Ophthalmologic apparatus and processing program for the same

Abstract

To perform analysis processing of pattern index images more accurately.SOLUTION: An ophthalmologic apparatus includes pattern index projection means for projecting a pattern index to obtain the corneal shape of an eye to be examined onto the cornea of the eye to be examined, image acquisition means for acquiring an anterior segment image by capturing an image of the anterior segment of the eye to be examined onto which the pattern index is projected using an image sensor, and processing means for processing the anterior segment image acquired by the image acquisition means. The processing means extracts a pattern index image corresponding to the pattern index projected onto the eye to be examined by comparing and processing at least two anterior segment images having different projection states of the pattern index, and analyzes the corneal shape of the eye to be examined on the basis of the extracted pattern index image.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] An ophthalmic device is known that projects a pattern index (placido ring) onto the cornea of ​​the test eye to obtain distribution information of the corneal shape of the test eye over a wide area, obtains an image of the pattern index image of the test eye captured by an imaging element, and obtains the corneal shape of the test eye (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-342536 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the illumination light of the pattern index is red to infrared light, it may be difficult to extract the pattern index image in the anterior eye image because of strong reflection from the iris of the subject's eye. The technology of Patent Document 1 proposed to deal with this problem is to make it easier to obtain the luminance change of the pattern index image near the boundary between the pupil and the iris, but the contrast between the iris and the pattern index image does not change, and the pattern index image may not be analyzed accurately due to the influence of the iris image reflected in the pattern index image.

[0005] In view of the above-mentioned conventional techniques, the present disclosure has an object to provide an ophthalmic apparatus and a processing program therefor that can perform analysis processing of a pattern target image with higher accuracy. [Means for solving the problem]

[0006] (1) An ophthalmic apparatus according to a first aspect of the present disclosure includes a pattern index projection means for projecting a pattern index onto the cornea of ​​the test eye to obtain the corneal shape of the test eye, an image acquisition means for acquiring an anterior segment image by capturing an image of the anterior segment of the test eye onto which the pattern index is projected using an image sensor, and a processing means for processing the anterior segment image acquired by the image acquisition means, wherein the processing means extracts a pattern index image corresponding to the pattern index projected onto the test eye by comparative processing of at least two anterior segment images having different projection states of the pattern index, and analyzes the corneal shape of the test eye based on the extracted pattern index image. (2) The processing program of an ophthalmic apparatus according to the second aspect of the present disclosure is executed by a control unit of an ophthalmic apparatus equipped with a pattern index projection means for projecting a pattern index onto the cornea of ​​the test eye to obtain the corneal shape of the test eye, thereby causing the ophthalmic apparatus to execute an image acquisition step of capturing an image of the anterior segment of the test eye onto which the pattern index is projected using an imaging element to obtain an anterior segment image, and a processing step of processing the anterior segment image acquired by the image acquisition step, in which at least two anterior segment images having different projection states of the pattern index are compared and processed to extract a pattern index image corresponding to the pattern index projected onto the test eye, and the corneal shape of the test eye is analyzed based on the extracted pattern index image. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram illustrating components such as an eye examination optical system and a control system of the ophthalmic apparatus. [Diagram 2] 3A and 3B are diagrams for explaining a pattern target of a pattern target projection optical system. [Diagram 3] 5A to 5C are diagrams illustrating a comparison process of anterior eye images in the first embodiment. [Figure 4] FIG. 13 is a diagram showing an example of a bright spot of an anterior eye illumination reflected in an anterior eye image. [Diagram 5] 13A to 13C are diagrams illustrating a comparison process of anterior eye images in the second embodiment. [Figure 6]11A and 11B are diagrams illustrating a process for removing bright points of anterior eye illumination reflected in an anterior eye image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [overview] Hereinafter, one exemplary embodiment will be described with reference to the drawings. Note that the items grouped in <> below can be used independently or in conjunction with each other.

[0009] For example, an ophthalmic apparatus (e.g., the ophthalmic apparatus 1) includes a pattern index projection means (e.g., the pattern index projection optical system 100), an image acquisition means (e.g., the anterior eye imaging optical system 150, the control unit 50), and a processing means (e.g., the control unit 50). For example, the ophthalmic apparatus may include an anterior eye illumination means (e.g., the anterior eye illumination optical system 110). For example, the ophthalmic apparatus may include a Mayer ring index projection means (e.g., the Mayer ring index projection optical system 120).

[0010] <Pattern index projection means> For example, the pattern index projection means is used to project a pattern index (e.g., pattern index 104) for obtaining the corneal shape of the subject's eye onto the cornea of ​​the subject's eye. For example, the pattern index projection means may be a light source for illuminating the pattern index, and may include a light source (e.g., light source 105) that emits light in the infrared to infrared region. For example, the pattern index may be formed in a multiple ring shape. For example, the ring-shaped pattern index may have a ring-shaped light-shielding portion (e.g., light-shielding portion 104a) and a ring-shaped light-transmitting portion (e.g., light-transmitting portion 104b) alternately formed in a concentric shape around the eye examination axis. In other words, the pattern index projection means may project a so-called Placido ring. Note that the pattern index may be a dot-shaped index arranged in a ring shape, and is not limited to a ring shape, and the shape and arrangement are not important as long as the corneal shape can be measured. Also, for example, the pattern index projection means may be configured as a Placido plate type or a cone type.

