the image of the imaging aperture. The alignment direction is the direction in which the distance between the edge of the image of the illumination aperture and the edge of the image of the imaging aperture is shortest at the pupil conjugate plane. By positioning the illumination aperture and the imaging aperture to achieve an appropriate pupil separation amount, it is possible to prevent the intrusion of reflected light from the lens surface of the objective lens, which is a cause of central ghosting (objective lens surface flare), into the optical path of the imaging optical system without the need for a black spot plate. Similarly, even if the eye being examined has a small pupil, it becomes possible to obtain images useful for diagnosing small pupils.

[0022] Specifically, by positioning the illumination aperture and the imaging aperture so that the pupil separation amount is greater than a predetermined central ghosting suppression threshold, the occurrence of central ghosting (objective lens surface flare) can be suppressed. Furthermore, by positioning the illumination aperture and the imaging aperture so that the pupil separation amount is smaller than a predetermined small pupil imaging threshold, it becomes possible to keep the illumination and imaging beams within a range that enables small pupil imaging, thereby enabling small pupil imaging. For example, by optically designing the system so that the pupil separation amount is greater than a predetermined central ghosting suppression threshold and smaller than a predetermined small pupil imaging threshold, it becomes possible to suppress central ghosting and perform small pupil imaging without providing a black spot plate. As a result, small pupil imaging can be suitably achieved without complicating control and while avoiding the loss of intraocular information.

[0023] More specifically, the ophthalmic apparatus according to the embodiment includes an objective lens, an illumination optical system, an optical scanner, an imaging optical system, and a pupil-splitting member. The illumination optical system includes an illumination diaphragm positioned approximately optically conjugate to the pupil of the eye under examination and having one or more illumination apertures formed thereon, and is configured to emit slit-shaped illumination light. The optical scanner is positioned approximately optically conjugate to the pupil and is configured to deflect the illumination light and guide it to the eye under examination via the objective lens. The imaging optical system is configured to guide the reflected light of the illumination light from the eye under examination via the objective lens to an image sensor positioned approximately optically conjugate to the imaging site of the eye under examination (e.g., the fundus). The pupil-splitting member includes an imaging diaphragm positioned approximately optically conjugate to the pupil of the eye under examination and having one or more imaging apertures formed thereon, and is configured to spatially separate the optical path of the illumination optical system and the optical path of the imaging optical system. In this case, the illumination aperture and the imaging aperture are formed such that the pupil separation amount, which is the shortest distance in the alignment direction between the image of the illumination aperture and the image of the imaging aperture at the pupil conjugate plane at a position optically approximately conjugate to the pupil of the eye being examined, is greater than a predetermined central ghost generation suppression threshold.

[0024] The reflected light from the imaging site is the scattered (reflected) light from the illumination light that irradiates the eye being examined. In some embodiments, the reflected light from the imaging site includes the scattered (reflected) light from the illumination light from the imaging site, and fluorescence and its scattered light, which are excited by the illumination light that irradiates the imaging site.

[0025] The shape of the illumination aperture may be any shape. The shape of the imaging aperture may be any shape. In some embodiments, the illumination optical system includes an optical scanner. In some embodiments, the imaging optical system includes an image sensor.

[0026] This configuration allows for spatial separation of illumination light and reflected light (photographic light) on the lens surface and within the objective lens. As a result, it is possible to prevent reflected light from the lens surface of the objective lens, which is a cause of central ghosting (objective lens surface flare), from entering the optical path of the imaging optical system. Therefore, it becomes unnecessary to provide a black spot plate, and it becomes possible to acquire an image of the eye under examination that does not suffer from black spot shadows (i.e., intraocular information such as fundus information is not lost).

[0027] In some embodiments, the illumination aperture and the imaging aperture are formed such that the pupil separation amount is smaller than a predetermined threshold for small pupil imaging.

[0028] With this configuration, even when photographing eyes with small pupils, it becomes possible to obtain intraocular images of the eye being examined that allow for appropriate diagnosis, without complicating the control system.

[0029] In some embodiments, the image sensor is configured to capture the light reception result in a virtual aperture area of ​​the light-receiving surface corresponding to the illumination area of ​​the imaging area, which is moved in a predetermined scanning direction by the optical scanner, using a rolling shutter method.

[0030] This makes it possible to acquire clear intraocular images, even when photographing eyes with small pupils, without complicating control or being affected by unwanted scattered light.

[0031] In some embodiments, the imaging site is the fundus of the eye under examination. The imaging site in the embodiment may be the anterior segment or the posterior segment. The anterior segment includes the cornea, iris, lens, ciliary body, and zonules of Zinn. The posterior segment includes the vitreous humor, fundus, or its vicinity (retina, choroid, sclera, etc.).

[0032] The control method for the ophthalmic device according to the embodiment includes one or more steps performed in controlling the ophthalmic device according to the embodiment. The program (computer program) / instruction according to the embodiment causes a computer (processor) to execute each step of the control method for the ophthalmic device according to the embodiment. The computer program product according to the embodiment includes a computer program / instruction. The computer program product realizes each step of the control method for the ophthalmic device according to the embodiment when the computer program / instruction is executed by the processor. The recording medium according to the embodiment is a computer-readable non-temporary storage medium (recording medium) on which the program according to the embodiment is recorded (stored). The computer-readable storage medium according to the embodiment stores the computer program / instruction. The computer-readable storage medium realizes each step of the control method for the ophthalmic device according to the embodiment when the computer program / instruction is executed by the processor.

[0033] In this specification, a processor includes, for example, circuits such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), and a programmable logic device (e.g., SPLD (Simple Programmable Logic Device), CPLD (Complex Programmable Logic Device), FPGA (Field Programmable Gate Array)). The processor realizes the functions according to the embodiment by, for example, reading and executing a program stored in a memory circuit or storage device. The memory circuit or storage device may be included in the processor. Alternatively, the memory circuit or storage device may be provided outside the processor.

[0034] The following description focuses on the case where the imaging site is the fundus. However, the following embodiments can also be applied to cases where the imaging site is a part other than the fundus.

[0035] Furthermore, the following description will focus on the case where the illumination aperture has a single illumination aperture and the photographic aperture has a single photographic aperture. However, the following embodiments can also be applied to cases where at least one of the illumination aperture and the photographic aperture has two or more apertures.

[0036] [Optical System Configuration] Figures 1 to 3 show schematic diagrams of the optical system configuration of the ophthalmic apparatus according to the embodiment. Figure 1 shows an example of the optical system configuration of the ophthalmic apparatus according to the embodiment. In Figure 1, the fundus conjugate position P, which is the optically conjugate position of the fundus Ef of the eye under examination, and the pupil (iris) conjugate position Q, which is the optically conjugate position of the pupil (iris) Eu of the eye under examination, are shown. Figure 2 schematically shows an example of the configuration of the iris diaphragm 21 in Figure 1 when viewed from the direction of the optical axis O. Figure 3 schematically shows the pupil dividing member 45 in Figure 1, with a front view when viewed from the direction of the optical axis O and a side view when viewed from a direction perpendicular to the optical axis O corresponding. In Figures 1 to 3, the same parts are denoted by the same reference numerals, and explanations are omitted as appropriate.

[0037] An ophthalmic apparatus 1 according to this embodiment includes a light source 10, an illumination optical system 20, an optical scanner 30, a projection optical system 35, an imaging optical system 40, and an imaging device 50. In some embodiments, the illumination optical system 20 includes at least one of the light source 10, the optical scanner 30, and the projection optical system 35. In some embodiments, the imaging optical system 40 includes an imaging device 50. In some embodiments, the projection optical system 35 includes an optical scanner 30.

[0038] (light source 10) Light source 10 includes a visible light source that generates light in the visible region. For example, light source 10 generates light having a central wavelength in the wavelength range of 420 nm to 700 nm. Such light source 10 includes, for example, an LED (Light Emitting Diode), an LD (Laser Diode), a halogen lamp, or a xenon lamp. In some embodiments, light source 10 includes a white light source or a light source capable of outputting light for each of the RGB color components. In some embodiments, light source 10 includes a light source capable of switching between outputting light in the infrared region and light in the visible region. For example, light source 10 is positioned optically non-conjugate to the fundus Ef and the iris, respectively.

