JP2021069409A - Corneal endothelial imaging device and image order setting method - Google Patents

Abstract

To provide a technology to improve the possibility of selecting images taken of the same position from a plurality of images taken in different imaging periods.SOLUTION: A corneal endothelial imaging device includes: an illumination optical system including an illumination light source for irradiating an eye to be examined with a slit light flux obliquely; an imaging optical system including an image pickup device for receiving a reflection light flux from the cornea of the eye to be examined, and taking a cornea image; a distance changing unit for changing a distance to the eye to be examined by integrating the illumination optical system and the imaging optical system; a coordinate association unit for associating each of a plurality of images taken by the image pickup device at a plurality of positions whose distances to the eye to be examined are different from one another with coordinate information; and an order setting unit for setting a priority order with a distance between an imaging position in a state that the imaging optical system focuses on the corneal endothelial and an imaging position where the image is taken as at least one order criterion on the basis of the coordinate information for the plurality of images taken during imaging periods.SELECTED DRAWING: Figure 3

Description

The present invention relates to a corneal endothelium imaging device and a method for setting an image ranking.

Conventionally, the cellular state of the cornea, particularly the corneal endothelium, has been observed when determining the presence or absence of an eye disease or diagnosing the postoperative course of the eye.

When observing such a cell state of the corneal endothelium, a corneal endothelium imaging device that images the corneal endothelium in the eye to be inspected without contact is known. For example, in Patent Document 1, a slit-shaped illumination light is obliquely irradiated to the cornea of the eye to be inspected by an illumination optical system, and the reflected light from the cornea is received by the imaging optical system to image the corneal endothelium. The device is disclosed.

Patent No. 4914176

It is desirable to observe the change over time of the corneal endothelium due to the disease and to compare the corneal endothelium before and after the operation by using an image in which the focused part of the corneal endothelium is captured without blurring. However, in the conventional corneal endothelium imaging device, it has not been sufficiently considered to select an image in which the same position is captured from each of a plurality of captured images captured in different imaging periods.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for improving the possibility of selecting an image captured at the same position from each of a plurality of captured images captured in different imaging periods. To do.

In order to achieve the above object, the corneal endothelial imaging device receives an illumination optical system including an illumination light source that irradiates the slit light beam obliquely to the eye to be inspected, and a light beam reflected from the corneum of the eye to be inspected by the slit light beam. An imaging optical system including an imaging element that captures a corneal image, a distance changing unit that changes the distance to the eye to be inspected by integrating the illumination optical system and the imaging optical system, and an imaging element at a plurality of positions where the distance to the eye to be inspected is different. Based on the coordinate information, the coordinate corresponding unit that associates the coordinate information indicating the imaging position with each of the plurality of captured images, and each of the plurality of captured images captured during the preset imaging period. A ranking setting unit for setting a priority is provided with at least one ordering reference of the distance between the imaging position in a state where the imaging optical system is in focus on the corneal inner skin and the imaging position where the captured image is captured.

Further, in order to achieve the above object, the image ranking setting method is as follows: an illumination optical system including an illumination light source that irradiates the slit light beam obliquely to the eye to be inspected, and a light beam reflected from the corneum of the eye to be inspected by the slit light beam. An image using a corneal endothelial imaging device including an imaging optical system including an imaging element that receives light and images a corneal image, and a distance changing unit that integrally changes the distance to the eye to be inspected by integrating the illumination optical system and the imaging optical system. This is a ranking setting method, which is preset with a coordinate matching step of associating coordinate information indicating an imaging position with each of a plurality of captured images imaged by an imaging element at a plurality of positions having different distances from the eye to be inspected. For each of the plurality of captured images captured during the period, the distance between the imaging position in the state where the imaging optical system is in focus on the corneal endothelial during the period and the imaging position where the captured image was captured is determined by at least one ordering criterion. As a result, a ranking setting process for setting priorities is provided.

That is, in the above-mentioned corneal endothelium imaging device and the image ranking setting method, when a plurality of captured images are captured in different imaging periods, the priority is given to each of the plurality of captured images captured in the different imaging periods. Is set. Therefore, when the image with the highest priority is selected from each of the plurality of captured images, each of the selected captured images is a captured image having a high degree of focus on the corneal endothelium and is similar. There is a high possibility that an captured image associated with the coordinate information will be selected. That is, it is possible to improve the possibility that an image captured at the same position can be selected from each of the plurality of captured images captured in different imaging periods. It is also possible to increase the possibility of selecting an image having a high degree of focus on the corneal endothelium.

Further, in order to achieve the above object, the corneal endothelial imaging device receives an illumination optical system including an illumination light source that irradiates the slit light beam obliquely to the eye to be inspected, and a light beam reflected from the corneum of the eye to be inspected by the slit light beam. An imaging optical system including an imaging element that captures a corneal image, a distance changing unit that changes the distance to the eye to be examined by integrating the illumination optical system and the imaging optical system, and an imaging element at a plurality of positions where the distance to the eye to be examined is different. A coordinate corresponding unit that associates coordinate information indicating an imaging position with each of the plurality of captured images captured in the image, and a first captured image and a second captured image that are the plurality of captured images captured during the first imaging period. It is provided with a similar extraction unit that extracts similar captured images from each of the second captured images, which are a plurality of captured images captured during the imaging period, using at least coordinate information as a similar determination criterion.

That is, in the above-mentioned corneal endothelium imaging device, an image captured with similar coordinate information associated with each of a plurality of captured images captured in different imaging periods can be extracted as a similar image. ..

Further, in order to achieve the above object, the corneal endothelial imaging device receives an illumination optical system including an illumination light source that irradiates the slit light beam obliquely to the eye to be inspected, and a light beam reflected from the corneum of the eye to be inspected by the slit light beam. An imaging optical system including an imaging element that captures a corneal image, a distance changing unit that changes the distance to the eye to be examined by integrating the illumination optical system and the imaging optical system, and an imaging element at a plurality of positions where the distance to the eye to be examined is different. Each of the plurality of captured images captured in the image is provided with a coordinate corresponding unit for associating coordinate information indicating an imaging position, and the imaging optical system includes a plurality of imaging images captured during a preset imaging period. The corneal image is imaged at the imaging position indicated by the coordinate information associated with one of the images to be captured.

That is, in the above-mentioned corneal endothelium imaging device, imaging by the imaging element can be performed at the imaging position indicated by the coordinate information associated with one target image. Therefore, it is possible to increase the possibility that the captured image captured at the same imaging position as the corneal image captured in one target captured image can be captured.

It is explanatory drawing which shows the structure of the apparatus optical system. It is explanatory drawing which shows the structure of the corneal endothelium imaging apparatus. It is explanatory drawing explaining the control circuit and the like connected to the device optical system. It is a flow of the imaging procedure of the corneal endothelium executed by the imaging control circuit. It is explanatory drawing which shows the anterior eye part of the eye to be examined displayed on the display screen. It is explanatory drawing which shows the outline of each layer which constitutes a cornea. It is explanatory drawing which shows the distribution of the reflected light flux reflected in each layer which constitutes a cornea. It is explanatory drawing which shows the change of the moving speed in isolation movement of an apparatus optical system. It is explanatory drawing which shows the captured image which was taken by the CCD. It is explanatory drawing for demonstrating the horizontal line drawn in the captured image. It is explanatory drawing which shows the captured image which was taken by the CCD. It is explanatory drawing which shows the example of the list display of the captured image. It is explanatory drawing which shows the example which the captured image is displayed side by side on the display part. It is explanatory drawing which shows the structure of the corneal endothelium imaging apparatus. It is explanatory drawing which shows the luminance information of the pixel on one horizontal line in the captured image. It is explanatory drawing which shows the position number which shows the position of a pixel in a captured image.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of the corneal endothelium imaging device of the first embodiment:
(2) Configuration of the corneal endothelium imaging device of the second embodiment:
(3) Configuration of the corneal endothelium imaging device of the third embodiment:
(4) Other embodiments:

(1) Configuration of the corneal endothelium imaging device of the first embodiment:
FIG. 1 is an explanatory diagram showing a configuration of an apparatus optical system 10 included in the corneal endothelium imaging apparatus 100 according to the embodiment of the present invention. The corneal endothelium imaging device 100 will be described with reference to FIGS. 2 and 3. The apparatus optical system 10 includes an observation optical system 12, an image pickup illumination optical system 14, a position detection optical system 16, a position detection illumination optical system 18, and an image pickup optical system 20. In the device optical system 10, the imaging illumination optical system 14 and the position detection optical system 16 are provided on the lower side of the paper surface from the observation optical system 12, and the position detection illumination optical system 18 and the image pickup optical system are provided on the upper side of the paper surface from the observation optical system 12. System 20 is arranged. The optical axis of the imaging illumination optical system 14 (position detection optical system 16) and the optical axis of the position detection illumination optical system 18 (imaging optical system 20) are arranged on the same plane as the optical axis of the observation optical system 12. .. In the present embodiment, the illumination optical system includes an imaging illumination optical system 14 and a position detection illumination optical system 18.

