Ophthalmic device and ophthalmic device control program

Abstract

An ophthalmic apparatus and an ophthalmic apparatus control program are provided that can reduce the influence of the iris color of the subject's eye. [Solution] An ophthalmic device for measuring the corneal shape of a test eye, comprising: an illumination optical system that projects an index image of a pattern index onto the cornea of ​​the test eye using light containing multiple wavelengths; an imaging optical system that photographs the index image of the pattern index projected onto the cornea of ​​the test eye; a separation means that separates the image photographed by the imaging optical system into multiple color channels; and a control unit, wherein the control unit obtains corneal shape information of the test eye by weighting the images separated by the separation means for each test eye.

Description

[Technical Field]

[0001] The present disclosure relates to an ophthalmic apparatus and an ophthalmic apparatus control program for measuring the corneal shape of a subject's eye. [Background technology]

[0002] Conventionally, ophthalmic devices for measuring the corneal shape of a subject's eye have been known. For example, some ophthalmic devices for measuring the corneal shape of a subject's eye use visible light, such as red, green, or blue, to project an index pattern. When using visible light of a specific wavelength, the contrast between the iris and the image of the pattern index increases for a specific iris color. This is therefore effective in avoiding the influence of iris color on measurement (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-135536 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when using visible light of a specific wavelength, depending on the iris color of the subject's eye, the contrast between the iris and the target image of the pattern index projected onto the cornea of ​​the subject's eye may be low. Furthermore, for example, simply using light including multiple wavelengths (e.g., white light including light of various wavelengths from 400 nm to 700 nm) may not provide sufficient contrast (brightness ratio) between the iris and the target image of the pattern index. Thus, depending on the iris color, the low contrast between the iris and the target image of the pattern index may affect measurement accuracy, raising concerns. The present disclosure aims to provide an ophthalmic apparatus and an ophthalmic apparatus control program that can reduce the influence of the iris color of the subject's eye. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention is characterized by having the following configuration.

[0006] (1) An ophthalmic device for measuring a corneal shape of a subject's eye includes an illumination optical system that projects an image of a patterned index onto the cornea of ​​the subject's eye using light having a plurality of wavelengths, an imaging optical system that captures the image of the patterned index projected onto the cornea of ​​the subject's eye, a separation unit that separates the image captured by the imaging optical system into a plurality of color channels, and a control unit. The control unit acquires corneal shape information of the subject's eye by weighting the image separated by the separation unit for each subject's eye. (2) An ophthalmic apparatus control program for use in an ophthalmic apparatus for measuring the corneal shape of a subject's eye includes an illumination optical system that projects an image of a patterned marker onto the cornea of ​​the subject's eye, an imaging optical system that captures the image of the patterned marker projected onto the cornea of ​​the subject's eye, a separation unit that separates the image captured by the imaging optical system into multiple color channels, and a control unit. When executed by the control unit, the ophthalmic apparatus control program causes the ophthalmic apparatus to execute a corneal shape acquisition step of acquiring corneal shape information of the subject's eye by weighting the image separated by the separation unit for each subject's eye. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an ophthalmologic apparatus. [Figure 2] 1 is a diagram illustrating an outline of an optical system and a control system of an ophthalmic apparatus. [Figure 3] FIG. 2 is a diagram illustrating the pattern target projection unit from the front direction on the side where the subject is positioned. [Figure 4] FIG. 2 is a diagram illustrating a cross section of a surface light-emitting panel. [Figure 5] 10 is a flowchart illustrating steps of corneal topography measurement. [Figure 6] 10 is a graph showing luminance information of an image obtained by converting a color image into a grayscale image. [Figure 7]10 is a graph showing luminance information of each color channel image. [Figure 8] 10 is an image of the cornea of ​​the subject's eye onto which a pattern index is projected. [Figure 9] 1 is an image of a shape map based on corneal shape information. DETAILED DESCRIPTION OF THE INVENTION

[0008] The ophthalmic apparatus (e.g., the ophthalmic apparatus 1) of the present disclosure includes an inspection window, an illumination optical system, an imaging optical system, an optical path combining unit, a color channel separating means, a control unit, etc. The inspection window (e.g., the inspection window 18) allows the inspection light from the anterior eye observation system, the reflected light from the anterior eye, etc. to pass through. The illumination optical system (e.g., the first pattern target projection optical system 20 and the second pattern target projection optical system 70) projects a pattern target onto the cornea of ​​the subject's eye. The optical path combining unit (e.g., the dichroic mirror 74) guides the light beam from the illumination optical system inside the inspection window to the cornea of ​​the subject's eye and an imaging element. The imaging optical system (e.g., the front imaging optical system 60) is used to capture an image of the pattern target projected onto the cornea of ​​the subject's eye. The imaging optical system includes an imaging element. The color channel separating means (e.g., the control unit 2) separates the captured image of the pattern target into color channels, such as a red channel, a green channel, and a blue channel. The control unit (for example, the control unit 2) is used to perform weighting processing on the image of the target image of the pattern target captured by the imaging optical system, and to acquire corneal shape information of the subject's eye.