[0039] (Illumination optical system 20) The illumination optical system 20 generates a slit-shaped illumination beam using light from the light source 10. The illumination optical system 20 guides the generated illumination beam to the optical scanner 30.

[0040] The illumination optical system 20 includes an iris diaphragm 21, a slit 22, and a relay lens 23. Light from the light source 10 passes through an aperture (one or more apertures) formed in the iris diaphragm 21, through an aperture formed in the slit 22, and through the relay lens 23. The relay lens 23 includes one or more lenses. The light that has passed through the relay lens 23 is guided to the optical scanner 30.

[0041] (Iris diaphragm 21) The iris diaphragm 21 (specifically, the aperture described later) can be positioned as an illumination diaphragm at a position that is approximately optically conjugate to the iris (pupil) Eu of the eye E under examination (the pupil (iris) conjugate position Q or its vicinity). The iris diaphragm 21 has one or more apertures (illumination apertures) formed at positions eccentric from the optical axis O. In this embodiment, the iris diaphragm 21 has a single aperture formed at a position eccentric from the optical axis O.

[0042] For example, as shown in Figure 2, a rectangular aperture 21A is formed in the iris diaphragm 21 at a position away from the optical axis O of the illumination optical system 20. The shape of the aperture 21A may be rectangular or parallelogram. Alternatively, the shape of the aperture 21A may be triangular, a polygon with pentagons or more, elliptical, or circular. The aperture formed in the iris diaphragm 21 defines the incident position (incidence shape) of the illumination light in the iris (pupil) Eu of the eye under examination E. For example, by forming the aperture 21A as shown in Figure 2, when the pupil center of the eye under examination E is positioned on the optical axis O, it is possible to cause the illumination light to enter the eye from an eccentric position from the pupil center.

[0043] Furthermore, by changing the relative position between the light source 10 and the aperture formed in the iris diaphragm 21, it is possible to change the light intensity distribution of the light passing through the aperture formed in the iris diaphragm 21. For example, the relative position between the light source 10 and the aperture formed in the iris diaphragm 21 can be changed based on the diopter (refractive index) of the eye under examination E, or image quality evaluation information for at least a portion of the fundus image obtained by the ophthalmic device 1.

[0044] (Slit 22) The slit 22 (specifically, the opening described later) can be positioned at a location that is approximately optically conjugate to the fundus Ef of the eye under examination (the fundus conjugate position P or its vicinity). The slit 22 has a single slit-shaped (line-shaped) opening (slit opening). For example, the slit 22 has an opening in a direction corresponding to the line direction (row direction) read out by the rolling shutter method from the image sensor 51, which will be described later. For example, the slit 22 has an opening such that the direction perpendicular to the direction of movement of the receivable range of the reflected light (virtual opening range) on the light-receiving surface of the image sensor 51 is the slit direction (longitudinal direction of the slit). The opening formed in the slit 22 defines the illumination pattern of the illumination light at the fundus Ef of the eye under examination.

[0045] The slit 22 is movable in the optical axis direction of the illumination optical system 20 by a moving mechanism (moving mechanism 22D described later). The moving mechanism moves the slit 22 in the optical axis direction under control from the control unit 100 described later. For example, the control unit 100 controls the moving mechanism according to the state of the eye E under examination. This makes it possible to move the position of the slit 22 according to the state of the eye E under examination (specifically, refractive power, shape of fundus Ef).

[0046] In some embodiments, the slit 22 is configured to change at least one of the position and shape of the aperture without being moved in the optical axis direction, depending on the state of the eye E being examined. Such a function of the slit 22 is realized, for example, by a liquid crystal shutter.

[0047] Light from the light source 10 that passes through the opening formed in the iris diaphragm 21 is output as slit-shaped illumination light by passing through the opening formed in the slit 22. The slit-shaped illumination light passes through the relay lens 23 and is guided to the optical scanner 30.

[0048] (Optical scanner 30) The optical scanner 30 (specifically, the deflection surface) is positioned at a location that is approximately optically conjugate to the pupil (iris) Eu of the eye under examination (the pupil (iris) conjugate position Q or its vicinity). The optical scanner 30 deflects the slit-shaped illumination light (the slit-shaped light that has passed through the opening formed in the slit 22) that has been transmitted through the relay lens 23. Specifically, the optical scanner 30 deflects the slit-shaped illumination light while changing the deflection angle within a predetermined deflection angle range, with the pupil (iris) Eu or its vicinity of the eye under examination as the scan center position, and guides the deflected illumination light to the projection optical system 35. As a result, a predetermined illumination range in the fundus Ef is sequentially illuminated by the slit-shaped illumination light.

[0049] The optical scanner 30 is capable of deflecting illumination light in one or two dimensions. When deflecting in one dimension, the optical scanner 30 includes a galvanoscanner that deflects the illumination light within a predetermined deflection angle range with respect to a predetermined deflection reference direction. When deflecting in two dimensions, the optical scanner 30 includes a first galvanoscanner and a second galvanoscanner. The first galvanoscanner deflects the illumination light so as to move the illumination position of the illumination light in a horizontal direction perpendicular to the optical axis of the illumination optical system 20. The second galvanoscanner deflects the illumination light deflected by the first galvanoscanner so as to move the illumination position of the illumination light in a vertical direction perpendicular to the optical axis of the illumination optical system 20. Examples of scanning modes for moving the illumination position of the illumination light by the optical scanner 30 include horizontal scanning, vertical scanning, cross scanning, radial scanning, circular scanning, concentric scanning, and spiral scanning.

[0050] (Projection optical system 35) The projection optical system 35 guides the illumination light deflected by the optical scanner 30 to the fundus Ef of the eye E under examination. In this embodiment, the projection optical system 35 guides the illumination light deflected by the optical scanner 30 to the fundus Ef via an optical path coupled with the optical path of the imaging optical system 40 by a pupil splitting member 45, which will be described later as an optical path coupling member.

[0051] The projection optical system 35 includes a relay lens 41, a reflective mirror 42, and a relay lens 43. Each of the relay lenses 41 and 43 includes one or more lenses.

[0052] In the projection optical system 35, the illumination light deflected by the optical scanner 30 passes through the relay lens 41, is reflected by the reflection mirror 42, passes through the relay lens 43, and is guided to the pupil division member 45.

[0053] In some embodiments, the illumination optical system 20 is configured to include an optical scanner 30 and a projection optical system 35.

[0054] (Imaging optical system 40) The imaging optical system 40 guides the illumination light that has been guided by the projection optical system 35 to the fundus Ef of the eye under examination E, and also guides the reflected light from the fundus Ef to the imaging device 50.

[0055] In the imaging optical system 40, the optical path of the illumination light from the projection optical system 35 and the optical path of the reflected illumination light from the fundus Ef are coupled. By using the pupil splitting member 45 as an optical path coupling member to couple these optical paths, it is possible to spatially split (pupillary split) the optical path of the illumination light and the optical path of its reflected light at the pupil conjugate plane at a position optically conjugate to the pupil Eu of the eye under examination E.

[0056] The imaging optical system 40 includes a pupil-splitting member 45, an objective lens 46, a focusing lens 47, a relay lens 48, and an imaging lens 49. The relay lens 48 includes one or more lenses.

[0057] (Pupil division member 45) The pupil-splitting member 45 includes a photographic aperture and spatially separates the optical path of the illumination optical system 20 (the optical path of illumination light from the projection optical system 35) from the optical path of the photographic optical system 40. In this embodiment, the pupil-splitting member 45 is a reflective mirror with a photographic aperture. Here, the photographic aperture is positioned at a position optically conjugate to the pupil Eu of the eye under examination (pupil conjugate position Q or nearby), and has one or more apertures (light-receiving aperture, photographic aperture) formed at a position eccentric from the optical axis of the photographic optical system 40. In this embodiment, a single aperture is formed in the photographic aperture. Furthermore, the pupil-splitting member 45 includes a reflective mirror that deflects the illumination light deflected by the optical scanner 30 toward the eye under examination E (specifically, the objective lens 46).