The observation optical system 12 is provided 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 close to the eye E to be inspected on the optical axis O1. Further, two observation light sources 30 are arranged at predetermined positions facing the eye E to be inspected. The observation light source 30 is an infrared LED that emits an infrared luminous flux. The cold mirror 27 transmits infrared light while reflecting visible light. The reflected light flux emitted from the observation light source 30 and reflected by the anterior segment of the eye E to be inspected is imaged on the CCD 28 through the objective lens 24 and the cold mirror 27.

The imaging illumination optical system 14 is provided in the order of a projection lens 32, a cold mirror 34, a slit 36, a condenser lens 38, and an imaging light source 40 from a position close to the eye E to be inspected. The imaging light source 40 is an LED that emits a visible luminous flux. The cold mirror 34 transmits infrared light while reflecting visible light. The luminous flux emitted from the imaging light source 40 is converted into a slit luminous flux by passing through the condenser lens 38 and the slit 36. The slit luminous flux is reflected by the cold mirror 34 and is irradiated to the cornea C from an oblique direction through the projection lens 32.

A part of the optical axis of the position detection optical system 16 coincides with the optical axis of the imaging illumination optical system 14. The position detection optical system 16 is provided in the order of the projection lens 32, the cold mirror 34, and the line sensor 44 from the position closest to the eye E to be inspected. The luminous flux emitted from the observation light source 54, which will be described later, and reflected by the cornea C is formed on the line sensor 44 through the projection lens 32 and the cold mirror 34.

On the other hand, the position detection illumination optical system 18 is provided in the order of the objective lens 46, the cold mirror 48, the condenser lens 52, and the observation light source 54 as the position detection light source from the position closest to the eye E to be inspected. The observation light source 54 is preferably an infrared light source such as an infrared LED. The infrared light flux emitted from the observation light source 54 is obliquely irradiated to the cornea C. The observation 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, its illuminance is preferably smaller than that of the imaging light source 40. By making the illuminance of the visible light source smaller than the illuminance of the imaging light source 40, the burden on the subject when irradiating the luminous flux from the observation light source 54 such as alignment is reduced. The observation 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.

A part of the optical axis of the imaging optical system 20 coincides with the optical axis of the position detection illumination optical system 18. The imaging optical system 20 is provided in the order of the objective lens 46, the cold mirror 48, the slit 56, the magnification lens 58, the focusing lens 60, the cold mirror 27, and the CCD 28 from a position close to the eye E to be inspected. The luminous flux emitted 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 converted into a parallel luminous flux by the slit 56. This parallel light flux 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 image sensor.

Further, the half mirror 22 provided on the observation optical system 12 constitutes a part of the fixation target optical system 64 and the alignment optical system 66.

The fixation target optical system 64 is provided in the order of the half mirror 22, the projection lens 68, the half mirror 70, the pinhole plate 72, and the fixation target light source 74 from the position closest to the eye E to be inspected. The fixation target light source 74 is a light source that emits visible light such as an LED. The luminous flux emitted from the fixation target light source 74 passes through the pinhole plate 72 and the half mirror 70, and then is converted into a parallel luminous flux by the projection lens 68. This parallel light flux is reflected on the half mirror 22 to irradiate the eye E to be inspected.

The alignment optical system 66 includes 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 order from a position closest to the eye E to be inspected. .. Infrared light is emitted from the alignment light source 82, and the infrared light is collected by the condenser lens 80, passes through the pinhole plate 78, and is guided to the aperture 76. Then, the light that has passed through the aperture 76 is reflected by the half mirror 70 to be a parallel luminous flux by the projection lens 68, and then reflected by the half mirror 22 and irradiated to the eye E to be inspected.

Further, the half mirror 26 provided on the observation optical system 12 constitutes a part of the alignment detection optical system 84.

The alignment detection optical system 84 is provided in the order of the half mirror 26 and the position-detectable alignment detection sensor 88 from the position closest to the eye E to be inspected. The luminous flux emitted from the alignment light source 82 and reflected by the cornea C is reflected by the half mirror 26 and is guided to the alignment detection sensor 88.

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 the eye to be inspected in a non-contact manner. The corneal endothelium imaging device 100 includes a base 102, a main body 104, a case 106, an operation stick 108, and a display screen 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 accommodates each control circuit described later. The device optical system 10 described with reference to FIG. 1 is housed inside the case 106. The case 106 is configured to be driveable in the front-rear direction and the up-down, left-right direction on the main body portion 104. The operation stick 108 is provided on the base 102. The operation stick 108 is configured to be able to drive the case 106. The display screen 110 is provided on the main body 104. The display screen 110 is an image display means including a liquid crystal monitor and the like.

FIG. 3 is an explanatory diagram for explaining a control circuit and the like connected to the apparatus optical system 10 described with reference to FIG. As shown in FIG. 3, the corneal endothelium imaging device 100 is driven by driving the case 106 to move the device optical system 10 in the direction of approaching, separating, or in the vertical and horizontal directions with respect to the eye E to be inspected. Is provided. When the device optical system 10 is moved by the driving means, each optical system (device optical system 10, observation optical system 12, imaging illumination optical system 14, position detection optical system 16) constituting the device optical system 10 is used. , The position detection illumination optical system 18 and the image pickup optical system 20) are moved together. The drive means is composed of a rack pinion mechanism. In the present embodiment, the X-axis drive mechanism 112 that drives the case 106 in the X direction, which is the vertical direction on the paper surface of FIG. 3, is perpendicular to the paper surface of FIG. Includes a Y-axis drive mechanism 114 that drives the case 106 in the Y direction, which is the direction, and a Z-axis drive mechanism 116 that drives the case 106 in the Z direction, which is the left-right direction in FIG. In other words, the X-axis drive mechanism 112 drives the case 106 vertically with respect to the eye E to be inspected, and the Y-axis drive mechanism 114 drives the case 106 left and right with respect to the eye E to be inspected, and the Z-axis. The drive mechanism 116 drives the case 106 in the front-rear direction with respect to the eye E to be inspected. The front direction referred to here is a direction approaching the eye E to be inspected, and the rear direction is a direction in which the eye E is isolated from the eye to be inspected E. The Z-axis drive mechanism 116 can also be called a distance changing unit. The position of the case 106 is manipulated by the driving means driving the case 106 according to the direction in which the operation stick 108 is tilted.

The corneal endothelium imaging device 100 is provided with an imaging control circuit 117 as an imaging control means for controlling the operation of imaging of a corneal image by the device optical system 10. The image pickup control circuit 117 is connected to the X-axis drive mechanism 112, the Y-axis drive mechanism 114, and the Z-axis drive mechanism 116, which are the drive means, and is configured to be able to output a drive signal for driving the drive means. Further, the XY alignment detection circuit 118 provided in the corneal endothelium imaging device 100 is connected to the alignment detection sensor 88, the imaging control circuit 117, and the image selection circuit 122. Further, the Z alignment detection circuit 120 provided in the corneal endothelium imaging device 100 is connected to the line sensor 44, the imaging control circuit 117, and the image selection circuit 122. The detection information of the alignment detection sensor 88 and the line sensor 44 is input to the image pickup control circuit 117. Although not shown, the imaging control circuit 117 is also connected to the illumination light sources 30, 40, 54, 74, and 82, and controls the light emission of these illumination light sources.

