Ophthalmic devices

Abstract

To present an abnormality occurrence location in a condition of tear fluid with good positional accuracy over a wide range of an anterior eye segment.SOLUTION: An ophthalmologic apparatus includes: an interference photographing system which performs photographing of an interference pattern representing the condition of tear fluid on the cornea; an anterior eye segment photographing system; an optical path coupling element which couples the optical paths of both photographing systems; a first lens group which is arranged on a subject eye side with respect to the optical path coupling element and functions as objective lenses for both photographing systems; a second lens group which is arranged on the interference photographing system with respect to the optical path coupling element and functions as the objective lens for the interference photographing system; a projection system which projects alignment light to the anterior eye segment along the inclination direction with respect to the optical axis of the optical path from the optical path coupling element to the subject eye; a detection system which detects reflected light in the anterior eye segment of the alignment light; and a first alignment part which executes alignment in the optical axis direction based on the output from the detection system. The lens closest to the optical path coupling element side in the anterior eye segment photographing system is arranged at or near the focal position of the first lens group.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ophthalmic apparatus for examining the state of tears in a subject's eye. [Background technology]

[0002] In recent years, the number of dry eye patients has been increasing. This is thought to be due to overuse of the eyes from work using computer displays (VDT work), dry air from air conditioning and heating, wearing contact lenses, etc.

[0003] The most common test for dry eye is the Schirmer test, which measures tear volume, but other tests include fluorescein-stained corneas observed under a slit lamp microscope and tear stability tests (tear breakup time (BUT) tests).

[0004] The following devices are known as devices for performing dry eye examinations: Patent Document 1 discloses an ophthalmic device in which a light projection system is arranged so that light rays are incident almost perpendicularly on the corneal surface in order to efficiently obtain specularly reflected light from the anterior segment of the subject's eye, and an aperture with a size almost the same as the exit pupil diameter of the specularly reflected light is arranged near the exit pupil.

[0005] Patent Document 2 discloses an ophthalmic device that obtains time-series changes in the hue of an interference pattern formed by the tear film from time-series images obtained by color photographing the interference pattern, in order to objectively examine the condition of the tear film.

[0006] Patent Document 3 discloses an ophthalmic device that evaluates the progression of dry eye by analyzing the interference pattern for each color component of an image obtained by color photographing the interference pattern formed by the tear film in order to quantify the progression of dry eye with high precision and accuracy.

[0007] Patent Document 4 discloses an ophthalmologic device that evaluates the position and shape of dry spots and the direction of tear movement around the dry spots by processing multiple frontal images obtained by continuously photographing the anterior segment of the subject's eye in order to objectively evaluate the type of dry eye. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 9-289970 [Patent Document 2] JP 2001-309889 A [Patent Document 3] JP 2005-211173 A [Patent Document 4] JP 2017-136212 A Summary of the Invention [Problem to be solved by the invention]

[0009] As disclosed in Patent Document 4, one of the important points in evaluating dry eye is the location of the dry spot (more generally, the distribution of tear thickness or the distribution of tear abnormality). Naturally, it is not known where in the anterior segment the abnormality will occur before the examination. Therefore, in order not to overlook abnormalities occurring at the edge of the cornea and in order to perform the examination efficiently, it is desirable to be able to observe a wide range of the anterior segment.

[0010] In addition, when presenting the test results, it is desirable to display the location and distribution of abnormalities superimposed on the anterior segment image so that the location of abnormalities in the anterior segment can be easily (intuitively) grasped. It is desirable for this anterior segment image to depict a wide range of the anterior segment.

[0011] Furthermore, considering the possibility that a positional shift may occur between the interference pattern image and the anterior eye image due to eye movement or body movement, it is desirable to photograph the interference pattern to obtain the location and distribution of abnormalities and the anterior eye to obtain the anterior eye image almost simultaneously.

[0012] With conventional technology, it has been difficult to satisfy these demands regarding ophthalmic devices used to examine dry eye.

[0013] An object of the present invention is to make it possible to indicate the location of an abnormal tear condition over a wide range of the anterior segment with good positional accuracy. [Means for solving the problem]

[0014] An ophthalmic apparatus according to a first aspect of some exemplary embodiments includes an illumination system, an interference photography system, an anterior eye imaging system, a first optical path coupling element, and a control unit. The illumination system projects illumination light output from a light source onto an anterior eye of an examinee's eye. The interference photography system has a configuration for capturing an interference pattern representing a state of tears on the cornea formed on the cornea by the illumination light. The anterior eye imaging system has a configuration for capturing an image of the anterior eye onto which the illumination light is projected. The first optical path coupling element couples an optical path of the interference photography system with an optical path of the anterior eye imaging system. The control unit causes a display device to display an interference image representing a state of tears on the cornea, which is acquired by capturing an interference pattern representing a state of tears on the cornea by the interference photography system, on an anterior eye image acquired by the anterior eye imaging system, superimposed on the anterior eye image.

[0015] A second aspect of some exemplary embodiments is the ophthalmic device of the first aspect, further including a first lens group arranged on a side of the subject's eye with respect to the first optical path coupling element, and a second lens group arranged on an opposite side of the subject's eye with respect to the first optical path coupling element. The first lens group and the second lens group function as objective lenses of an interference imaging system. The first lens group functions as an objective lens of an anterior segment imaging system.

[0016] A third aspect of some exemplary embodiments is an ophthalmic device of the second aspect, wherein the lens included in the anterior segment imaging system that is located closest to the first optical path coupling element is positioned at or near the focal position of the first lens group.

[0017] A fourth aspect of some exemplary embodiments is an ophthalmic device of any of the first to third aspects, further including a second optical path coupling element that couples the optical path of the illumination system and the optical path of the interference photography system.

[0018] According to a fifth aspect of some exemplary embodiments, the ophthalmic device of the fourth aspect is provided, in which each of the first optical path coupling element and the second optical path coupling element is a beam splitter. Return light of the illumination light for capturing an interference pattern is reflected by each of the first optical path coupling element and the second optical path coupling element and guided to an image capture element of the interference capturing system.

[0019] A sixth aspect of some exemplary embodiments is the ophthalmic apparatus of any one of the first to fifth aspects, further including an illumination intensity changing unit that changes the intensity of the illumination light projected onto the anterior segment.

[0020] A seventh aspect of some exemplary embodiments is the ophthalmic device of any one of the first to sixth aspects, further including an exciter filter and a barrier filter. The exciter filter generates excitation light for a fluorescent agent administered to the anterior segment from the illumination light. The barrier filter selectively passes fluorescence emitted by the fluorescent agent receiving the excitation light.

[0021] An eighth aspect of some exemplary embodiments is the ophthalmic device of any one of the first to seventh aspects, further including a projection system, a detection system, and a first alignment unit. The projection system projects alignment light onto the anterior segment along a direction inclined with respect to an optical axis of an optical path from the first optical path coupling element toward the subject's eye. The detection system detects reflected light of the alignment light at the anterior segment. The first alignment unit performs alignment in the direction along the optical axis based on an output from the detection system.

[0022] A ninth aspect of some exemplary embodiments is the ophthalmic device of the eighth aspect, wherein the projection system includes an alignment light source that outputs alignment light, and the detection system includes an image sensor that detects reflected light of the alignment light at an anterior segment of the eye, the alignment light source and the image sensor being disposed on the opposite side of the subject's eye with respect to the first optical path coupling element.

[0023] A tenth aspect of some exemplary embodiments is the ophthalmic apparatus of any one of the first to ninth aspects, further including a second alignment unit. The second alignment unit performs alignment in a direction perpendicular to an optical axis of the optical path from the first optical path coupling element to the subject's eye, based on an anterior eye image acquired by the anterior eye imaging system.