[0058] The pupil-splitting member 45 couples the optical path of the illumination light from the projection optical system 35 (illumination optical system 20) and the optical path of the imaging optical system 40 substantially coaxially. Therefore, the optical axis of the common optical path of the illumination light and the return light in the imaging optical system 40 substantially coincides with the optical axis O of the illumination optical system 20.

[0059] Alternatively, the pupil-splitting member 45 includes a base body 45a and a reflective member 45b, as shown in Figure 3, for example. In this case, the base body 45a has, for example, one or more apertures (light-receiving aperture, imaging aperture). In the configuration shown in Figure 3, the one or more apertures formed in the base body 45a function as imaging apertures. In this embodiment, the base body 45a has a single aperture 45A. The reflective member 45b deflects the illumination light from the projection optical system 35 toward the objective lens 46.

[0060] In some embodiments, the base 45a includes a photographic aperture in which a single aperture 45A is formed.

[0061] In Figure 3, a reflective member 45b is provided on the surface of the base body 45a. The base body 45a and the reflective member 45b are provided with an aperture 45A at a position eccentric from the optical axis O of the imaging optical system 40. For example, the pupil division member 45 may be a hole mirror in which a reflective member 45b is provided around an aperture 45A formed as an imaging aperture. For example, the pupil division member 45 may have a reflective member 45b provided around an aperture 45A formed in an imaging aperture provided on the base body 45a.

[0062] In some embodiments, a reflective member 45b is formed by depositing a reflective film onto the surface of a substrate 45a. The reflective film may be a metal film or a dielectric multilayer film. The reflective film is formed by depositing a metal film (mirror deposition) onto the surface of the substrate 45a, or by depositing a dielectric in multiple layers onto the surface of the substrate 45a.

[0063] In some embodiments, the base 45a may be a transparent member. In this case, an opening 45A may be formed in the reflective member 45b provided on the surface of the base 45a.

[0064] When the optical system is aligned with the eye E under examination, the pupil division member 45 is positioned at a location corresponding to the optical axis O that is approximately conjugate to the pupil Eu of the eye E under examination. At this time, the illumination light from the projection optical system 35 is reflected by the reflecting member 45b and guided to the objective lens 46. The reflected light from the illumination light of the eye E under examination passes through the aperture 45A and is guided to the imaging optical system 40. In this embodiment, the pupil division member 45 spatially divides the illumination light and the reflected light from the eye under examination at the pupil conjugate plane at a location that is approximately conjugate to the pupil of the eye E under examination.

[0065] Figure 4 shows an explanatory diagram of the pupillary conjugate surface according to the embodiment. Figure 4 schematically represents the image IPI of the illumination aperture and the image SPI of the imaging aperture in the pupillary conjugate surface PL. In Figure 4, the same reference numerals are used for parts that are the same as in Figures 1 to 3, and explanations are omitted as appropriate.

[0066] By performing pupil division with the pupil division member 45 described above, the illumination aperture image IPI, which is the image of the aperture formed in the iris diaphragm 21, and the imaging aperture image SPI, which is the image of the aperture formed in the imaging diaphragm (pupil division member 45), are spatially separated at the pupil conjugate plane PL. At this time, the illumination aperture image IPI and the imaging aperture image SPI are separated by a pupil separation amount GP, which corresponds to the shortest distance in the alignment direction (separation direction) between the illumination aperture image IPI and the imaging aperture image SPI.

[0067] By increasing the pupil separation amount GP, the overlap of the light beam cross-sections of the illumination light and the reflected light on the lens surface or inside the objective lens 46 can be reliably avoided, and the occurrence of central ghosting can be suppressed without providing a black spot plate. Therefore, it is desirable that an opening 21A (or one or more openings) is formed in the iris diaphragm 21 and an opening 45A (or one or more openings) is formed in the pupil dividing member 45 (photographic diaphragm) so that the pupil separation amount GP is greater than a predetermined central ghosting suppression threshold.

[0068] In this case, as shown in Figure 3, it is desirable that an opening 21A (or one or more openings) is formed in the iris diaphragm 21 and an opening 45A (or one or more openings) is formed in the pupil division member 45 so that the pupil separation amount GP is approximately constant in a direction perpendicular to the alignment direction. Here, the alignment direction is the alignment direction of the image of the opening 21A (or one or more openings) formed in the iris diaphragm 21 and the image of the opening 45A (or one or more openings) formed in the pupil division member 45 on the pupil conjugate plane. This makes it possible to maximize the pupil separation amount GP while ensuring sufficient light by increasing the size of the openings 21A and 45A.

[0069] On the other hand, increasing the pupil separation amount GP increases the size of the pupil diameter that can be photographed, making it impossible to photograph eyes with small pupils. Therefore, it is desirable that an opening 21A (or one or more openings) is formed in the iris diaphragm 21 and an opening 45A (or one or more openings) is formed in the pupil dividing member 45 (photography diaphragm) so that the pupil separation amount GP is smaller than a predetermined threshold for photographing small pupils.

[0070] The threshold for suppressing central ghosting and the threshold for enabling imaging of small pupils will be discussed later.

[0071] (Focusing lens 47) The focusing lens 47 is movable in the optical axis direction of the imaging optical system 40 by a moving mechanism (not shown). The moving mechanism receives control from the control unit 100 (described later) and moves the focusing lens 47 in the optical axis direction. This allows the reflected light of the illumination light that has passed through the aperture 45A formed in the pupil division member 45 to be imaged onto the light-receiving surface of the image sensor 51 of the imaging device 50, depending on the state of the eye E under examination.

[0072] In such an imaging optical system 40, illumination light from the projection optical system 35 is reflected by the reflecting member 45b toward the objective lens 46. The illumination light reflected by the reflecting member 45b is refracted by the objective lens 46 and enters the eye through the pupil of the eye under examination E, illuminating the fundus Ef of the eye under examination E.

[0073] The reflected light from the retinal ef is refracted by the objective lens 46, passes through the aperture 45A formed in the pupil division member 45, passes through the focusing lens 47, passes through the relay lens 48, and is imaged by the imaging lens 49 onto the light-receiving surface of the image sensor 51 of the imaging device 50.

[0074] (Imaging device 50) The imaging device 50 includes an image sensor 51 that receives the reflected light of illumination light that has been guided from the fundus Ef of the eye E under examination through the imaging optical system 40. The imaging device 50 can receive control from the control unit 100 (described later) and output the result of the reflected light reception.

[0075] (Image sensor 51) The image sensor 51 functions as a pixelated light receiver. The light-receiving surface (detection surface, imaging surface) of the image sensor 51 can be positioned in a location that is approximately optically conjugate to the fundus Ef.

[0076] The light reception results from the image sensor 51 are captured and read out using a rolling shutter method. In some embodiments, the control unit 100, described later, controls the readout of the light reception results by controlling the image sensor 51. In some embodiments, the image sensor 51 can automatically output light reception results for a predetermined line along with information indicating the light reception position.

[0077] Such an image sensor 51 is a complementary metal-oxide-semiconductor (CMOS) image sensor. In this case, the image sensor 51 includes a plurality of pixels arranged in two dimensions, a plurality of vertical signal lines, and a horizontal signal line. Each pixel includes a photodiode (light-receiving element) and a capacitor. The plurality of vertical signal lines are provided for each group of pixels in the column direction (vertical direction) orthogonal to the row direction (horizontal direction). Each vertical signal line is selectively electrically connected to a group of pixels where a charge corresponding to the light-receiving result has been accumulated. The horizontal signal line is selectively electrically connected to the plurality of vertical signal lines. Each pixel accumulates a charge corresponding to the light-receiving result of the reflected light, and the accumulated charge is read out sequentially, for example, for each group of pixels in the row direction. For example, for each line in the row direction, a voltage corresponding to the charge accumulated in each pixel is supplied to the vertical signal line. The plurality of vertical signal lines are selectively electrically connected to the horizontal signal line. By sequentially performing the above row-direction line-by-line read operation in the vertical direction, it is possible to read the light reception results of multiple pixels arranged in a two-dimensional array.

[0078] By capturing (reading out) the reflected light from such an image sensor 51 using a rolling shutter method, a light-receiving image corresponding to a desired virtual aperture shape extending in the low direction is obtained. Such control is disclosed, for example, in U.S. Patent No. 8,237,835.