[0011] <Image acquisition method> For example, the image acquiring means acquires an anterior eye image by capturing an image of the anterior eye of the subject's eye onto which the pattern index is projected using an imaging element (e.g., the imaging element 155). For example, the image acquiring means may acquire at least two anterior eye images in which the projection state of the pattern index is different.

[0012] For example, the image acquiring means may control the pattern target projection means to acquire an anterior eye image onto which the pattern target is projected and an anterior eye image onto which the pattern target is not projected.

[0013] For example, the image acquisition means may control the pattern index projection means to acquire at least two anterior eye images in which the regions of the pattern index are different from each other. In this case, for example, the image acquisition means may control the pattern index projection means to divide the region of the pattern index into two or more divisions, and project each of the divided pattern indexes onto the subject's eye to acquire anterior eye images corresponding to the divided pattern indexes. For example, the division of the pattern index may be performed by dividing the region of the pattern index into two or more divisions. For example, in the case where the pattern index is a multiple ring-shaped index, the ring-shaped index may be divided every other ring-shaped index, every other ring-shaped index, etc., or may be divided into an inner half region and an outer half region. For example, the pattern index may be divided into an upper region and a lower region.

[0014] For example, the image acquisition means may continuously capture images of the anterior segment by the imaging element to obtain at least two anterior segment images with different projection states of the pattern index. This makes it possible to suppress the influence of the movement of the subject's eye (positional deviation of the subject's eye) in the imaging to obtain at least two anterior segment images. This allows the pattern index image to be extracted with high accuracy, and the pattern index image can also be analyzed satisfactorily. For example, the continuous imaging by the imaging element may be such that anterior segment images are continuously obtained at the frame rate of the imaging element.

[0015] <Processing means> For example, the processing means processes the anterior eye image acquired by the image acquisition means. For example, the processing means extracts a pattern index image corresponding to the pattern index projected on the subject's eye by comparing and processing at least two anterior eye images in which the pattern index is projected by the pattern index projection means in different states, and analyzes the corneal shape of the subject's eye based on the extracted pattern index image. This processing means reduces the influence of the iris image reflected on the pattern index image, and can perform the analysis processing of the pattern index image with high accuracy.

[0016] For example, the processing means may extract the pattern index image by performing a comparison process between an anterior eye image on which a pattern index is projected and an anterior eye image on which a pattern index is not projected. In this case, for example, the processing means may extract the pattern index image by performing a difference process on the luminance value at each pixel position between each anterior eye image.

[0017] Also, for example, the processing means may extract the pattern index image by performing a comparative process on at least two anterior eye images having different pattern index regions. For example, the processing means may obtain a bright composite anterior eye image by synthesizing pixels with higher luminance values ​​among the pixels of each anterior eye image, and obtain a dark composite anterior eye image by synthesizing pixels with lower luminance values ​​among the pixels of each anterior eye image, and perform differential processing on the luminance values ​​of the same pixel positions between the two to obtain an image with the pattern index image remaining, and extract the pattern index image based on this. Alternatively, for example, the processing means may perform differential processing on the luminance values ​​of the same pixel positions between each anterior eye image, and perform sign inversion processing on the luminance values ​​of the remaining pixels with negative values ​​to obtain an image with the pattern index image remaining, and extract the pattern index image based on this.

[0018] Furthermore, for example, when comparing two or more anterior eye images, the processing means may detect a positional shift between the anterior eye images and correct the positional shift between the anterior eye images based on the detection result. Even if the subject's eye moves beyond an allowable amount, the positional shift between the anterior eye images is corrected, so that the pattern target image can be extracted more accurately and its analysis process can be performed more accurately.

[0019] <Mechanism for projecting Mayer ring index> For example, the Mayer ring index projection means is used to measure the corneal shape. For example, the Mayer ring index projection means projects a so-called Mayer ring, which is a ring-shaped index, onto the cornea of ​​the test eye. The Mayer ring index projection means may be used as a part of the pattern index projection means. For example, the Mayer ring may be used as a part of the pattern index for obtaining the corneal shape.

[0020] <Anterior segment illumination means> For example, the anterior eye illumination means is used to project illumination light for illuminating the anterior eye of the subject's eye. For example, the anterior eye illumination means may be configured so that a reflected bright spot of illumination light is formed outside the area where the pattern index image is projected in the anterior eye image captured by the imaging element. This makes it possible to illuminate the anterior eye of the subject's eye while avoiding the bright spot of the anterior eye illumination projected in the anterior eye image being superimposed on the area of ​​the pattern index image when obtaining an anterior eye image on which the pattern index is not projected. In other words, it is possible to suppress the bright spot of the anterior eye illumination from affecting the extraction of the pattern index image.

