Corneal endothelial imaging device

Abstract

To provide a technology to prevent a time for acquiring an image suitable for analysis from being unnecessarily lengthened.SOLUTION: A corneal endothelial imaging device includes: an imaging part for imaging the corneal of an eye to be examined; and a control part for causing the imaging part to start re-imaging when an image acquiring by the imaging does not satisfy a criterion, causing a display part to display a thumbnail image of the image and a cancellation button for the re-imaging during the re-imaging, and cancelling the re-imaging when the cancellation button is selected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a corneal endothelium imaging device. [Background technology]

[0002] Conventionally, the cornea has been observed when determining the presence or absence of eye disease, diagnosing the postoperative progress of the eye, and the like. When observing the cellular state of the cornea, a device that captures an image of the cornea of ​​the subject's eye without contact is known. Patent Document 1 describes re-capturing an image when it is determined that the captured image is an analysis error image (0039, 0201, etc.). Patent Document 2 describes displaying a cancel button for interrupting the alignment process during the alignment process (FIG. 2, 0027). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-103433 A [Patent Document 2] JP 2023-46651 A Summary of the Invention [Problem to be solved by the invention]

[0004] If re-imaging is performed a predetermined number of times, the subject may be confined for a longer period of time, which may increase the burden on the subject. The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a technique for preventing the time required to obtain an image suitable for analysis from being unnecessarily long. [Means for solving the problem]

[0005] In order to achieve the above-mentioned objective, the corneal endothelium imaging device includes an imaging unit that images the cornea of ​​the test eye, and a control unit that causes the imaging unit to start re-imaging if the image obtained by imaging does not satisfy a standard, causes a thumbnail image of the image and a cancel button for re-imaging to be displayed on the display unit during re-imaging, and cancels the re-imaging when the cancel button is selected.

[0006] That is, the corneal endothelium imaging device is configured to automatically start re-imaging if the criteria are not met, thereby reducing the operator's effort in obtaining an image that meets the criteria. Also, the corneal endothelium imaging device is configured to display thumbnail images of images that are determined not to meet the criteria and a cancel button for re-imaging during re-imaging, thereby providing the operator with an opportunity to determine whether or not re-imaging is necessary. Also, the corneal endothelium imaging device cancels re-imaging in response to the operator's selection of the cancel button if the operator determines that re-imaging is not necessary, thereby preventing the time required to obtain an image suitable for analysis from being unnecessarily extended. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is an explanatory diagram illustrating a configuration of an apparatus optical system. [Diagram 2] FIG. 1 is an explanatory diagram showing the configuration of a corneal endothelium imaging device. [Diagram 3] FIG. 2 is an explanatory diagram for explaining a control circuit and the like connected to the optical system of the apparatus. [Figure 4] 13 is a flowchart of a photographing process. [Diagram 5] 13 is a flowchart of an alignment process. [Figure 6] FIG. 2 is a diagram showing an example of a captured image. [Figure 7] FIG. 13 is a diagram showing an example of a screen display. [Figure 8] FIG. 8A is a diagram showing an example of a captured image, FIG. 8B is a diagram showing an example of a specified endothelial region, and FIG. 8C is a diagram explaining an example of offset value calculation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Here, the embodiments of the present invention will be described in the following order. (1) Corneal endothelium imaging device configuration: (1-1) Control system configuration: (1-2) Shooting process: (2) Other embodiments:

[0009] (1) Corneal endothelium imaging device configuration: Fig. 1 is an explanatory diagram showing the configuration of a device optical system 10 provided in a corneal endothelium imaging device 100 according to one embodiment of the present invention. Figs. 2 and 3 are diagrams for explaining the corneal endothelium imaging device 100. The device optical system 10 includes an anterior eye imaging optical system 12, a corneal illumination optical system 14, an axial position detection optical system 16, an axial illumination optical system 18, and a cornea detection optical system 20. In this embodiment, the corneal illumination optical system 14 and the cornea detection optical system 20 constitute a corneal imaging optical system, and the axial position detection optical system 16 and the axial illumination optical system 18 constitute an axial position adjustment optical system.

[0010] In the device optical system 10, a corneal illumination optical system 14 and an axial position detection optical system 16 are provided on the lower side of the anterior eye imaging optical system 12 in the drawing, and an axial illumination optical system 18 and a cornea detection optical system 20 are disposed on the upper side of the anterior eye imaging optical system 12 in the drawing. An optical axis 14a (16a) of the corneal illumination optical system 14 (axial position detection optical system 16) and an optical axis 18a (20a) of the axial illumination optical system 18 (cornea detection optical system 20) are disposed on the same plane as the optical axis 12a of the anterior eye imaging optical system 12.

[0011] The anterior eye imaging optical system 12 is provided on the optical axis 12a in the order of the half mirror 22, the objective lens 24, the half mirror 26, the cold mirror 27, and the CCD 28 from the position closest to the subject's eye E. Two observation light sources 30 are provided at a predetermined position facing the subject's eye E. The observation light source 30 is an infrared LED that emits infrared light, and is an illumination light source that illuminates the anterior eye of the subject's eye E. The cold mirror 27 transmits infrared light and reflects visible light. The reflected light emitted from the observation light source 30 and reflected by the anterior eye of the subject's eye E is imaged on the CCD 28 through the objective lens 24 and the cold mirror 27. That is, the CCD 28 is an anterior eye imaging element that receives the reflected light from the anterior eye by the observation light source 30, which is an illumination light source, and captures an anterior eye image, which is an image of the anterior eye.