[0024] An eleventh aspect of some exemplary embodiments is the ophthalmologic apparatus according to any one of the first to seventh aspects, including two or more imaging units and a third alignment unit. The two or more imaging units capture images of the anterior eye from different directions. The third alignment unit performs three-dimensional alignment based on two or more captured images acquired by the two or more imaging units, respectively. Effect of the Invention

[0025] According to the embodiment, it is possible to indicate the location of an abnormal tear condition over a wide range of the anterior segment with good positional accuracy. [Brief description of the drawings]

[0026] [Figure 1] 1 is a schematic diagram illustrating an example of a configuration of an ophthalmologic apparatus according to an exemplary embodiment. [Diagram 2] 1 is a schematic diagram illustrating an example of a configuration of an ophthalmologic apparatus according to an exemplary embodiment. [Diagram 3] 1 is a schematic diagram for explaining an example of a configuration of an ophthalmologic apparatus according to an exemplary embodiment. [Figure 4] 10 is a flowchart illustrating an example of an operation of an ophthalmologic apparatus according to an exemplary embodiment. [Figure 5A]FIG. 13 is a schematic diagram illustrating an example of a configuration of an ophthalmologic apparatus according to a modified example. [Figure 5B] FIG. 13 is a schematic diagram illustrating an example of a configuration of an ophthalmologic apparatus according to a modified example. [Figure 6] FIG. 13 is a schematic diagram illustrating an example of a configuration of an ophthalmologic apparatus according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] An ophthalmic device according to some exemplary embodiments will now be described in detail with reference to the drawings.

[0028] First, an outline of the embodiment will be described. The ophthalmologic apparatus of the embodiment is configured to photograph an interference pattern representing the state of the tear fluid on the cornea to obtain an interference image, photograph an anterior segment to obtain an anterior segment image, and present the interference image superimposed on the anterior segment image. At least a part of the element group for the interference photography (interference photography system) is different from the element group for the anterior segment photography (anterior segment photography system).

[0029] The presented interference image may be the interference image itself (raw image) acquired by the interference photography system, or may be an interference image (processed image) obtained by processing this raw image. The processed image may be, for example, a color map that represents the parameter distribution represented by the raw image in pseudocolor, or a map that represents an area in which the parameter value belongs to a predetermined range. This parameter may be, for example, the thickness of any one layer, any two layers, or all three layers among the oil layer, aqueous layer, and mucin layer that constitute the tear fluid. The processed image may also be an image obtained by applying any image processing such as correction, adjustment, and emphasis to the raw image.

[0030] Similarly, the presented anterior eye image may be the anterior eye image itself (raw image) acquired by the anterior eye imaging system, or may be an anterior eye image (processed image) obtained by processing the raw image. The processed image may be an image obtained by applying any image processing such as correction, adjustment, and emphasis to the raw image.

[0031] The display device on which the interference image and the anterior eye image are displayed may or may not be included in the ophthalmic apparatus according to the embodiment. In the latter case, the display device is a peripheral device of the ophthalmic apparatus according to the embodiment.

[0032] In this specification, unless otherwise specified, no distinction is made between "image data" and an "image" based on the image data. Similarly, unless otherwise specified, no distinction is made between a site or tissue of a subject's eye and an image representing the site or tissue.

[0033] In this specification, unless otherwise specified, a "lens" refers to a single lens or a combination of two or more lenses. Similarly, unless otherwise specified, a "lens group" refers to a collection of two or more lenses or a single lens.

[0034] In addition, in this specification, the term "processor" refers to a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). The processor realizes the functions according to the embodiment by, for example, reading and executing a program stored in a memory circuit or a storage device.

[0035] <composition> 1 and 2 show an example of the configuration of an ophthalmic apparatus according to an embodiment. The ophthalmic apparatus 1 has a function of capturing an interference pattern representing the state of tear fluid on the cornea Ec of a subject's eye E, a function of capturing an image of the anterior eye segment Ea, and a function of presenting an interference image representing the interference pattern superimposed on an image of the anterior eye segment.

[0036] As an exemplary configuration for realizing these functions, the ophthalmic apparatus 1 includes an examination unit 2, a unit moving mechanism 70, a display device 80, an operation device 90, and a computer 100. The computer 100 may be, for example, an embedded system of the ophthalmic apparatus 1.

[0037] Various optical systems and mechanisms are housed in the inspection unit 2. An exemplary inspection unit 2 includes an illumination system 10, an interference photography system 20, an anterior eye photography system 30, a first lens group including two lenses 41 and 42, a second lens group including two lenses 43 and 44, an optical path coupling element 51, a reflecting mirror 52, an optical path coupling element 53, an alignment light source 61, and an image sensor 62.

[0038] The illumination system 10 is configured to project illumination light onto the anterior segment Ea of the subject's eye E. The exemplary illumination system 10 includes an illumination light source 11, a collimator lens 12, an exciter filter 13, and a variable filter 14. The optical path of the illumination system 10 is formed by the illumination light source 11, the collimator lens 12, the exciter filter 13, the variable filter 14, (optical path coupling element 53), a reflecting mirror 52, a lens 44, a lens 43, an optical path coupling element 51, a lens 42, and a lens 41.

[0039] The illumination light source 11 outputs illumination light. The operation of the illumination light source 11 is controlled by a computer 100.

[0040] The collimating lens 12 converts the illumination light output from the illumination light source 11 into a parallel light beam. The collimating lens 12 is, for example, made up of a single lens or a combination of two or more lenses.

[0041] The exciter filter 13 is placed in the optical path when the modality of anterior segment imaging is fluorescence angiography (state shown by solid line), and is placed outside the optical path in other cases (state shown by dotted line). The movement of the exciter filter 13 is performed by an exciter filter moving mechanism 13A. The exciter filter moving mechanism 13A includes an actuator that operates according to commands from the computer 100. This actuator may be, for example, a solenoid actuator.

[0042] In fluorescence angiography, a fluorescent agent (fluorescent dye) is administered to the anterior segment Ea. The exciter filter 13 generates excitation light for the fluorescent agent from the illumination light. In other words, the exciter filter 13 selectively passes wavelengths that excite the fluorescent agent. In a typical example, the fluorescent dye is fluorescein, and the central passing wavelength of the exciter filter 13 is set to 494 nm, the maximum absorption wavelength of fluorescein, or in the vicinity thereof (for example, in the range of 490 to 500 nm).

[0043] The variable filter 14 is an optical element for changing the intensity (amount of light) of the illumination light projected onto the subject's eye E. Since a certain amount of time (10 seconds or more) is required to evaluate the time-series change in the interference pattern caused by tears, it is considered desirable to be able to adjust the intensity of the illumination light so that the subject can keep his or her eye open throughout that time. The variable filter 14 is an example of an element for realizing this desire.

[0044] The variable filter 14 may include, for example, either one or both of a neutral density filter (ND filter) and a band pass filter (BPF). The variable filter 14 includes a single filter or two or more filters.

[0045] When the variable filter 14 is composed of a single filter, the variable filter 14 is, for example, an optical filter whose filter characteristics (for example, pass characteristics, absorption characteristics) can be changed continuously or discretely. The control for changing the filter characteristics is performed by the computer 100.

[0046] When the variable filter 14 includes two or more filters, these filters are selectively arranged in the optical path. In a typical example of this case, the variable filter 14 includes two or more filters mounted on a turret and an actuator that moves (typically rotates) the turret. The actuator may be, for example, a pulse motor that operates according to a command (pulse control signal) from the computer 100.

[0047] It is also possible to change the intensity of the illumination light projected onto the subject's eye E without using the variable filter 14. For example, some exemplary embodiments may be configured to change the intensity of the illumination light projected onto the subject's eye E by changing either or both of the intensity and the wavelength band of the illumination light output by the illumination light source (11). Also, some exemplary embodiments may be configured to change the intensity of the illumination light projected onto the subject's eye E by a combination of control of the illumination light source and control of the variable filter.

[0048] Furthermore, any one of the two or more filters provided in the variable filter 14 may be the exciter filter 13. In the case where the exciter filter 13 is included in the variable filter 14, when performing fluorescence contrast imaging, the computer 100 controls the variable filter 14 to insert the exciter filter 13 into the optical path and retract it from the optical path.

[0049] According to the illumination system 10 of this example, the illumination light output from the illumination light source 11 is converted into a parallel beam by the collimator lens 12. When fluorescence angiography is applied, the illumination light that has passed through the collimator lens 12 is converted into excitation light by the exciter filter 13, and the intensity of this excitation light is adjusted by the variable filter 14. When fluorescence angiography is not applied, the intensity of the illumination light that has passed through the collimator lens 12 is adjusted by the variable filter 14. The illumination light (excitation light) that has passed through the variable filter 14 is projected onto the anterior eye segment Ea via the optical path coupling element 53, the reflecting mirror 52, the lens 44, the lens 43, the optical path coupling element 51, the lens 42, and the lens 41.