Further, the corneal endothelium imaging device 100 is provided with an image selection circuit 122 that selects images captured by the CCD 28. Further, the corneal endothelium imaging device 100 is provided with a storage device 124 as a storage means for storing images selected by the image selection circuit 122. Further, the corneal endothelium imaging device 100 is provided with a user I / F unit 127 for inputting an operation instruction by the examiner and a display unit 129 for displaying various information. The mode of the user I / F unit 127 is not limited as long as it can input operation instructions, and can be configured by, for example, various buttons, a keyboard, a mouse, a touch panel, and the like. The display unit 129 may be a touch panel display or the like as long as it is a display capable of displaying an image, characters, or the like.

Next, the flow of the corneal endothelium imaging procedure executed by the imaging control circuit 117 in the corneal endothelium imaging device 100 having such a structure is shown in FIG. 4, and will be described in order below. While the imaging procedure described below is being executed, the focal length of the imaging optical system 20 of the present embodiment is fixed at a preset constant distance.

First, in S1, the device optical system 10 is aligned (XY alignment) with respect to the eye E to be inspected in the XY direction. When performing the XY alignment, the fixation target light emitted from the fixation target light source 74 is applied to the eye E to be inspected. Then, by causing the subject to fix the fixation target light, the direction of the optical axis of the eye E to be examined is made to coincide with the direction of the optical axis O1 of the observation optical system 12. In such a state, the luminous flux irradiated from the observation light source 30 and reflected by the anterior segment of the eye E to be inspected is guided onto the CCD 28. As shown in FIG. 5, the luminous flux guided on the CCD 28 is displayed on the display screen 110 as the anterior segment of the eye E to be inspected.

Further, on the display screen 110, the rectangular frame-shaped alignment pattern 125 generated by the superimpose signal or the like is displayed superimposed on the eye E to be inspected. Then, the luminous flux emitted from the alignment light source 82 toward the eye E to be inspected is reflected by the anterior segment of the eye E to be inspected and guided onto the CCD 28, so that the display screen 110 is displayed as a point-shaped alignment light 126. Is displayed. The operator of the corneal endothelium imaging device 100 operates the operation stick 108 to drive the case 106, so that the alignment light 126 is within the frame of the alignment pattern 125, so that the position of the device optical system 10 with respect to the eye E to be inspected is set. To move.

Further, a part of the light beam emitted from the alignment light source 82 and reflected by the anterior segment of the eye E to be inspected is reflected by the half mirror 26 and guided to the alignment detection sensor 88. The alignment light source 82 irradiates an infrared light beam that is not recognized by the subject, thereby reducing the burden on the subject. When the alignment light 126 is within the frame of the alignment pattern 125, the alignment detection sensor 88 determines the position of the alignment light 126 in the X direction (vertical direction with respect to the eye E to be inspected) and the position in the Y direction (horizontal direction with respect to the eye to be inspected E). It is configured to be detectable. The X-direction position and the Y-direction position detected by the alignment detection sensor 88 are input to the image pickup control circuit 117 via the XY alignment detection circuit 118. The image pickup control circuit 117 outputs a drive signal for driving the X-axis drive mechanism 112 so that the optical axis O1 of the observation optical system 12 approaches the optical axis of the eye E to be inspected based on the input information of the position in the X direction. Based on the input Y-direction position information, a drive signal for driving the Y-axis drive mechanism 114 is output so that the optical axis O1 of the observation optical system 12 approaches the optical axis of the eye E to be inspected. By these processes, the device optical system 10 is aligned (XY alignment) with respect to the eye E to be inspected in the XY direction. As will be described later, the XY alignment is performed at an appropriate timing even during imaging. Further, in the present embodiment, the alignment light source 82 and the observation light source 30 are alternately blinked in a short time, and the alignment detection sensor 88 detects the alignment light source 82 in accordance with the lighting timing of the alignment light source 82. .. By adopting such a configuration, consideration is given so that the infrared luminous flux of the observation light source 30 does not affect the XY alignment. Since the alternating blinking of the alignment light source 82 and the observation light source 30 is performed at a speed higher than the conversion speed of the light receiving signal of the CCD 28, the alignment light source 82 is displayed on the display screen 110 to which the light receiving signal of the CCD 28 is output. And the observation light source 30 is not displayed blinking, but is displayed as if the alignment light source 82 and the observation light source 30 are continuously lit.

Next, in S2, the image pickup control circuit 117 drives the Z-axis drive mechanism 116 to move the device optical system 10 in a direction approaching the eye E to be inspected. While the device optical system 10 is being moved, the line sensor 44 receives a light beam emitted from the observation light source 54 and reflected by the cornea C of the eye E to be inspected. In the present embodiment, since the luminous flux emitted from the observation light source 54 is an infrared luminous flux, the burden on the subject is reduced.

The infrared light beam emitted from the observation light source 54 is reflected by different amounts of reflected light depending on each layer such as the corneal epithelium, the corneal stroma, and the corneal endothelium that constitute the cornea C. As schematically shown in FIG. 6, a part of the infrared light flux Lr from the observation light source 54 is reflected by the corneal epithelium e which is the interface between the air and the cornea C. Further, the infrared luminous flux Lr transmitted through the corneal epithelium e is reflected by the corneal stroma s and the corneal endothelium en. The light amount of the reflected light flux e'reflected by the corneal epithelium e is the largest, the light amount of the reflected light flux en'reflected by the corneal endothelial en is smaller than the light amount of the reflected light beam e', and the reflected light flux s reflected by the corneal parenchyma s. The amount of light of'is smaller than the amount of light of the reflected luminous flux e'and the reflected luminous flux en'. Since the anterior chamber a is filled with aqueous humor, the infrared luminous flux Lr is hardly reflected by the anterior chamber a.

Each of the reflected light fluxes reflected on each layer constituting the cornea C is detected by the line sensor 44. The light amount distribution shown in FIG. 7 shows the light amount distribution of the reflected light flux reflected by each layer constituting the cornea C and detected by the line sensor 44. In FIG. 7, the first peak 128 having the highest amount of light indicates the reflected luminous flux from the corneal epithelium e. The second peak 130, which has the next largest amount of light, indicates the reflected luminous flux from the corneal endothelium en. While performing the imaging procedure, the focal length by the imaging optical system 20 is fixed at a preset constant distance. Therefore, when the apparatus optical system 10 is moved in the Z direction by the driving means, the position of the cornea C in which the imaging optical system 20 is focused changes in the Z direction. In the present embodiment, the reflected light from the subject focused by the imaging optical system 20 is detected at a predetermined position on the line sensor 44. Then, the default position is specified in advance. Further, as shown in FIG. 7, it is necessary to specify whether the reflected light detected at the predetermined position of the line sensor 44 is the light from the corneal epithelium e or the corneal endothelium en based on the two peaks of the amount of light. Can be done. Therefore, in the image pickup control circuit 117, the part where the image pickup optical system 20 is in focus is which part of the cornea C in the Z direction based on the amount of reflected light detected at the predetermined position of the line sensor 44. Can be identified.

The image pickup control circuit 117 drives the Z-axis drive mechanism 116 by the drive signal, and from the position where the image pickup optical system 20 specified based on the detection by the line sensor 44 is in focus on the corneal epithelium e, the human eye The apparatus optical system 10 is moved in the direction approaching the cornea C by a set distance D1 set in consideration of the physiological variation in the corneal thickness. The set distance is set so that the focusing position by the imaging optical system 20 moves from the corneal endothelium to the anterior side in the Z direction. Here, the focusing position is a position in the Z direction in which the subject imaged by the imaging optical system 20 is in focus. That is, when viewed from the imaging optical system 20, the distance to the subject in focus does not change, but when the imaging optical system 20 moves in the Z direction by moving the case 106 in the Z direction, it is arranged in front of the case 106. The position in the Z direction in which the subject is in focus within the eye E to be inspected may fluctuate.