[0012] The corneal illumination optical system 14 is provided with a projection lens 32, a cold mirror 34, a slit 36, a condenser lens 38, and an imaging light source 40 in this order from the position closest to the subject's eye E. The imaging light source 40 is an LED that emits visible light. The cold mirror 34 transmits infrared light and reflects visible light. The light emitted from the imaging light source 40 is made into slit light by passing through the condenser lens 38 and the slit 36. This slit light is reflected by the cold mirror 34 and passes through the projection lens 32, and is irradiated obliquely onto the cornea C. That is, the imaging light source 40 is an illumination light source that irradiates the subject's eye E with slit light obliquely.

[0013] A part of the optical axis of the axial position detection optical system 16 coincides with the optical axis of the corneal illumination optical system 14. The axial position detection optical system 16 is provided with a projection lens 32, a cold mirror 34, and a line sensor 44, in this order from the position closest to the subject's eye E. Light irradiated from an adjustment light source 54 (to be described later) and reflected by the cornea C passes through the projection lens 32 and the cold mirror 34, and forms an image on the line sensor 44.

[0014] On the other hand, the axial illumination optical system 18 is provided with the objective lens 46, the cold mirror 48, the condenser lens 52, and the adjustment light source 54 as a light source that outputs detection light for detecting the axial position, in this order from the position closest to the eye E. The adjustment light source 54 is preferably an infrared light source such as an infrared LED. The detection light emitted from the adjustment light source 54 is irradiated obliquely to the cornea C. The adjustment light source 54 does not necessarily have to be an infrared light source, and a visible light source such as a halogen lamp or a visible light LED may be used. When a visible light source is used, it is preferable that the illuminance is smaller than that of the imaging light source 40. By making the illuminance of the visible light source smaller than that of the imaging light source 40, the burden on the subject when irradiating light from the adjustment light source 54 for alignment, etc. is reduced. The adjustment light source 54 may be configured by combining a visible light source such as a halogen lamp or a visible light LED with an infrared filter.

[0015] The cornea detection optical system 20 has a part of its optical axis coinciding with the optical axis of the axial illumination optical system 18. The cornea detection optical system 20 is provided in the following order from the position close to the subject's eye E: the objective lens 46, the cold mirror 48, the slit 56, the variable magnification lens 58, the focusing lens 60, the cold mirror 27, and the CCD 28. The light irradiated from the imaging light source 40 and reflected by the cornea C passes through the objective lens 46 and is reflected by the cold mirror 48, and then is made into a parallel light by the slit 56. This parallel light passes through the variable magnification lens 58 and the focusing lens 60, is reflected by the cold mirror 27, and is imaged on the CCD 28, which is an imaging element. That is, the CCD 28 is also a corneal imaging element that receives the reflected light from the cornea of ​​the subject's eye E by the slit light, which is the light emitted from the imaging light source 40 and passed through the condenser lens 38 and the slit 36, and captures a corneal image, which is an image of the cornea.

[0016] In this embodiment, the anterior eye imaging optical system 12 is attached to the corneal endothelium imaging device 100 so that the optical axis 12a of the anterior eye imaging optical system 12 faces a specific direction. In addition, the anterior eye imaging optical system 12 is attached to the corneal endothelium imaging device 100 so that the optical axis 12a passes through the subject's eye E to be measured when the subject fixes his or her face facing the corneal endothelium imaging device 100. As a result, the front direction of the subject's eye E and the optical axis 12a approximately coincide with each other.

[0017] The optical axis 14a (16a) of the corneal illumination optical system 14 (axial position detection optical system 16) and the optical axis 18a (20a) of the axial illumination optical system 18 (cornea detection optical system 20) are inclined in opposite directions with respect to the optical axis 12a of the anterior eye imaging optical system 12. In this embodiment, the optical axis 14a (16a) and the optical axis 18a (20a) intersect at one point, and the optical axis 12a also intersects at this point. When the intersection of the optical axis 14a (16a), the optical axis 18a (20a), and the optical axis 12a is taken as the center of rotation, the inclination angle α with respect to the optical axis 12a is the same for the optical axis 14a (16a) and the optical axis 18a (20a). That is, when the intersection is the center of rotation and the inclination angle of the optical axis 14a (16a) relative to the optical axis 12a is defined as an acute angle, and when the intersection is the center of rotation and the inclination angle of the optical axis 18a (20a) relative to the optical axis 12a is defined as an acute angle, both inclination angles are equal to α. In the above-described embodiment, the optical axis 12a of the anterior eye imaging optical system 12 corresponds to the predetermined axis.

[0018] In this embodiment, the distance between an object that can be imaged in a focused state by the cornea imaging optical system and the cornea imaging optical system in the direction of the optical axis 12a is constant. Specifically, in this embodiment, when an object exists at the point where the optical axis 14a (16a) and the optical axis 20a (18a) intersect, the positions of the optical components of the cornea imaging optical system are adjusted so that the CCD 28 images the object in a focused state. Therefore, when the distance between the cornea imaging optical system in the direction of the optical axis 12a and the part of the cornea to be imaged is a specific distance, the CCD 28 can image an arbitrary object in a focused state. Note that, when the imaged object is the endothelium of the cornea, light is refracted by the cornea, but the distance between the endothelium of the cornea and the cornea imaging optical system in the direction of the optical axis 12a in a focused state on the endothelium of the cornea may be considered to be the same as the distance to the arbitrary object.