[0009] The ophthalmic apparatus of this embodiment includes an examination window, a first pattern index projection optical system that projects first pattern indices onto the subject's eye from outside the examination window, and a second pattern index projection optical system that projects second pattern indices, different from the first pattern index, onto the subject's eye from inside the examination window. A first corneal reflection image formed by the first pattern index projected by the first pattern index projection optical system and a second corneal reflection image formed by the second pattern index projected by the second pattern index projection optical system are captured by an imaging optical system including an image sensor via an objective lens. The first pattern index projected from outside the examination window is projected using visible light, and the second pattern index projected from inside the examination window is projected using infrared light. This allows an optical path combining unit that combines the optical paths of the imaging optical system and the second pattern index projection optical system to employ an optical element that exhibits less attenuation of visible light than infrared light in the optical path from the cornea of ​​the subject's eye to the image sensor. As a result, the first corneal reflection image formed by the first pattern index can be efficiently captured. Furthermore, it becomes easier to simplify the light source of the first pattern target projection optical system.

[0010] The outside of the examination window refers to the outside including the exterior of the housing of the ophthalmic device 1. The inside of the examination window refers to the inside of the housing of the ophthalmic device 1. Furthermore, the characteristic of a low attenuation rate of an optical element refers to a characteristic of a low loss of light amount due to the influence of the reflectance and transmittance of the optical element for a predetermined light. In other words, the optical element is an optical element that has a characteristic of having a higher light receiving efficiency at the image sensor for visible light than for infrared light. The optical path from the cornea of ​​the test eye to the image sensor refers to the optical path from the objective lens to the image sensor.

[0011] In addition, for example, the second pattern indicator in the ophthalmologic apparatus is a ring-shaped pattern, and this allows the corneal shape of the central part of the cornea of ​​the subject's eye to be measured using the second pattern indicator.

[0012] Furthermore, for example, in an ophthalmic device, the wavelength of the light source of the second pattern index projection optical system is the same as the wavelength of the light source of the anterior eye illumination optical system. Note that "same" here does not necessarily mean completely the same. "same" here includes being substantially the same to the extent that no significant difference occurs. This prevents the wavelengths of other measurement light sources installed in the ophthalmic device from overlapping with the light source of the second pattern index projection optical system. Projecting the second pattern index at a wavelength used for the other measurement light sources may affect the optical path coupling at the optical path coupling unit inside the ophthalmic device. However, by configuring the second pattern index to be projected at a wavelength different from that of the other measurement light sources, the optical path coupling unit can be easily designed.

[0013] Furthermore, for example, the ophthalmologic apparatus turns off the light source of the anterior eye illumination optical system while the second pattern target projection optical system projects the second pattern target, thereby preventing unevenness in the pattern target due to the anterior eye illumination when projecting the pattern target onto the subject's eye.

[0014] Furthermore, for example, the control unit may acquire corneal topography information for each subject eye by weighting the images separated by the separation unit. This allows corneal topography information to be acquired using images that have been processed according to the characteristics of the subject eye. This reduces the influence of the iris color of the subject eye on the acquisition of corneal topography information.

[0015] Furthermore, for example, the control unit may acquire corneal topography information of the test eye by separating an image of a pattern index projected onto the cornea of ​​the test eye by an illumination optical system into multiple color channels and performing weighting processing based on the luminance information of each color channel image. This ensures contrast between the iris and the pattern index image regardless of iris color, thereby improving the accuracy of measuring the corneal topography of the test eye. For example, when an image of a pattern index projected using white light is captured, the image is separated into red, green, and blue color channels. By applying a large weighting coefficient to a color channel with a high contrast between the iris and the pattern index image based on the luminance information of each color channel, an image with a high contrast between the iris and the pattern index image can be synthesized. Furthermore, since corneal topography information of the test eye is acquired by performing image processing after capture, accurate corneal topography measurement can be performed with a single capture.

[0016] Furthermore, for example, the control unit may acquire corneal shape information of the subject's eye by weighting each color channel image based on the contrast of each color channel image separated into multiple color channels by the separation unit. Among the color channel images, color channel images with high contrast are weighted heavily, and color channel images with low contrast are weighted lightly. In other words, the image processing is performed with emphasis on color channel images with high contrast. This increases the contrast of the image generated by the image processing, thereby improving the accuracy of measuring the corneal shape of the subject's eye.

[0017] Furthermore, for example, the control unit may acquire iris color information of the subject's eye and perform weighting processing on the color channel images based on the iris color information to acquire corneal shape information of the subject's eye. For example, image processing can be performed using a weighting coefficient set in advance in accordance with the iris color of the subject's eye. This allows for more accurate image processing because the color channel images can be processed using the iris color information.

[0018] The corneal shape information may include, for example, an anterior segment image of the subject's eye onto which an index image of a pattern index is projected. The anterior segment image of the subject's eye is obtained by separating an image captured by an imaging optical system into color channel images and then weighting the color channel images. The image acquired by the ophthalmic apparatus may be the weighted color channel image itself, or may be an image obtained by combining the weighted color channel images through image processing. In addition, the corneal shape information may include, for example, parameters related to the corneal shape.

[0019] The ophthalmologic apparatus performs weighting processing on the multiple color channel images separated from the captured image, acquires corneal topography information, and outputs the acquired corneal topography information. For example, the corneal topography information may be displayed on a display unit. One output method is to display parameters of the corneal topography information in a color map format on the anterior segment image.

[0020] The ophthalmic device according to the present embodiment will be described below with reference to the drawings. The drawings are used to explain technical features that may be adopted in the present disclosure, and the configurations and the like described therein are not intended to be limiting but are merely illustrative examples.