[0050] The interference photography system 20 is configured to photograph an interference pattern formed on the cornea by illumination light projected onto the anterior eye segment Ea by the illumination system 10. This interference pattern is formed by the illumination light being reflected by the tear layer (layer boundary). For example, a pattern according to the distribution of the thickness of the oil layer is formed by interference between light reflected from the front surface and the back surface of the tear oil layer.

[0051] The interference photography system 20 includes an aperture 21, a telecentric lens 22, and an interference photography camera 23. The optical path of the interference optical system 20 is formed by a lens 41, a lens 42, an optical path coupling element 51, a lens 43, a lens 44, a reflecting mirror 52, an optical path coupling element 53, the aperture 21, the telecentric lens 22, and the interference photography camera 23.

[0052] The diaphragm 21 is an optical element for limiting (adjusting) the amount of light guided to the interferometry camera 23. The diaphragm 21 may be a variable diaphragm controlled by the computer 100.

[0053] The telecentric lens 22 may be, for example, an image-space telecentric lens. This allows light rays to be incident almost perpendicularly on the entire imaging surface of the interference photography camera 23, eliminating roll-off and vignetting, and ultimately making the peripheral illumination ratio uniform. The telecentric lens 22 is, for example, a single lens or a combination of two or more lenses.

[0054] The interference camera 23 detects the light that has passed through the telecentric lens 22, and generates an image (interference image) that represents an interference pattern formed on the cornea. The interference camera 23 has sensitivity at least in the visible range. The interference camera 23 may be, for example, a color video camera, and may typically be a 3CCD video camera or a 3CMOS video camera. This makes it possible to obtain interference images of various color components.

[0055] The reflected light of the illumination light projected onto the anterior segment Ea by the illumination system 10 is guided to the interference photography camera 23 via a lens 41, a lens 42, an optical path coupling element 51, a lens 43, a lens 44, a reflecting mirror 52, an optical path coupling element 53, an aperture 21, and a telecentric lens 22.

[0056] The anterior eye imaging system 30 is configured to image the anterior eye Ea onto which illumination light is projected by the illumination system 10. The anterior eye imaging system 30 includes a barrier filter 31, a lens 32, and an anterior eye imaging camera 33. The optical path of the anterior eye imaging system 30 is formed by a lens 41, a lens 42, (an optical path coupling element 51), the barrier filter 31, the lens 32, and the anterior eye imaging camera 33.

[0057] The barrier filter 31 is placed in the optical path when the modality of anterior segment imaging is fluorescence angiography (state shown by solid line), and is placed outside the optical path in other cases (state shown by dotted line). The barrier filter 31 is moved by a barrier-filter moving mechanism 31A. The barrier-filter moving mechanism 31A includes an actuator that operates according to commands from the computer 100. This actuator may be, for example, a solenoid actuator.

[0058] The computer 100 synchronously controls the operation of the exciter filter moving mechanism 13A and the operation of the barrier filter moving mechanism 31A. In other words, when the modality of the anterior segment imaging is fluorescent angiography, the computer 100 controls the exciter filter moving mechanism 13A and the barrier filter moving mechanism 31A so that both the exciter filter 13 and the barrier filter 31 are placed in the optical path, and when the modality of the anterior segment imaging is not fluorescent angiography, the computer 100 controls the exciter filter moving mechanism 13A and the barrier filter moving mechanism 31A so that both the exciter filter 13 and the barrier filter 31 are placed outside the optical path.

[0059] In fluorescence angiography, a fluorescent agent (fluorescent dye) administered to the anterior segment Ea emits fluorescence of a specific wavelength upon receiving excitation light generated by the exciter filter 13. The barrier filter 31 selectively passes this wavelength of fluorescence. As a typical example, when the fluorescent dye is fluorescein, the central passing wavelength of the barrier filter 31 is set to 521 nm, the maximum emission wavelength of fluorescein, or in the vicinity thereof.

[0060] The lens 32 is, for example, an imaging lens that forms an image of light on the light receiving surface of the anterior eye imaging camera 33. Alternatively, the lens 32 may be a (image side) telecentric lens, similar to the interference imaging system 20. The lens 32 is, for example, a single lens or a combination of two or more lenses.

[0061] The lens 32 located closest to the optical path coupling element 51 is disposed at or near the focal position of the first lens group consisting of the two lenses 41 and 42. When the lens 32 is a single lens, the lens 32 is disposed at or near the rear focal position of the first lens group. When the lens 32 is a two or more lens, the lens located closest to the optical path coupling element 51 among these lenses, that is, the lens located closest to the subject's eye E, is disposed at or near the rear focal position of the first lens group. This makes it possible to widen the photographing field of the anterior eye photographing camera 33, and to photograph a wide range of the anterior eye Ea.

[0062] The anterior eye photographing camera 33 photographs the anterior eye Ea by detecting light that has passed through the lens 32. This provides an anterior eye image. The anterior eye photographing camera 33 is sensitive to at least the wavelength range for fluorescence angiography. The anterior eye photographing camera 33 is sensitive to, for example, the visible range and the infrared range. The anterior eye photographing camera 33 may be, for example, a color video camera or a monochrome video camera, and may typically be a CCD video camera, a 3CCD video camera, a CMOS camera, or a 3CMOS video camera.

[0063] A first lens group consisting of two lenses 41 and 42 is disposed on the side of the eye E to be examined with respect to the optical path coupling element 51. Moreover, a second lens group consisting of two lenses 43 and 44 is disposed on the opposite side of the eye E to the optical path coupling element 51. In other words, the second lens group is disposed on the side of the interference photography camera 23 with respect to the optical path coupling element 51.

[0064] The lens 41 has, for example, a concave or flat surface on the side of the subject's eye E (front surface) and a convex aspheric surface on the opposite side of the subject's eye E (rear surface). The lens 42 has, for example, both the front and rear surfaces formed in a convex or flat shape.

[0065] The lens 43 and the lens 44 form a laminated lens. The lens 43 has, for example, a convex front and rear surface, and the lens 44 has, for example, a concave front and rear surface.

[0066] This lens configuration is intended to satisfy the following two conditions: (1) illumination light is incident approximately perpendicularly to each position on the cornea Ec; (2) reflected light from each position on the cornea Ec travels in the opposite direction along a path approximately identical to the incident path of the illumination light to that position, reaches the lens 41, and is detected by the interference photography system 20.

[0067] It can be seen from the ray diagram (simulation diagram) in Fig. 3 that the interference photography system 20 according to this example satisfies these two conditions. Note that, although matters relating to these two conditions are described in Patent Document 1, a specific optical system that actually satisfies these two conditions has not been disclosed in publicly known documents, and is believed to have been devised by the inventors for the first time.

[0068] By applying an optical system that satisfies the above two conditions, the path of the illumination light corresponding to each position on the cornea Ec and the path of the reflected light are made to approximately coincide, making it possible to accurately capture the distribution of the tear state on the curved cornea Ec from a direction perpendicular to the curved surface.

[0069] The configurations for satisfying the above two conditions are not limited to these. As a result of extensive research, the inventors have confirmed that at least the optical system configurations (A) to (C) shown below satisfy the above two conditions. Note that these are merely examples, and any modifications (omissions, substitutions, additions, etc.) are permitted.

[0070] (A) The optical system configuration of this example uses the following three lenses instead of the four lenses 41 to 44 in FIG. 1. The first lens closest to the subject's eye has a concave front surface and a convex aspheric rear surface. The second lens adjacent to the first lens has both a convex front and rear surface. The third lens, whose front surface is attached to the rear surface of the second lens, has a concave front surface and a convex rear surface.

[0071] (B) The optical system configuration of this example uses the following four lenses instead of the four lenses 41 to 44 in FIG. 1. The first lens closest to the subject's eye has a gently convex or flat front surface and a convex aspheric rear surface. The second lens next closest to the subject's eye after the first lens has both its front and rear surfaces formed as convex surfaces. The third lens, whose front surface is attached to the rear surface of the second lens, has a concave front surface and a convex rear surface. The fourth lens, whose front surface faces the rear surface of the third lens, has a convex front surface and a concave rear surface.