[0021] For example, the anterior eye illumination means may be configured to be able to change the light emission position of the illumination light for illuminating the anterior eye of the subject's eye. In this case, the image acquisition means may acquire at least two anterior eye images in which the bright spots of the illumination light are formed at different positions due to the change in the light emission position. In this case, the processing means may acquire an anterior eye image in which the pattern index is not projected, in which the bright spots are removed by comparing the anterior eye images acquired by the image acquisition means. In this way, when acquiring an anterior eye image in which the pattern index is not projected, an anterior eye image in which the bright spots of the anterior eye illumination are removed is acquired, so that the pattern index image can be accurately extracted in the comparison process of the multiple anterior eye images in the subsequent process.

[0022] In addition, the present disclosure is not limited to the devices described in the present embodiment. For example, a processing program (software) that performs the functions of the following embodiments is supplied to a system or device via a network or various storage media. Then, a control device (e.g., a CPU, etc.) of the system or device can read and execute the program.

[0023] The processing program of the ophthalmic apparatus is executed by the control unit of the ophthalmic apparatus equipped with a pattern index projection means for projecting a pattern index onto the cornea of ​​the test eye to obtain the corneal shape of the test eye, causing the ophthalmic apparatus to execute an image acquisition step of capturing an image of the anterior segment of the test eye onto which the pattern index is projected using an imaging element to obtain an anterior segment image, and a processing step of processing the anterior segment image acquired by the image acquisition step, in which at least two anterior segment images having different projection states of the pattern index are compared to extract a pattern index image corresponding to the pattern index projected onto the test eye, and the corneal shape of the test eye is analyzed based on the extracted pattern index image.

[0024] [Example] An embodiment of an ophthalmic apparatus according to the present disclosure will be described with reference to the drawings. Fig. 1 is a diagram illustrating components of an ophthalmic apparatus 1, such as an eye examination optical system, a control system, etc.

[0025] The eye examination optical system 2 of the ophthalmic apparatus 1 includes a pattern index projection optical system 100 and an anterior eye imaging optical system 150. The pattern index projection optical system 100 is used to project a pattern index onto the cornea of ​​the subject's eye to obtain the corneal shape of the subject's eye. The ophthalmic apparatus 1 also includes an anterior eye illumination optical system 110. The ophthalmic apparatus 1 may also include a Mayer ring index projection optical system 120. The ophthalmic apparatus 1 may also additionally include an alignment index projection optical system 160 and a fixation target optical system 170. The ophthalmic apparatus 1 may also be a composite apparatus including a second eye characteristic measuring optical system 200 that measures eye characteristics of the subject's eye that are different from the corneal shape.

[0026] <Pattern target projection optical system> The pattern target projection optical system 100 includes a pattern target unit 102. The pattern target unit 102 includes a pattern plate 103. The pattern plate 103 includes a pattern target 104 for obtaining a corneal shape formed on a light-transmitting plate. In this embodiment, the pattern target 104 is a multiple ring-shaped pattern target as shown in FIG. 2. The pattern target 104 includes a ring-shaped light-shielding portion 104a painted black on the pattern plate 103 and a ring-shaped light-transmitting portion 104b that is not painted, which are alternately formed in a concentric shape around the ophthalmic axis L1. A light source 105 is arranged in a ring shape behind each light-transmitting portion 104b. For example, an LED that emits light in the red to infrared region is used as the light source 105. The light source 105 illuminates the pattern target 104. The light from the light source 105 passes through the light-transmitting portion 104b, and the Placido ring pattern of the pattern target 104 is projected onto the cornea of ​​the test eye. The optical system for illuminating each light-transmitting portion 104b of the pattern target 104 from behind may be one that guides light from the light source 105 via a light-transmitting body.

[0027] The pattern index 104 is not limited to a ring index, and may be dot-shaped indices arranged in a ring shape, or may have any shape and arrangement that allows measurement of the corneal shape.

[0028] <Anterior segment illumination optical system> The anterior eye illumination optical system 110 includes an illumination light source 111 that emits infrared light. In this embodiment, the illumination light source 111 is disposed outside the pattern index unit 102. As shown in Fig. 2, two illumination light sources 111 are disposed on the upper side and two illumination light sources 111 are disposed on the lower side across the examination axis L1. That is, the anterior eye illumination optical system 110 is configured to form a reflection bright point outside the area where the index image (in this embodiment, a ring image) of the pattern index 104 is reflected.

[0029] <Mayer ring target projection optical system> The Mayer ring index projection optical system 120 is disposed inside the pattern index unit 102, centered on the examination axis L1. In this embodiment, the Mayer ring index projection optical system 120 is configured to project double Mayer ring indexes. The Mayer ring index projection optical system 120 includes, from the inside, a ring-shaped first light source 121a and a ring-shaped second light source 121b. The two Mayer rings (ring-shaped indices) projected onto the cornea of ​​the test eye by the Mayer ring index projection optical system 120 are used as part of the pattern index 104 for obtaining the corneal shape during corneal shape measurement.

