JP2017055866A - Ophthalmologic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cornea imaging apparatus capable of tracking a change with a lapse of time in a corneal endothelial cell of the same subject.SOLUTION: A cornea imaging apparatus includes image storage means for storing a captured corneal endothelial image together with information on a subject, extraction means for extracting a contour of a corneal endothelial cell, reference means for specifying and referring to past image data stored by the storage means when observing the same subject, region specifying means for taking correlation of an arbitrary region to be watched between an observation image and the past image data during the observation, and specifying a matching region of the two images, and display means for displaying the region specified by the region specifying means on the observation image in real time.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cornea imaging apparatus that captures a cornea image by irradiating illumination light to a subject's eye and receiving reflected light from the cornea of the subject's eye.

Conventionally, the cell 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 the cell state of such corneal endothelium, a corneal imaging apparatus is known that can image corneal endothelial cells in a non-contact manner with respect to an eye to be examined. In Patent Document 1, as an example of the corneal imaging apparatus, an illumination optical system that irradiates slit light obliquely toward the cornea of an eye to be examined and corneal endothelial cells that receive reflected light from the corneal endothelial cells of the cornea There is disclosed a configuration including an imaging optical system that captures an image of the subject and a fixation target light projection optical system that projects fixation target light for fixing the subject's eye toward the subject's eye.

Japanese Patent No. 2580464

However, in the conventional corneal imaging apparatus, during observation of the corneal endothelium image, the positional relationship between the site displayed on the screen and the previously imaged corneal endothelium image cannot be grasped. For this reason, it has been difficult to track changes with time in corneal endothelial cells at the same position in the same subject.

The present invention has been made in view of the above-described circumstances, and its purpose is to present information by real-time processing in an observation screen using data captured in the past in observation of a corneal endothelium image of an eye to be examined. It is to provide a corneal imaging apparatus that is possible.

In order to achieve the above object, an invention according to claim 1 is directed to an illumination optical system including an irradiation light source that irradiates a slit light beam obliquely to the eye to be examined, and a reflected light beam from the cornea of the eye to be examined by the slit light beam. And an optical imaging system that includes a photoelectric element that captures a corneal image and moves the illumination optical system and the imaging optical system as a whole toward or away from the eye to be focused. In a corneal imaging apparatus including a driving unit, an image storage unit that stores a captured corneal endothelium image together with subject information, an extraction unit that extracts a corneal endothelial cell contour, and the storage when observing the same subject The reference means for specifying and referring to the past image data stored by the means, and correlating an arbitrary gaze area between the observation image and the past image data during observation, and obtaining a matching area between the two images Wherein the constant region specifying means, further comprising a display means for displaying in real time on the observation image region specified by the region specifying unit.

According to a second aspect of the present invention, in the cornea photographing apparatus according to the first aspect, the region specifying unit extracts and / or extracts a characteristic pattern in the stored past image as a reference marker. Or it has a reference marker preservation | save means which designates and preserve | saves, and a calculation means which calculates the matching of a preserve | saved image and an observation image using the said reference marker, It is characterized by the above-mentioned.

According to a third aspect of the present invention, in the cornea photographing apparatus according to the first or second aspect, the saved past image and the observation image coincidence area specified by the area specifying means. On the other hand, it has a change degree determination means for judging the magnitude of the change degree by sequentially comparing the specified cell regions using the corneal endothelial cell contour of the saved past image. .

According to a fourth aspect of the present invention, in the cornea photographing apparatus according to the third aspect, the colored display is superimposed on the image being observed or photographed based on the determination result by the change degree determining means. It is characterized by performing.

Further, according to a fifth aspect of the present invention, in the cornea photographing apparatus according to the third aspect, the saved image is stored when the degree of change is not more than a specified value based on a determination result by the change degree determining unit. It is characterized in that a corneal endothelial cell outline of a past image is superimposed and displayed on an image being observed.

According to a sixth aspect of the present invention, in the cornea photographing apparatus according to the third aspect, the saved image is stored when the degree of change is not more than a specified value based on a determination result by the change degree determining unit. Using the corneal endothelial cell contour region of the past image, the cell density is superimposed and displayed in real time on the image being observed.