[0019] Furthermore, the half mirror 22 provided on the anterior eye imaging optical system 12 constitutes a part of a fixation target optical system 64 and a vertical illumination optical system 66. The fixation target optical system 64 is provided in the following order from a position closest to the subject's eye E: the half mirror 22, a projection lens 68, a half mirror 70, and a fixation target light source 74. The fixation target light source 74 is a light source that emits visible light such as an LED, and guides the line of sight of the subject's eye E in a predetermined direction. The fixation target light source 74 can be realized by, for example, a dot matrix LED in which a plurality of LEDs are arranged in a matrix.

[0020] The vertical illumination optical system 66 is configured by providing a half mirror 22, a projection lens 68, a half mirror 70, an aperture 76, a pinhole plate 78, a condenser lens 80, and an alignment light source 82 in this order from the position closest to the eye E. The alignment light source 82 outputs infrared light as detection light for detecting the vertical position, and the infrared light is condensed by the condenser lens 80, passes through the pinhole plate 78, and is guided to the aperture 76. The light that passes through the aperture 76 is reflected by the half mirror 70, is collimated by the projection lens 68, and is then reflected by the half mirror 22 to be irradiated to the eye E. In this embodiment, the infrared light as detection light for detecting the vertical position is directed by the half mirror 22 in a direction parallel to the optical axis 12a. Therefore, the detection light for detecting the vertical position is irradiated to the eye E from a direction along the optical axis 12a.

[0021] The vertical position detection optical system 84 is provided with the half mirror 26 and the alignment detection sensor 88 capable of detecting the position, in that order from the position closest to the subject's eye E. Light emitted from the alignment light source 82 and reflected by the cornea C is reflected by the half mirror 26, and the reflected light is guided to the alignment detection sensor 88. The half mirror 26 provided on the anterior eye imaging optical system 12 constitutes a part of the vertical position detection optical system 84. In this embodiment, the vertical illumination optical system 66 and the vertical position detection optical system 84 constitute a vertical position adjustment optical system.

[0022] The alignment detection sensor 88 is a two-dimensional sensor that receives reflected light from the subject's eye E by detection light for detecting the vertical position. The position at which the reflected light is received by the two-dimensional sensor varies as the positional relationship between the subject's eye E and the vertical position adjustment optical system varies in the direction perpendicular to the optical axis 12a. Therefore, based on the position at which the reflected light is received by the two-dimensional sensor, the relative positional relationship of the vertical position adjustment optical system to the subject's eye E can be specified in the direction perpendicular to the optical axis 12a.

[0023] FIG. 2 is an explanatory diagram showing the configuration of the corneal endothelium imaging device 100. The corneal endothelium imaging device 100 is a device for imaging the corneal endothelium in a test eye in a non-contact manner. The corneal endothelium imaging device 100 includes a base 102, a main body 104, a head 106 (imaging unit), an operation stick 108, and a display 110. The base 102 has a built-in power supply device. The main body 104 is provided on the base 102. The main body 104 houses each control circuit described below. The device optical system 10 described in FIG. 1 is housed inside the head 106.

[0024] In this embodiment, the base 102 of the corneal endothelium imaging device 100 is installed on a horizontal plane. The corneal endothelium imaging device 100 includes a support unit (not shown), and the directions of the subject's left and right, up and down, and front and back directions when the subject's face is supported by the support unit are referred to as the X direction, Y direction, and Z direction in this specification. In FIG. 2, each direction is indicated by the X axis, the Y axis, and the Z axis. In this specification, the rear as seen from the subject is indicated as the positive direction of the Z direction, the left as seen from the subject is indicated as the positive direction of the X direction, and the upper direction is indicated as the positive direction of the Y direction. Note that the Z direction is parallel to the optical axis 12a of the anterior eye imaging optical system 12, and therefore the direction along the optical axis 12a is the Z direction. On the other hand, any direction on a plane parallel to the X direction and the Y direction is perpendicular to the optical axis 12a.

[0025] The head 106 is configured to be movable in both positive and negative directions along the X, Y, and Z directions above the main body 104. The device optical system 10 is housed and fixed in the head 106. Therefore, the corneal illumination optical system 14, the axial position detection optical system 16, the axial illumination optical system 18, the corneal detection optical system 20, the vertical illumination optical system 66, and the vertical position detection optical system 84 are driven as a unit in accordance with the movement of the head 106.

[0026] The operation stick 108 is provided on the base 102. The operation stick 108 is configured to be capable of driving the head 106. The display 110 is provided on the head 106. The display 110 is a touch panel display. Therefore, the display 110 is capable of displaying any image and also capable of accepting input via the touch panel. The display unit and the input unit are not limited to a touch panel display, and may be various other devices.

[0027] (1-1) Control system configuration: Fig. 3 is an explanatory diagram for explaining a control circuit and the like connected to the device optical system 10 described in Fig. 1. The corneal endothelium imaging device 100 is provided with an X-axis drive mechanism 112, a Y-axis drive mechanism 114, and a Z-axis drive mechanism 116 for moving the head 106 in the X-, Y-, and Z-directions, respectively. These drive mechanisms can be configured, for example, by a rack-and-pinion mechanism.

[0028] Furthermore, the corneal endothelium imaging device 100 includes a control unit 117, an XY alignment detection circuit 118, a Z alignment detection circuit 120, an image processing circuit 122, and a storage device 124. The control unit 117 is a circuit that controls the operation of capturing a corneal image by the device optical system 10. The control unit 117 is connected to the X-axis driving mechanism 112, the Y-axis driving mechanism 114, and the Z-axis driving mechanism 116, and is capable of outputting driving signals for driving these driving mechanisms.