[0021] The ophthalmic apparatus of this embodiment is an apparatus capable of acquiring corneal shape information of a subject's eye. For example, the ophthalmic apparatus may include an optical system used to measure the corneal shape, a corneal shape information acquiring unit, etc. Furthermore, for example, the ophthalmic apparatus may include a wavefront aberration information acquiring unit, an axial length information acquiring unit, an anterior segment information acquiring unit, an eye refractive power information acquiring unit, etc.

[0022] FIG. 1 is an external view of an ophthalmic apparatus 1. The ophthalmic apparatus 1 includes a control unit 2, an opthalmological examination unit 10, a base 12, a drive unit 13, a face support unit 14, a display unit 15, an operation unit 16, a corneal shape measurement unit 17, and an examination window 18. The opthalmological examination unit 10 includes a corneal shape measurement unit 17 for measuring the corneal shape of the subject's eye E. A first pattern target projection optical system 20 of the corneal shape measurement unit 17 is disposed on the front side (the subject's eye side) of the opthalmological examination unit 10. The first pattern target projection optical system 20 is disposed facing the subject's eye. The corneal shape measurement unit 17 includes an examination window 18 centered on a measurement optical axis L1 (see FIG. 2). In addition to the corneal shape measurement unit 17, the ophthalmic apparatus 1 may also include an examination unit for examining (measuring or photographing) optical characteristics of the subject's eye other than corneal shape measurement. In this embodiment, an example will be described in which the opthalmological examination unit 10 includes an anterior segment cross-sectional imaging unit 200 (see FIG. 2).

[0023] The drive unit 13 changes the positional relationship of the optometry unit 10 with respect to the eye to be examined. For example, the drive unit 13 moves the optometry unit 10 three-dimensionally with respect to the base 12, thereby moving the optometry unit 10 in the X direction (left-right direction), Y direction (up-down direction), and Z direction (front-back direction) with respect to the eye to be examined E. The face support unit 14 is used to fix the face of the subject in front of the optometry unit 10. The face support unit 14 is fixed to the base 12, and fixes the eye to be examined E by supporting the face of the subject.

[0024] 2 is a schematic diagram of the optical system arranged in the optometry unit 10 and the control system of the ophthalmologic apparatus 1. The corneal shape measurement unit 17 includes a first pattern target projection optical system 20 for measuring the corneal shape of the subject's eye E, a front photographing optical system 60, a working distance detection optical system 80, a second pattern target projection optical system 70, and a fixation target presenting optical system 90. The anterior segment cross-sectional photographing unit 200 includes a cross-sectional photographing optical system 100.

[0025] The first pattern index projection optical system 20 includes a first pattern index projection unit 21. The first pattern index projection unit 21 includes a first pattern index plate 22 and a surface light-emitting panel 30. The first pattern index projection unit 21 may additionally include a reflector 26 on the outer periphery of the first pattern index plate 22.

[0026] FIG. 3 is a diagram illustrating the configuration of the first pattern indicator plate 22. FIG. 3 shows the first pattern indicator projection unit 21 from the front direction on the side where the subject is positioned. A surface light-emitting panel 30 (see FIG. 4) is arranged behind the first pattern indicator plate 22. The first pattern indicator plate 22 is made of a light-transmitting plate (e.g., acrylic resin) that guides illumination light from the surface light-emitting panel 30. The first pattern indicator plate 22 has first pattern indicators 23 formed on the light-transmitting plate for obtaining the corneal shape. In this embodiment, the first pattern indicator 23 is a multiple ring-shaped pattern indicator, as shown in FIG. 2. The first pattern indicator 23 has a plurality of ring-shaped light-shielding portions 23b painted black and unpainted ring-shaped light-transmitting portions 23a that are alternately formed in a concentric pattern around the measurement optical axis L1 on the first pattern indicator plate 22. The pattern plate 120 includes a flat transparent portion 23a, a light-shielding portion 23b, and an unpainted transparent portion 23c and a black-painted light-shielding portion 23d, which are arranged on the outer periphery of the transparent portion 23a and the light-shielding portion 23b. The transparent portion 23a and the light-shielding portion 23b each have a central opening 25 through which the measurement optical axis L1 of the front imaging optical system 60 passes. The entire circumference of the transparent portion 23a and the light-shielding portion 23b is circular with the center of the central opening 25 as the reference, and a ring-shaped first pattern indicator 23 is formed on almost the entire surface.

[0027] 4 is a diagram illustrating the configuration of the surface-emitting panel 30. The surface-emitting panel 30 is configured with a light guide plate 31, an illumination light source 32, a reflection pattern 33, a reflection sheet 34, and a diffusion plate 35 as main elements.

[0028] The light guide plate 31 is made of a light-transmitting body (e.g., acrylic resin). Light from the surface-emitting panel 30 passes through the light-transmitting portions 23a and 23c and projects the Placido ring pattern of the first pattern indicator 23 onto the cornea Ec of the subject's eye. The surface-emitting panel 30 has a central opening (not shown) through which a light beam for corneal shape measurement passes, and various light-passing holes (not shown) through which a light beam from the cross-section imaging optical system 210, a light beam from the working distance detection optical system 80, and illumination light that illuminates the subject's eye during alignment and observation of the subject's eye pass, just like the first pattern indicator plate 22. Note that the optical system that illuminates the light-transmitting portions 23a and 23c of the first pattern indicator 23 from behind may be, for example, a ring-shaped light source provided behind the light-transmitting portions 23a and 23c.