As described above, the corneal imaging device according to the present invention can identify a previously imaged region and acquire an image at the same position as the past image acquisition position in observing a corneal endothelium image of the eye to be examined. It becomes possible to track changes with time.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing for demonstrating the optical system as one Embodiment of this invention. Explanatory drawing for demonstrating the cornea imaging device as one Embodiment of this invention. Explanatory drawing for demonstrating the control circuit etc. which are connected to the optical system shown in FIG. The flowchart which shows the imaging | photography procedure of a cornea imaging device. Explanatory drawing for demonstrating the anterior eye part displayed on a display screen. Explanatory drawing for demonstrating the reflected light beam in each layer of a cornea. Explanatory drawing which shows light quantity distribution detected by a light quantity detection means. Explanatory drawing which shows the change of the moving speed of an apparatus optical system. Explanatory drawing for demonstrating the detection method of corneal-endothelium reflected light, and the selection method of an image. Explanatory drawing for demonstrating the selection method of an image. Explanatory drawing for demonstrating the structure of each layer of a cornea. Explanatory drawing which shows the example which displayed the area | region image | photographed in the past on the observation screen.

Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows an apparatus optical system 10 as an embodiment of a cornea photographing apparatus according to the present invention. The apparatus optical system 10 includes an imaging illumination optical system 14 and a position detection optical system 16 on one side with an observation optical system 12 for observing the anterior eye portion of the eye E to be examined, and a position detection illumination on the other side. The optical system 18 and the imaging optical system 20 are provided. In particular, in the present embodiment, the illumination optical system is configured to include the imaging illumination optical system 14 and the position detection illumination optical system 18.

The observation optical system 12 is configured such that a half mirror 22, an objective lens 24, a half mirror 26, a cold mirror 27, and a CCD 28 as a photoelectric element are provided on the optical axis O1 in order from a position close to the eye E. In addition, a plurality (two in the present embodiment) of observation light sources 30 and 30 are disposed in front of the eye E. As the observation light sources 30, 30, for example, infrared LEDs that emit infrared light flux are used. The cold mirror 27 transmits infrared light while reflecting visible light, and the reflected light beam emitted from the observation light sources 30 and 30 and reflected by the anterior eye portion of the eye E is examined. The image is formed on the CCD 28 through the objective lens 24 and the cold mirror 27.

The imaging illumination optical system 14 includes a projection lens 32, a cold mirror 34, a slit 36, a condensing lens 38, and an imaging light source 40 in order from a position close to the eye E. The imaging light source 40 is, for example, an LED that emits a visible light beam. The cold mirror 34 transmits infrared light while reflecting visible light. Then, the light beam emitted from the imaging light source 40 passes through the objective lens 38 and the slit 36 and is irradiated to the cornea C from an oblique direction.

The position detection optical system 16 has a part of its optical axis aligned with the optical axis of the imaging illumination optical system 14, and is provided with a projection lens 32, a cold mirror 34, and a line sensor 44 in order from a position close to the eye E. Is configured. A light beam emitted from an observation light source 54 to be described later and reflected by the cornea C is imaged 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 includes an objective lens 46, a cold mirror 48, a condenser lens 52, and an observation light source 54 as a position detection light source in order from a position close to the eye E. . As the observation light source 54, for example, an infrared light source such as an infrared LED is suitably employed. The infrared light beam emitted from the observation light source 54 is irradiated to the cornea C from an oblique direction. Note that 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. However, the observation light source 54 is not necessarily 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, the illuminance is preferably made smaller than the illuminance of the imaging light source 40. Thereby, the burden on the subject when irradiating the light beam from the observation light source 54 such as alignment can be reduced.

The imaging optical system 20 has a part of its optical axis aligned with the optical axis of the position detection illumination optical system 18, and the objective lens 46, cold mirror 48, slit 56, magnification change in order from the position close to the eye E to be examined. A lens 58, a focusing lens 60, a cold mirror 27, and a CCD 28 are provided. Then, the light beam irradiated from the imaging light source 40 and reflected by the cornea C is reflected by the cold mirror 48 through the objective lens 46, passes through the slit 56, and is converted into a parallel light beam by the variable power lens 58, After passing through the focusing lens 60, the light is reflected by the cold mirror 27 and imaged on the CCD 28.