[0030] The Mayer ring index projection optical system 120 may be provided as a part of the pattern index unit 102. In this case, at least one of the ring-shaped first light source 121a and the second light source 121b is selectively turned on during kerato measurement, and is used for kerato measurement.

[0031] The Mayer ring target projection optical system 120 may also be used as an alignment optical system for aligning the eye examination optical system 2 with respect to the subject's eye.

[0032] <Anterior segment imaging optical system> The anterior eye imaging optical system 150 is used to image the anterior eye of the pattern index 104 projected onto the subject's eye by the pattern index projection optical system 100. The anterior eye imaging optical system 150 includes an objective lens 151, an imaging lens (not shown), an imaging element 155, and the like. The imaging element 155 of the anterior eye imaging optical system 150 captures an anterior eye image including an index image of the pattern index (Placido ring index) 104 of the pattern index unit 102 projected onto the subject's cornea. The anterior eye imaging optical system 150 also serves as a detection optical system for the alignment index projected onto the subject's cornea.

[0033] <Alignment target projection optical system, fixation target optical system> The alignment index projecting optical system 160 has, for example, an optical system symmetrical with respect to the examination axis L1, and projects an index at infinity by irradiating a parallel light beam onto the cornea of ​​the test eye. The Mayer ring index projecting optical system 120 is also used as an optical system for projecting an alignment index at finite distance. When aligning the optometry optical system 2 with the test eye, an anterior eye image including an alignment index image projected onto the cornea of ​​the test eye is captured (acquired), and the signal is input to the control unit 50. Then, based on the index image of the alignment index projecting optical system 160 and the Mayer ring image by the Mayer ring index projecting optical system 120, the alignment state of the optometry optical system 2 with the test eye in the X direction (left and right direction), Y direction (up and down direction), and Z direction (front and back direction) is acquired.

[0034] The fixation target optical system 170 has a fixation target that is presented to the subject's eye, and guides the line of sight of the subject's eye by the fixation target.

[0035] <Eye characteristic measurement optical system> The eye characteristic measuring optical system 200 is, for example, an eye refractive power measuring optical system that measures the eye refractive power of the subject eye. The eye refractive power measuring optical system includes a light projecting optical system that projects a spot-shaped measurement light onto the fundus of the subject eye through the center of the pupil of the subject eye, and a light receiving optical system that extracts reflected light from the fundus of the subject eye in a ring shape from the peripheral part of the pupil and receives the ring-shaped reflected image on the light receiving element 212.

[0036] <Control system> 1, a control unit 50 is responsible for the overall control of the ophthalmic apparatus 1. The control unit 50 is connected to each electrical element of the ophthalmic examination optical system 2 including a pattern target projection optical system 100, an anterior eye illumination optical system 110, a Mayer ring target projection optical system 120, an anterior eye imaging optical system 150, etc. The control unit 50 also acquires the captured image captured by the imaging element 155. That is, the control unit 50 functions as an image acquiring means for acquiring an image by capturing an image of the anterior segment of the eye to be examined by the imaging element 155. The control unit 50 also functions as a processing means for performing image processing on the acquired image.

[0037] The control unit 50 is connected to a display unit 52, an operation unit 54, and a storage unit 56. The display unit 52 displays various information such as an image captured by the image sensor 155, an image processed by the control unit 50, and an analysis result of the corneal shape. The operation unit 54 includes a pointing device such as a mouse operated by the examiner, a keyboard, and the like. The operation unit 54 may be a touch panel provided on the display unit 52. The storage unit 56 stores various information such as the image acquired by the control unit 50 and the analysis result. The storage unit 56 also stores a control and processing program for obtaining the corneal shape. The control unit 50 analyzes the corneal shape of the subject's eye using the control and processing program.

[0038] <Control and processing operations> The operation of the ophthalmic apparatus 1 having the above-mentioned configuration will be described. First, the position of the optometry optical system 2 with respect to the subject's eye in the XYZ directions is aligned based on the index image of the alignment index projecting optical system 160 and the Mayer ring image by the Mayer ring index projecting optical system 120. When the positioning of the optometry optical system 2 with respect to the subject's eye is completed, for example, first, a measurement is performed by the eye characteristic measuring optical system 200, and the eye refractive power of the subject's eye is obtained.

[0039] Next, in a state where the alignment of the optometry optical system 2 with respect to the subject's eye is completed, the corneal shape is measured using the pattern index projection optical system 100. The control unit 50 captures an anterior segment of the subject's eye onto which the pattern index 104 is projected by the pattern index projection optical system 100, using the image sensor 155 to obtain an anterior segment image. Then, the control unit 50 extracts the pattern index 104 image projected onto the subject's eye by performing a comparative process on at least two anterior segment images having different projection states of the pattern index 104 according to a processing program, and analyzes the corneal shape of the subject's eye based on the extracted pattern index 104 image. In this embodiment, two Mayer rings by the Mayer ring index projection optical system 120 are used as part of the pattern index 104 projected onto the subject's eye.