[0072] (C) The optical system configuration of this example uses the following five lenses instead of the four lenses 41 to 44 in FIG. 1. The first lens closest to the eye to be examined has a planar or concave front surface and a convex aspheric rear surface. The second lens adjacent to the first lens has a planar front surface and a convex rear surface. The third lens adjacent to the second lens has both a convex front and rear surface. The fourth lens, the front surface of which is attached to the rear surface of the third lens, has a concave front surface and a convex rear surface. The fifth lens adjacent to the fourth lens has a convex front surface and a concave rear surface.

[0073] 1, four lenses 41, 42, 43, and 44, i.e., a first lens group and a second lens group, function as objective lenses of the interference imaging system 20. In addition, two lenses 41 and 42, i.e., the first lens group, function as objective lenses of the anterior eye imaging system 30.

[0074] This allows the illumination light to be incident on each position of the cornea Ec almost perpendicularly to the interference photography system 20, and allows the reflected light from each position of the cornea Ec to be guided along a path that is almost the same as the incident path. On the other hand, the anterior eye photography system 30 can ensure a wide photography field of view, that is, can capture an image of a wide range of the anterior eye Ea.

[0075] The light detected by the interference imaging system 20 and the light detected by the anterior eye imaging system 30 are both return light from the anterior eye Ea, but are different from each other. It will be understood by those skilled in the art that it is not easy to configure an optical system that detects such different light from each other using separate optical systems configured to satisfy different requirements.

[0076] The optical path combining element 51 is an optical element that combines the optical path of the interference photography system 20 with the optical path of the anterior eye photography system 30. The optical path combining element 51 combines, for example, the optical path of the interference photography system 20 with the optical path of the anterior eye photography system 30 coaxially (i.e., combines them so that their optical axes intersect).

[0077] The optical path combining element 51 may be any beam splitter. In this example, since the interference photography system 20 uses wideband visible light and the anterior eye photography system 30 uses visible fluorescence (fluorescein), a half mirror can be used as the optical path combining element 51. In the example shown in Fig. 1, the optical path combining element 51 also has a function of combining the optical path of the illumination system 10 and the optical path of the anterior eye photography system 30.

[0078] In some exemplary embodiments, when a configuration is adopted in which the transmitted light (transmitted light) and the reflected light are separated by wavelength, a dichroic mirror can be used as the optical path coupling element 51. In some other exemplary embodiments, when a configuration is adopted in which the transmitted light (transmitted light) and the reflected light are separated by polarization, a polarizing beam splitter can be used as the optical path coupling element 51. Note that these are merely examples of an element (first optical path coupling element) for coupling the optical path of the interference photography system and the optical path of the anterior eye photography system, and any modification (omission, substitution, addition, etc.) is allowed.

[0079] The reflecting mirror 52 bends the optical path of the illumination system 10 and the optical path of the interference photography system 20. This allows the optical system configuration to be made compact, and as a result, the ophthalmic apparatus 1 can be made smaller. Any element can be used for this purpose or other purposes, and any configuration can be adopted. For example, the position, arrangement angle, number, size, etc. of the reflecting mirror can be designed appropriately. Also, an element other than the reflecting mirror may be used.

[0080] The optical path combining element 53 is an optical element that combines the optical path of the illumination system 10 with the optical path of the interference photography system 20. The optical path combining element 53 combines the optical path of the illumination system 10 with the optical path of the interference photography system 20 coaxially, for example.

[0081] The optical path combining element 53 may be any beam splitter. In this example, since both the illumination system 10 and the interference photography system 20 use broadband visible light, a half mirror can be used as the optical path combining element 53. As in the case of the optical path combining element 51, a dichroic mirror, a polarizing beam splitter, or another beam splitter can be used instead of the half mirror, if necessary.

[0082] 1, the light guided by the interference photography system 20 (i.e., the return light of the illumination light for photographing the interference pattern caused by the tear fluid on the cornea Ec) passes through two beam splitters and is reflected by both of them. That is, the light guided by the interference photography system 20 is reflected by the optical path combining element 51 and also by the optical path combining element 53, and is guided to the interference photography camera 23.

[0083] This configuration is intended to avoid the disturbance of the light when it passes through the beam splitter, thereby making it possible to detect the interference pattern generated on the cornea Ec with high accuracy.

[0084] The alignment light source 61 and the image sensor 62 are used for alignment in a direction (Z direction) along the optical axis of the lens 41 (Z alignment). The alignment light source 61 projects light (e.g., infrared light) for performing Z alignment onto the subject's eye E. The light output from the alignment light source 61 is projected obliquely onto the cornea Ec via the lenses 42 and 41. The corneal reflected light of this light is imaged on the light receiving surface of the image sensor 62 by the lenses 41 and 42 (as well as other lenses not shown).

[0085] The image sensor 62 may be any one-dimensional or two-dimensional image sensor. That is, the image sensor 62 provided in the Z alignment system may be any image sensor in which a plurality of light detection elements (photodiodes, etc.) are arranged one-dimensionally or two-dimensionally. The image sensor 62 is typically a line sensor.

[0086] In some exemplary embodiments, light traveling from the alignment light source 61 toward the lens 42 passes through, for example, a notch, an opening, or a light-transmitting portion formed in the light path coupling element 51 to reach the lens 42. Similarly, light traveling from the lens 42 toward the image sensor 62 passes through, for example, a notch, an opening, or a light-transmitting portion formed in the light path coupling element 51 to reach the lens 42. This makes it possible to provide an element for alignment while satisfying the above conditions regarding the interference photography system 20 and expanding the field of view of the anterior eye photography system 30.

[0087] When the position of the cornea Ec (corneal apex) changes in the Z direction, the projection position of light on the light receiving surface of the image sensor 62 changes. The computer 100 can determine the position of the cornea Ec (corneal apex) based on the position where the image sensor 62 detects light. Furthermore, the computer 100 performs Z alignment of the inspection unit 2 by controlling the unit moving mechanism 70 based on the determined position of the cornea Ec (corneal apex). This Z alignment method is an example of an alignment method that uses an optical lever.

[0088] The unit moving mechanism 70 moves the inspection unit 2 three-dimensionally. In a typical example, the unit moving mechanism 70 includes a Z stage movable in a Z direction (front-back direction), a Z moving mechanism for moving the Z stage, an X stage movable in an X direction (left-right direction) perpendicular to the Z direction, an X moving mechanism for moving the X stage, a Y stage movable in a Y direction (up-down direction) perpendicular to both the Z direction and the X direction, and a Y moving mechanism for moving the Y stage. Each of these moving mechanisms includes an actuator (e.g., a pulse motor) that operates under the control of the computer 100.

[0089] The display device 80 functions as a part of the user interface unit, and displays information under the control of the computer 100. The display device 80 may be, for example, a liquid crystal display (LCD) or an organic light emitting diode (OLED) display.

[0090] The operation device 90 functions as a part of the user interface unit, and is used to operate the ophthalmic apparatus 1. The operation device 90 may include various hardware keys (joystick, button, switch, etc.) provided on the ophthalmic apparatus 1. The operation device 90 may also include various peripheral devices (keyboard, mouse, joystick, operation panel, etc.) connected to the ophthalmic apparatus 1. The operation device 90 may also include various software keys (buttons, icons, menus, etc.) displayed on a touch panel.

[0091] The computer 100 executes various calculations and various controls for operating the ophthalmic apparatus 1. The computer 100 includes one or more processors and one or more storage devices. Examples of the storage device include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), and a solid-state drive (SSD). Various computer programs are stored in the storage device, and the processor operates based on the programs to realize the calculations and controls according to this example.

[0092] 2 shows an example of the configuration of the computer 100. The computer 100 includes an inspection processing unit 110, a display processing unit 120, an illumination intensity change processing unit 130, and an alignment processing unit 140.

[0093] The examination processing unit 110 executes processes (calculation, control, etc.) related to the examination performed by the ophthalmic apparatus 1. The examination processing unit 110 is realized by cooperation between hardware including a processor and examination processing software.