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 includes a half mirror 22, a projection lens 68, a half mirror 70, a pinhole plate 72, and a fixation target light source 74 in order from a position close to the eye E. The fixation target light source 74 is a light source that emits visible light, such as an LED, and the light beam emitted from the fixation target light source 74 is transmitted through the pinhole plate 72 and the half mirror 70 and then converted into a parallel light beam by the projection lens 68. Then, it is reflected by the half mirror 22 and irradiated to the eye E.

The alignment optical system 66 includes a half mirror 22, a projection lens 68, a half mirror 70, a diaphragm 76, a pinhole plate 78, a condenser lens 80, and an alignment light source 82 in order from a position close to the eye E. . 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 diaphragm 76. The light that has passed through the diaphragm 76 is reflected by the half mirror 70, converted into a parallel light beam by the projection lens 68, reflected by the half mirror 22, and applied to the eye E.

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 includes a half mirror 26 and an alignment detection sensor 88 capable of detecting the position in order from a position close to the eye E. The light beam emitted from the alignment light source 82 and reflected by the cornea C is reflected by the half mirror 26 and guided to the alignment detection sensor 88.

The apparatus optical system 10 having such a structure is accommodated in the cornea photographing apparatus 100 shown in FIG. The cornea photographing apparatus 100 is configured such that a main body 104 is provided on a base 102, and a case 106 is provided on the main body 104 so as to be movable back and forth, right and left, and up and down. The base 102 has a built-in power supply device and is provided with an operation stick 108 so that the case 106 can be driven by operating the operation stick 108. Further, the main body unit 104 accommodates control circuits and the like described later, and a display screen 110 including a liquid crystal monitor, for example.

Further, as shown in FIG. 3, the cornea photographing apparatus 100 is provided with driving means for moving the apparatus optical system 10 forward, backward, up, down, left and right with respect to the eye E by driving the case 106. These driving means are constituted by, for example, a rack and pinion mechanism, and in this embodiment, an X-axis driving mechanism 112 that drives the apparatus optical system 10 in the vertical X direction in FIG. 3, and a paper surface in FIG. A Y-axis drive mechanism 114 that drives in the vertical Y direction and a Z-axis drive mechanism 116 that drives in the left-right Z direction in FIG. 3 are provided.

Further, the cornea photographing apparatus 100 is provided with an imaging control circuit 117 serving as an imaging control unit that performs operation control of imaging of the cornea image by the apparatus optical system 10. The X-axis drive mechanism 112, the Y-axis drive mechanism 114, and the Z-axis drive mechanism 116 are connected to the imaging control circuit 117, and are driven based on a drive signal from the imaging control circuit 117. Yes. The alignment detection sensor 88 is connected to an XY alignment detection circuit 118, and the XY alignment detection circuit 118 is connected to an imaging control circuit 117. The line sensor 44 is connected to the Z alignment detection circuit 120, and the Z alignment detection circuit 120 is connected to the imaging control circuit 117. Thereby, detection information of the alignment detection sensor 88 and the line sensor 44 is input to the imaging control circuit 117. In addition, although illustration is abbreviate | omitted, the imaging control circuit 117 is also connected to each illumination light source 30,40,54,74,82, and it can control these light emission.

Further, the cornea photographing apparatus 100 is provided with an image selection circuit 122 that receives an image received by the CCD 28 and selects the image, and stores the image selected by the image selection circuit 122. A storage device 124 is provided as a means.

Next, in the corneal imaging device 100 having such a structure, an outline of the corneal endothelium imaging procedure executed by the imaging control circuit 117 is shown in FIG.

First, in S1, the alignment (XY alignment) of the apparatus optical system 10 in the X direction and the Y direction is performed on the eye E. During such XY alignment, the fixation target light emitted from the fixation target light source 74 is guided to the eye E. Then, by fixing the fixation target light applied to the subject, the optical axis direction of the eye E can be matched with the direction of the optical axis O1 of the observation optical system 12. Under such a state, the light beam irradiated from the observation light sources 30 and 30 and reflected by the anterior eye portion of the eye E is guided onto the CCD 28. As a result, as shown in FIG. 5, the anterior segment of the eye E is displayed on the display screen 110.