[0040] First Embodiment The first embodiment is an example in which at least two anterior eye images for extracting a pattern index image projected onto a test eye are used, including an anterior eye image onto which a pattern index 104 is projected and an anterior eye image onto which the pattern index 104 is not projected.

[0041] For example, in a state where the alignment of the optometry optical system 2 with respect to the subject's eye is completed, first, the light source 105 of the pattern index unit 102 and the light sources 121a and 121b of the Mayer ring are turned on under the control of the control unit 50, and the pattern index 104 is projected onto the cornea of ​​the subject's eye. An image of the anterior segment of the subject's eye onto which the pattern index 104 is projected is captured by the image sensor 155 of the anterior segment imaging optical system 150, and the anterior segment image (first anterior segment image) is stored in the storage unit 56.

[0042] Next, in order to obtain an anterior eye image without projecting the pattern index 104, the anterior eye of the test eye is imaged by the imaging element 155 with the light source 105 and the Mayer ring light sources 121a and 121b turned off, and the anterior eye image (second anterior eye image) is stored in the memory unit 56.

[0043] At this time, the first anterior eye image and the second anterior eye image may be captured continuously by the image sensor 155 under the control of the control unit 50. That is, the control unit 50 controls the turning on and off of the light source 105 of the pattern target 104 unit 102 and the light sources 121a and 121b of the Mayer ring so that images are captured in consecutive frames at the frame rate of the image sensor 155. This reduces the influence of the movement of the subject's eye caused by different timings of capturing images when two or more anterior eye images are obtained.

[0044] When capturing an anterior eye image on which the pattern target 104 is not projected, the illumination light source 111 of the anterior eye illumination optical system 110 is turned on, so that the anterior eye of the subject's eye is illuminated with infrared light.

[0045] When the two anterior eye images, the first and second anterior eye images, are acquired, the two anterior eye images are compared by the control unit 50, which functions as a processing means, and the pattern index image projected onto the test eye is extracted.

[0046] 3(a) is an example of a first anterior-segment image EA1 onto which a pattern target 104 is projected. In the first anterior-segment image EA1, the reflection of the illumination light (illumination light of the pattern target) in the iris region outside the pupil is strong, so the contrast between the pattern target image (in the embodiment, a ring image) PLI and the iris image IRI is poor (there is little luminance difference between the two) with respect to the pupil image PUI, and it is difficult to extract the pattern target image PLI from only this image.

[0047] 3B is an example of the second anterior-segment image EA2 on which the pattern target 104 is not projected. In the second anterior-segment image EA2, a pupil image PUI and an iris image IRI appear without a pattern target image PLI superimposed thereon.

[0048] The control unit 50 performs differential processing of the luminance value at each pixel position between the first anterior eye image EA1 and the second anterior eye image EA2 to obtain a processed image EA3 in which the pattern index image PLI remains, as shown in Fig. 3(c). That is, the luminance of the iris image IRI, the pupil image PUI, etc. in the background of the pattern index image PLI in the first anterior eye image EA1 is offset, and only the pattern index image PLI remains with good contrast. Then, the pattern index image PLI is extracted with high accuracy based on this processed image EA3.

[0049] When the pattern target image PLI is extracted, the corneal shape is analyzed based on the pattern target image PLI. For example, the edge coordinates of each ring image of the pattern target image PLI are detected, and the corneal shape is analyzed for each predetermined meridian (for example, for each degree) based on the position of the optical axis L1. The analysis result of the corneal shape is expressed as a corneal shape map, for example, a color-coded color map, a contour map, or the like, and displayed on the display unit 52.

[0050] In the above, when the second anterior eye image EA2 on which the pattern index 104 is not projected is captured, the illumination light source 111 of the anterior eye illumination optical system 110 is turned on, and the bright spots MS (four bright spots MS in this embodiment) caused by the illumination light are reflected in the anterior eye image EA2 (see FIG. 4). However, in this embodiment, the anterior eye illumination optical system 110 is provided so that the bright spots MS are formed outside the area where the pattern index image PLI of the pattern index 104 is reflected, so that the image is processed so that the bright spots MS are excluded from the processed image EA3 in FIG. 3(c).

[0051] As described above, the influence of the iris image IRI reflected on the pattern target image PLI can be reduced, and the analysis process of the pattern target image PLI can be performed with high accuracy.