[0094] The inspection processing unit 110 controls, for example, the illumination light source 11, the exciter filter moving mechanism 13A, the interference photographing camera 23, the barrier filter moving mechanism 31A, and the anterior eye photographing camera 33.

[0095] The control of the illumination light source 11 includes, for example, turning it on and off, changing the output light amount, and changing the output wavelength range. The control of the exciter filter moving mechanism 13A includes, for example, inserting the exciter filter 13 into the optical path and retracting the exciter filter 13 from the optical path.

[0096] The control of the interference photography camera 23 includes, for example, exposure adjustment, gain adjustment, detection rate adjustment, and selection of a detection wavelength range (image sensor to be used). When the aperture 21 is a variable aperture, the inspection processing unit 110 controls the aperture 21.

[0097] The control of the barrier filter moving mechanism 31A includes, for example, inserting the barrier filter 31 into the optical path and retracting the barrier filter 31 from the optical path. The control of the anterior eye imaging camera 33 includes, for example, exposure adjustment, gain adjustment, and detection rate adjustment.

[0098] Furthermore, the inspection processing unit 110 can perform processing and calculations related to the interference image obtained by the interference photography camera 23. For example, the inspection processing unit 110 can construct a processed image from a raw image acquired by the interference photography system 20. The processed image may be, for example, a color map that represents the parameter distribution represented by the raw image in pseudocolor, or a map that represents an area in which the parameter value belongs to a predetermined range. This parameter may be, for example, the thickness of any one layer, any two layers, or all three layers among the oil layer, aqueous layer, and mucin layer that constitute the tear fluid. The processed image may also be an image obtained by applying any image processing such as correction, adjustment, and emphasis to the raw image.

[0099] Furthermore, the test processing unit 110 may be capable of executing the processes disclosed in Patent Documents 1 to 4 and other known processes. For example, the test processing unit 110 may be capable of identifying a time-series change in the hue of an interference image (interference pattern), evaluating the progress of dry eye based on the interference pattern for each color component, evaluating the position of a dry spot, evaluating the shape of a dry spot, and evaluating the direction of tear movement around a dry spot.

[0100] The inspection processing unit 110 can perform processing and calculations on the anterior eye image obtained by the anterior eye imaging camera 33. For example, the inspection processing unit 110 can construct a processed image from a raw image acquired by the anterior eye imaging system 30. As described above, the processed image may be an image obtained by applying any image processing such as correction, adjustment, and emphasis to the raw image.

[0101] The display processing unit 120 performs processing for displaying information on the display device 80. The display processing unit 120 is realized by cooperation between hardware including a processor and display processing software.

[0102] For example, in order to display the second information superimposed on the first information, the display processing unit 120 executes, for example, a control to present the second layer on the first layer, a control to display the first information on the first layer, and a control to display the second information on the second layer. Alternatively, the display processing unit 120 may execute a process of synthesizing (embedding) the second information into the first information, and a process of displaying the synthesized information obtained thereby.

[0103] The illumination intensity change processing unit 130 executes processing for changing the intensity of illumination light projected onto the anterior eye segment Ea by the illumination system 10. The illumination intensity change processing unit 130 is realized by cooperation between hardware including a processor and illumination intensity change processing software.

[0104] When the variable filter 14 is used to change the illumination intensity, the illumination intensity change processing unit 130 executes, for example, control to change the filter characteristics of the variable filter 14, or control to place any of two or more filters in the optical path.

[0105] When changing the intensity of the illumination light projected onto the anterior eye segment Ea by changing either or both of the intensity and the wavelength band of the illumination light output by the illumination light source (11), the illumination intensity change processing unit 130 controls the illumination light source (11).

[0106] The illumination intensity change processing unit 130 performs control to change the illumination intensity according to, for example, a signal from the operation device 90. That is, the ophthalmic apparatus 1 may be configured so that the illumination intensity can be changed manually. Here, the operation device 90 is operated by the examiner or the subject. Note that the variable range of the illumination intensity can be set in advance to a range in which at least one of the coherence imaging and the anterior eye imaging can be suitably performed.

[0107] When the illumination intensity is changed automatically, for example, the illumination intensity change processing unit 130 may be configured to obtain information on the illumination intensity applied to the subject (the subject's eye E) in a previous examination from medical information (e.g., an electronic medical record) associated with the subject, and reproduce this illumination intensity.

[0108] As another example of automatic change of illumination intensity, the illumination intensity change processing unit 130 may be configured to output visual or auditory information to the ophthalmic device 1 to ask the subject about the degree of glare when illumination light is projected onto the anterior eye segment Ea, and to adjust the illumination intensity according to the subject's response.

[0109] As yet another example of the case where the illumination intensity is automatically changed, the illumination intensity change processing unit 130 may be configured to adjust the illumination intensity based on a biological signal of the subject when the illumination light is projected onto the anterior eye Ea. The biological signal may be, for example, miosis, brain waves, heart rate, sweating, facial expression, etc. The ophthalmic apparatus 1 includes, for example, a device for detecting any of the biological signals, or is connected to the device. Miosis can be detected, for example, by the anterior eye imaging camera 33 and the illumination intensity change processing unit 130. Brain waves can be detected, for example, by an electroencephalograph. Heart rate can be detected, for example, by an electrocardiograph or a pulse oximeter. Sweating can be detected, for example, by a sweat meter. Facial expression can be detected, for example, by a camera and the illumination intensity change processing unit 130. Biological signals other than these examples can be detected by corresponding devices.

[0110] The alignment processing unit 140 executes processing related to position adjustment (alignment) of the optical system with respect to the subject's eye E. The alignment processing unit 140 is realized by cooperation between hardware including a processor and alignment processing software.

[0111] The ophthalmologic apparatus 1 may be capable of performing alignment in the X and Y directions (XY alignment) in addition to Z alignment. The alignment processing unit 140 executes processing related to Z alignment and processing related to XY alignment.

[0112] First, processing related to Z alignment will be described. The alignment processing unit 140 can execute control of the alignment light source 61 and control of the image sensor 62. The control of the alignment light source includes turning it on and off, adjusting the amount of light, adjusting the aperture, etc. The control of the image sensor 62 includes adjusting the exposure, gain, detection rate, etc.

[0113] Furthermore, the alignment processing unit 140 receives a signal output from the image sensor 62, and based on this signal, specifies the projection position of the light on the light receiving surface of the image sensor 62. The alignment processing unit 140 obtains the position of the corneal apex of the subject's eye E based on the specified projection position, and based on this, controls the unit moving mechanism 70 to move the examination unit 2 in the front-back direction (Z alignment).

[0114] Next, XY alignment will be described. The ophthalmologic apparatus 1 may be configured to perform XY alignment based on an anterior eye image acquired by the anterior eye imaging system 30.

[0115] For example, the alignment processing unit 140 first analyzes the anterior eye image to detect a feature point (e.g., the pupil center or the pupil centroid). Next, the alignment processing unit 140 calculates the deviation of the feature point from a predetermined position (e.g., the frame center) of the frame of the anterior eye image. Then, the alignment processing unit 140 controls the unit moving mechanism 70 to move the examination unit 2 in the left-right and / or up-down directions so that the calculated deviation is cancelled (XY alignment). This allows XY alignment to be performed so that the feature point of the anterior eye is located at a predetermined position of the frame.

[0116] The computer 100 may include elements different from those shown in FIG. 2. For example, the computer 100 may include a communication interface. The communication interface has a function for communicating with an external device (not shown). The external device may include, for example, any ophthalmic device, a device (reader) that reads information from a recording medium, and a device (writer) that writes information to a recording medium. The external device may also include any information processing device, such as a Hospital Information System (HIS) server, a DICOM (Digital Imaging and COmmunication in Medicine) server, a doctor terminal, a mobile terminal, a personal terminal, or a cloud server.

[0117] <Operation> The operation of the ophthalmic apparatus 1 according to this embodiment will be described below. An example of the operation of the ophthalmic apparatus 1 is shown in FIG.

[0118] (S1: Start illumination of the anterior segment) First, the illumination light source 11 is turned on to project illumination light onto the anterior eye segment Ea.