In this embodiment, the set distance is 1250 μm. The set distance D1 may be appropriately set within the range of, for example, 1000 to 1500 μm. By moving the device optical system 10 in the direction (forward direction) approaching the cornea C by the set distance D1, the focusing position by the imaging optical system 20 is on the back side (forward direction) in the Z direction from the corneal endothelium en. Moved to the side). The position where the focusing position by the imaging optical system 20 is moved by the set distance D1 from the position where the focus position is on the corneal epithelium e is called an inversion position.

Next, after the device optical system 10 is moved to the inverted position, in S3, the image pickup control circuit 117 drives the Z-axis drive mechanism 116 in a direction (rear direction) isolated from the eye E to be inspected. The device optical system 10 is moved. The moving speed of the device optical system 10 from the start of movement from the inverted position to the end of imaging described later is configured to be variable. FIG. 8 shows a change in the moving speed of the device optical system 10 in isolation movement.

The isolation movement of the device optical system 10 is started from the inverted position (P1 in FIG. 8). The moving speed in the isolation movement is, for example, 500 μm to 3000 μm / sec, more preferably around 2000 μm / sec. When the imaging optical system 20 reaches a position closer to the corneal C side (P2 in FIG. 8) by a set distance D2 (see FIG. 7) from the position where the imaging optical system 20 is focused on the corneal endothelium en after the movement by S3 is started. As S4, the observation light source 30 is turned off and the imaging light source 40 starts emitting light. The position where S4 starts is the set distance D2 (see FIG. 7) from the reference position based on the position where the light amount distribution becomes a predetermined threshold value slightly smaller than the second peak 130 (the position closer to the cornea C). It may be located only closer to the side of the cornea C. The value of the distance adopted as the set distance D2 is preferably a large value so that the corneal endothelium can be reliably imaged in consideration of the detection accuracy of the line sensor 44, the positional deviation of the eye E to be inspected, and the like. When the value of D2 becomes large, the light emitting time of the imaging light source 40 becomes long, which increases the burden on the subject. Therefore, a value within the range of 200 to 500 μm is preferably adopted as the value of the set distance D2. Further, the image pickup light source 40 blinks and emits light at predetermined short intervals from S4 to S8 described later. At the timing when the image pickup light source 40 is turned off, the XY alignment in S1 described above is performed.

The position where the reflected luminous flux was detected by the CCD 28 from a position 30 μm away from the corneal endothelium en on the anterior chamber a side while moving the device optical system 10 in a direction of isolating it from the eye E to be inspected at a relatively high speed VF ( From the time when P3) is reached in FIG. 8, deceleration of the apparatus optical system 10 is started as S5. For the detection of the reflected luminous flux in S5, for example, the captured image 132 shown in FIG. 9 is used. In FIG. 9, the anterior chamber corresponding portion 134 is imaged from the left end of the paper surface to the front of the right end of the paper surface, and the corneal endothelium corresponding portion 136 is imaged at the right end of the paper surface. Then, as shown in FIG. 10, one or more (five in this embodiment) appropriate horizontal lines l1 to l5 are drawn with respect to the captured image 132 as shown in FIG. 9, and the horizontal lines l1? From the brightness values of the pixels on l5, it is determined that the reflected light beam from a position 30 μm away from the corneal endothelium en on the anterior chamber a side is detected based on the pixels having the brightness value equal to or higher than the set value. In the present embodiment, the brightness value of each pixel in the captured image 132 is defined and detected in the range of 255 gradations (the brightness value 1 is the darkest and the brightness value 255 is the brightest), and the luminous flux reflected by the corneal endothelium en is detected. In order to take into account the unevenness of the image, the luminance value of each pixel on the five horizontal lines l1 to l5 on the captured image 132 is detected. Then, the number of pixels whose luminance value becomes 25 to 255 in each pixel on the horizontal line l1 to l5 is counted. The brightness values 25 to 255 are such that the reflected light that is clearly visible can be visually recognized. Then, when the average value of the brightness values in the pixels counted on the horizon l1 to l5 matches the amount of light of the reflected luminous flux reflected from the portion at a position 30 μm away from the corneal endothelium en on the side of the anterior chamber a, the light intensity thereof. The position where the captured image 132 is captured is defined as the deceleration start point (P3 in FIG. 8). The position of the corneal endothelium en, which is a reference for determining the position of the deceleration start point, is specified based on the position of the second peak 130 in the light amount distribution. The maximum luminance value of the pixels counted on the horizontal lines l1 to l5 may be used as the numerical value of the pixel to be compared with the amount of light of the reflected luminous flux.

Then, the deceleration operation in S5 is started, and in S6, continuous imaging in the vicinity of the corneal endothelium is started by the CCD28. The continuous imaging is performed by inputting the captured images captured by the CCD 28 into the image selection circuit 122 at preset time intervals (for example, 1/30 second). Therefore, a plurality of captured images captured at a plurality of positions having different distances from the eye E to be inspected are input to the image selection circuit 122. The input plurality of captured images are sent to the storage device 124 after performing image selection described later by the image selection circuit 122. The storage device 124 stores the captured image sent from the image selection circuit 122.

Next, from the time when the deceleration movement is started in S5 and the slow / slow speed VS described later is reached (P4 in FIG. 8), the apparatus optical system 10 is isolated and moved while maintaining the slow / slow speed VS. Then, continuous imaging and image selection in S6 are performed over a preset distance range (P4 to P6 in FIG. 8) from the time when the slow / slow speed VS is entered. The range of P4 to P6 also includes the position where the imaging optical system 20 focuses on the corneal endothelium en (P5 in FIG. 8).

FIG. 11 shows an image taken in the vicinity of the position where the imaging optical system 20 focuses on the corneal endothelium en. In FIG. 11, the anterior chamber corresponding portion 134 is imaged at the left end of the paper surface, the corneal endothelium corresponding portion 136 is imaged near the center of the paper surface, and the corneal stroma corresponding portion 138 is imaged at the right end of the paper surface. It has been imaged. In the captured image 139 shown in FIG. 11, the corneal endothelium is imaged in a wider range than in the captured image 132 shown in FIG.

The slow / slow speed VS at which deceleration in S5 is completed is appropriately determined in consideration of the distance range (P4 to P6 in FIG. 8) for continuous imaging while moving at a low speed, the image capture time by the CCD 28, the number of images to be imaged, and the like. It is determined. For example, as a range for moving at a low speed to perform continuous imaging, a range of 200 μm or more can be preferably adopted in consideration of fine movement of the eye E to be inspected. Assuming that the image capture time of the CCD28 is 1/30 second per image and the continuous imaging range is 200 μm, 600 μm / sec for 10 images and 300 μm / sec for 20 images, 30 It is set to 200 μm / sec for image pickup, 150 μm / sec for 40 images, and 120 μm / sec for 50 images. Therefore, in order to reliably image the corneal endothelium by continuous imaging, a speed of 100 to 300 μm / sec is preferably adopted. As described above, in the present embodiment, the number of images taken by continuous imaging is adjusted by changing the moving speed of the apparatus optical system 10 while keeping the image acquisition time by the CCD 28 constant. In another embodiment, the number of images to be imaged is adjusted by keeping the moving speed of the apparatus optical system 10 constant and changing the interval of the image capture time by the CCD 28 based on the detection of the reflected light from the corneal endothelium in S5. Alternatively, both the moving speed of the apparatus optical system 10 and the image acquisition time by the CCD 28 may be controlled.

Then, at the time when the movement by the slow speed VS and the start position of continuous imaging (P4 in FIG. 8) are isolated and moved by a set distance range (for example, 200 μm in the present embodiment) (P6 in FIG. 8). , S7, the acceleration is started and the apparatus optical system 10 is accelerated to a relatively high speed VF before the deceleration is started. As a criterion for determining the acceleration start position, not only the moving distance but also the reflected luminous flux by the corneal endothelial en is no longer detected according to the same method as the procedure for detecting the reflected luminous flux by the corneal endothelial en in S5 described above. Acceleration may be started from a time point, acceleration may be started when a preset set time has elapsed from the start of continuous imaging, or they may be used in an appropriate combination.