[0052] <Second embodiment> The second embodiment is an example in which at least two anterior eye images for extracting a pattern index image projected onto the subject's eye are used, in which the areas of the pattern index 104 are different from each other. In this case, the pattern index 104 is divided into two or more parts and projected onto the subject's eye. For example, the pattern index 104 is divided into two parts, an odd-numbered ring-shaped pattern index 104 from the inside and an even-numbered ring-shaped pattern index 104 from the inside, and projected onto the subject's eye. That is, when the pattern index 104 is a Placido ring, which is an example of a ring-shaped index, the Placido ring is projected onto the subject's eye every other Placido ring.

[0053] For example, in a state where the alignment of the optometry optical system 2 with respect to the subject's eye is completed, first, the light source 105 corresponding to the odd-numbered ring-shaped pattern index 104 from the inside and the light source 121a of the Mayer ring are turned on under the control of the control unit 50, and the odd-numbered pattern index 104 is projected onto the cornea of ​​the subject's eye. An anterior eye image of the subject's eye onto which the odd-numbered pattern index 104 is projected is captured by the imaging element 155 of the anterior eye imaging optical system 150, and the anterior eye image (first anterior eye image) is stored in the storage unit 56. Next, the light source 105 corresponding to the odd-numbered ring-shaped pattern index 104 and the light source 121a of the Mayer ring are turned off, and the light source 105 corresponding to the even-numbered ring-shaped pattern index 104 from the inside and the light source 121b of the Mayer ring are turned on, and the even-numbered pattern index 104 is projected onto the cornea of ​​the subject's eye. An image of the anterior segment of the subject's eye onto which the even-numbered pattern targets 104 are projected is captured by the imaging element 155 of the anterior segment imaging optical system 150, and the anterior segment image (second anterior segment image) is stored in the storage unit .

[0054] In the second embodiment, unlike the first embodiment, the anterior eye segment onto which the pattern index 104 is not projected is not imaged, but the pattern index 104 is divided and projected onto the test eye to illuminate the test eye, so illumination by the anterior eye illumination optical system 110 is not required when imaging the anterior eye segment to extract the pattern index image projected onto the test eye.

[0055] Then, when the two anterior eye images, the first and second anterior eye images, are acquired, the two anterior eye images are compared by the control unit 50 to extract the pattern target image projected onto the test eye.

[0056] Fig. 5(a) is an example of an anterior eye image EB1 onto which odd-numbered ring-shaped pattern indicators 104 are projected. Fig. 5(b) is an example of an anterior eye image EB2 onto which even-numbered ring-shaped pattern indicators 104 are projected. The control unit 50 first compares the luminance values ​​at the same pixel positions between the anterior eye image EB1 and the anterior eye image EB2.

[0057] First, the pixels with higher luminance values ​​between the pixels of the anterior eye image EB1 and the anterior eye image EB2 are synthesized to generate a brightly synthesized third anterior eye image EB3 in which the pattern target image PLI is superimposed with the iris image IRI and the pupil image PUI, as shown in Fig. 5(c). That is, the brightly synthesized anterior eye image EB3 corresponds to the first anterior eye image EA1 in Fig. 3(a) on which the pattern target 104 is projected in the first embodiment.

[0058] Next, the pixels with lower luminance values ​​between the anterior eye image EB1 and the anterior eye image EB2 are synthesized to generate a fourth anterior eye image EB4 by dark synthesis, in which the iris image IRI and the pupil image PUI are erased from the pattern target image PLI, as shown in Fig. 5(d). That is, this dark synthesis anterior eye image EB4 corresponds to the second anterior eye image EA2 in Fig. 3(b) in which the pattern target 104 is not projected in the first embodiment.

[0059] When the third anterior eye image EB3 of the bright synthesis and the fourth anterior eye image EB4 of the dark synthesis are obtained, the luminance values ​​of the same pixel positions are subjected to differential processing between the anterior eye image EB3 and the anterior eye image EB4 in the same manner as in the first embodiment, to obtain a processed image EB5 in which a predetermined pattern index image PLI remains, as shown in Fig. 5(e). Then, based on this processed image EB5, the pattern index image PLI corresponding to the pattern index 104 projected on the subject's eye is accurately extracted.

[0060] In the above, the anterior eye image EB1 and the anterior eye image EB2 are compared to generate the third anterior eye image EB3 and the fourth anterior eye image EB4, but this is not necessarily required. For example, the anterior eye image EB1 and the anterior eye image EB2 may be compared to generate the processed image EB5 in which the pattern index image PLI corresponding to the pattern index 104 remains. That is, for example, the luminance of the anterior eye image EB2 is subjected to a difference process with respect to the anterior eye image EB1, so that the pattern index image PLI corresponding to the odd-numbered ring-shaped pattern index 104 of the anterior eye image EB1 remains as a positive value, and the pattern index image PLI corresponding to the even-numbered ring-shaped pattern index 104 of the anterior eye image EB2 remains as a negative value. Then, the sign of the even-numbered pattern index image PLI remaining as a negative value is inverted to generate the processed image EB5 in which the pattern index image PLI remains.