[0029] The XY alignment detection circuit 118 is connected to the alignment detection sensor 88 and the control unit 117. The Z alignment detection circuit 120 is connected to the line sensor 44 and the control unit 117. Detection information of the alignment detection sensor 88 and the line sensor 44 is input to the control unit 117 via the XY alignment detection circuit 118 and the Z alignment detection circuit 120. Although not shown, the control unit 117 is also connected to the observation light source 30, the imaging light source 40, the adjustment light source 54, and the alignment light source 82, and controls the emission of these illumination light sources. The control unit 117 is also connected to the display 110, and can display any image on the display 110 and can accept input from the operator via a touch panel.

[0030] The image processing circuit 122 is a circuit that acquires an image captured by the CCD 28. A storage device 124 is connected to the image processing circuit 122, and the storage device 124 stores image data of the image output from the image processing circuit 122.

[0031] (1-2) Shooting process: Next, the photographing process executed by the control unit 117 in the corneal endothelium imaging device 100 configured as described above will be described. FIG. 4 is a flowchart showing the photographing process. The control unit 117 starts the photographing process when the operator performs a touch operation on the display 110 to instruct the start of the photographing process. When the photographing process starts, the control unit 117 initializes the number of re-photographs to 0 (step S200). In this embodiment, after the first photographing, the image captured does not satisfy the criteria, the image is re-photographed. The number of re-photographs is a value that is increased by 1 each time re-photographing is performed. During re-photographing, a cancel button for canceling the re-photographing at the operator's discretion and a thumbnail image of the captured image (the image determined not to satisfy the criteria) are displayed on the display 110. The operator can determine whether or not re-photographing is necessary based on the thumbnail image. If the re-photographing is not canceled at the operator's discretion, the re-photographing is performed up to a preset upper limit number of times.

[0032] Next, the control unit 117 performs alignment processing (step S205). FIG. 5 is a flowchart of the alignment processing. When the alignment processing is started, the control unit 117 performs coarse adjustment (step S100). Specifically, when the imaging processing is started, the control unit 117 turns on the observation light source 30 and starts imaging by the anterior eye imaging optical system 12. As a result, an image of the anterior eye captured by the CCD 28 is acquired by the image processing circuit 122 and stored in the storage device 124. The control unit 117 acquires image data indicating the image stored in the storage device 124, and controls the display 110 to display the image. As a result, the image of the anterior eye is displayed live on the display 110.

[0033] The operator performs coarse adjustment by operating the operation stick 108 in a state where the image of the anterior eye segment is displayed live on the display 110. That is, when the operator operates the operation stick 108, the control unit 117 drives the X-axis driving mechanism 112 and the Y-axis driving mechanism 114 according to the operation direction and operation amount of the operation stick 108, and moves the head 106 in the X direction and the Y direction. The operator operates the operation stick 108 while visually checking the display on the display 110, and performs coarse adjustment so that the center of the cornea of ​​the subject's eye E coincides with a predetermined position (for example, the center) of the display 110. The coarse adjustment in the Z direction may be performed automatically or by the operator. As an automatic configuration, a configuration in which the position of the head 106 in the Z direction is set to a predetermined initial position, or a configuration in which the head 106 is moved in the Z direction based on the output of the line sensor 44 so that, for example, reflected light from the epithelium is detected within a predetermined range, etc. can be adopted.

[0034] Next, the control unit 117 adjusts the position in the direction perpendicular to the optical axis 12a using the vertical position adjustment optical system, that is, performs XY alignment, which is the alignment of the device optical system 10 in the XY direction with respect to the subject's eye E (step S105). Specifically, the control unit 117 turns on the alignment light source 82. As a result, detection light for detecting the vertical position is output from the alignment light source 82 and irradiated toward the subject's eye E. When the detection light for detecting the vertical position is reflected by the subject's eye E, the reflected light is guided to the alignment detection sensor 88 and detected by the alignment detection sensor 88. Note that the intensity of the reflected light of the detection light for detecting the vertical position reflected by the subject's eye E is large at the corneal apex, so the position at which the reflected light is detected corresponds to the position at which the reflected light from the corneal apex is detected. Here, the corneal apex is the position of the cornea C that is closest to the anterior eye imaging optical system 12 in the Z direction.

[0035] As described above, the control unit 117 performs XY alignment in a state in which the reflected light from the subject's eye E by the detection light for detecting the vertical position is detected by the alignment detection sensor 88. Specifically, the control unit 117 refers to the output result of the alignment detection sensor 88 and specifies a position on the alignment detection sensor 88 where a detection value equal to or greater than a threshold is detected. The position is regarded as a position where the reflected light is received by the alignment detection sensor 88. The threshold is a value determined in advance as a value for detecting the reflected light.

[0036] The control unit 117 performs control to make the position where the reflected light is received by the alignment detection sensor 88 coincide with a preset position on the alignment detection sensor 88 (the center of the sensor in this embodiment). That is, the control unit 117 specifies the difference between the position where the reflected light is received by the alignment detection sensor 88 and the preset position on the alignment detection sensor 88. Furthermore, the control unit 117 specifies the movement direction of the head 106 in the XY plane to reduce the difference. Then, the control unit 117 controls the X-axis driving mechanism 112 and the Y-axis driving mechanism 114 to move the head 106 in the movement direction.