When the device optical system 10 is accelerated and reaches a relatively high speed VF before the deceleration is started (P7 in FIG. 8), in S8, for example, in consideration of fine movement of the eye E to be inspected in the Z direction, for example. After the device optical system 10 has been isolated and moved by a distance of about 100 μm, the isolation movement is stopped, the imaging light source 40 is turned off, and imaging is completed (P8 in FIG. 8).

Next, in S6, an image selection performed after a plurality of captured images captured by continuous imaging are input to the image selection circuit 122 will be described. The image selection circuit 122 includes a coordinate correspondence unit 122a and a ranking setting unit 122b as functions for selecting images (shown in FIG. 3). In continuous imaging, each time the captured image is captured by the CCD 28, the detection information detected by the alignment detection sensor 88 and the line sensor 44 for the captured image is transmitted via the XY alignment detection circuit 118 and the Z alignment detection circuit 120. , Is input to the image selection circuit 122. The detection information detected by the alignment detection sensor 88 and the line sensor 44 for the captured image is coordinate information indicating the imaging position (that is, the position of the case 106) when the captured image is captured. The coordinate information is information defined by an X-direction position, a Y-direction position, and a Z-direction position, and in the description of the present specification, (X, Y, Z) = (Xn, Yn, Zn). (Xn, Yn, Zn each indicate an arbitrary value). The imaging position when the optical axis O1 of the observation optical system 12 coincides with the optical axis of the eye E to be inspected is (X, Y, Z) = (0,0, Zn). Then, the position where the imaging optical system 20 focuses on the corneal endothelium en is set to (X, Y, Z) = (0,0,0). The position corresponding to 0 in the Z direction position is specified based on the detection of the second peak 130 by the line sensor 44.

The coordinate correspondence unit 122a associates coordinate information indicating an imaging position with each of a plurality of captured images captured by the CCD 28 at a plurality of positions having different distances with respect to the eye E to be inspected. When a plurality of captured images are acquired by the imaging procedure shown in FIG. 4, the coordinate corresponding unit 122a associates the imaging position when each of the plurality of captured images is captured with each of the plurality of captured images. The captured image associated with the coordinate information is recorded in a RAM (not shown) of the image selection circuit 122. The number of captured images to be captured is not limited, but here, it is assumed that 50 captured images are obtained. The 50 captured images include an image in which the corneal endothelium is hardly imaged as shown in FIG. 9 and an image in which the corneal endothelium en is imaged in the center of the imaging region as shown in FIG.

The ranking setting unit 122b sets the imaging position in the state where the imaging optical system is in focus on the corneal endothelium and the imaging position where the captured image is captured for each of the plurality of captured images captured during the preset imaging period. The priority is set by using the distance of at least one ordering criterion. In the present embodiment, the period during which the imaging procedure shown in FIG. 4 is performed once is the imaging period, and the priority order is set for the plurality of captured images captured by the one imaging procedure based on the respective imaging positions. To. Further, in the present embodiment, the image selection circuit 122 has a function of displaying a predetermined number of captured images having a higher priority from the captured images for which the priority has been set on the display unit 129.

Specifically, the ranking setting unit 122b sets the imaging position in a state where the imaging optical system 20 is in focus on the corneal endothelium and a plurality of imaging images of the plurality of captured images recorded in the RAM by the function of the coordinate corresponding unit 122a. The distance between each imaging position of the image is specified. In the present embodiment, the position where the imaging optical system 20 focuses on the corneal endothelium en is (X, Y, Z) = (0,0,0). Therefore, when the coordinate information of the captured image is (X, Y, Z) = (Xa, Ya, Za), the imaging optical system 20 focuses on the corneal endothelium based on the coordinate information associated with each coordinate. The distance L between the imaging position and the imaging positions of each of the plurality of captured images in the state of being captured can be calculated by the following formula.
L = (Xa ² + Ya ² + Za ² ) ^1/2

When the distance L is obtained for each of the plurality of captured images recorded in the RAM, the ranking setting unit 122b is in the order of the shortest distance L from the imaging position in the state where the imaging optical system 20 is in focus on the corneal endothelium en. , Considers high priority and saves the default number of images with high priority. Here, an example in which the default number is 16 will be described. In this case, the ranking setting unit 122b extracts 16 captured images in ascending order from the plurality of captured images recorded in the RAM, and stores them in the storage device 124 in a state where the coordinate information is associated with each other. In the present embodiment, the captured image to which the coordinate information is associated is stored in the storage device 124 provided in the corneal endothelium imaging device 100, but instead of the storage device 124, the corneal endothelium imaging device via a network. It may be stored in a database connected to 100. At this time, the ranking setting unit 122b stores the captured image in the storage device 124 in association with the date and time when the captured image is captured. The default number may be set arbitrarily, and may be, for example, one.

In the present embodiment, when a plurality of captured images are stored in the storage device 124, the image selection circuit 122 reads out the stored 16 captured images and controls the display unit 129 to prioritize these captured images. Display according to. The display mode may be various, and for example, 8 out of 16 sheets are displayed in a list on the display unit 129 by writing numerical values indicating the priority order in accordance with the priority order. Further, the ranking setting unit 122b erases the display of the eight captured images displayed in the list in response to the operation instruction to the user I / F unit 127, and the remaining eight images (priority is 9th to 16th). The captured images) are displayed in a list in the same manner in order of priority.

FIG. 12 is a diagram showing an example of the above list display. In FIG. 12, images Ie captured by the observation optical system 12 of the eye E to be inspected are displayed in the upper right of the figure, and images I _{1 to} I _{8 of the corneal endothelium en are listed on the left and lower sides of the image.} There is. In the present embodiment, _{numerical values indicating the priority order of the captured images I 1 to} I ₈ are shown at the upper left corner of the captured images. That is, _{the priority of the captured images I 1 to} I ₈ is in the order of 1 to 8. When the "Next Page" button displayed on the screen shown in FIG. 12 is touched, the display of the captured images I _{1 to} I ₈ is deleted, and the captured images having the 9th to 16th priority are displayed instead. Will be done.

In the example shown in FIG. 12, the captured image I ₀ displayed at the left end is an enlarged image of an image selected from the eight captured images displayed in the list. That is, when _{any of the captured images I 1 to} I ₈ is touched, the image selection circuit 122 acquires the touched captured image from the storage device 124 and controls the display unit 129 to display the enlarged image. With the above configuration, the examiner can select a desired image from the captured images displayed in the list, enlarge the display, and use it for diagnosis and the like. Further, the list display is extracted in ascending order of the distance L between the imaging position in the state where the imaging optical system 20 is in focus on the corneal endothelium and the imaging position of each of the plurality of captured images. Therefore, it is possible to easily and early select an image captured in a state where the imaging optical system 20 is in focus on the corneal endothelium en.

In the present embodiment, when the examiner wants to compare the state of the corneal endothelium in different imaging periods, the image selection circuit 122 specifies the imaging period to be compared by accepting the examiner's operation on the user I / F unit 127. Accept. The image selection circuit 122 refers to the storage device 124, and extracts each of the captured images having the highest priority from the captured images captured in each of the designated imaging periods.

FIG. 13 shows an example in which the captured images captured in the captured image having the highest priority among the captured images captured in each of the different imaging periods are displayed side by side on the display unit 129. In the example shown in FIG. 13, analysis is performed based on each displayed captured image. That is, the image selection circuit 122 detects the cells of the corneal endothelium en by performing predetermined image processing on each displayed image. Then, the control unit calculates a predetermined test value (for example, cell density (denoted as CD (Cell Density) in FIG. 13)) and displays it on the display unit 129.