[0061] In the second embodiment, at least two anterior eye images in which the projection positions of the pattern index 104 are different from each other are not limited to those in which the ring-shaped pattern index 104 is divided into two. For example, three anterior eye images in which the ring indexes of the pattern index 104 are divided into three at intervals of two (i.e., three anterior eye images consisting of the first and fourth ring indexes from the inside, the second and fifth pattern indexes 104 from the inside, and the first and fourth ring indexes from the inside) may be acquired, and a processed image in which the pattern index image PLI remains may be acquired based on the above-mentioned comparison process.

[0062] Furthermore, the division of the pattern index 104 is not limited to the above, and for example, the area of ​​the pattern index 104 may be divided into the inner half of the pattern index (for example, the first to third ring indexes from the inside) and the outer half of the pattern index (for example, the fourth to sixth ring indexes from the inside). Alternatively, for example, the area of ​​the pattern index 104 may be divided into two, into an upper half and a lower half. Furthermore, the area of ​​the pattern index 104 may be divided into three or more parts, so that three anterior eye images can be acquired.

[0063] In the second embodiment, when two or more anterior-segment images are acquired, the anterior-segment images may be captured successively by the image sensor 150 as described in the first embodiment.

[0064] <Example of transformation> Although typical embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, and various modifications are possible.

[0065] For example, in the above description, two or more anterior eye images are continuously captured by the image sensor 150. However, if the movement of the subject's eye is fast, continuous capture may not be sufficient (there is a possibility of affecting the extraction accuracy of the pattern index image PLI). In this case, when comparing the anterior eye images, the positional deviation (left and right direction, up and down direction, rotation direction) of each anterior eye image may be detected, and the positional deviation of each anterior eye image may be corrected based on the detection result, thereby performing the positional alignment process of each anterior eye image. For example, an image matching method (for example, the use of phase-limited correlation) can be used to detect the positional deviation of each anterior eye image. For example, the image matching is performed on a predetermined tissue site (for example, iris pattern) that appears in common in each anterior eye image. Note that the positional alignment process of each anterior eye image is particularly effectively applied when two or more anterior eye images are not continuously captured by the image sensor 150.

[0066] In the above-described first embodiment, when obtaining the anterior eye image (EA2) on which the pattern index 104 is not projected, the anterior eye is illuminated by the anterior eye illumination optical system 110, and the bright spot (MS) caused by the illumination light is formed outside the area where the pattern index image (PLI) is projected, but this is not limited to the above. For example, when the bright spot caused by the anterior eye illumination optical system 110 is formed within the area where the pattern index image (PLI) is projected, the anterior eye image from which the bright spot of the anterior eye illumination is removed may be obtained as follows.

[0067] For example, the anterior eye illumination optical system 110 for illuminating the anterior eye of the subject's eye is configured to be able to change the emission position of the illumination light. For example, assume that the four light sources 111 of the anterior eye illumination optical system 110 shown in FIG. 4 are arranged so that the four bright spots MS of the anterior eye illumination optical system 110 appear in the iris image. Then, under the control of the control unit 50, only the upper two light sources 111 are turned on first, and an anterior eye image EA2a in which two bright spots MS appear on the upper side of the subject's eye is captured by the imaging element 155 as shown in FIG. 6(a). Next, the upper two light sources 111 are turned off and the lower two light sources 111 are turned on, and the emission position of the illumination light is changed, and an anterior eye image EA2b in which two bright spots MS appear on the lower side is captured by the imaging element 155 as shown in FIG. 6(b). That is, by changing the emission position of the illumination light, two anterior eye images EA2a and EA2b in which the bright spots MS of the anterior eye illumination light are formed at different positions are acquired.

[0068] Then, when the anterior eye image EA2a and the anterior eye image EA2b are obtained, a comparison process is performed between the pixels of the two anterior eye images so that the pixels with the lower brightness values ​​are synthesized, and an anterior eye image EA2c is created from which the four bright spots MS have been removed, as shown in Fig. 6(c). The anterior eye image EA2c corresponds to the anterior eye image EA2 in Fig. 3(c). Note that, although an example in which the light emission position of the anterior eye illumination light is divided into two has been described here, it may be divided into three or more.

[0069] Furthermore, the present disclosure is not limited to the use of the pattern index 104 for obtaining distribution information of the corneal shape of the test eye over a wide range, but may be used in keratometry for obtaining the corneal shape by obtaining a Mayer ring image using the Mayer ring index projection optical system 120. For example, even when obtaining an anterior segment image of a Mayer ring image, the Mayer ring image may be superimposed on an iris image depending on the test eye. In this case, the technique shown in the first or second embodiment is used to reduce the influence of the iris image reflected on the anterior segment image of the Mayer ring image, and the Mayer ring image is extracted with high accuracy.