Further, on the display screen 110, for example, an alignment pattern 125 having a rectangular frame shape generated by a superimpose signal or the like is displayed over the eye E. At the same time, the light beam emitted from the alignment light source 82 toward the subject eye E is reflected by the anterior eye portion of the subject eye E and guided to the CCD 28, so that the display screen 110 has the dotted alignment light 126. It is displayed. Then, the operator operates the operation stick 108 to drive the apparatus optical system 10 and adjust the position of the apparatus optical system 10 so that the alignment light 126 enters the frame of the alignment pattern 125.

A part of the light beam irradiated from the alignment light source 82 and reflected by the anterior eye portion of the eye E is reflected by the half mirror 26 and guided to the alignment detection sensor 88. The alignment light source 82 emits an infrared beam that is not recognized by the subject, thereby reducing the burden on the subject. Here, the alignment detection sensor 88 can detect the position of the alignment light 126 in the X direction and the position of the Y direction when the alignment light 126 enters the frame of the alignment pattern 125. The X direction position and the Y direction position are input to the XY alignment detection circuit 118. The XY alignment detection circuit 118 drives the X-axis drive mechanism 112 so that the optical axis O1 of the observation optical system 10 approaches the optical axis of the eye E based on the positional information in the X direction, and uses the positional information in the Y direction. Based on this, the Y-axis drive mechanism 114 is driven so that the optical axis O1 of the observation optical system 10 approaches the optical axis of the eye E to be examined. Thereby, the alignment of the apparatus optical system 10 with respect to the eye E in the XY directions is performed. As will be described later, such XY alignment is performed at an appropriate timing even during imaging. Particularly in the present embodiment, the alignment light source 82 and the observation light sources 30 and 30 are alternately blinked in a short time, and detection by the alignment detection sensor 88 is performed in accordance with the lighting timing of the alignment light source 82. ing. As a result, the infrared light beams of the observation light sources 30 and 30 are not affected during the XY alignment. The blinking of the alignment light source 82 and the observation light sources 30 and 30 is performed at a higher speed than the conversion speed of the CCD 28 into the light reception signal. 30 is not recognized by flashing, but is recognized as if the light sources 82 and 30 are continuously lit.

Next, in S <b> 2, the Z-axis drive mechanism 116 is driven, and the apparatus optical system 10 is moved forward in a direction approaching the eye E to be examined. Thus, in the present embodiment, the pre-imaging advance control means is configured including S2 and the Z-axis drive mechanism 116. Then, the observation light source 54 is caused to emit light, and the infrared light beam irradiated from the observation light source 54 is irradiated obliquely onto the cornea C of the eye E, and the light beam reflected from the cornea C is Light is received by the sensor 44. In particular, in this embodiment, since the light beam emitted from the observation light source 54 is an infrared light beam, the burden on the subject is reduced.

The infrared light beam from the observation light source 54 is reflected with a different amount of reflected light for each layer of the cornea C, such as epithelial cells of the cornea C, corneal stroma, and corneal endothelium. As schematically shown in FIG. 6, the infrared light beam L from the observation light source 54 is first reflected by the epithelial cells e that form the boundary surface between the air and the cornea C. Further, a part of the light beam transmitted through the epithelial cell e is reflected by the corneal stroma s and the corneal endothelium en. The amount of the reflected light beam e ′ reflected by the epithelial cell e is the largest, the amount of the reflected light beam en ′ reflected by the corneal endothelium en is relatively small, and the reflected light beam s ′ reflected by the corneal substance s. The light intensity is the smallest. Further, since the anterior chamber a is filled with aqueous humor, the infrared light beam L is hardly reflected in the anterior chamber a.