[0079] Figure 5 shows an explanatory diagram of the operation of the ophthalmic device 1 according to the embodiment. Figure 5 schematically represents the irradiation range IP of the slit-shaped illumination light irradiated onto the fundus Ef and the virtual aperture range (receivable range) OP on the light-receiving surface SR of the image sensor 51.

[0080] For example, the control unit 100, described later, deflects the slit-shaped illumination light formed by the illumination optical system 20 using the optical scanner 30. As a result, in the fundus Ef, the illumination range IP of the slit-shaped illumination light is sequentially moved in a direction perpendicular to the slit direction (e.g., the vertical direction) (e.g., the horizontal direction).

[0081] On the light-receiving surface SR of the image sensor 51, a virtual aperture range OP is set, for example, by changing the pixels to be captured on a line-by-line basis by the control unit 100 described later. It is desirable that the aperture range OP is wider than the light-receiving range IP' or light-receiving range IP' of the reflected light of the illumination light on the light-receiving surface SR. For example, the control unit 100 described later performs movement control of the aperture range OP in synchronization with the movement control of the illumination light irradiation range IP. This makes it possible to acquire high-quality images of the fundus Ef with strong contrast in a simple configuration without being affected by unwanted scattered light.

[0082] Figures 6 and 7 schematically show an example of the control timing for a rolling shutter system on the image sensor 51. Figure 6 shows an example of the timing for readout control on the image sensor 51. Figure 7 shows the timing of the movement control of the illumination range IP (receiving range IP') of the illumination light superimposed on the readout control timing in Figure 6. In Figures 6 and 7, the horizontal axis represents the row number of the image sensor 51, and the vertical axis represents time.

[0083] In Figures 6 and 7, for the sake of explanation, the number of rows of the image sensor 51 is assumed to be 1920, but the configuration according to this embodiment is not limited to the number of rows. Also, in Figure 7, for the sake of explanation, the slit width (width in the row direction) of the slit-shaped illumination light is assumed to be 40 rows.

[0084] Row-direction readout control includes reset control, exposure control, charge transfer control, and output control. Reset control initializes the amount of charge accumulated in the row-direction pixels. Exposure control involves shining light on the photodiode to accumulate charge in the capacitor corresponding to the amount of light received. Charge transfer control transfers the amount of charge accumulated in the pixels to the vertical signal lines. Output control outputs the amount of charge accumulated in multiple vertical signal lines via the horizontal signal lines. That is, as shown in Figure 6, the readout time T for the amount of charge accumulated in the row-direction pixels is the sum of the time Tr required for reset control, the time Te required for exposure control (exposure time), the time Tc required for charge transfer control, and the time Tout required for output control.

[0085] In Figure 6, by shifting the readout (acquisition) start timing (start timing of time Tc) in row units, the light reception results (amount of charge) accumulated in a desired range of pixels on the image sensor 51 are acquired. For example, if the pixel range shown in Figure 6 is an image for one frame, the frame rate FR is uniquely determined.

[0086] In this embodiment, the illumination position of the illumination light at the fundus Ef, which has a slit width of multiple rows, is sequentially shifted in the direction corresponding to the column direction at the fundus Ef.

[0087] For example, as shown in Figure 7, the illumination position of the illuminating light in the fundus Ef is shifted in rows in the direction corresponding to the column direction at predetermined shift time Δt intervals. The shift time Δt is obtained by dividing the exposure time Te of a pixel in the image sensor 51 by the slit width of the illumination light (for example, the number of rows of the slit width = 40) (Δt = Te / 40). Synchronized with this illumination position movement timing, the start timing of reading each row of pixels is delayed and started at shift time Δt intervals. This makes it possible to acquire high-quality images of the fundus Ef with strong contrast using simple control and in a short time.

[0088] In some embodiments, the image sensor 51 is composed of one or more line sensors.

[0089] In this embodiment, as described above, by making the pupil separation amount GP greater than the central ghosting suppression threshold and smaller than the small pupil imaging threshold, it becomes possible to perform small pupil imaging while suppressing the occurrence of central ghosting without providing a black spot plate.

[0090] The following describes the central ghosting suppression threshold and the small pupil imaging threshold according to the embodiment.

[0091] The central ghosting suppression threshold is determined by identifying the conditions under which the intersection of the illumination ray and the receiving ray (imaging ray) is not located on the lens surface or inside the objective lens 46. Such a central ghosting suppression threshold can be determined based on the working distance of the ophthalmic device 1, the diopter of the eye E that can be photographed, the viewing angle of the illumination light relative to the fundus Ef (imaging area), and the viewing angle of the reflected light relative to the fundus Ef, as follows. Here, by using the diopter of a highly myopic eye, it becomes possible to suppress the occurrence of central ghosting without providing a black spot plate, even if the eye E is highly myopic.

[0092] The threshold for small pupil imaging can be determined based on a predetermined pupil diameter for small pupil imaging, the pupil separation amount GP on the pupil conjugate surface PL, the width of the opening 21A (or one or more openings) in the alignment direction, and the width of the opening 45A (or one or more openings) in the alignment direction. Here, the alignment direction is the alignment direction of the image of the opening 21A (or one or more openings) formed on the iris diaphragm 21 and the image of the opening 45A (or one or more openings) formed on the pupil division member 45 on the pupil conjugate surface.

[0093] [Central ghost generation suppression threshold] Figure 8 schematically shows the illumination ray and the receiving ray according to the embodiment. Figure 8 schematically represents a two-dimensional xy coordinate system for expressing the intersection point of the illumination ray and the receiving ray in terms of x and y positions. Hereafter, all distances will be assumed to be the path length.

[0094] In the xy coordinate system shown in FIG. 8, the direction of the optical axis O of the optical system of the ophthalmic device 1 from the pupil center C toward the fundus Ef is taken as the x direction, and the arrangement direction of the image of the aperture 21A and the aperture 45A at the pupil position orthogonal to the x direction is taken as the y direction.

[0095] Hereinafter, the focal length of the lens of the subject eye E is f, the origin position is the pupil center C of the subject eye E, and the distance in the x direction from the pupil center C to the fundus Ef is L f (>0), and the distance in the x direction from the pupil center C to the fundus conjugate position arranged in the direction toward the device side is L f ′(>0). Also, from the pupil center C to the illumination light ray W IL and the received light ray W SL the distance in the x direction to the intersection point of and is taken as L0.

[0096] When the intersection position of the illumination light ray W IL and the received light ray W SL exists on the lens surface or inside the lens of the objective lens 46, a central ghost (objective lens surface flare) occurs. Therefore, when the above intersection position exists outside the lens of the objective lens 46, the generation of the central ghost can be suppressed.

[0097] In obtaining the intersection position, the illumination light ray is assumed to pass through the lower edge of the image of the illumination aperture (aperture 21A formed in the iris diaphragm 21) at the pupil Eu and the lower edge of the aperture (slit aperture) formed in the slit 22 at the fundus conjugate position.

[0098] Here, the distance from the lower edge of the image of the illumination aperture to the optical axis is G, the width of the aperture formed in the slit 22 is d G and the optical magnification from the fundus to the fundus conjugate position is β. The above illumination light ray passes through the position (0, G) of the lower edge of the image of the illumination aperture and the position (L f ′, -β × d G / 2) of the lower edge of the slit aperture at the fundus conjugate position, and can be expressed as in Equation (1).

[0099]

Equation

[0100] Similarly, when determining the intersection position, the received light ray is assumed to pass through the upper edge of the image of the imaging aperture at the pupil Eu and the upper edge of the exposure width on the light-receiving surface of the image sensor 51 at the fundus conjugate position.

[0101] Here, let H be the distance from the optical axis to the upper edge of the imaging aperture, and let d be the exposure width on the light-receiving surface of the image sensor 51 at the fundus conjugate position. H The above light-receiving rays are located at the upper edge of the image at the imaging aperture (0, -H) and at the upper edge of the exposure width on the light-receiving surface of the image sensor 51 at the fundus conjugate position (-L). f ′,β×d H It passes through (2) and can be expressed as in equation (2).

[0102]

number

[0103] The x-coordinate of the intersection point of the illumination ray and the receiving ray can be expressed as shown in equation (3) from equations (1) and (2).