[0070] In addition, the control and processing programs described in the first and second embodiments may be configured to be executed when it is determined that it is difficult to extract the pattern index image, rather than being executed all the time. For example, the color of the iris varies depending on race and individual. For this reason, in the case of an eye to be examined in which the iris is less reflective of the illumination light of the pattern index 104 in the infrared to infrared region, the pattern index image may be extracted based on one anterior eye image in which a predetermined pattern index 104 is projected and captured as in the past. In this case, for example, the control unit 50 may determine whether or not to apply the control and processing programs described above based on the luminance of the iris image in the anterior eye image obtained at the stage of aligning the optometry optical system 2 with respect to the eye to be examined. Then, when it is determined that there is an influence of the iris image, the control unit 50 may automatically switch to a measurement mode in which the above-mentioned control and processing programs are applied. Alternatively, the control unit 50 may display the determination result on the display unit 52, so that the examiner can switch to a measurement mode in which the above-mentioned processing programs are applied.

[0071] Moreover, the pattern target projection optical system 100 described above may be configured such that the pattern target unit 102 is replaced with a cone type.

[0072] In the second embodiment, in the continuous imaging of at least two anterior eye images having different regions of the pattern index 104, the light source 105 for illuminating the pattern index 104 is set to emit light at different timings in the above embodiment, but the present invention is not limited to this. For example, anterior eye images of the pattern index image having different projection states may be acquired by projecting index light having different polarization states in the divided regions of the pattern index 104 (for example, odd-numbered ring indexes and even-numbered ring indexes) and selectively inserting and removing a polarizing plate that extracts different polarization states corresponding to the divided regions of the pattern index 104 in the light receiving side anterior eye imaging optical system 150. Alternatively, anterior eye images of the pattern index image having different projection states may be acquired by projecting index light having different wavelengths in the divided regions of the pattern index 104 and providing a wavelength selection filter on the light receiving side corresponding to the projected light. In this case, two or more image sensors 155 may be provided. [Explanation of symbols]

[0073] 1 Ophthalmology equipment 50 Control section 100 Pattern target projection optical system 104 Pattern Indicators 110 Anterior segment illumination optical system 120 Mayer ring index projection optical system 150 Anterior segment imaging optical system 155 Image sensor

Claims

1. A pattern target projection means for projecting a pattern target onto the cornea of ​​the subject's eye in order to obtain a corneal shape of the subject's eye; an image acquiring means for acquiring an image of the anterior segment of the subject's eye onto which the pattern target is projected, by using an image sensor; A processing means for processing the anterior eye image acquired by the image acquisition means, the processing means extracts a pattern target image corresponding to the pattern target projected onto the subject's eye by performing a comparative process on at least two anterior eye images having different projection states of the pattern target, and analyzes a corneal shape of the subject's eye based on the extracted pattern target image. An ophthalmic apparatus comprising:

2. 2. The ophthalmic apparatus of claim 1, The processing means extracts the pattern index image by comparing an anterior eye image on which the pattern index is projected with an anterior eye image on which the pattern index is not projected, or extracts the pattern index image by comparing at least two anterior eye images in which the pattern index areas are different from each other.

3. The ophthalmic apparatus according to claim 1 or 2, The image acquisition means is configured to continuously capture images of the anterior segment by the imaging element in order to obtain at least two anterior segment images in which the pattern target is projected in different states.

4. In the ophthalmic apparatus according to any one of claims 1 to 3, an anterior segment illumination means for projecting illumination light for illuminating an anterior segment of an eye to be examined; An ophthalmic apparatus characterized in that the anterior eye illumination means is configured to form a reflected bright spot of the illumination light outside the area in which the pattern target image is reflected in the anterior eye image captured by the imaging element.

5. In the ophthalmic apparatus according to any one of claims 1 to 3, an anterior segment illumination means capable of changing an emission position of illumination light for illuminating an anterior segment of an eye to be examined; the image acquisition means acquires at least two anterior-segment images in which the bright points of the illumination light are formed at different positions by changing the light-emitting position; The processing means is an ophthalmic device characterized in that it compares and processes each of the anterior eye images acquired by the image acquisition means to acquire an anterior eye image in which the bright spots have been removed and in which the pattern index is not projected.

6. In the ophthalmic apparatus according to any one of claims 1 to 5, The ophthalmologic apparatus according to claim 1, wherein the processing means detects a positional shift between the anterior eye images when performing comparative processing of the anterior eye images, and corrects the positional shift between the anterior eye images based on the detection result.

7. The control unit of an ophthalmic apparatus including a pattern target projection unit that projects a pattern target onto the cornea of ​​the subject's eye to obtain a corneal shape of the subject's eye is executed, an image acquiring step of acquiring an anterior segment image by capturing an image of the anterior segment of the subject's eye onto which the pattern target is projected, using an image sensor; a processing step of processing the anterior eye images acquired by the image acquiring step, the processing step being to extract a pattern index image corresponding to the pattern index projected onto the subject's eye by performing a comparative processing of at least two anterior eye images having different projection states of the pattern index, and to analyze a corneal shape of the subject's eye based on the extracted pattern index image; 4. A processing program for an ophthalmic apparatus, comprising:

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