[0037] The control unit 117 executes XY alignment by repeating the above process until the difference between the position where the reflected light is received by the alignment detection sensor 88 and a predetermined position on the alignment detection sensor 88 becomes equal to or less than a threshold value. During XY alignment, live display in step S100 may be performed. Once XY alignment is performed, the control unit 117 starts tracking in the XY directions (step S110). That is, the control unit 117 constantly executes XY alignment by continuously repeating the alignment in step S105.

[0038] Next, the control unit 117 adjusts the axial position using the axial position adjustment optical system, that is, performs Z alignment. For this purpose, first, the control unit 117 performs Z alignment so that the position of the epithelium + the position of the target distance is in focus (step S115). Specifically, the control unit 117 turns on the adjustment light source 54. As a result, detection light for detecting the axial position is output from the adjustment light source 54 and is irradiated toward the subject's eye E. When the detection light for detecting the axial position is reflected by the subject's eye E, the reflected light is guided to the line sensor 44 and detected by the line sensor 44. In this embodiment, the endothelium of the cornea is the subject of imaging. In order to perform imaging in a state where the endothelium of the cornea is in focus, the endothelium of the cornea needs to be present at the point where the optical axis 14a of the corneal illumination optical system 14 and the optical axis 20a of the corneal detection optical system 20 intersect.

[0039] The optical axis 14a of the cornea illumination optical system 14 and the optical axis 16a of the axial position detection optical system 16 coincide with each other around the subject's eye E, and the optical axis 18a of the axial illumination optical system 18 and the optical axis 20a of the cornea detection optical system 20 coincide with each other around the subject's eye E. Therefore, the point where the optical axis 14a of the cornea illumination optical system 14 and the optical axis 20a of the cornea detection optical system 20 intersect with the point where the optical axis 18a of the axial illumination optical system 18 and the optical axis 16a of the axial position detection optical system 16 intersect with each other. Therefore, by analyzing the position where the reflected light from the corneal endothelium is detected by the line sensor 44, it is possible to determine whether the corneal endothelium is in focus in the cornea detection optical system.

[0040] Next, the control unit 117 scans the output of the line sensor 44 from the anterior chamber side (step S120). Specifically, the control unit 117 refers to the light reception results received by the line sensor 44 from the anterior chamber side toward the epithelium side, and compares the detection value at each position on the line sensor 44 with a predetermined threshold value to identify an endothelial peak. The endothelial peak is a peak of reflected light from the endothelium of the cornea. When the detection result of the reflected light from the cornea has a complex shape, the control unit 117 considers the peak closest to the anterior chamber of the subject's eye E to be the reflected light from the endothelium.

[0041] Next, the control unit 117 determines whether or not the endothelial peak has been identified (step S125). That is, if the endothelial peak has not been identified by the processing of step S120, the control unit 117 executes step S130, and if the endothelial peak has been identified, the control unit 117 executes step S140.

[0042] If the endothelial peak is not identified in step S125, the control unit 117 checks in step S130 whether the position of the epithelium plus the position of the target distance is in focus in the corneal imaging optical system. If it is not determined in step S130 that the position of the epithelium plus the position of the target distance is in focus in the corneal imaging optical system, the control unit 117 repeats step S115 again.

[0043] On the other hand, if it is determined in step S130 that the position of the epithelium+the position of the target distance is in focus in the corneal imaging optical system, the control unit 117 changes the target distance (step S135) and repeats the processes from step S115 onwards.

[0044] When the endothelial peak is identified in step S125, the control unit 117 judges whether or not the endothelial peak is near the focused position (step S140). That is, the control unit 117 calculates the difference between the position of the endothelial peak identified in step S125 and the focused position, and judges that the endothelial peak is near the focused position when the difference is equal to or smaller than a threshold. Note that the threshold is a value determined in advance as a value for judging whether or not the endothelial peak is sufficiently close to the focused position, and in this embodiment, it is the same as the change width of the target distance in step S135.

[0045] If it is not determined in step S140 that the endothelial peak is present near the focal position, the control unit 117 performs the processes from step S130 onward. That is, if there is an effect of fixational eye movement, the processes from step S115 onward are repeated without changing the target distance, and if there is no effect of fixational eye movement, the target distance is changed and the processes from step S115 onward are repeated.

[0046] If it is determined in step S140 that the endothelial peak is near the focal position, the control unit 117 performs Z alignment so that the endothelial peak is at the focal position (step S145). That is, the control unit 117 moves the head 106 so that the focal position on the line sensor 44 coincides with the position where the reflected light from the endothelium of the cornea is received by the line sensor 44. Specifically, the control unit 117 identifies the position of the endothelial peak based on the detection result of the line sensor 44, identifies the difference between the identified position of the endothelial peak and the focal position, and identifies the distance on the optical axis 12a that corresponds to the difference on the line sensor. Then, the control unit 117 controls the Z-axis driving mechanism 116 to move the head 106 by the distance. As a result, the Z alignment is performed so that the endothelium of the cornea is in a focal state in the corneal imaging optical system.

[0047] Once Z alignment has been performed, control unit 117 starts tracking in the Z direction (step S150). That is, control unit 117 constantly performs Z alignment by continuously repeating the alignment in step S145. After an endothelial peak existing near the focal position is found by the processes of steps S115 to S140, it is possible to easily continue tracking the endothelial peak. Through the above processes, the corneal imaging optical system is continuously maintained in focus on the endothelium of the cornea.