[0104]

number

[0105] Therefore, the distance L0 can be expressed as shown in equation (4) from equation (3).

[0106]

number

[0107] When the distance L0 between the intersection point and the pupil center C is equal to the working distance WD of the ophthalmic device 1, the pupil separation amount (G0 + H0) can be determined when the intersection point of the illumination ray and the receiving ray coincides with the lens surface of the objective lens 46 (see equation (5)).

[0108]

number

[0109] Here, let D be the diopter of the eye E being examined. If the eye E is highly myopic, D will be a negative value. Also, L f Between ' and D, equation (6) is satisfied.

[0110]

number

[0111] Furthermore, from the paraxial imaging formula, L f Between D and f, equation (7) is satisfied.

[0112]

number

[0113] Here, the optical magnification β can be expressed as shown in equation (8).

[0114]

number

[0115] β and L in equation (5) f Substituting equations (6) to (8) into ', the pupil separation amount (G0+H0) in equation (5) can be expressed as in equation (9).

[0116]

number

[0117] Here, in Figure 8, d G d H This can be expressed using the visual angle relative to the fundus Ef as the imaging area.

[0118] Figure 9 shows an explanatory diagram of the viewing angle according to the embodiment. In Figure 9, the same reference numerals are used for parts that are the same as in Figure 8, and their descriptions are omitted as appropriate.

[0119] As shown in Figure 9, in the same xy coordinate system as in Figure 8, if the viewing angle of the illumination light relative to the fundus Ef is α, then d in Figure 8 G This can be expressed as shown in equation (10) using the visual angle α of the illumination light relative to the fundus Ef. Similarly, in the xy coordinate system, if γ is the visual angle of the reflected light relative to the fundus Ef at the fundus conjugate position (fundus position), then in Figure 8, d H This can be expressed as shown in equation (11) using the visual angle of the reflected light relative to the fundus Ef.

[0120]

number

[0121] Therefore, by substituting equations (10) and (11) into equation (9), we obtain equation (12).

[0122]

number

[0123] As is clear from Figure 8, increasing the pupil separation amount GP (=G+H) shifts the intersection point towards the device. Therefore, in order to suppress the occurrence of central ghosting (objective lens surface flare), the intersection point only needs to be on the device side of the lens surface of the objective lens 46. The pupil separation amount GP (=G+H) at that time only needs to be greater than the pupil separation amount (G0+H0) when the intersection point coincides with the lens surface of the objective lens 46, and satisfy equation (13). In other words, the pupil separation amount (G0+H0) becomes the threshold for suppressing central ghosting.

[0124]

number

[0125] [Threshold for small pupil imaging] Furthermore, in order to enable small pupil imaging, the following relationship must be satisfied between the pupil separation amount (G+H) (=GP) and the pupil diameter φ for small pupil imaging.

[0126] Figure 10 schematically shows the image P1 of the illumination aperture and the image P2 of the imaging aperture in the pupillary conjugate plane according to the embodiment. In Figure 10, the same reference numerals are used for parts that are the same as in Figure 4, and explanations are omitted as appropriate.

[0127] In order to perform small pupil imaging, the pupil separation amount (G+H) and the sum of the width g of the image P1 of the illumination aperture and the width h of the image P2 of the imaging aperture in the alignment direction must be smaller than the pupil diameter φ for small pupil imaging (Equation (15)).

[0128] Here, width g corresponds to the width of opening 21A (or one or more openings) in the above-mentioned arrangement direction. Width h corresponds to the width of opening 45A (or one or more openings) in the above-mentioned arrangement direction. That is, (φ-(g+h)) is the threshold for small pupil imaging.

[0129] As described above, by setting the pupil separation amount to satisfy equations (14) and (15), even if the eye E under examination is highly myopic, it becomes possible to perform small pupil imaging while suppressing the occurrence of central ghosting without using a black spot plate.

[0130]

number

[0131] [System Configuration] As shown in Figure 11, the processing system (control system) of the ophthalmic device 1 is centered around the control unit 100. Note that at least a portion of the processing system's configuration may be included within the ophthalmic device 1.

[0132] (Control unit 100) The control unit 100 controls each part of the ophthalmic device 1. The control unit 100 includes a main control unit 101 and a storage unit 102. The main control unit 101 includes a processor and performs control processing for each part of the ophthalmic device 1 by executing processing according to the program stored in the storage unit 102.

[0133] (Main control unit 101) The main control unit 101 controls the light source 10, the moving mechanism 10D, the illumination optical system 20, the optical scanner 30, the imaging optical system 40, the imaging device 50, and the image forming unit 200. Furthermore, the main control unit 101 can also control the operation unit 110 and the display unit 120. Based on the operation information input from the operation unit 110, the main control unit 101 can control each part of the ophthalmic device 1.

[0134] Control of the light source 10 includes switching the light source on and off (or the wavelength range of light), and controlling the amount of light from the light source.

[0135] The moving mechanism 10D changes at least one of the position and orientation of the light source 10 by a known mechanism. The main control unit 101 can change at least one of the relative position and relative orientation of the light source 10 with respect to the iris diaphragm 21 and the slit 22.

[0136] Control of the illumination optical system 20 includes control of the moving mechanism 22D. The moving mechanism 22D moves the slit 22 in the direction of the optical axis of the illumination optical system 20. The main control unit 101 controls the moving mechanism 22D according to the state of the eye E under examination, thereby positioning the slit 22 to a position corresponding to the state of the eye E under examination. The state of the eye E under examination includes the shape of the fundus Ef, diopter (refractive power), and axial length. Diopter can be obtained from a known refractive power measuring device, such as those disclosed in Japanese Patent Publication No. 61-293430 or Japanese Patent Publication No. 2010-259495. Axial length can be obtained from a known axial length measuring device or from measurements taken by an optical coherence tomography (OCT).

[0137] For example, first control information, in which the position of the slit 22 on the optical axis of the illumination optical system 20 is pre-associated with the diopter, is stored in the storage unit 102. The main control unit 101 refers to the first control information to identify the position of the slit 22 corresponding to the refractive power and controls the movement mechanism 22D so that the slit 22 is positioned at the identified location.

[0138] Here, as the slit 22 moves, the light intensity distribution of the light passing through the opening formed in the slit 22 changes. At this time, as described above, the main control unit 101 can change the position and orientation of the light source 10 by controlling the movement mechanism 10D.

[0139] Control of the optical scanner 30 includes setting the deflection start angle and deflection end angle of the deflection surface that deflects the illumination light, and controlling the angle of the deflection surface. By controlling the angle range of the deflection surface, it is possible to control the scan range (scan start position and scan end position). By controlling the rate at which the angle of the deflection surface changes, it is possible to control the scan speed.

[0140] Control of the imaging optical system 40 includes control of the movement mechanism 47D. The movement mechanism 47D moves the focusing lens 47 in the optical axis direction of the imaging optical system 40. The main control unit 101 can control the movement mechanism 47D based on the analysis results of the image acquired using the image sensor 51. The main control unit 101 can also control the movement mechanism 47D based on user operations using the operation unit 110.

[0141] The control of the imaging device 50 includes the control of the image sensor 51. The control of the image sensor 51 includes control for reading out the light reception result using a rolling shutter method (for example, setting the light reception size corresponding to the size of the illumination pattern). The control of the image sensor 51 also includes reset control, exposure control, charge transfer control, output control, etc. It is possible to change the time Tr required for reset control, the time Te required for exposure control (exposure time), the time Tc required for charge transfer control, the time Tout required for output control, etc.

[0142] The control of the image forming unit 200 includes various image processing and analysis processes for the light reception results acquired from the image sensor 51, and image forming processes using the light reception results. Image processing includes noise reduction processing for the light reception results and brightness correction processing to make it easier to identify predetermined parts depicted in the light reception image based on the light reception results. Analysis processing includes processes for determining the focus state.

[0143] The image forming unit 200 can form a light-receiving image (image) corresponding to an arbitrary aperture range based on the light-receiving result read from the image sensor 51 using a rolling shutter method. The image forming unit 200 can sequentially form light-receiving images corresponding to the aperture range and form an image of the eye under examination E from the multiple light-receiving images formed.