[0119] (S2: Adjust the lighting intensity) Next, the intensity of the illumination light projected onto the anterior eye segment Ea is adjusted by controlling the variable filter 14. The illumination intensity adjustment can be performed, for example, in the manner described above.

[0120] (S3: Alignment) Next, alignment is performed. In this embodiment, for example, Z alignment is performed after XY alignment. XY alignment and Z alignment can be performed, for example, in the manner described above.

[0121] (S4: Place a filter for fluorescence angiography in the light path) Next, the exciter filter 13 and the barrier filter 31 are disposed in the corresponding optical paths.

[0122] (S5: Start interference photography and anterior segment photography) When the above preparations are completed, interference photography by the interference photography system 20 and anterior eye segment photography by the anterior eye segment photography system 30 are started.

[0123] The interference photography captures an interference pattern that represents the state of the tear film on the cornea Ec (e.g., thickness distribution). The interference photography is performed, for example, for a preset time. Alternatively, the interference photography is performed until the state of the tear film on the cornea Ec reaches a predetermined state (e.g., until tear film breakdown has progressed sufficiently).

[0124] For example, the anterior eye photographing is performed during at least a part of the period during which the coherent photography is performed. This allows an anterior eye image to be obtained at approximately the same time as a certain interference image obtained by the coherent photography. When the anterior eye photographing is performed throughout the entire period during which the coherent photography is performed, such as when the coherent photography and the anterior eye photographing are performed in parallel, an anterior eye image corresponding in time to each interference image obtained by the coherent photography can be obtained.

[0125] The timing of the interference photography and the timing of the anterior eye photography can be synchronized. For example, the interference photography and the anterior eye photography can be performed at the same repetition timing (photography rate, frame rate).

[0126] (S6: Capture interference image and anterior eye image) The display processing unit 120 captures, for example, an interference image and an anterior eye image that are acquired almost simultaneously. Note that the display processing unit 120 may capture an interference image and an anterior eye image that are acquired at substantially different times.

[0127] (S7: Interference image is superimposed on the anterior segment image) The display processing unit 120 displays the interference image and the anterior-segment image captured in step S6 on the display device 80. At this time, the display processing unit 120 displays the interference image superimposed on the anterior-segment image.

[0128] In step S6, when the interference image and the anterior segment image are captured at substantially the same time, the interference image can be overlaid on the anterior segment image without performing registration between these images.

[0129] On the other hand, when the interference image and the anterior-segment image are captured at substantially different times in step S6, it is desirable to perform registration between these images. Here, since the contents depicted in the interference image and the contents depicted in the anterior-segment image are different, it is difficult to perform registration by directly comparing these images.

[0130] Therefore, in addition to the displayed anterior eye image, an anterior eye image (auxiliary anterior eye image) acquired almost simultaneously with the interference image is used. The auxiliary anterior eye image can be selected based on, for example, the synchronization between the above-mentioned interference photography and the anterior eye photography. The display processing unit 120 can perform registration between the displayed anterior eye image and the auxiliary anterior eye image, and obtain the deviation of the latter relative to the former. Furthermore, the display processing unit 120 can perform registration between the interference image and the displayed anterior eye image so that the obtained deviation is cancelled. This is the end of this operation example (end).

[0131] <Modification> In the above embodiment, Z alignment using an optical lever and XY alignment using an anterior eye image are performed. An example of an alignment method that can be applied instead of this will be described below.

[0132] In this modification, three-dimensional alignment (XYZ alignment) is performed based on two or more captured images obtained by capturing images of the anterior eye Ea from different directions. Examples of a configuration for achieving this are shown in Figs. 5A, 5B, and 6. Figs. 5A and 5B show examples of the external appearance of an ophthalmic apparatus according to this modification. The configuration shown in Fig. 6 can be applied in place of the configuration shown in Fig. 2.

[0133] The configuration of the ophthalmic apparatus according to this modification may be the same as the configuration of the ophthalmic apparatus 1 according to the above embodiment, except that, for example, two anterior eye cameras 300A and 300B are provided, an alignment processing unit 140A is provided instead of the alignment processing unit 140, and the alignment light source 61 and the image sensor 62 are not included. However, this does not exclude the ophthalmic apparatus according to this modification from including the alignment light source 61 and the image sensor 62. In the following description, the same reference numerals as those in the description of the ophthalmic apparatus 1 are used unless otherwise specified.

[0134] The ophthalmic apparatus according to the modified example includes a chin rest and a forehead rest for supporting the face of the subject. The ophthalmic apparatus 1 according to the above embodiment may be similar.

[0135] A driving system and a processing system are housed in the base 310. For example, the unit moving mechanism 70 and the computer 100 shown in FIG.

[0136] An optical system and a driving system are housed in a housing 320 provided on the base 310. For example, the housing 320 houses the inspection unit 2 shown in FIG.

[0137] At least a lens 41 is housed in a lens housing portion 330 provided to protrude from the front surface of the housing 320 .

[0138] 1 may be provided in the housing 320. In addition, the operation device 90 may be provided in at least one of the base 310 and the housing 320.

[0139] Two anterior eye cameras 300A and 300B are provided on the front surface of the housing 320. The two anterior eye cameras 300A and 300B capture images of the anterior eye Ea of the subject's eye E from two different directions (two different positions).

[0140] Each of the two anterior eye cameras 300A and 300B includes an imaging element such as a CCD image sensor or a CMOS image sensor. In this modification, the two anterior eye cameras 300A and 300B are provided on the subject side surface of the housing 320. As shown in FIG. 5A, the two anterior eye cameras 300A and 300B are provided at positions deviated from the optical path passing through the lens 41.

[0141] In this modification, two anterior eye cameras 300A and 300B are provided, but the number of anterior eye cameras may be any number equal to or greater than two. However, in consideration of the processing load of calculations for three-dimensional alignment, a configuration capable of photographing the anterior eye from two different directions is sufficient (but is not limited to this). Alternatively, a movable anterior eye camera may be provided to sequentially photograph the anterior eye from two or more different positions.

[0142] In this modified example, two anterior eye cameras 300A and 300B are provided separately from the anterior eye imaging system 30, but one of the two or more anterior eye cameras may be the anterior eye imaging system 30.

[0143] When two or more anterior eye cameras are provided, the anterior eye can be photographed substantially simultaneously from two or more different directions. "Substantially simultaneously" refers to the case where the photographing timings of the two or more anterior eye cameras are simultaneous, and also to the case where there is a difference in the photographing timing to such an extent that eye movement can be ignored. By performing such substantially simultaneous photographing, it becomes possible to obtain two or more anterior eye images when the subject's eye is in substantially the same position and orientation.

[0144] The two or more anterior eye cameras may capture video or still images. In the case of video capture, the above-mentioned substantially simultaneous anterior eye images can be realized by controlling the timing of the start of capture to be synchronized, or by controlling the frame rate and the capture timing of each frame. On the other hand, in the case of still image capture, the substantially simultaneous anterior eye images can be realized by controlling the timing of capture to be synchronized.

[0145] The two anterior segment images acquired substantially simultaneously by the two anterior segment cameras 300A and 300B are sent to the computer 100.

[0146] The alignment processing unit 140A determines the three-dimensional position of the subject's eye E by analyzing two captured images (anterior eye images) obtained substantially simultaneously by the two anterior eye cameras 300A and 300B.

[0147] This analysis may include, for example, identifying feature positions and calculating three-dimensional positions as disclosed in U.S. Patent Application Publication No. 2015 / 0085252. Prior to these processes, a process may be performed to correct distortion of the captured images obtained by each of the two anterior eye cameras 300A and 300B.

[0148] In identifying the characteristic position, the alignment processing unit 140A, for example, analyzes each of two anterior eye images captured substantially simultaneously by the two anterior eye cameras 300A and 300B to identify a position (referred to as a characteristic position) in the captured image that corresponds to a predetermined characteristic portion of the anterior eye Ea. This characteristic portion is typically the pupil center (or the pupil centroid).

[0149] In order to identify the position of the pupil center, the alignment processing unit 140A first identifies an image area (pupil area) corresponding to the pupil of the subject's eye E based on the distribution of pixel values ​​(e.g., luminance values) of the captured image. Since the pupil is generally depicted with lower luminance than other parts, the pupil area can be identified by searching for an image area with low luminance. At this time, the pupil area may be identified taking into consideration the shape of the pupil. In other words, the pupil area can be configured to be identified by searching for an image area with a substantially circular shape and low luminance.