[0048] Returning to the description of the photographing process in FIG. 4, the control unit 117 photographs the image while focusing on the endothelium of the cornea (steps S210 to S225). The control unit 117 repeatedly photographs the image at a predetermined cycle (for example, 40 ms) within a predetermined period (for example, 2 seconds) (step S215), and stores a predetermined number of images (for example, 16 images) having good image quality in the storage device 124. That is, the control unit 117 acquires the image data output from the image processing circuit 122 and stored in the storage device 124, and when the number of captured image data exceeds a predetermined number, the control unit 117 compares the image data having the worst image quality among the predetermined number of images with the latest image data. The control unit 117 discards the image data having the worst image quality as a result of the comparison. In this way, a predetermined number of image data having relatively good image quality among the image data captured within a predetermined period is stored in the storage device 124.

[0049] In order to determine the image quality, the control unit 117 determines whether the image data is an image in focus and whether endothelial cells are included in the image data. In this embodiment, the control unit 117 determines that the image data is in focus when black slit regions at the ends of the image data appear with equal widths on both the left and right ends as shown in FIG. 6. In addition, the control unit 117 calculates the sum of the differences in luminance values ​​between adjacent pixels on the left and right sides on each of the five dashed lines shown in FIG. 6, for example. In the image data, there is a difference in luminance value between the inner region of the endothelial cells and the boundary line of the endothelial cells. The control unit 117 considers that more endothelial cells are located on the line when the sum of the differences in luminance values ​​is large than when the sum of the differences in luminance values ​​is small. The control unit 117 compares the image with the smallest sum of the differences in luminance values ​​among the captured image data with the sum of the latest image data, and determines that the image with the larger value (i.e., the image may contain many endothelial cells) and in focus has better image quality.

[0050] After one image is captured in step S215, the control unit 117 determines whether or not a cancellation has been made (step S220). That is, the control unit 117 determines whether or not a cancel button displayed during re-capture has been selected. While the number of re-captures is 0, the thumbnail image and the cancel button are not displayed, and therefore it is not determined in step S220 that a cancellation has been made. If the number of re-captures is 1 or more, the thumbnail image and the cancel button are displayed in step S240, which will be described later. In this state, if the cancel button is selected, the control unit 117 determines in step S220 that a cancellation has been made, stops capturing even if a predetermined period of time has not elapsed, and proceeds to step S280.

[0051] When the shooting in steps S210 to S225 is completed, a predetermined number of image data are newly stored. The control unit 117 determines whether the number of reshoots is smaller than the maximum value (step S230). The maximum value (maximum number) of the number of reshoots is set in advance, and in step S230, a comparison is made with the preset maximum number of reshoots. Of course, the operator can change the default maximum value to a desired value via the menu screen.

[0052] If it is not determined in step S230 that the number of re-imaging times is less than the maximum value, the control unit 117 proceeds to step S280. If it is determined in step S230 that the number of re-imaging times is less than the maximum value, the control unit 117 determines whether or not re-imaging is necessary (step S235). If the image satisfies the criterion, the control unit 117 determines that re-imaging is unnecessary, and if the image does not satisfy the criterion, it determines that re-imaging is necessary. The criterion is that the proportion of an endothelial region indicating a region where endothelial cells are located in an image is equal to or greater than a threshold. An endothelial region is a region in which endothelial cells are present in a plurality of consecutive areas without being spaced apart in image data. An endothelial region is a region having a higher brightness than a region where endothelial cells are not located. Therefore, the control unit 117 identifies the endothelial region by utilizing the brightness difference. FIG. 8A is a diagram showing an example of an image including endothelial cells (shown as a closed region). The closed region indicating endothelial cells has a higher brightness than the other regions. An explanation will be given using FIG. 8A as an example.

[0053] The control unit 117 smoothes the image data based on pixel values ​​of pixels in the vertical direction of the pixel of interest ± a predetermined pixel to remove noise, and then scans each line extending in the horizontal direction from the left end to the right end to identify a pixel at a boundary where the luminance difference changes from a low value to a high value by a predetermined value or more. Furthermore, the control unit 117 smoothes and connects the positions of the identified pixels to derive one boundary line when scanning from the left end to the right end. Similarly, the control unit 117 scans each line extending in the horizontal direction from the right end to the left end to identify a pixel at a boundary where the luminance difference changes from a low value to a high value by a predetermined value or more, and smooths and connects the positions of the identified pixels to derive one boundary line when scanning from the right end to the left end. Furthermore, the control unit 117 smoothes the image data based on pixel values ​​of pixels in the horizontal direction of the pixel of interest ± a predetermined pixel, and then scans each line extending in the vertical direction from the top end to the bottom end to identify a pixel at a boundary where the luminance difference changes from a low value to a high value by a predetermined value or more. The control unit 117 smoothes and joins the positions of the identified pixels to derive one boundary line when scanning from the upper end to the lower end. Similarly, the control unit 117 scans each line extending in the vertical direction from the lower end to the upper end, identifies pixels at the boundary where the luminance difference changes from a low value to a high value by a predetermined value or more, smoothes and joins the positions of the identified pixels to derive one boundary line when scanning from the lower end to the upper end. The control unit 117 specifies a closed region surrounded by the boundary line derived in this way as an endothelial region. FIG. 8B is a diagram showing a schematic diagram of an endothelial region specified when the above-mentioned process is performed on an image in which endothelial cells are captured as shown in FIG. 8A.