[0029] The illumination light source 32 is, for example, an LED that emits white light containing light of various wavelengths from 400 nm to 700 nm. The illumination light source 32 illuminates the first pattern index plate 22. A plurality of illumination light sources 32 are arranged side by side at the end of the light guide plate 31. The reflection pattern 33 may be formed, for example, by reflective dots formed by printing reflective paint in the form of dots on the back side of the light guide plate 31.

[0030] The reflective sheet 34 is disposed on the rear surface of the surface-emitting panel 30, sandwiching the reflective pattern 33 therebetween. This causes light from the illumination light source 32, which is guided by the light guide plate 31, to be reflected toward the front surface. The diffusion plate 135 is disposed on the front surface side of the surface-emitting panel 30, and diffuses the light emitted from the surface of the surface-emitting panel 30.

[0031] Returning to FIG. 2 , the anterior eye illumination optical system 50 includes an illumination light source 51 that emits infrared light or white light. In this embodiment, the illumination light source 51 is embedded in the first pattern index projection unit 21. Six light passage holes 24c are formed in the first pattern index plate 22 around the measurement optical axis L1 on a first concentric circle outside the light passage holes 24b at 0-degree, 45-degree, 135-degree, 180-degree, 225-degree, and 315-degree directions. Four light passage holes 24c are also formed on a second concentric circle outside the first concentric circle at 45-degree, 135-degree, 225-degree, and 315-degree directions. The illumination light source 51 illuminates the subject's eye E through the light passage holes 24c, and is therefore provided in the same position as the light passage holes 24c on the first pattern index plate 22.

[0032] The front photographing optical system 60 includes an objective lens 61, an imaging lens 62, and an imaging element 63 on the measurement optical axis L1. The front photographing optical system 60 is a device for capturing an image. The front photographing optical system 60 is, for example, a color camera. The front photographing optical system 60 is disposed, for example, at a pupil conjugate position of the anterior segment of the subject's eye. The front photographing optical system 60 is used to capture an index image of the first pattern index 23 projected onto the cornea of ​​the subject's eye when measuring the corneal shape. In addition, a front image of the anterior segment of the subject's eye illuminated by the anterior segment illumination light source 50 is captured by the imaging element 63. In addition, the front photographing optical system 60 also serves as a detection optical system that detects an index image projected onto the cornea Ec of the subject's eye by the second pattern index projection optical system 70. The index image by the second pattern index projection optical system 70 is captured by the imaging element 63.

[0033] The imaging element 63 is an imaging element capable of simultaneously acquiring light of each wavelength. The imaging element 63 is disposed in the front imaging optical system 60 so that its imaging surface is positioned at the image plane of the imaging lens 62. The imaging element 63 may be, for example, a CCD (charge-coupled device) image sensor. The imaging element 63 may be composed of a microlens, a color filter, a photodiode, etc. (none of which are shown). The microlens focuses light onto the photodiode. The color filter may have a Bayer array in which rows of red filters and green filters are alternately arranged with rows of green filters and blue filters. Alternatively, the color filter may be arranged using an array method other than the Bayer array. The photodiode converts the received light into an electrical signal. The imaging element 63 captures an image formed on the imaging surface via the imaging lens 62 and generates an image signal representing the captured image.

[0034] In the front imaging optical system 60, an imaging light beam from a light source 71 passes through a second pattern target plate 72 and a lens 73, and is transmitted through a dichroic mirror 74, which is an optical element, to be made coaxial with the measurement optical axis L1, and is reflected by a mirror 75 to reach the cornea Ec of the subject's eye via the objective lens 61 and the examination window 18. The returned light from the cornea Ec of the subject's eye passes through the objective lens 61, the mirror 75, the dichroic mirror 74, the half mirror 96, and the imaging lens 62 to reach the imaging element 63. As a result, an index image of the pattern target projected onto the cornea Ec of the subject's eye is acquired.

[0035] The dichroic mirror 74 is an optical element that transmits the first corneal reflection image and the second corneal reflection image by transmitting a portion of the light beam from the light source 71 between the subject's eye E and the image sensor 63. The dichroic mirror 74 has a branching ratio of reflection and transmission such that the rate at which the first pattern index projected with visible light is attenuated is smaller than the rate at which the second pattern index projected with infrared light is attenuated in the optical path from the subject's eye cornea Ec to the image sensor 63.

[0036] The dichroic mirror 74 may have a characteristic that the transmittance of infrared light having a wavelength of 700 nm to 900 nm is approximately 80%, for example. Also, the dichroic mirror 74 may have a characteristic that the transmittance of light having a wavelength shorter than 600 nm and a wavelength longer than 920 nm is approximately 20%. In this case, the dichroic mirror 74 has an attenuation ratio of A:B (where A>B) between the infrared light for projecting the second pattern index and the visible light for projecting the first pattern index.

[0037] The working distance detection optical system 80 includes a light projecting optical system 81 and a light receiving optical system 85. The light projecting optical system 81 includes a light source 82 that emits infrared light and a lens 83. The light receiving optical system 85 includes a lens 86 and a light receiving element 87. The working distance detection optical system 80 is used to align the optometry unit 10 with respect to the subject's eye in the working distance direction (Z direction).