These reflected light beams are detected by the line sensor 44, and the light quantity distribution as shown in FIG. In FIG. 7, the first peak portion 128 having the largest amount of light indicates the reflected light from the corneal epithelium. Next, the second peak portion 130 with the largest amount of light indicates the reflected light from the corneal endothelium. Then, the imaging control circuit 117 drives the Z-axis drive mechanism 116 to set the device at a predetermined distance D1 in consideration of the physiological corneal thickness variation of the human eye from the position of the corneal epithelium detected by the line sensor 44. The optical system 10 is driven forward in a direction approaching the cornea C. The moving distance from the corneal epithelium is appropriately set within a range of 1000 to 1500 μm, for example. Thereby, the focus position of the imaging optical system 20 in the apparatus optical system 10 is positioned behind the endothelial cells in the cornea C. A position behind the corneal epithelium by a predetermined distance: D1 is set as the inversion position of the apparatus optical system 10.

Next, when the apparatus optical system 10 is positioned at the reversal position, in S3, the Z-axis drive mechanism 116 is driven in the opposite direction, so that the apparatus optical system 10 moves away from the eye E on the Z-axis. It can be operated backwards. As described above, in the present embodiment, the reversal operation control means and the imaging reverse control means are configured including S3 and the Z-axis drive mechanism 116. Here, the apparatus optical system 10 is configured such that the reverse speed is changed from when the reverse operation is started from the inversion position to when the imaging is completed. FIG. 8 shows changes in the moving speed in the backward operation of the apparatus optical system 10.

First, as described above, the apparatus optical system 10 starts to move backward from the reverse position (P1 in FIG. 8). Such reverse operation is performed at a relatively high speed of, for example, about 500 μm to 3000 μm / sec, more preferably about 2000 μm / sec. Then, in S4, the observation light sources 30, 30 are turned off and the imaging light source is turned off from the time when it reaches a position (P2 in FIG. 8) behind the corneal endothelial cell position by a predetermined distance: D ₂ (see FIG. 7). The light source 40 starts to emit light. In the present embodiment, the predetermined distance from the corneal endothelial cells: D ₂ has predetermined positions to be slightly smaller predetermined threshold value than the light quantity distribution is the second peak portion 130 detected by the line sensor 44 It is said to be a separation distance from. The predetermined distance: Specific values of D _2, in consideration of the positional deviation or the like of the detection accuracy and the eye E to be reliably capture the corneal endothelial cells of the line sensor 44, the value of some degree margin preferred, predetermined distance: D ₂ increases the light emission time of the image pickup light source 40 becomes longer, since it allowed to increase the burden on the patient, a predetermined distance: D ₂ has a value within the range of 200~500μm Preferably employed. The imaging light source 40 is flashed at predetermined short intervals, and the XY alignment in S1 is simultaneously performed at the timing when the imaging light source 40 is turned off.

Then, while the apparatus optical system 10 is moved backward at a relatively high speed, the reflected light from the endothelial cells of the cornea C is detected by the CCD 28 in S5 (P3 in FIG. 8). Deceleration starts. The detection of the reflected light from the endothelial cells in S5 is, for example, as shown in FIG. 9, one or more (in this embodiment, five) appropriate horizontal lines in the image 132 imaged by the CCD 28: l ₁ to the brightness value of the pixels on l _5, based on the number of pixels having a luminance value equal to or larger than a predetermined value, determines that detects reflected light from the corneal endothelial cells. In the present embodiment, the luminance value of each pixel in the image 132 is detected with 255 gradations (luminance value 1 is the darkest and luminance value 255 is the brightest) from luminance value 1 to luminance value 255, and unevenness of the endothelial reflected light is detected. , The luminance values of the respective pixels on the _five horizontal lines on the image 132: l _{1 to} l ₅ are detected. Then, the number of pixels having a luminance value of 25 to 255 in each pixel on the horizontal line: l _{1 to} l ₅ is counted. Note that the luminance values 25 to 255 are amounts of light that can recognize reflected light that is clearly visible. Then, Horizon: l ₁ to l counted average number of pixels in the _5, or horizontal lines: maximum value of the number of pixels that have been counted in l ₁ to l ₅ is converted into the distance on the corneal endothelium The position corresponding to the amount of reflected light at approximately 30 μm is set as the deceleration start point (P3 in FIG. 8).