With the above configuration, among the captured images captured in different imaging periods, the captured images captured at the closest imaging position to the imaging position in the state of focusing on the corneal endothelium en can be compared with each other. Thus, for example, in order to compare the corneal endothelium before and after surgery, by designating the imaging period when the imaging procedure is performed before surgery and the imaging period when the imaging procedure is performed after surgery, for example. The state of the corneal endothelium before and after surgery can be easily compared. In other words, it is possible to easily compare the state of the corneal endothelium between the captured images captured in different imaging periods.

In the configuration described above, priority is set for each of the plurality of captured images captured in different imaging periods. Therefore, when the captured image having the highest priority is selected from each of the plurality of captured images, each of the selected captured images is an captured image having a high degree of focus on the corneal endothelium en, and There is a high possibility that a captured image associated with similar coordinate information will be selected. Therefore, it is possible to improve the possibility that an image in which the corneal endothelium en at the same position is captured can be selected from each of the plurality of captured images captured in different imaging periods. It is also possible to increase the possibility of selecting an image having a high degree of focus on the corneal endothelium en.

(2) Configuration of the corneal endothelium imaging device of the second embodiment:
FIG. 14 is an explanatory diagram for explaining the configuration of the corneal endothelium imaging device 100a of the second embodiment. The corneal endothelium imaging device 100a has the same configuration as the corneal endothelium imaging device 100 of the first embodiment, except that the image selection circuit 122 includes a similar extraction unit 122c and the processing in the ranking setting unit 122b is different.

In the second embodiment as well, as in the first embodiment, after the coordinate information is associated with the 50 captured images input to the image selection circuit 122 during one imaging period, the priority is given. An example will be described in which the top 16 captured images are sent to the storage device 124 and stored. In this embodiment, it is assumed that imaging by the imaging procedure shown in FIG. 4 is performed twice or more. Here, of the two imaging periods, the imaging period in which the imaging is performed first is referred to as the first imaging period, and the imaging period in which the imaging is performed later is referred to as the second imaging period. When a plurality of captured images are acquired in each imaging period, the coordinate corresponding unit 122a associates the imaging position when each of the plurality of captured images is captured with each of the plurality of captured images and records them in the RAM. ..

The ranking setting unit 122b extracts a predetermined number (16 images in this case) of captured images in ascending order of the distance between the imaging position in the state where the imaging optical system is in focus on the corneal endothelium and the imaging position where the captured image is captured. The coordinate information is associated and stored in the storage device 124. As described in the first embodiment, the default number may be set arbitrarily, and may be, for example, one. However, in the second embodiment, the captured image is extracted by the ranking setting unit 122b during the first imaging period, but in the second and subsequent imaging periods, the captured image is extracted by the ranking setting unit 122b. Instead, a similar captured image is extracted by the similar extraction unit 122c.

The similar extraction unit 122c provides coordinate information from each of the first captured image, which is an captured image captured in the first imaging period, and the second captured image, which is a plurality of captured images captured in the second imaging period. Is used as a similar criterion, and similar captured images are extracted. In the present embodiment, the coordinate information serving as a similar determination criterion is the coordinate information CI associated with one captured image included in the first captured image. In the present embodiment, the first imaging period is the first imaging period, and the imaging period after the first imaging period is the second imaging period.

The similar extraction unit 122c accepts the selection of one captured image included in the first captured image based on the operation instruction input by the examiner via the user I / F unit 127. The selection of the captured image may be performed by various screens. For example, there is a configuration in which the similar extraction unit 122c displays a screen as shown in FIG. 12 based on the first captured image captured in the first imaging period and stored in the storage device 124 by the ranking setting unit 122b. Examples of the image to be selected by the examiner include an image captured in focus on the corneal endothelium, an image with a large area showing the corneal endothelium, and a site where the state change before and after surgery is to be observed. Examples thereof include an image taken before the operation and an image taken after the operation in a state of being in focus. When the examiner selects the captured image, the similarity extraction unit 122c refers to the storage device 124 and acquires the coordinate information CI associated with the selected captured image.

On the other hand, the imaging of the plurality of captured images in the second imaging period is executed at an arbitrary timing after the first imaging period. When a plurality of captured images are acquired, the coordinate corresponding unit 122a associates the imaging positions when each of the plurality of captured images is captured with each of the plurality of captured images and records them in the RAM.

The similar extraction unit 122c extracts an captured image whose associated coordinate information is close to the above-mentioned coordinate information CI from, for example, 50 captured images recorded in the RAM in this way. That is, in the process shown in FIG. 4, the imaging position in the state where the imaging optical system is in focus on the corneal endothelium is set to (X, Y, Z) = (0, 0, 0). Therefore, even if the captured images are captured in different imaging periods, it can be considered that the captured images are similar as the coordinate information is closer.

Therefore, the similarity extraction unit 122c refers to the coordinate information associated with the captured image recorded in the RAM, and acquires the distance Lm of both coordinates based on the coordinate information and the above-mentioned coordinate information CI.

Specifically, the similarity extraction unit 122c has, with respect to a plurality of captured images stored in the storage device 124 in a state where the coordinate information is associated with the image pickup position indicated by the coordinate information CI serving as a similar determination criterion, and a second image. 2 Specify the distance between each of the captured images and the captured position. The coordinate information CI that serves as a similar determination criterion is expressed as (X, Y, Z) = (X1, Y1, Z1), and the coordinate information associated with the captured image included in the second captured image is expressed as (X, Y, Z). When expressing Y, Z) = (X2, Y2, Z2), the distance Lm from the captured image, which is a determination standard, can be calculated by the following formula.
Lm = {(X1-X2) ² + (Y1-Y2) ² + (Y1-Y2) ² } ^1/2

The similar extraction unit 122c acquires the distance Lm for each of the second captured images captured in the second imaging period, and extracts the second captured images satisfying the acquisition criteria in ascending order of the distance Lm. The acquisition standard may be a standard set in advance for acquiring similar captured images, for example, the number of captured images to be acquired (one or more), the maximum value of the distance Lm, and the like. Can be mentioned. When the captured image is extracted from the second captured image in this way, the similar extraction unit 122c associates the extracted captured image with the coordinate information and stores it in the storage device 124.

In the present embodiment, a process for selecting an captured image to be analyzed is performed from the second captured image stored in the storage device 124. That is, the image selection circuit 122 reads out the second captured image stored in the storage device 124, controls the display unit 129, and displays these captured images in order of priority. As the priority order, for example, the order in which the priority is considered to be higher in ascending order of the distance Lm can be mentioned. As a result of this processing, for example, the second captured image is listed as shown in FIG. As described above, in the second embodiment, a plurality of similar captured images are extracted from the second captured image with respect to one captured image included in the first captured image, and then the image is combined into one captured image. A plurality of similar captured images are ranked in ascending order of distance Lm to the imaging position indicated by the associated coordinate information. According to such a form, a plurality of captured images similar to the captured image selected by the examiner can be extracted from each of the captured images captured in different imaging periods, and each of the plurality of captured images can be extracted. By confirming the order set in, it is possible to identify the captured image having the shortest distance to the imaging position of one captured image as a determination criterion among the plurality of captured images.

The image selection circuit 122 accepts selection by the examiner in response to an operation instruction to the user I / F unit 127. When the selection is accepted, the selected captured image becomes the second captured image to be analyzed. Then, the image selection circuit 122 analyzes the second captured image to be analyzed and the captured image associated with the coordinate information CI, and causes the display unit 129 to display the analysis result. Examples of the display include the example shown in FIG.

With the above configuration, it becomes possible to easily compare the state of the corneal endothelium between the captured images captured in different imaging periods. Further, according to the present embodiment, a second captured image similar to the captured image associated with the coordinate information CI is displayed on the display unit 129 and selected by the examiner. Therefore, even if the captured image captured in a state where the imaging optical system 20 is in focus on the corneal endothelium is a blurred image due to a shift due to fixation tremor of the eye to be examined or the like, the examiner can image the image. Instead, an image taken by the examiner himself / herself can be selected as being imaged at a position close to the state in which the optical system 20 is focused on the corneal endothelium en. Then, based on the selected captured image, it is possible to perform an analysis in which the coordinate information CI is compared with the associated captured image. Therefore, the corneal endothelium before and after surgery can be easily compared.