[0144] The image forming unit 200 includes a processor and performs processing according to a program stored in a memory unit or the like to realize the above functions.

[0145] In some embodiments, the light source 10 includes two or more light sources. For example, each of the two or more light sources is provided corresponding to two or more apertures formed in the iris diaphragm 21. In this case, the main control unit 101 can change at least one of the position and orientation (the orientation in which the light intensity distribution is maximized) of each light source by controlling a moving mechanism provided corresponding to each of the two or more light sources. For example, the two or more light sources are provided corresponding to a single aperture formed in the iris diaphragm 21. In this case, the main control unit 101 can adjust the light intensity distribution of the light passing through the iris diaphragm 21 by independently changing the light intensity of each of the two or more light sources.

[0146] (Storage unit 102) The memory unit 102 stores various computer programs and data. The computer programs include calculation programs and control programs for controlling the ophthalmic device 1.

[0147] (Operation unit 110) The operation unit 110 includes an operating device or an input device. The operation unit 110 includes buttons and switches (e.g., operating handles, operating knobs, etc.) and operating devices (mouse, keyboard, etc.) provided on the ophthalmic device 1. The operation unit 110 may also include any operating device or input device such as a trackball, operating panel, switches, buttons, dials, etc.

[0148] (Display section 120) The display unit 120 displays the image of the eye E under examination generated by the image forming unit 200. The display unit 120 includes a display device such as a flat panel display such as an LCD (Liquid Crystal Display). The display unit 120 may also include various display devices such as a touch panel provided on the housing of the ophthalmic device 1.

[0149] The operation unit 110 and the display unit 120 do not necessarily need to be configured as separate devices. For example, a device that integrates display and operation functions, such as a touch panel, can be used. In that case, the operation unit 110 is configured to include this touch panel and a computer program. The operations performed on the operation unit 110 are input to the control unit 100 as electrical signals. Alternatively, operations and information input may be performed using a graphical user interface (GUI) displayed on the display unit 120 and the operation unit 110. In some embodiments, the functions of the display unit 120 and the operation unit 110 are realized by a touchscreen.

[0150] (Other configurations) In some embodiments, the ophthalmic apparatus 1 further includes a fixation projection system. For example, the optical path of the fixation projection system is coupled to the optical path of the imaging optical system 40 in the optical system configuration shown in Figure 1. The fixation projection system can present an internal or external fixation target to the eye under examination E. When presenting an internal fixation target to the eye under examination E, the fixation projection system includes an LCD that displays the internal fixation target under control from the control unit 100, and projects the fixation light beam output from the LCD onto the fundus of the eye under examination E. The LCD is configured to allow the display position of the fixation target on its screen to be changed. By changing the display position of the fixation target on the LCD, it is possible to change the projection position of the fixation target on the fundus of the eye under examination E. The display position of the fixation target on the LCD can be specified by the user using the operation unit 110.

[0151] In some embodiments, the ophthalmic device 1 includes an alignment system. In some embodiments, the alignment system includes an XY alignment system and a Z alignment system. The XY alignment system is used to align the device optical system and the eye under examination E in a direction intersecting the optical axis of the device optical system (objective lens 46). The Z alignment system is used to align the device optical system and the eye under examination E in the direction of the optical axis of the ophthalmic device 1 (objective lens 46).

[0152] For example, the XY alignment system projects a bright spot (a bright spot in the infrared or near-infrared region) onto the eye E under examination. The control unit 100 or image forming unit 200 acquires an anterior segment image of the eye E on which the bright spot is projected, and determines the displacement between the bright spot image depicted in the acquired anterior segment image and the alignment reference position. The control unit 100 moves the device optical system and the eye E under examination relative to each other in a direction intersecting the optical axis direction using a moving mechanism (not shown) so that the determined displacement is canceled out.

[0153] For example, the Z-alignment system projects alignment light in the infrared or near-infrared region from a position off-axis from the optical axis of the device optical system and receives the alignment light reflected by the anterior segment of the eye E under examination. The control unit 100 or image forming unit 200 determines the distance of the eye E under examination relative to the device optical system from the receiving position of the alignment light, which changes according to the distance of the eye E under examination relative to the device optical system. The control unit 100 moves the device optical system and the eye E under examination relative to the optical axis in the direction of the optical axis using a moving mechanism (not shown) so that the determined distance becomes the desired working distance.

[0154] In some embodiments, the alignment system function is realized by two or more anterior segment cameras positioned off-axis from the optical axis of the device optical system. For example, as disclosed in Japanese Patent Application Publication No. 2013-248376, the control unit 100 or image forming unit 200 analyzes the anterior segment images of the eye under examination E acquired substantially simultaneously by two or more anterior segment cameras and determines the three-dimensional position of the eye under examination E using known trigonometry. The control unit 100 moves the device optical system and the eye under examination E three-dimensionally relative to each other using a moving mechanism (not shown) such that the optical axis of the device optical system substantially coincides with the axis of the eye under examination E and the distance of the device optical system to the eye under examination E is a predetermined working distance.

[0155] As described above, in the ophthalmic device 1, the slit 22 (aperture), the imaging site (fundus Ef), and the image sensor 51 (light-receiving surface) are positioned in approximately optically conjugate positions. By moving the light-receiving range of the image sensor 51 in conjunction with the illumination position of the illumination light, the ophthalmic device 1 makes it possible to acquire a clear image of the imaging site while suppressing the effects of unwanted scattered light.

[0156] The iris diaphragm 21 is an example of an "illumination diaphragm" according to the embodiment. The opening 21A formed in the iris diaphragm 21 is an example of an "illumination opening" according to the embodiment. The opening 45A formed in the pupil division member 45 or the photographic diaphragm included in the pupil division member 45 is an example of a "photographic diaphragm" according to the embodiment. The opening 45A formed in the pupil division member 45 is an example of a "photographic opening" or "light-receiving opening" according to the embodiment. The opening formed in the slit 22 is an example of a "slit opening" according to the embodiment.

[0157] [Operation] Next, we will explain the operation of the ophthalmic device 1.

[0158] Figure 12 shows an example of operation of the ophthalmic device 1 according to the embodiment. Figure 12 is a flowchart of the operation example of the ophthalmic device 1 according to the embodiment. The memory unit 102 stores a computer program for realizing the process shown in Figure 12. The main control unit 101 executes the process shown in Figure 12 by operating according to this computer program.

[0159] Prior to the process shown in Figure 12, it is assumed that the alignment between the eye E and the optical system has been completed and the fixation target has been projected onto the predetermined fixation position in the fundus Ef.

[0160] (S1: Obtain diopter) First, the main control unit 101 acquires the diopter. For example, the main control unit 101 moves the focusing lens 47 to determine the focus state and determines the diopter from the position of the focusing lens 47 on the optical axis (or the control result of the actuator that drives the movement mechanism 47D) set to the focus state. The main control unit 101 may also acquire the diopter of the eye under examination E from an external ophthalmic measuring device or electronic medical record.

[0161] (S2: Change the position of the slit) Next, the main control unit 101 changes the position of the slit 22 in the optical axis of the illumination optical system 20 according to the diopter of the eye E to be examined, which was acquired in step S1.

[0162] Specifically, the main control unit 101 refers to the first control information stored in the memory unit 102 to determine the position of the slit 22 corresponding to the diopter, and controls the moving mechanism 22D so that the slit 22 is positioned at the determined location.

[0163] (S3: Turn on the light source) Next, the main control unit 101 controls the light source 10 to turn it on and causes the illumination optical system 20 to generate a slit-shaped illumination beam. Furthermore, the main control unit 101 controls the optical scanner 30 to start deflection control of the optical scanner 30, thereby starting the irradiation of the illumination beam to the desired illumination range in the fundus Ef. Once the irradiation of the illumination beam begins, the slit-shaped illumination beam is sequentially irradiated within the desired illumination range, as described above.

[0164] (S4: Obtain light reception results) The main control unit 101 acquires the light reception results of pixels within the aperture range of the image sensor 51 corresponding to the illumination range of the illumination light in the fundus Ef in step S3.