[0150] Next, the alignment processing unit 140A identifies the center position of the identified pupil region. Since the pupil is substantially circular as described above, the outline of the pupil region is identified, and the center position of this outline (or its approximate circle or ellipse) is identified, and this can be set as the pupil center.

[0151] In calculating the three-dimensional position, the alignment processing unit 140A calculates the three-dimensional position of the characteristic part of the subject's eye E based on the respective positions of the two anterior eye cameras 300A and 300B and the characteristic positions in the two captured images identified in the above process. This calculation is performed using trigonometry as described in U.S. Patent Application Publication No. 2015 / 0085252.

[0152] Based on the three-dimensional position of the test eye E calculated in this manner, the alignment processing unit 140A controls the unit moving mechanism 70 so that the optical axis of the optical system coincides with the axis of the test eye E (corresponding to XY alignment), and also controls the unit moving mechanism 70 so that the distance between the test eye E and the optical system coincides with a predetermined working distance (corresponding to Z alignment).

[0153] <Action and Effects> The operation and effects of the ophthalmic apparatus according to some exemplary embodiments will be described.

[0154] An ophthalmic apparatus according to an exemplary embodiment includes an illumination system, an interference imaging system, an anterior segment imaging system, a first optical path coupling element, and a controller.

[0155] The illumination system projects illumination light output from a light source onto the anterior segment of the subject's eye. In the above example, the illumination system 10 corresponds to the illumination system. The illumination system 10 is configured to project illumination light output from an illumination light source 11 onto the anterior segment Ea.

[0156] The interference photography system photographs an interference pattern formed on the cornea by illumination light projected onto the anterior segment Ea by the illumination system. In the above example, the interference photography system 20 corresponds to the interference photography system. The interference photography system 20 obtains an interference image by photographing an interference pattern formed on the cornea Ec by illumination light projected onto the anterior segment Ea by the illumination system 10.

[0157] The anterior eye imaging system images the anterior eye segment onto which illumination light is projected by the illumination system. In the above example, the anterior eye imaging system 30 corresponds to the anterior eye imaging system. The anterior eye imaging system 30 images the anterior eye segment Ea onto which illumination light is projected by the illumination system 10. The anterior eye imaging system 30 is configured to image a wide range of the anterior eye segment Ea from the front.

[0158] The first optical path combining element combines the optical path of the interference photography system with the optical path of the anterior eye photography system. In the above example, the optical path combining element 51 corresponds to the first optical path combining element. The optical path combining element 51 is configured to combine the optical path of the interference photography system 20 with the optical path of the anterior eye photography system 30. Furthermore, the optical path combining element 51 combines the optical path of the illumination system 10 with the optical path of the anterior eye photography system 30.

[0159] The control unit causes the display device to display the interference image acquired by the interference photography system superimposed on the anterior eye image acquired by the anterior eye photography system. The displayed interference image may be a raw image acquired by the interference photography system or a processed image obtained therefrom. The display device may be an element of the ophthalmic device or a peripheral device of the ophthalmic device.

[0160] In the above example, the computer 100 (particularly the display processing unit 120) corresponds to the control unit. The computer 100 is configured to display on the display device 80 the interference image acquired by the interference photography system 20 superimposed on the anterior eye image acquired by the anterior eye photography system 30.

[0161] According to the exemplary embodiment configured as described above, the interference photography system and the anterior eye image capturing system are provided separately, and the optical paths of both systems are coupled to each other by the first optical path coupling element, so that the interference photography and the anterior eye image capturing can be performed almost simultaneously, thereby reducing the risk of misalignment between the interference image and the anterior eye image caused by eye movement or body movement.

[0162] Furthermore, according to the exemplary embodiment, a wide range of the anterior segment can be photographed by an anterior segment imaging system provided separately from the interference imaging system, which reduces the risk of overlooking abnormalities occurring at the edge of the cornea and enables efficient examination.

[0163] In addition, according to the exemplary embodiment, an interference image representing the state of the tear can be displayed superimposed on the anterior segment image, so that the location and distribution of the tear abnormality can be displayed superimposed on the anterior segment image, thereby presenting the location of the abnormality to the user in a manner that allows the user to easily (intuitively) grasp it.

[0164] As described above, according to the exemplary embodiment, it is possible to indicate the location of an abnormal tear condition over a wide range of the anterior segment with good positional accuracy.

[0165] The ophthalmic apparatus according to some exemplary embodiments may further include a first lens group arranged on the side of the test eye with respect to the first optical path coupling element, and a second lens group arranged on the opposite side of the test eye with respect to the first optical path coupling element, wherein the first lens group and the second lens group may be configured to function as objective lenses of an interference imaging system, and the first lens group may be configured to function as objective lenses of an anterior segment imaging system.

[0166] In the above example, the two lenses 41 and 42 correspond to the first lens group, and the two lenses 43 and 44 correspond to the second lens group. Furthermore, the four lenses 41 to 44 function as objective lenses of the interference imaging system 22, and the two lenses 41 and 42 function as objective lenses of the anterior eye imaging system 30.

[0167] In some exemplary embodiments, the lens included in the anterior segment imaging system and located closest to the first optical path coupling element may be disposed at or near the focal position of the first lens group.

[0168] In the above example, the lens 32 included in the anterior eye imaging system 30 that is located closest to the optical path coupling element 51 is positioned at or near the focal position of the first lens group consisting of two lenses 41 and 42.

[0169] The exemplary embodiment configured in this manner provides at least the following two advantages. First, the interference imaging system can cause illumination light to be incident on each position on the cornea substantially perpendicularly, and reflected light from each position on the cornea can be detected traveling in the opposite direction along a path substantially identical to the path of incidence of the illumination light to the corresponding position. This allows the path of the illumination light corresponding to each position on the cornea and the path of the reflected light to be substantially identical, making it possible to accurately capture the distribution of the state of the tear fluid on the curved cornea from a direction perpendicular to the curved surface.

[0170] Secondly, the anterior eye imaging system can be disposed near the first optical path coupling element, and further, the anterior eye imaging system (lens) can be disposed at or near the rear focal position of the first lens group, thereby making it possible to expand the imaging field of the anterior eye imaging system.

[0171] The ophthalmic apparatus according to some exemplary embodiments may further include a second optical path coupling element that couples the optical path of the illumination system and the optical path of the interference photography system. In the above examples, the optical path coupling element 53 corresponds to the second optical path coupling element. The optical path coupling element 53 is configured to couple the optical path of the illumination system 10 and the optical path of the interference photography system 20.

[0172] In some exemplary embodiments, each of the first optical path coupling element and the second optical path coupling element may be a beam splitter, and the return light of the illumination light for capturing an interference pattern may be configured to be reflected by each of the first optical path coupling element and the second optical path coupling element and guided to an image capture element of the interference photography system.

[0173] In the above example, each of the optical path combining element 51 and the optical path combining element 53 is a beam splitter (such as a half mirror). Furthermore, the return light of the illumination light for photographing the interference pattern may be reflected by each of the optical path combining element 51 and the optical path combining element 53 and guided to the interference photographing camera 23 corresponding to the imaging element.

[0174] According to the exemplary embodiment configured in this manner, it is possible to compact the optical system while avoiding the disturbance of light when passing through the beam splitter, thereby making it possible to detect the interference pattern generated on the cornea with high accuracy.

[0175] The ophthalmic apparatus according to some exemplary embodiments may further include an illumination intensity changer that changes the intensity of the illumination light projected onto the anterior segment of the eye. In the above example, the variable filter 14 and the illumination intensity change processor 130 correspond to the illumination intensity changer.

[0176] According to the exemplary embodiment configured as described above, it is possible to perform an examination using light of a suitable intensity. For example, in an examination that takes a certain amount of time, such as a tear breakup time (BUT) test, it is possible to reduce the risk of the examinee closing his / her eyes due to glare, and to reduce the burden on the examinee.