[0038] Light from the light source 82 is converted into a substantially parallel beam by a lens 83 and passes through a light-passing hole (not shown) formed in the surface-emitting panel 30 and a light-passing hole 24b formed in the first pattern index plate 22, and is then irradiated obliquely onto the cornea of ​​the subject's eye. The optical axis of the light-receiving optical system 85 is arranged symmetrically with the optical axis of the light-projecting optical system 81 with respect to the measurement optical axis L1. Corneal reflection light from the light-projecting optical system 81 is incident on a light-receiving element 87 through the light-passing hole 24b formed in the first pattern index plate 22, a light-passing hole (not shown) formed in the surface-emitting panel 30, and a lens 86. When the subject's eye moves relatively in the working distance direction (Z direction), the target image (image of the light source 82) formed on the subject's eye cornea Ec also moves on the light-receiving element 167. Therefore, the target image on the light-receiving element 87 is detected and processed, and the alignment state of the optometry unit 10 in the working distance direction with respect to the subject's eye is detected.

[0039] The second pattern index projection optical system 70 includes a light source 71 that emits infrared light, a second pattern index plate 72, a lens 73, and a dichroic mirror 74. For example, a double ring index is formed on the second pattern index plate 72. The light beam of the ring index on the second pattern index plate 72 illuminated by the light source 71 is made coaxial with the measurement optical axis L1 via the lens 73 and the dichroic mirror 74 and projected onto the cornea of ​​the subject's eye. As a result, an index image of the second pattern index is formed on the cornea Ec of the subject's eye. The index image of the second pattern index projected onto the cornea Ec of the subject's eye is received by the image sensor 63 of the front imaging optical system 60 as a second corneal reflection image. The second corneal reflection image may be received by the image sensor 63 and processed by the control unit 2 to be used to detect the alignment state in the XY directions of the relative positional relationship between the subject's eye and the optometry unit 10.

[0040] The fixation target presenting optical system 90 presents a fixation target to the subject's eye. The fixation target presenting optical system 90 includes at least a light source 91 that emits visible light and a fixation target plate 92. A fixation light beam from the light source 91 passes through the fixation target plate 92, a lens 93, a half mirror 94, and a lens 95, and is reflected by a half mirror 96 to be made coaxial with the measurement optical axis L1. The fixation light beam then passes through the objective lens 61 and reaches the fundus of the subject's eye.

[0041] The cross-section photographing optical system 100 is used to photograph a cross-sectional image of the anterior segment of the eye. The cross-section photographing optical system 100 includes a light projecting optical system 101 and a light receiving optical system 105.

[0042] The light projection optical system 101 is coaxial with the measurement optical axis L1 and projects slit light, which is an example of imaging light, onto the anterior segment. The light projection optical system 101 includes a light source 102 and a slit 103. The light source 102 uses, for example, red visible light or near-infrared light as imaging light. The slit 103 may be disposed at a pupil conjugate position. For example, the slit 103 is disposed so that the slit light optically cuts the anterior segment in the horizontal direction (X direction).

[0043] The light receiving optical system 105 includes a lens system 106 and an image sensor 107, which is an example of a photodetector. In the light receiving optical system 105, the lens system 106 and the image sensor 107 are disposed in a Scheimpflug relationship with a cut surface set in the anterior segment. That is, the optical arrangement is such that the extensions of the cut surface, the principal plane of the lens system 106, and the image sensor 107 intersect at a single intersection (single axis). The image sensor 107 receives return light (reflected light or scattered light) from the anterior segment, which has been optically cut by the slit light. Then, a cross-sectional image of the anterior segment is acquired based on a signal from the image sensor 107.

[0044] In the cross-section photographing optical system 100, a photographing light beam from a light source 102 passes through a slit 103 to become a slit light beam, which passes through a lens 104, a half mirror 94, and a lens 95 and is reflected by a half mirror 96 to be made coaxial with the measurement optical axis L1. The photographing light beam then passes through a dichroic mirror 74, a mirror 75, and an objective lens 61 to reach the anterior segment. Return light from a cut surface formed in the anterior segment passes through a light passing hole 24a formed in the first pattern index plate 22, a light passing hole (not shown) formed in the surface-emitting panel 30, and a lens system 106 to reach an image sensor 107. In this way, a cross-sectional image of the anterior segment of the subject's eye is acquired.

[0045] 2, the control unit 2 is responsible for overall control of the ophthalmologic apparatus 1. The control unit 2 is connected to various electrical elements, such as the image sensor 63, the image sensor 107, the light sources of the optical system, the display unit 15, and the drive unit 13. The control unit 2 also has an image processing function for processing the images captured by the image sensor 63 and the image sensor 107. For example, the control unit 2 acquires an image of the target image of the pattern target projected onto the cornea Ec of the test eye during corneal shape measurement, captured by the image sensor 63, and analyzes the image according to a predetermined program to obtain the corneal shape of the cornea Ec of the test eye. The control unit 2 also acquires a cross-sectional image of the anterior segment captured by the image sensor 107 and analyzes the image according to a predetermined program to obtain the shape of the anterior segment tissue.

[0046] The display unit 15 may function as a touch panel that also serves as the operation unit 16. The display unit 15 displays the measurement results of the subject's eye (anterior segment cross-sectional images, corneal shape measurement results, etc.) on a screen. The control unit 2 is connected to a memory unit 3, which is an example of a storage device. The memory unit 3 stores the frontal anterior segment images acquired by the image sensor 63, the anterior segment cross-sectional images acquired by the image sensor 107, the measurement results, etc. The memory unit 3 also stores various control programs.

[0047] The operation of the ophthalmologic apparatus 1 having the above-described configuration will now be briefly described with reference to the flowchart of FIG.