[0165] (S5: Next irradiation position?) The main control unit 101 determines whether there is an illumination position to be illuminated next with illumination light. The main control unit 101 can determine whether there is an illumination position to be illuminated next with illumination light by determining whether the illumination range of the sequentially moving illumination light covers the predetermined imaging range of the fundus Ef.

[0166] Next, when it is determined that there is an irradiation area to be illuminated with the illumination light (S5:Y), the operation of the ophthalmic device 1 proceeds to step S6. Next, when it is determined that there is no irradiation area to be illuminated with the illumination light (S5:N), the operation of the ophthalmic device 1 proceeds to step S7.

[0167] (S6: Change the deflection angle of the illumination light) In step S5, when it is determined that there is an illumination position to be illuminated by the illumination light next (S5:Y), the main control unit 101 controls the optical scanner 30 to change the deflection angle of the deflection plane of the optical scanner 30 by a predetermined step.

[0168] Next, the operation of the ophthalmic device 1 proceeds to step S4. In step S4, the main control unit 101 acquires the light reception results of pixels within the aperture range of the image sensor 51 corresponding to the illumination range of the illumination light in the fundus Ef that was moved in step S6.

[0169] (S7: Turn off the light source) In step S5, if it is determined that there is no illumination position to be illuminated next with illumination light (S5:N), the main control unit 101 controls the light source 10 to turn it off. Furthermore, the main control unit 101 controls the optical scanner 30 to stop the deflection operation of the optical scanner 30.

[0170] (S8: Forming an image) Next, the main control unit 101 causes the image forming unit 200 to form a fundus image of the eye E under examination from the light reception results repeatedly acquired in steps S4 to S6 while changing the illumination range of the illumination light.

[0171] For example, the image forming unit 200 synthesizes multiple light reception results, each with a different illumination range (aperture range on the light-receiving surface SR of the image sensor 51), based on the order in which the illumination ranges move, for the number of times the processing in steps S4 to S6 is repeated. As a result, a fundus image for one frame of fundus Ef is formed.

[0172] In some embodiments, in step S6, illumination light is shone onto an illumination range that is set to have overlapping regions with adjacent illumination ranges. As a result, in step S8, a fundus image for one frame is formed by combining fundus images so that their overlapping regions overlap.

[0173] This concludes the operation of ophthalmic device 1 (end).

[0174] Figures 13A and 13B show schematic diagrams illustrating the operation of the ophthalmic device 1 according to the embodiment when photographing the fundus Ef of the eye under examination E. Figure 13A schematically represents the illumination and imaging light beams when photographing the fundus Ef of the eye under examination E according to the embodiment. Figure 13B shows an example of a fundus image of the eye under examination E obtained according to the embodiment. In Figure 13A, the same reference numerals are used for parts that are the same as in Figure 14A, and explanations are omitted as appropriate.

[0175] As described above, the iris diaphragm 21 is configured to illuminate the fundus Ef with light passing through an aperture 21A formed at an eccentric position from the optical axis, and the pupil splitting member 45 is configured to receive the reflected light from the fundus Ef that has passed through an aperture 45A formed at an eccentric position from the optical axis. As a result, as shown in Figure 13A, the illumination light beam IL and the imaging light beam SL are spatially separated on the lens surface SF and inside the objective lens 46. Consequently, it is possible to prevent reflected light from the lens surface of the objective lens, which is a cause of central ghosting (objective lens surface flare), from entering the optical path of the imaging optical system 40.

[0176] Therefore, without using a black spot plate, the acquired fundus image IMG0 does not suffer from black spot shadows (no loss of fundus information), as shown in Figure 13B. Consequently, it becomes possible to acquire a fundus image of the eye being examined that allows for appropriate diagnosis without complicating the control system.

[0177] At this time, by dividing the pupil so that the pupil separation amount on the pupil conjugate plane is greater than a predetermined central ghost generation suppression threshold, even if the eye E under examination is highly myopic, the illumination light and the reflected light (photographic light) can be spatially separated on the lens surface of the objective lens 46. Furthermore, by dividing the pupil so that the pupil separation amount is smaller than a predetermined threshold for small pupil imaging, even if the eye E under examination has a small pupil, it becomes possible to obtain a fundus image of the eye that allows for appropriate diagnosis. Therefore, even when imaging eyes with small pupils, it becomes possible to obtain a fundus image of the eye that allows for appropriate diagnosis, even for eyes with small pupils, without complicating the control system.

[0178] [Differentiation] The configuration according to this embodiment is not limited to the above configuration. The shapes of the illumination aperture and the imaging aperture according to this embodiment may be any shape. Also, the number of illumination apertures and imaging apertures according to this embodiment may be two or more.

[0179] Furthermore, the illumination optical system 20 may include a projector equipped with a light source, and the projector may be configured to output slit-shaped illumination light. In this case, a projector is provided instead of the light source 10 and slit 22 in Figure 1. Examples of projectors include LCD (Liquid Crystal Display) projectors using transmissive liquid crystal panels, LCOS (Liquid Crystal On Silicon) projectors using reflective liquid crystal panels, and DLP (Digital Light Processing) (registered trademark) projectors using DMD (Digital Mirror Device). For example, the illumination optical system 20 may be configured to irradiate the iris diaphragm 21 with slit-shaped illumination light output by the projector.

[0180] [Effect] An ophthalmic device according to an embodiment will be described.

[0181] The ophthalmic apparatus (1) according to the first embodiment includes an objective lens (46), an illumination optical system (20), an optical scanner (30), an imaging optical system (40), and a pupil division member (45). The illumination optical system includes an illumination diaphragm (iris diaphragm 21) positioned at a location substantially conjugate to the pupil (Eu) of the eye under examination and having one or more illumination apertures (apertures 21A) formed thereon, and emits slit-shaped illumination light. The optical scanner is positioned at a location substantially conjugate to the pupil of the eye under examination and deflects the illumination light to guide it to the eye under examination via the objective lens. The imaging optical system guides the reflected light of the illumination light from the eye under examination via the objective lens to an image sensor (51) positioned at a location substantially conjugate to the imaging area of ​​the eye under examination. The pupil-splitting member is positioned approximately optically conjugate to the pupil of the eye under examination and includes a photographic aperture in which one or more photographic apertures (apertures 45A) are formed, spatially separating the optical path of the illumination optical system and the optical path of the photographic optical system. The illumination aperture and the photographic aperture are formed such that the pupil separation amount (GP), which is the shortest distance in the alignment direction between the image of the illumination aperture and the image of the photographic aperture at the pupil-conjugate plane (PL) at a position approximately optically conjugate to the pupil of the eye under examination, is greater than a predetermined central ghost generation suppression threshold.

[0182] In this configuration, it becomes possible to spatially separate the illumination light and the reflected light on the lens surface and inside the objective lens. As a result, it is possible to prevent reflected light from the lens surface of the objective lens, which is a cause of central ghosting (objective lens surface flare), from entering the optical path of the imaging optical system. Therefore, it becomes unnecessary to provide a black spot plate, and it becomes possible to obtain an image of the eye under examination that does not suffer from black crushing caused by black spot shadows (i.e., intraocular information such as fundus information is not lost).

[0183] In a second embodiment, the illumination aperture and the imaging aperture are formed such that the pupil separation amount is substantially constant in a direction perpendicular to the arrangement direction, as in the first embodiment. Here, the arrangement direction is the arrangement direction of the images from one or more illumination apertures and one or more imaging apertures on the pupil conjugate plane.

[0184] This configuration makes it possible to maximize pupil separation while ensuring sufficient light intensity by increasing the aperture size.

[0185] In a third embodiment, in the second embodiment, a predetermined central ghosting suppression threshold is determined according to the working distance (WD) of the ophthalmic device, the diopter (D) of the eye to be photographed, the viewing angle of the illumination light with respect to the imaging site (α), and the viewing angle of the reflected light with respect to the fundus (Ef) (γ).

[0186] In this configuration, by determining the working distance of the ophthalmic device, the diopter of the eye being photographed, the viewing angle of the illumination light relative to the imaging site, and the viewing angle of the reflected light relative to the fundus, the occurrence of central ghosting can be reliably suppressed without the need for a black spot plate.

[0187] In the fourth embodiment, in the third embodiment, the diopter is the diopter of a highly myopic eye.