[0177] The ophthalmic device according to some exemplary embodiments may further include an exciter filter that generates excitation light for the fluorescent agent administered to the anterior segment from the illumination light, and a barrier filter that selectively passes the fluorescence emitted by the fluorescent agent receiving the excitation light. In the above examples, the exciter filter 13 corresponds to the exciter filter, and the barrier filter 31 corresponds to the barrier filter.

[0178] According to the exemplary embodiment configured in this manner, it is possible to perform fluorescent contrast imaging of the anterior segment, so that it is possible to appropriately observe the state of the cornea and the state of the tear fluid.

[0179] The ophthalmic device according to some exemplary embodiments may include an element for alignment. The alignment can facilitate the examination. Examples of the configuration for alignment are given below.

[0180] As a first example, an ophthalmic apparatus according to some exemplary embodiments may include a projection system, a detection system, and a first alignment unit. The projection system projects alignment light onto the anterior segment along a direction inclined with respect to an optical axis of an optical path from a first optical path coupling element toward the subject's eye. The detection system detects reflected light of the alignment light projected onto the anterior segment by the projection system. The first alignment unit performs alignment in the direction along the optical axis based on an output from the detection system.

[0181] In the above example, the alignment light source 61, the lens 42, and the lens 41 correspond to the projection system. The lens 41, the lens 42, and the image sensor 62 correspond to the detection system. Furthermore, the unit moving mechanism 70 and the alignment processing unit 140 correspond to the first alignment unit. These elements realize Z alignment.

[0182] In a first example, the projection system may include an alignment light source that outputs alignment light. The detection system may include an image sensor that detects reflected light of the alignment light. Furthermore, the alignment light source and the image sensor may be disposed on the opposite side of the subject's eye with respect to the first optical path coupling element.

[0183] In the above example, the alignment light source 61 corresponds to the alignment light source, and the image sensor 62 corresponds to the image sensor. Furthermore, the alignment light source 61 and the image sensor 62 are disposed on the opposite side of the subject's eye E with respect to the optical path coupling element 51, that is, on the side of the anterior segment imaging system 30. The optical path coupling element 51 may be configured to have a notch, an opening, a light transmitting portion, or the like formed therein, and the light may be configured to pass through the optical path coupling element 51 via the notch, an opening, a light transmitting portion, or the like.

[0184] As a second example, the ophthalmic apparatus according to some exemplary embodiments may further include a second alignment unit that performs alignment in a direction perpendicular to the optical axis of the optical path from the first optical path coupling element to the test eye based on the anterior eye image acquired by the anterior eye imaging system.

[0185] In the above example, the unit moving mechanism 70 and the alignment processing section 140 correspond to the second alignment section. XY alignment is achieved by these elements.

[0186] As a third example, an ophthalmic apparatus according to some exemplary embodiments includes two or more image capturing units and a third alignment unit. The two or more image capturing units capture images of an anterior segment from different directions. The third alignment unit performs three-dimensional alignment based on two or more captured images acquired by the two or more image capturing units, respectively.

[0187] In the above example, the two anterior eye cameras 300A and 300B correspond to two or more imaging units, and the unit moving mechanism 70 and the alignment processing unit 140A correspond to a third alignment unit. These elements realize three-dimensional alignment (XYZ alignment). [Explanation of symbols]

[0188] 1 Ophthalmology equipment 2 Inspection Unit 10 Lighting system 11 Lighting source 13 Exciter Filter 13A Exciter filter moving mechanism 14 Variable Filter 20 Interference photography system 23 Interferometric Camera 30 Anterior segment imaging system 31 Barrier Filter 31A Barrier filter moving mechanism 32 Lens 33 Anterior Eye Camera 41, 42, 43, 44 Lenses 51, 53 Optical path coupling element 61 Alignment Light Source 62 Image Sensor 70 Unit movement mechanism 80 Display Devices 100 Computers 110 Inspection processing section 120 Display processing unit 130 Illumination intensity change processing unit 140 Alignment processing section

Claims

1. an illumination system that projects illumination light onto an anterior segment of a subject's eye; an interference photography system for photographing an interference pattern formed on a cornea by the illumination light, the interference pattern representing a state of tears on the cornea; an anterior eye imaging system for imaging the anterior eye onto which the illumination light is projected; an optical path coupling element that couples an optical path of the interference photography system and an optical path of the anterior eye segment photography system; a first lens group that is disposed on the subject's eye side with respect to the optical path coupling element and functions as an objective lens of the interference imaging system and an objective lens of the anterior eye imaging system; a second lens group that is disposed on the side of the interference photography system with respect to the optical path coupling element and functions as an objective lens of the interference photography system together with the first lens group; a projection system that projects alignment light onto the anterior segment along a direction inclined with respect to an optical axis of an optical path from the optical path coupling element toward the subject's eye; a detection system for detecting reflected light of the alignment light at the anterior segment of the eye; a first alignment unit that performs alignment in a direction along the optical axis based on an output from the detection system; Including, Among the lenses included in the anterior eye imaging system, the lens located closest to the optical path coupling element is disposed at or near the focal position of the first lens group. An ophthalmic apparatus comprising:

2. the projection system includes an alignment light source that outputs the alignment light, the detection system includes an image sensor that detects the reflected light of the alignment light at the anterior segment of the eye, The alignment light source and the image sensor are disposed on the opposite side of the eye to be examined with respect to the optical path coupling element.

2. An ophthalmic apparatus according to claim 1 .

3. the optical path coupling element is a beam splitter that reflects light guided from the subject's eye to the interference photography system and transmits light guided from the subject's eye to the anterior eye photography system, the alignment light source and the image sensor are disposed on a side of the anterior segment imaging system with respect to the beam splitter; the alignment light output from the alignment light source passes through any one of a first cutout, a first opening, and a first light transmitting portion formed in the beam splitter and is projected onto the subject's eye; The reflected light of the alignment light at the anterior eye segment passes through any one of a second notch, a second opening, and a second light transmitting portion formed in the beam splitter and is detected by the image sensor.

3. An ophthalmic apparatus according to claim 2.

4. and a second alignment unit that performs alignment in a direction perpendicular to the optical axis based on the anterior eye image acquired by the anterior eye imaging system.

4. An ophthalmic apparatus according to claim 1, wherein the ophthalmic apparatus is a microscope.

5. an illumination system that projects illumination light onto an anterior segment of a subject's eye; an interference photography system for photographing an interference pattern formed on a cornea by the illumination light, the interference pattern representing a state of tears on the cornea; an anterior eye imaging system for imaging the anterior eye onto which the illumination light is projected; an optical path coupling element that couples an optical path of the interference photography system and an optical path of the anterior eye segment photography system; a first lens group that is disposed on the subject's eye side with respect to the optical path coupling element and functions as an objective lens of the interference imaging system and an objective lens of the anterior eye imaging system; a second lens group that is disposed on the side of the interference photography system with respect to the optical path coupling element and functions as an objective lens of the interference photography system together with the first lens group; a second alignment unit that performs alignment in a direction perpendicular to an optical axis of an optical path from the optical path coupling element to the subject's eye based on an anterior eye image acquired by the anterior eye imaging system; Including, Among the lenses included in the anterior eye imaging system, the lens located closest to the optical path coupling element is disposed at or near the focal position of the first lens group. An ophthalmic apparatus comprising:

6. an illumination system that projects illumination light onto an anterior segment of a subject's eye; an interference photography system for photographing an interference pattern formed on a cornea by the illumination light, the interference pattern representing a state of tears on the cornea; an anterior eye imaging system for imaging the anterior eye onto which the illumination light is projected; an optical path coupling element that couples an optical path of the interference photography system and an optical path of the anterior eye segment photography system; a first lens group that is disposed on the subject's eye side with respect to the optical path coupling element and functions as an objective lens of the interference imaging system and an objective lens of the anterior eye imaging system; a second lens group that is disposed on the side of the interference photography system with respect to the optical path coupling element and functions as an objective lens of the interference photography system together with the first lens group; Two or more imaging units that image the anterior segment from different directions; a third alignment unit that performs three-dimensional alignment based on two or more captured images acquired by the two or more imaging units; Including, Among the lenses included in the anterior eye imaging system, the lens located closest to the optical path coupling element is disposed at or near the focal position of the first lens group. An ophthalmic apparatus comprising:

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