[0054] Note that various other methods can be adopted to identify the endothelial region, but since it is necessary to process the predetermined number of image data captured in step S215, a method with a small processing load (short processing time) is desirable. The control unit 117 calculates the area of ​​the endothelial region for each of the predetermined number of image data captured in step S215, calculates the ratio of the area of ​​the endothelial region to the area of ​​the entire image for the image data with the largest area of ​​the endothelial region, and determines that re-imaging is necessary if the ratio does not meet a criterion that the endothelial region area is equal to or greater than a threshold value (e.g., 60%).

[0055] If it is not determined in step S235 that re-imaging is necessary, the control unit 117 proceeds to step S280. If it is determined in step S235 that re-imaging is necessary, the control unit 117 displays a thumbnail image and a cancel button (step S240). The thumbnail image is a reduced image of the image to be re-imaging-necessity judgment. FIG. 7 shows a display example of a thumbnail image 300 and a cancel button 301. The thumbnail image 300 and the cancel button 301 are displayed superimposed on a live image of the subject's eye. In this embodiment, the image displayed as the thumbnail image 300 is a thumbnail image of an image with the best image quality among a plurality of images to be judged as to whether re-imaging is necessary. That is, in this embodiment, the thumbnail image 300 is a thumbnail image of an image in which the ratio of the area of ​​the endothelium region to the entire image is the largest among the image data captured in steps S210 to S225 but is less than a threshold value. By presenting the image with the best image quality to the operator, it is possible to provide the operator with an element for judging whether re-imaging should be continued.

[0056] Next, the control unit 117 calculates an offset value (step S245). The offset value is the moving distance of the head for moving the position of the endothelial region to a predetermined position of the imaging element. When the endothelial region is biased toward the end of the image as in the example of FIG. 8, the control unit 117 sets the offset value so as to eliminate the bias. As a method of setting the offset value, for example, as shown in FIG. 8C, a rectangular frame F (a rectangular frame having two sides parallel to the vertical direction of the image and two sides parallel to the horizontal direction of the image) in which the endothelial region is inscribed is set, and the vertical and horizontal distances (Kx, Ky) between the center of gravity P1 of the rectangular frame F and the center P2 of the image in the image in the vertical and horizontal directions are converted into offset values ​​in the X direction and Y direction, respectively. Alternatively, when one of the upper and lower ends of the rectangular frame F mentioned above is in contact with one of the upper and lower ends of the image but the other is not in contact with the other of the upper and lower ends of the image, or when one of the left and right ends of the rectangular frame F is in contact with one of the left and right ends of the image but the other is not in contact with the other of the left and right ends of the image, the offset value in the X direction and the offset value in the Y direction may be calculated based on the vertical and horizontal distances in the image between the end of the rectangular frame F that is not in contact with the end of the image and the end of the image. Specifically, for example, in the example shown in Fig. 8C, the left end of the rectangular frame F is in contact with the left end of the image but the right end is not in contact with the right end of the image, and the upper end of the rectangular frame F is in contact with the upper end of the image but the lower end is not in contact with the lower end of the image. Therefore, the distance Kx2 in the image between the right end of the rectangular frame F and the right end of the image may be converted into an offset amount in the X direction, and the distance Ky2 between the lower end of the rectangular frame F and the lower end of the image may be converted into an offset value in the Y direction. In this way, by setting an offset value based on the position of the endothelial region contained in the image and moving the head based on that offset value to re-take the image, it is possible to increase the likelihood of capturing an image that meets the criteria in the re-take.

[0057] Next, the control unit 117 retracts the head (step S250) and starts alignment (step S255). Since it has been determined that re-imaging is necessary, the control unit 117 retracts the head 106 once and performs alignment again in an attempt to capture an image that satisfies the criteria.

[0058] Next, the control unit 117 judges whether or not cancellation has occurred (step S260). That is, the control unit 117 judges whether or not the cancel button shown in FIG. 7 has been selected. If it is not judged in step S260 that cancellation has occurred, the control unit 117 moves the head (step S265). That is, the control unit 117 performs XY alignment at a position where the head has been moved in the XY directions by the distance indicated by the offset value calculated in step S245. The control unit 117 performs XY tracking by continuously repeating XY alignment at that position. Furthermore, the control unit 117 performs Z alignment and Z direction tracking so that the endothelial peak becomes the focused position.

[0059] If it is determined in step S260 that cancellation has occurred, or if it is determined in step S220 that cancellation has occurred, or if it is determined in step S230 that the number of re-shooting attempts is not less than the maximum value, or if it is determined in step S235 that re-shooting is not necessary, the control unit 117 hides the thumbnail image and the cancel button, and suspends shooting and head movement (step S280). As for shooting, shooting is not performed after it is determined that cancellation has occurred for a predetermined period of time. In addition, as for head movement, the head may be configured to immediately stop mid-movement, or may be configured to move to a preset position and then stop.

[0060] After executing step S265, the control unit 117 judges whether the photographing condition is satisfied (step S270). That is, the control unit 117 judges whether the focus is on the corneal endothelium. If it is not judged that the condition is satisfied in step S270, the control unit 117 returns to step S260. If it is judged that the condition is satisfied in step S270, the control unit 117 increments the number of re-photographing attempts and returns to step S210.