[0048] First, the measurement of the corneal shape will be described. When the subject's face is supported by the face support unit 14, the front imaging optical system 60 captures a front image of the subject's eye E illuminated by the anterior eye illumination optical system 50. The control unit 2 displays the front image of the subject's eye E captured by the front imaging optical system 60 on the display unit 15. The control unit 2 processes the front image of the anterior eye acquired by the front imaging optical system 60 and detects the alignment state of the optometry unit 10 (measurement optical axis L1) in the X and Y directions relative to the corneal vertex based on the target (corneal reflection bright spot) projected onto the subject's cornea Ec by the second pattern target projection optical system 70. The control unit 2 also detects the alignment state in the Z direction based on the output of the light-receiving element 87 of the working distance detection optical system 80. The control unit 2 then controls the drive unit 13 to move the optometry unit 10 in the X, Y, and Z directions so that the alignment states in the X, Y, and Z directions fall within predetermined tolerance ranges. This completes the alignment of the ophthalmologic apparatus 1.

[0049] Once the alignment is complete, the control unit 2 turns on the anterior eye illumination optical system 50 and captures an image of the anterior eye of the subject's eye E (S1). The image sensor 63 of the front imaging optical system 60 generates an image signal representing the captured image and transfers the image signal to the storage unit 3. The storage unit 3 stores the image signal generated by the image sensor 63. The control unit 2 acquires iris color information of the subject's eye by performing image processing to calculate the ratio of color components of the captured image stored in the storage unit 3 (S2). Here, for example, it is assumed that the control unit 2 determines that the iris color of the subject's eye is brownish based on the acquired iris color information of the subject's eye.

[0050] Next, the control unit 2 turns on the surface light-emitting panel 30 and projects an index image of the first pattern index 23 onto the cornea Ec of the subject's eye (S3). At this time, the control unit 2 may turn off the anterior eye illumination optical system 50. The control unit 2 photographs the cornea Ec of the subject's eye (S4). The image sensor 63 of the front photographing optical system 60 generates an image signal indicating the photographed image and transfers the image signal to the memory unit 3. The memory unit 3 stores the image signal generated by the image sensor 63.

[0051] For example, the control unit 2 may separate the captured image stored in the storage unit 3 into three color channel images: a red channel image, a green channel image, and a blue channel image (S5). The control unit 2 acquires luminance information for each color channel image in the captured image of the subject's eye having a brownish iris (S6). FIG. 6 shows an example of luminance information for the approximately central portion of the subject's eye, from the inner corner to the outer corner, when the captured image of the subject's eye having a brownish iris is converted to grayscale. FIG. 7 shows an example of luminance information for the approximately central portion of the subject's eye, from the inner corner to the outer corner, in each color channel image of the captured image (red channel image: FIG. 7(a), green channel image: FIG. 7(b), blue channel image: FIG. 7(c)).

[0052] In the luminance information graphs of FIGS. 7(a) to 7(c), the range 300 where the vertical width of the grayscale values ​​is approximately constant is the pupil range of the subject's eye. Furthermore, in the luminance information graphs of FIGS. 7(a) and 7(b), the range 301 where the grayscale values ​​are located to the left and right of the pupil range of the subject's eye is the iris range of the subject's eye. In FIGS. 7(a) and 7(b), the vertical width of the grayscale values ​​in range 301 is inconstant. This is thought to be due to the fact that the grayscale values ​​of the iris range of the subject's eye are inconstant in the red channel image and the green channel image. In comparison, the vertical width of the grayscale values ​​in range 301 in FIG. 7(c) is approximately constant. In other words, the grayscale values ​​of the iris color of the subject's eye are thought to be approximately constant in the blue channel image. In this way, by analyzing a color image by color channel, it is possible to separate the grayscale values ​​into color channels that are heavily influenced by the iris color of the subject's eye and color channels that are less influenced by this influence.

[0053] The control unit 2 acquires weighting coefficients for each color channel image set for each iris color based on the acquired iris color information (S7). The weighting coefficients for the red channel image, green channel image, and blue channel image acquired by the control unit 2 are weight values ​​a, b, and c, respectively. Note that, for example, the weighting coefficients for each color channel image set for a test eye with a brown iris color may be weight value a=0, weight value b=0.5, and weight value c=1.0.

[0054] The control unit 2 obtains a weighted average image of the three color channel images using weight values ​​a, b, and c (S8). That is, the control unit 2 performs image processing to move the image toward the color channel image with the larger weight value among the color channel images (i.e., toward the blue channel image) based on weight values ​​a to c. This reduces the influence of the iris color of the subject's eye on the target image of the pattern target, thereby obtaining an image in which the influence of the iris color of the subject's eye on the target image of the pattern target is reduced.

[0055] The acquired anterior eye image is stored in the memory unit 3 or the like. The control unit 2 detects black and white edges of the target image of the pattern target in the processed image stored in the memory unit 3 (S9), and calculates the corneal curvature for each predetermined angle based on the distance of each edge from the corneal center. Based on this corneal curvature, the corneal refractive power of the subject's eye E is calculated. In this way, the control unit 2 acquires corneal shape parameters to be used, for example, for outputting a shape map described below (S10).

[0056] The control unit 2 may output corneal shape information based on the acquired corneal shape parameters of the subject's eye E (S11). The control unit 2 may output the measurement results by displaying them as a shape map on the display unit 15 (see FIG. 9). The control unit 2 may also output the corneal shape information by displaying a front image of the subject's eye E onto which an index image of the pattern index is projected on the display unit 15 (see FIG. 8).