According to the configuration described above, the captured image as the determination criterion for extraction is arbitrarily selected by the examiner via the user I / F unit 127. Then, from each of the captured images captured in different imaging periods, an captured image similar to the captured image selected by the examiner can be extracted. Therefore, the image captured at the position desired by the examiner can be provided to the examiner regardless of the distance from the position where the imaging optical system 20 is in focus on the corneal endothelium en.

The corneal endothelial imaging apparatus described in the second embodiment receives an illumination optical system including an illumination light source that irradiates a slit light beam obliquely to the eye to be inspected, and a light beam reflected from the corneum of the eye to be inspected by the slit light beam. An imaging optical system including an imaging element that captures a corneal image, a distance changing unit that integrates the illumination optical system and the imaging optical system to change the distance to the eye to be inspected, and a plurality of positions having different distances to the eye to be inspected. In, a coordinate corresponding unit that associates coordinate information indicating an imaging position with each of the plurality of captured images captured by the imaging element, and a first captured image and a first captured image that are captured images during the first imaging period. It is provided with a similar extraction unit that extracts similar captured images from each of the second captured images, which are a plurality of captured images captured during the two imaging periods, using at least the coordinate information as a similar determination criterion.

Further, in the second embodiment, the coordinate information serving as the determination criterion is the coordinate information associated with one captured image included in the first captured image.

Further, in the second embodiment, the similar extraction unit extracts a plurality of similar captured images from the second captured image with respect to one captured image included in the first captured image. , The plurality of similar captured images are ranked in ascending order of the distance to the imaging position indicated by the coordinate information associated with the one captured image.

(3) Configuration of the corneal endothelium imaging device of the third embodiment:
The corneal endothelium imaging device 100b of the third embodiment can be realized with the same configuration as in FIG. However, the processing of the ranking setting unit 122b is different from that of the first embodiment. Also in the third embodiment, as in the first embodiment, the coordinate information is associated with the 50 captured images input to the image selection circuit 122 during one imaging period, and then the priority is given. An example will be described in which the top 16 captured images are sent to the storage device 124 and stored. Also in this embodiment, it is assumed that the imaging by the imaging procedure shown in FIG. 4 is performed twice or more. Here, of the two imaging periods, the imaging period in which the imaging is performed first is referred to as the first imaging period, and the imaging period in which the imaging is performed later is referred to as the second imaging period. When a plurality of captured images are acquired in each imaging period, the coordinate corresponding unit 122a associates the imaging position when each of the plurality of captured images is captured with each of the plurality of captured images and records them in the RAM. ..

The process executed by the ranking setting unit 122b in the first imaging period is the same as that in the second embodiment. Therefore, when the first imaging period ends, the coordinate information is associated with the predetermined number (16 images in this case) of the captured images and stored in the storage device 124. As described in the first embodiment, the default number may be set arbitrarily, and may be, for example, one. Further, the imaging position for capturing the captured image in the second imaging period is determined based on the coordinate information of the captured image selected from the plurality of captured images captured during the first imaging period.

Specifically, the rank setting unit 122b is included in the first captured image which is the captured image captured in the first imaging period based on the operation instruction input by the examiner via the user I / F unit 127. Accepts the selection of one captured image. The selection of the captured image may be performed by various screens. For example, it is possible to accept the selection on the screen as shown in FIG. The selection criteria may be the same criteria as in the second embodiment. When the examiner selects the captured image, the similarity extraction unit 122c refers to the storage device 124 and acquires the coordinate information CI associated with the selected captured image.

When the coordinate information CI is acquired, the rank setting unit 122b instructs the image pickup control circuit 117 of a plurality of image pickup positions changed in the Z direction for each predetermined step centering on the coordinate information CI. In this case, the imaging control circuit 117 acquires the captured image by the same processing as in FIG. 4, but here, the captured image may be captured after the deceleration in step S5, and a predetermined number of imaging positions centered on the coordinate information CI. The image is taken at. The default number may be determined in advance. For example, when the default number is 16, the imaging position is the same as the coordinate information CI, and the imaging positions are 7 locations that are moved by a predetermined interval in the -Z direction with respect to the coordinate information CI. Imaging is performed at eight imaging positions that are moved by a predetermined interval in the + Z direction.

When a predetermined number of captured images are acquired, the ranking setting unit 122b associates the captured captured images with coordinate information and stores them in the storage device 124. The captured image stored in the storage device 124 in this way is referred to as a second captured image. Also in this embodiment, a process for selecting an captured image to be analyzed is performed from the second captured image stored in the storage device 124. That is, the image selection circuit 122 reads out the second captured image stored in the storage device 124, controls the display unit 129, and displays these captured images in order of priority. As the priority order, for example, the order in which the coordinate information associated with the second captured image is considered to have the highest priority in the order of being closer to the coordinate information CI of the captured image selected from the first captured image can be mentioned. As a result of this processing, for example, the second captured image is listed as shown in FIG.

The image selection circuit 122 accepts selection by the examiner in response to an operation instruction to the user I / F unit 127. When the selection is accepted, the selected captured image becomes the second captured image to be analyzed. Then, the image selection circuit 122 analyzes the second captured image to be analyzed and the captured image associated with the coordinate information CI, and causes the display unit 129 to display the analysis result. Examples of the display include the example shown in FIG.

According to the configuration described above, the captured image associated with the coordinate information as the reference of the position to be imaged by the image sensor is arbitrarily selected by the examiner via the user I / F unit 127. Then, the image pickup by the image pickup device can be executed at the image pickup position indicated by the coordinate information associated with the selected captured image. Therefore, it is possible to provide the examiner with an image captured at a position where the examiner wants to observe again.

The corneal endothelial imaging apparatus described in the third embodiment receives an illumination optical system including an illumination light source that obliquely irradiates the eye to be inspected with a slit light beam and a light beam reflected from the corneum of the eye to be inspected by the slit light beam. An imaging optical system including an imaging element that captures a corneal image, a distance changing unit that integrates the illumination optical system and the imaging optical system to change the distance to the eye to be inspected, and a plurality of positions having different distances to the eye to be inspected. The imaging optical system includes a coordinate corresponding unit that associates coordinate information indicating an imaging position with each of the plurality of captured images captured by the imaging element, and the imaging optical system captures images during a preset imaging period. The corneal image is imaged at the imaging position indicated by the coordinate information associated with one target image among the captured images.

(4) Other embodiments:
In the first embodiment, in the image selection circuit 122, the priorities of the plurality of captured images are set based on the distance between the position where the imaging optical system 20 focuses on the corneal endothelium and the imaging position as an ordering reference. , The embodiment of the present invention is not limited to this. For example, in the image selection circuit 122, a plurality of captured images may be selected as follows. That is, first of all, with respect to the distance from the position where the imaging optical system 20 focuses on the corneal endothelium en, the positions in the X direction and the Y direction of the plurality of captured images were imaged within a certain distance range. Extract the captured image. Then, the priority may be set by ranking the extracted captured images in the order of closest positions in the Z direction with respect to the distance from the position where the imaging optical system 20 focuses on the corneal endothelium en. For example, when the coordinate information of the captured image is (X, Y, Z) = (Xa, Ya, Za), the imaging optical system 20 based on the X-direction position and the Y-direction position is aligned with the corneal endothelium en. The distance Lxy from the point of focus is expressed as ^{Lxy = (Xa 2} + Ya ² ) ^1/2. Then, the captured image in which the distance Lxy is within a certain distance range is extracted from the plurality of captured images. Further, the distance Lz from the position where the imaging optical system 20 focuses on the corneal endothelium en with respect to the position in the Z direction is expressed as Lz = Za. By ranking the extracted captured images in ascending order of distance Lz, the priority is set.