Then, the deceleration operation in S5 is started, and in S6, continuous imaging of the corneal endothelium image detected by the CCD 28 is started. Such continuous imaging is performed by inputting captured images (images) received by the CCD 28 to the image selection circuit 122 at predetermined time intervals (for example, 1/30 seconds). As a result, a plurality of cornea images having different times and positions are input to the image selection circuit 122. Along with such continuous imaging, the image selection circuit 122 selects the input image and stores it in the storage device 124. Thus, in this embodiment, the continuous imaging means and the image selection means are comprised including S6 and the image selection circuit 122. FIG.

9 and 10 illustrate an image selection method in the image selection circuit 122. FIG. First, in the same manner as in the detection of corneal endothelial cells in S5 described above, as shown in FIG. 9, one or more (in this embodiment, five) horizontal lines in the image 132 acquired by the CCD 28: l _1- to obtain the luminance value of each pixel on the l _5.

Then, as shown in FIG. 10 and (Equation 1), for each pixel (X _{1 to} X _n ) of the acquired horizontal line: l _{1 to} l ₅ , for each horizontal line: l _{1 to} l ₅ , respectively. Based on (Equation 1), (i) the absolute value of the luminance value difference between adjacent pixels is obtained, and (ii) the sum of the luminance value differences is obtained.

Each horizontal line on the basis of (Equation 1): the average value of the sum of the luminance value differences obtained for each l ₁ to l _5. It is recognized that the larger this value is, the wider the range of the corneal endothelial cell image. That is, as schematically shown in FIG. 11 and FIG. 6 described above, for example, in the captured image of the anterior chamber a, the irradiation light beam is transmitted through the aqueous humor and almost no reflected light beam is obtained. The image becomes dark. Further, since the cornea substance s is transparent, the photographed image of the cornea substance s is transmitted through the irradiation light beam in the same manner as the anterior chamber a, and becomes a dark image as a whole. Furthermore, since the amount of reflected light is large in the corneal epithelium e, the entire image becomes bright and uniform. Therefore, in the image of these parts, the difference in luminance value between adjacent pixels becomes small. On the other hand, in the corneal endothelium en, the contrast between the central part of the endothelial cells and the cell wall clearly appears, and the difference in luminance value between adjacent pixels increases, so that the corneal endothelial cell en is imaged over a wide range. In this case, the sum of the luminance value differences becomes large. Therefore, the corneal endothelial cell image can be effectively obtained by storing in the storage device 124 only the image in which the average value of the sum of the brightness values obtained for each of the horizontal lines: l _{1 to} l ₅ is equal to or greater than a predetermined value. Only selected images can be selected.

In particular, in the present embodiment, before performing the above determination, pixels having a luminance value of 240 or more are continuously set to about 50 μm to 100 μm on a predetermined horizontal line (for example, the horizontal lines: l _{1 to} l ₅ ). If it exists over a range, such an image is excluded. That is, when a part of the corneal epithelium is shown in the image, a large luminance value difference occurs on the boundary line between the corneal epithelium and the corneal stroma. Therefore, if the sum of the luminance value difference in the corneal endothelium becomes small because the in-focus position with the corneal endothelial cell cannot be obtained correctly (out of focus), the luminance value difference is affected by the boundary line with the corneal stroma. May increase, and an image obtained by imaging the corneal epithelium may be selected. Therefore, by using the above judgment criterion, an image showing a part of the corneal epithelium can be excluded.

Next, the deceleration operation is started in S5, and the apparatus optical system 10 is moved backward at such a relatively slow speed from a time point (P4 in FIG. 8) when a relatively slow speed described later is reached. Then, continuous imaging and image selection in S6 are performed over a predetermined range (P4 to P6 in FIG. 8) from the time when deceleration is completed. Note that the in-focus position with the corneal endothelial cell (P5 in FIG. 8) is also included in the range of P4 to P6.