[0061] As described above, according to the present embodiment, the corneal endothelium imaging device 100 is configured to automatically start re-imaging when the criteria are not met, thereby reducing the operator's efforts to obtain an image that meets the criteria. In addition, the corneal endothelium imaging device 100 is configured to display a thumbnail image of an image that is determined not to meet the criteria and a cancel button for re-imaging during re-imaging, thereby providing the operator with an opportunity and information to determine whether or not re-imaging is necessary. Even if re-imaging is automatically started because the criteria are not met, an image that is useful to the operator may have already been captured. The corneal endothelium imaging device 100 cancels re-imaging in response to the operator's selection of the cancel button when the operator determines that re-imaging is not necessary, thereby preventing the time required to obtain an image suitable for analysis from being unnecessarily extended. Furthermore, by stopping re-imaging when the operator determines that re-imaging is not necessary, it is possible to prevent many images from being unnecessarily stored in the storage device 124. By preventing many images from being unnecessarily stored, it is possible to simplify, for example, the task of the operator to select the best image.

[0062] (2) Other embodiments: The above embodiment is an example for carrying out the present invention, and various other embodiments can be adopted. For example, the necessity of re-imaging may be determined based on a criterion for at least one of the number and size of cellular regions showing each endothelial cell in the image. Specifically, for example, the control unit detects a contour line in the image, and detects each closed region surrounded by the contour line as a cellular region showing each endothelial cell. The control unit may be configured to determine that the criterion is not met and that re-imaging is necessary when the number of cellular regions detected in the image differs from the standard value by a predetermined value or more. In addition, the control unit may be configured to determine that the image does not meet the criterion and that re-imaging is necessary when the area of ​​one cellular region does not fall within the range of standard values ​​of the area. In addition, when the cellular regions are classified into three groups, for example, large, medium, and small, according to their areas, the number of cellular regions classified into each group may be counted, and it may be determined that the criterion is met if the number of cellular regions in each group is equal to or greater than a predetermined value.

[0063] The images displayed as thumbnail images may be configured to include at least the image with the best image quality among the multiple images for which the necessity of re-shooting is to be determined. Therefore, for example, thumbnail images of the multiple images may be displayed in descending order of image quality together with a cancel button.

[0064] In the above embodiment, when re-shooting, XY alignment is performed at a position where the head is moved by an XY offset value calculated by analyzing the captured image, but the process of calculating the XY offset value and moving the head based on the XY offset value may be omitted.

[0065] The cancel button is an image that is displayed on the display to instruct the user to stop re-shooting, and the name and display format of the cancel button are not limited to the examples shown in the above embodiment, and may be realized in various forms.

[0066] Furthermore, the technique of the present invention can also be applied as a program or method. The above-mentioned system, program, and method may be realized as a single device or may be realized by using parts shared with each part provided in the vehicle, and include various aspects. In addition, they can be modified as appropriate, such as being partly software and partly hardware. Furthermore, the invention can also be realized as a recording medium of a program that controls the system. Of course, the recording medium of the program may be a magnetic recording medium or a semiconductor memory, and any recording medium developed in the future can be considered in the same way. [Explanation of symbols]

[0067] 10...apparatus optical system, 12...anterior eye imaging optical system, 12a...optical axis, 14...corneal illumination optical system, 14a...optical axis, 16...axial position detection optical system, 16a...optical axis, 18...axial illumination optical system, 18a...optical axis, 20...cornea detection optical system, 20a...optical axis, 22...half mirror, 24...objective lens, 26...half mirror, 27...cold mirror, 28...CCD, 30...observation light source, 32...projection lens, 34...cold mirror, 36...slit, 38...condensing lens, 40...imaging light source, 44...line sensor, 46...objective lens, 48...cold mirror, 52...condensing lens, 54...adjustment light source, 56...slit, 58...variable magnification lens, 60...focusing lens, 64...fixation target optical system, 66...vertical illumination optical system , 68...projection lens, 70...half mirror, 74...fixation target light source, 76...diaphragm, 78...pinhole plate, 80...condenser lens, 82...alignment light source, 84...vertical position detection optical system, 88...alignment detection sensor, 100...corneal endothelium imaging device, 102...base, 104...main body, 106...head, 108...operation stick, 110...display, 112...X-axis drive mechanism, 114...Y-axis drive mechanism, 116...Z-axis drive mechanism, 117...control unit, 118...XY alignment detection circuit, 120...Z alignment detection circuit, 122...image processing circuit, 124...storage device, 300...thumbnail image, 301...cancel button, C...cornea, E...subject's eye, F...rectangular frame, P1...center of gravity, P2...center

Claims

1. An imaging unit that images the cornea of ​​the subject's eye; a control unit that starts re-shooting with the photographing unit when the image obtained by photographing does not satisfy a criterion, displays a thumbnail image of the image and a cancel button for the re-shooting on a display unit during the re-shooting, and cancels the re-shooting when the cancel button is selected; A corneal endothelium imaging device comprising:

2. The image displayed as the thumbnail image during the re-shooting includes at least the image having the best image quality among the plurality of images that are the objects of the determination of the necessity of the re-shooting. The corneal endothelium imaging device of claim 1 .

3. The criterion is that an endothelial region, which indicates a region where endothelial cells are located, occupies a proportion of the image equal to or greater than a threshold value. The corneal endothelium imaging device of claim 1 .

4. The criterion is a judgment criterion for at least one of the number and size of cellular regions representing each endothelial cell in the image. The corneal endothelium imaging device of claim 1 .

5. the control unit calculates an offset value based on a position of an endothelial region indicating a region where endothelial cells are located in the image that is the subject of the determination of the need for re-imaging, and moves the imaging unit based on the offset value to start the re-imaging. The corneal endothelium imaging device of claim 1 .

Images