[0057] 5, the control unit 2 uses the first pattern target projection optical system 20 to project an image of the first pattern target using visible light from the surface light-emitting panel 30 onto the cornea Ec of the test eye. At this time, the control unit 2 may turn off the anterior-segment illumination optical system 50. The first corneal reflection image, which is the return light from the cornea Ec of the test eye, is received by the image sensor 63 via the objective lens 61, the mirror 75, the dichroic mirror 74, the half mirror 96, and the imaging lens 62.

[0058] Furthermore, the control unit 2 uses the second pattern target projection optical system 70 to project an index image of the second pattern target by infrared light from the light source 71 onto the cornea Ec of the test eye. The second corneal reflection image, which is light returned from the cornea Ec of the test eye, reaches the image sensor 63 via the objective lens 61, the mirror 75, the dichroic mirror 74, the half mirror 96, and the imaging lens 62. More specifically, first, the control unit 2 causes the light source 71 to emit light. The infrared light beam from the light source 71 passes through the second pattern target plate 72 and becomes a beam of the second pattern target. The beam of the second pattern target passes through the lens 73 and passes through the dichroic mirror 74. By passing through the dichroic mirror 74, the beam of the second pattern target becomes coaxial with the measurement optical axis L1 and is projected onto the cornea Ec of the test eye via the mirror 75, the objective lens 61, and the examination window 18. The second corneal reflection image, which is the return light from the cornea Ec of the test eye, passes through the inspection window 18, the objective lens 61, and the mirror 75, is reflected by the dichroic mirror 74, and is received by the image sensor 63 via the half mirror 96 and the imaging lens 62. The light flux of the second pattern target and the second corneal reflection image are attenuated in light quantity when transmitted through and reflected from the dichroic mirror 74. In this way, by making the wavelengths of the light of the first pattern target and the second pattern target different, the attenuation of the light quantity of the first corneal reflection image, which is attenuated by the dichroic mirror 74, can be suppressed, and the first corneal reflection image and the second corneal reflection image can be guided to the image sensor 63.

[0059] FIG. 8 is a diagram showing the target images of the first and second pattern targets projected onto the cornea Ec of the test eye. The target image 400 is a target image of the first pattern target projected by visible light onto the cornea Ec of the test eye by the control unit 2 turning on the surface light-emitting panel 30. The target image 401 is a target image of the second pattern target projected by infrared light onto the cornea Ec of the test eye by the control unit 2 turning on the light source 71 of the second pattern target projecting optical system 70. As shown in FIG. 8, by projecting the target image 400 and the target image 401 onto the cornea Ec of the test eye, the target image can also be projected onto the central part of the cornea Ec of the test eye. Therefore, the measurement accuracy of the corneal topography can be maintained compared to when only the first pattern target is projected onto the cornea Ec of the test eye. In other words, adding this operation leads to maintaining the accuracy of the corneal topography measurement of the test eye Ec.

[0060] Next, measurement of the cross-sectional shape of the anterior eye segment will be described. The alignment state of the optometry unit 10 with respect to the subject's eye E is confirmed, and a cross-sectional image of the anterior eye segment of the subject's eye is captured when the alignment is complete. When the light source 102 of the cross-section photographing optical system 200 is turned on, the anterior eye segment of the subject's eye is optically sectioned by slit light from the slit 103. The image sensor 107 photographs the return light from the optically sectioned anterior eye segment, and the control unit 2 acquires a cross-sectional image of the anterior eye segment. The control unit 2 processes and analyzes the cross-sectional image, for example, to acquire the positions of the anterior and posterior corneal surfaces of the corneal tissue. The analysis results may be output by being displayed on the display unit 15 together with the cross-sectional image.

[0061] Although typical embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and various modifications are possible. For example, the first pattern indicator 23 is a ring indicator. Note that the first pattern indicator 23 is not limited to a ring indicator, and may be, for example, dot-shaped indicators arranged in a ring. The first pattern indicator 23 may have any shape and arrangement that allows for measurement of the corneal shape.

[0062] In the embodiment described above, the second pattern index plate 72 is formed with double ring indexes. However, the indexes of the second pattern index plate 72 are not limited to double rings. The indexes of the second pattern index plate 72 may be, for example, indexes with multiple points. The indexes of the second pattern index plate 72 may have any shape and arrangement that allows for measurement of the corneal shape.

[0063] In the above-described embodiment, the illumination light source 51 emits infrared light or white light. However, the illumination light source 51 may be, for example, a light source that emits either infrared light or white light. Alternatively, the illumination light source 51 may be a light source that emits both infrared light and white light.

[0064] In the above embodiment, the optical element of the optical path combining section is a single dichroic mirror. However, the optical element of the optical path combining section may be made up of a plurality of members.

[0065] In the embodiment described above, the iris color information of the subject's eye is obtained by image processing the photographed image of the anterior segment of the subject's eye E, which is photographed with the anterior segment illumination optical system 50 turned on. Note that, for example, the iris color information of the subject's eye may be obtained by image processing the photographed image of the subject's eye E onto which an index image of a pattern index is projected. The iris color information of the subject's eye may be obtained before weighting processing.

[0066] In the above-described embodiment, the control unit 2 is configured to separate the color channel images. However, for example, the separation of the color channel images may be performed by an image sensor of the frontal imaging optical system 60 or the like, based on the generation of color signals. The frontal imaging optical system 60 may separate the color channel images by using an image sensor equipped with an image processing engine (not shown). The image processing engine generates image data and performs various processes on the image data. The ophthalmic apparatus 1 may also include an image processing engine separate from the control unit 2. In this case, the image processing engine, rather than the control unit 2, may separate the color channel images.