In the second embodiment, the similar extraction unit 122c extracts a similar captured image using the coordinate information as a similar determination criterion, but the embodiment of the present invention is not limited to this. For example, in addition to the coordinate information, the similarity of images between captured images may be used as a criterion for similarity. The degree of similarity of images referred to here is the similarity with the characteristics of one captured image of interest, and SAD (Sum of Absolute Difference), SSD, which is used for so-called template matching as a measure of similarity. (Sum of Squared Difference), NCC (Normalized Cross-Correlation), ZNCC (Zero-mean Normalized Cross-Correlation) may be used. With respect to the values that can be used for the above-mentioned scale, it can be determined that the closer the value is shown by one captured image to be the target, the higher the similarity of the images. In this way, by using the coordinate information and the similarity of the images as the similar determination criteria, the accuracy of extracting similar captured images can be improved.

Further, in the first embodiment, coordinate information is used as a ranking reference in a plurality of captured images, but the embodiment of the present invention is not limited to this. For example, as the ordering reference, in addition to the coordinate information, the luminance information which is the luminance value of each pixel constituting the captured image may be used. In FIG. 15, as an example of the luminance information, the luminance information of the pixel on one horizontal line in the image captured by the CCD 28 is shown. Further, as shown in FIG. 16, the pixels on the horizon are assigned position numbers (X1, X2, X3 ... Xn ...) Indicating the number of pixels from the left in the captured image. Suppose you are. Hereinafter, three elements that can be used as the ordering reference from the luminance information shown in FIG. 15 will be described. The three elements described below are also described in paragraphs 0074 to 0088 of Japanese Patent No. 4914176.

As the first element, when the images are ordered, is there a pixel on the captured image having a brightness value equal to or higher than a preset threshold value La (shown in FIG. 15) based on the brightness information? May be used as one criterion. The threshold value is set to be lower than the brightness value of the pixel in which the corneal endothelium en is imaged and higher than the brightness value of the pixel in which the corneal stroma s is imaged. A captured image in which pixels having a brightness value equal to or higher than the threshold value are present has a higher order of images than a captured image in which the pixels do not exist. By using such a criterion, it is possible to select an captured image in which the corneal endothelium en is likely to be imaged.

As the second element, when the image is ordered, the position on the captured image where the boundary between the region where the pixel having the brightness value equal to or higher than the above threshold exists and the region where the pixel does not exist is located is 1 It may be used as one standard. Specifically, it is as follows. That is, in FIG. 15, the boundary corresponds to the pixel positions Xa and Xb. The pixel positions Xa and Xb are positions where the luminance value becomes the threshold value La. The pixel position Xa is considered to be the boundary between the corneal endothelium en and the anterior chamber a, and the pixel position Xb is considered to be the boundary between the corneal endothelium en and the stroma s. Then, whether or not the pixel positions Xa and Xb are located within the preset ranges Rl and Rr on the image may be used as the criteria for image selection. The region Rl is located on the left side of the image, and the region Rr is a region located on the right side of the image. When the pixel positions Xa and Xb are present, the order of the captured image is high, and when the pixel positions Xa and Xb are located within the range of the regions Rl and Rr, the order of the captured image is further high. By using such a criterion, it is possible to select an captured image in which the corneal endothelial en is likely to be captured within the range of regions Rl and Rr (closer to the center of the captured image).

As a third element, when the images are ordered, the average value of the sum of the brightness value differences of adjacent pixels may be used as one reference based on the brightness information. The average value is calculated as follows. That is, the luminance information shown in FIG. 15 is acquired for a plurality of horizontal lines, and Σ | X _n −X _n-1 | is applied to each of the horizontal lines to apply the luminance values of pixels adjacent to each other in the horizontal direction. After calculating the sum of the absolute values of the differences, it is calculated by calculating the average of the sum of each of the horizontal lines. The larger the value of the obtained average value, the wider the corneal endothelium is captured in the captured image. Therefore, it is considered that the captured image having a higher average value is the target to be selected. In other words, the higher the average value, the higher the order of the captured images. By using such a criterion, it is possible to select an captured image in which the corneal endothelium en is likely to be captured in a wide range.

The luminance information including the above-mentioned three elements can be used as follows when the images are ordered. That is, after extracting the captured image captured at a position where the distance L from the position where the imaging optical system 20 focuses on the corneal endothelium is within a certain distance, the luminance information is obtained with respect to the extracted captured image. The priority may be set based on. Further, when setting the priority order, the distance L from the position and the luminance information may be referred to, respectively. At this time, the score LS associated so that the smaller the distance L from the position, the higher the score, and the higher the possibility that the corneal endothelium en is imaged, the higher the possibility that the three elements shown in the brightness information are imaged. The higher the possibility that the corneal endothelium en is imaged closer to the center of the captured image, and the higher the possibility that the corneal endothelium en is captured in a wider range, the higher the score associated with the score BS. The total score added may be referred to when setting the priority. Further, the total score is expressed as (score LS × α) + (score BS × β), and the degree of contribution of the score LS and the score BS to the total score is determined by varying the values of the coefficients α and β. You may adjust. Such luminance information may be used as a determination criterion in addition to the coordinate information which was a similar determination criterion in the second embodiment. That is, the determination criterion may include the luminance information in each of the first captured image and the second captured image.

Further, the method of setting the order of images based on the coordinate information as in the present invention is also applicable as a program or a method. In addition, some of them are software and some of them are hardware, which can be changed as appropriate. Further, the invention is also established as a recording medium for a program that controls an apparatus. Of course, the recording medium of the software may be a magnetic recording medium or a semiconductor memory, and any recording medium to be developed in the future can be considered in exactly the same way.

10 ... device optical system, 12 ... observation optical system, 14 ... imaging illumination optical system, 16 ... position detection optical system, 18 ... position detection illumination optical system, 20 ... imaging optical system, 44 ... line sensor, 88 ... alignment detection sensor , 100 ... Corneal endothelial imaging device, 112 ... X-axis drive mechanism, 114 ... Y-axis drive mechanism, 116 ... Z-axis drive mechanism, 117 ... Imaging control circuit, 118 ... XY alignment detection circuit, 120 ... Z alignment detection circuit, 122 ... image selection circuit, 122a ... coordinate correspondence unit, 122b ... rank setting unit, 124 ... storage device, 124a ... similar extraction unit

Claims (3)

An illumination optical system including an illumination light source that irradiates the slit luminous flux diagonally to the eye to be inspected.
An imaging optical system including an imaging element that receives a reflected luminous flux from the cornea of the eye to be inspected by the slit luminous flux and captures a corneal image.
A distance changing unit that integrally changes the illumination optical system and the imaging optical system to change the distance to the eye to be inspected.
A coordinate-corresponding unit that associates coordinate information indicating an imaging position with each of a plurality of captured images captured by the image sensor at a plurality of positions having different distances from the eye to be inspected.
For each of the plurality of captured images captured during the preset imaging period, the imaging position and the captured image in a state where the imaging optical system is in focus on the corneal endothelium were imaged based on the coordinate information. A ranking setting unit that sets a priority using the distance from the imaging position as at least one ranking reference, and a ranking setting unit.
A corneal endothelium imaging device. In addition to the distance, the ordering criterion includes luminance information in the captured image.
The priority is set with the distance and the luminance information as the ordering reference.
The corneal endothelium imaging device according to claim 1. An illumination optical system including an illumination light source that irradiates a slit light beam at an angle to the eye to be inspected, and an imaging optical system including an imaging element that receives a reflected light beam from the corneum of the eye to be inspected by the slit light beam and images a corneal image. A method for setting the order of images using a corneal endothelial imaging device including the illumination optical system and the distance changing unit for changing the distance to the eye to be inspected by integrating the imaging optical system.
A coordinate matching step of associating coordinate information indicating an imaging position with each of a plurality of captured images imaged by the image sensor at a plurality of positions having different distances from the eye to be inspected.
For each of the plurality of captured images captured during the preset period, the imaging position in the state where the imaging optical system is in focus on the corneal endothelium and the imaging position where the captured image was captured during the period A ranking setting process for setting priorities using distance as at least one ranking criterion, and
A method of setting the order of images.

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