[0188] According to this configuration, even if the eye being examined is highly myopic, the occurrence of central ghosting can be reliably suppressed without the need for a black spot plate.

[0189] In the fifth embodiment, in the third embodiment, when the working distance is WD, the diopter is D, the viewing angle of the illumination light is α, the viewing angle of the reflected light is γ, and the pupil separation is GP, the above equation (13) is satisfied.

[0190] According to this embodiment, by ensuring a pupil separation amount greater than the central ghost generation suppression threshold corresponding to the working distance, the diopter of the eye under examination, the viewing angle of the illumination light, and the viewing angle of the reflected light, it becomes possible to reliably suppress the occurrence of central ghosting (objective lens surface flare).

[0191] In the sixth embodiment, the illumination aperture and the imaging aperture are formed such that, in any of the first to fifth embodiments, the pupil separation amount is smaller than a predetermined threshold for small pupil imaging.

[0192] According to this configuration, even if the eye being examined has a small pupil, the occurrence of central ghosting can be reliably suppressed without the need for a black spot plate.

[0193] In the seventh embodiment, in the sixth embodiment, a predetermined small pupil imaging threshold is determined according to a predetermined pupil diameter for small pupil imaging, the width of the illumination aperture in the image alignment direction, and the width of the imaging aperture in the image alignment direction. Here, the alignment direction is the alignment direction of the images of one or more illumination apertures and one or more imaging apertures on the pupil conjugate plane.

[0194] According to this embodiment, by determining a predetermined pupil diameter for small pupil imaging, the width in the image arrangement direction of one or more illumination apertures, and the width in the image arrangement direction of one or more imaging apertures, small pupil eyes can be reliably imaged.

[0195] In the eighth embodiment, in the seventh embodiment, when a predetermined pupil diameter for small pupil imaging is φ, the width of the illumination aperture in the image alignment direction is g, the width of the imaging aperture in the image alignment direction is h, and the pupil separation amount is GP, the above equation (15) is satisfied. Here, the alignment direction is the alignment direction of the images of one or more illumination apertures and one or more imaging apertures on the pupil conjugate plane.

[0196] In this configuration, by ensuring a pupil separation amount smaller than the threshold for small pupil imaging, corresponding to a predetermined pupil diameter for small pupil imaging, the width of the illumination aperture in the image alignment direction, and the width of the imaging aperture in the image alignment direction, it becomes possible to reliably image eyes with small pupils.

[0197] In the ninth aspect of the embodiment, in the first embodiment, the image sensor is configured to capture the light reception result in a virtual aperture area of ​​the light-receiving surface corresponding to the illumination area of ​​the illumination light at the imaging area moved in a predetermined scanning direction by the optical scanner, using a rolling shutter method.

[0198] This configuration ensures the elimination of unwanted scattered light and further improves the image quality of the eye being examined.

[0199] In the tenth aspect of the embodiment, in the ninth aspect, the image sensor is a CMOS image sensor.

[0200] According to this embodiment, it is possible to prevent the intrusion of reflected light from the lens surface of the objective lens, which is a cause of central ghosting (objective lens surface flare), into the optical path of the imaging optical system, with a simple configuration and at low cost.

[0201] In the eleventh embodiment, in the first embodiment, the imaging site is the fundus of the eye.

[0202] This configuration makes it possible to obtain fundus images of the eye under examination without using a black spot plate and without black spot shadows causing black crushing. Furthermore, even when photographing eyes with small pupils, it becomes possible to obtain fundus images of the eye under examination that allow for appropriate diagnosis even in eyes with small pupils, without complicating the control system.

[0203] The embodiments or modifications thereof described above are merely examples for carrying out the present invention. Anyone intending to carry out the present invention may make any modifications, omissions, additions, etc., within the scope of the gist of the present invention.

[0204] In the above embodiment, the ophthalmic device may have any functions usable in the field of ophthalmology, such as an axial length measurement function, an intraocular pressure measurement function, an optical coherence tomography (OCT) function, and an ultrasound examination function. The axial length measurement function is implemented by an optical coherence tomograph or the like. Alternatively, the axial length measurement function may be implemented by projecting light onto the eye under examination and detecting the reflected light from the fundus while adjusting the Z-direction (anterior-posterior direction) position of the optical system relative to the eye under examination. The intraocular pressure measurement function is implemented by a tonometer or the like. The OCT function is implemented by an optical coherence tomograph or the like. The ultrasound examination function is implemented by an ultrasound diagnostic device or the like. Furthermore, it is also possible to apply this invention to a device (combination device) that has two or more of these functions. [Explanation of symbols]

[0205] 1 Ophthalmology equipment 10 light source 20 Illumination optical system 21 Iris Diaphragm 22 slits 30 Optical Scanners 35 Projection optical system 40. Imaging optical system 41, 43, 48 Relay Lens 42 Reflective mirror 45 Pupil division member 46 Objective lens 47 Focusing Lens 49. Imaging lens 50 Imaging device 51 Image Sensor 100 Control Unit 101 Main Control Unit 102 Storage section 200 Image forming unit E. Eye being examined Ef fundus Eu pupil

Claims

1. The objective lens, An illumination optical system that includes an illumination diaphragm positioned approximately conjugate to the pupil of the eye under examination and having one or more illumination apertures formed therein, and which emits slit-shaped illumination light, An optical scanner positioned at a location approximately conjugate to the pupil, deflects the illumination light and guides it to the eye under examination via the objective lens, An imaging optical system that guides the reflected light from the eye under examination, which has passed through the objective lens, to an image sensor positioned at a location that is approximately conjugate to the imaging area of ​​the eye under examination, A pupil-splitting member that spatially separates the optical path of the illumination optical system from the optical path of the imaging optical system, including a photographic aperture which is positioned at a position substantially conjugate to the pupil and has one or more photographic apertures formed thereon, Includes, An ophthalmic apparatus in which the illumination aperture and the imaging aperture are formed such that the pupil separation amount, which is the shortest distance in the alignment direction between the image of the illumination aperture and the image of the imaging aperture at a pupillary conjugate plane at a position optically substantially conjugate to the pupil, is greater than a predetermined central ghost generation suppression threshold.

2. The illumination aperture and the imaging aperture are formed such that the pupil separation amount is substantially constant in a direction perpendicular to the aforementioned arrangement direction. The ophthalmic device according to feature 1.

3. The predetermined central ghosting suppression threshold is determined according to the working distance of the ophthalmic device, the diopter of the eye being photographed, the viewing angle of the illumination light relative to the imaging area, and the viewing angle of the reflected light relative to the fundus. The ophthalmic device according to feature 2.

4. The aforementioned diopter is the diopter of a highly myopic eye. The ophthalmic apparatus according to feature 3.

5. When the working distance is WD, the diopter is D, the viewing angle of the illumination light is α, the viewing angle of the reflected light is γ, and the pupil separation is GP, then the following equation (1) is satisfied. The ophthalmic apparatus according to feature 3. [Math 1]

6. The illumination aperture and the imaging aperture are formed such that the pupil separation amount is smaller than a predetermined threshold for small pupil imaging. An ophthalmic device according to any one of claims 1 to 5, characterized by the features described herein.

7. The predetermined threshold for small pupil imaging is determined according to the predetermined pupil diameter for small pupil imaging, the width of the image of the illumination aperture in the arrangement direction, and the width of the image of the imaging aperture in the arrangement direction. The ophthalmic device according to feature 6.

8. When the predetermined pupil diameter for small pupil imaging is φ, the width of the image of the illumination aperture in the arrangement direction is g, the width of the image of the imaging aperture in the arrangement direction is h, and the pupil separation amount is GP, then the following equation (2) is satisfied. The ophthalmic apparatus according to feature 7. [Math 2]

9. The image sensor is configured to capture, using a rolling shutter method, the light reception result in a virtual aperture area of ​​the light-receiving surface corresponding to the illumination area of ​​the illumination light in the image area being moved in a predetermined scanning direction by the optical scanner. The ophthalmic device according to feature 1.

10. The image sensor is a complementary metal-oxide-semiconductor image sensor. The ophthalmic device according to feature 9.

11. The area being photographed is the fundus of the eye. The ophthalmic device according to feature 1.

Images