[0067] In the above embodiment, the imaging element 63 of the front imaging optical system 60 is a CCD image sensor. However, the imaging element 63 may be a CMOS (complementary metal oxide semiconductor) image sensor.

[0068] In the above embodiment, the illumination light source 32 is configured as a white light LED. However, the illumination light source 32 may emit visible light containing light of multiple wavelengths. For example, it may emit reddish-purple visible light that is a mixture of red and blue light.

[0069] In the embodiment described above, the controller 2 is configured to acquire iris color information of the subject's eye E through image processing of the captured image. The controller 2 may acquire iris color information by having the examiner input the iris color information of the subject's eye by operating the operation unit 16 of the display unit 15. The controller 2 may also acquire iris color information from, for example, an external device. Furthermore, the controller 2 may perform image processing of the captured image without using iris information. In this case, the controller 2 may perform image processing by calculating weighting coefficients based on, for example, luminance information of each color channel of the captured image.

[0070] In the embodiment described above, the control unit 2 acquires the weighting coefficients for each color channel image set for each iris color based on the iris color information. The control unit 2 may also calculate the weighting coefficients for each color channel image based on the luminance information of each color channel image (FIG. 7). For example, the control unit 2 may refer to the luminance information of the iris portion and the index image of the pattern index in each color channel image and use a larger weighting coefficient for a color channel image that is less influenced by the iris color. Furthermore, the control unit 2 may assign a weighting coefficient to each color channel image based on the contrast (luminance ratio) of each color channel image. For example, the control unit 2 may assign a larger weighting coefficient to a color channel image with high contrast. The control unit 2 may also acquire the weighting coefficients for each color channel image set based on the level of contrast.

[0071] When obtaining the weighting coefficients, the control unit 2 may use both the iris color information and the luminance information of each color channel image. Alternatively, the control unit 2 may use both the iris color information and the contrast of each color channel image. Combining these pieces of information allows for more efficient analysis. For example, once analyzed, iris color information may be used as a reference for the iris color information of the contralateral eye of the subject's eye E. Furthermore, the analysis process for the contralateral eye of the subject's eye E may be omitted, and the iris color information of the subject's eye E may be used in the analysis process for the contralateral eye. Furthermore, once analyzed, iris color information of the subject's eye E may be called up for subsequent measurements of the subject's eye E. By calling up the iris color information, the iris color analysis process can be omitted, improving the efficiency of the analysis process.

[0072] In the above-described embodiment, corneal topography information is acquired by performing image processing using multiple color channel images. For example, only one color channel image with a weight value greater than 0 may be used to acquire corneal topography information. In this case, the control unit 2 may acquire corneal topography information based on the color channel image itself.

[0073] In the above-described embodiment, the measurement results and analysis results are output by being displayed on the display unit 15. However, the results may also be output by printing them on paper using a printer. Alternatively, the results may also be output by transferring the data to a computer in which a database is stored via a data communication means. [Explanation of symbols]

[0074] 1 Ophthalmology equipment 2. Control section 3 Storage section 15 Display 18 Inspection window 20 First pattern target projection optical system 22 First pattern index plate 50 Anterior segment illumination optical system 60 Frontal Shooting Optical System 61 Objective Lens 63 Image sensor 70 Second pattern target projection optical system 72 Second pattern index plate 74 Dichroic Mirror

Claims

1. An ophthalmic apparatus for measuring a corneal shape of a subject's eye, an illumination optical system that projects an index image of a pattern index onto the cornea of ​​the subject's eye using light including a plurality of wavelengths; an imaging optical system that captures an index image of the pattern index projected onto the cornea of ​​the subject's eye; a separation unit that separates an image captured by the imaging optical system into a plurality of color channels; and a control unit; The control unit performs weighting processing on the image separated by the separating unit for each of the examinee's eyes, thereby acquiring corneal shape information of the examinee's eyes.

2. The ophthalmic apparatus of claim 1, wherein the control unit acquires corneal shape information of the subject's eye by performing weighting processing on each color channel image based on luminance information of each color channel image separated into multiple color channels by the separation means.

3. The ophthalmic apparatus of claim 1, wherein the control unit acquires corneal shape information of the subject's eye by performing weighting processing on each color channel image separated into multiple color channels by the separation means based on the contrast of each color channel image.

4. The ophthalmologic apparatus according to claim 1 , wherein the control unit acquires iris color information of the subject's eye, and performs weighting processing on the color channel images based on the iris color information, thereby acquiring corneal shape information of the subject's eye.

5. An ophthalmic apparatus control program for use in an ophthalmic apparatus for measuring a corneal shape of an eye to be examined, the ophthalmic apparatus comprising: an illumination optical system that projects an index image of a pattern index onto the cornea of ​​the eye to be examined; an imaging optical system that captures the index image of the pattern index projected onto the cornea of ​​the eye to be examined; a separation means that separates the image captured by the imaging optical system into a plurality of color channels; and a control unit, a corneal shape acquiring step, which is executed by the control unit, to perform weighting processing on the image separated by the separating means for each of the examinee's eyes, thereby acquiring corneal shape information of the examinee's eyes; an ophthalmic apparatus control program to be executed by the ophthalmic apparatus;

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