Here, the relatively slow moving speed at which the deceleration in S5 is completed takes into consideration the range in which continuous imaging is performed while moving at a low speed (P4 to P6 in FIG. 8), the time for capturing images by the CCD 28, the number of images to be captured, and the like. It is determined appropriately. For example, as a range in which continuous imaging is performed by moving at a low speed, a range of 200 μm or more can be suitably adopted in consideration of the fine movement of the eye E to be examined. Then, assuming that the image capture time of the CCD 28 is 1/30 second per sheet and the continuous imaging range is 200 μm, 600 μm / sec when capturing 10 images, 300 μm / sec when capturing 20 images, 30 200 μm / sec is set when capturing a single image, 150 μm / sec when capturing 40 images, and 100 μm / sec when capturing 50 images. Therefore, a speed of 100 to 300 μm / sec is preferably employed in order to reliably acquire a corneal endothelium image by continuous imaging. As described above, in the present embodiment, the image capturing time by the CCD 28 is made substantially constant, and the moving speed of the apparatus optical system 10 is changed, whereby the number of images captured by continuous imaging is adjusted. The number of images to be captured may be adjusted by changing the interval of image capturing time by the CCD 28 based on the detection of the reflected light from the corneal endothelium in S5 with the moving speed of the apparatus optical system 10 constant. It is also possible to control both the moving speed and the capture time.

Then, at a time point (P6 in FIG. 8) that has moved backward by a predetermined distance (for example, 200 μm in the present embodiment) from the start position of low-speed movement and continuous imaging (P4 in FIG. 8), acceleration is performed in S7. Is started, and the apparatus optical system 10 is accelerated to the speed before the deceleration is started. Note that, as a criterion for determining the acceleration start position, not only the moving distance but also acceleration is performed at the stage where the corneal endothelial reflected light is not detected according to the same method as the detection procedure of the corneal endothelial reflected light in S5 described above, for example. Acceleration may be started when a predetermined time has elapsed from the start of imaging, or may be used in combination as appropriate.

When the apparatus optical system 10 is accelerated and reaches a relatively fast speed before decelerating is started (P7 in FIG. 8), in S8, for example, 100 μm is considered in consideration of the fine movement of the eye E. After being retracted to a certain extent, the backward operation is stopped, the imaging light source 40 is turned off, and imaging is terminated (P8 in FIG. 8).

Next, a method for grasping the positional relationship between two corneal endothelial cell images acquired at different times of the same subject with respect to the corneal endothelial cell images captured by such an imaging procedure will be described.

Assume a case in which corneal endothelial cell image capturing has been performed in the past, and a subject who has stored both the corneal endothelial cell image and the subject information is imaged again.

First, during corneal endothelium observation, the same site as the corneal endothelial cells photographed in the past is specified. As the method, there is a method of setting an arbitrary area of M × N pixels in which the corneal endothelium is reflected and finding a matching point. In addition, a matching point may be found in an area including a marker by setting a characteristic area as a marker in past shooting instead of an arbitrary area. As the feature region, for example, a region having a shape and luminance distribution that is clearly different from the surroundings, such as cell size and shape, or guttata scattered in a cell group, is used.

And based on the identification result of a coincidence part, the content of the result observed and analyzed in the past is displayed on an observation image in real time.

Specifically, as shown in FIG. 12A, the identified area is represented by a frame 201 on the observation screen 200, thereby confirming that the area captured in the past is recognized on the current screen. Can be displayed. Further, when a matching region is specified using a feature region without using an arbitrary region, only the cell outline 202 of the specific region may be highlighted as shown in FIG. The cells may be colored.

Alternatively, the entire area frame captured in the past from the specified gaze area may be displayed with the frame 203 on the currently displayed observation screen.

Furthermore, for the specified overlapped part, the image taken in the past using the corneal endothelial cell contour photographed and analyzed in the past is compared with the image being observed to determine the degree of change in the corneal endothelial cell contour. judge. Then, using the determination result of the degree of change, information that has been captured and analyzed in the past can be displayed on the observation image.

For example, in the case where the matching between the cell contour regions is high in the image captured in the past and the image being observed, that is, when the degree of change is small, the reference cell contour line 204 is displayed on the observed image as shown in FIG. May be. When only a few years have passed since the last imaging, it is common that the corneal endothelial cells do not change significantly, so this display method is effective.

At this time, the cell density in the frame is calculated by using the cell outline of the image captured in the past and calculating the cell density in the frame together with the overlapping region frame that matches the past imaging region on the display screen. As described above, the cell density 205 may be displayed on the observation screen. Thereby, the approximate cell density can be confirmed on the observation screen in real time.

In addition, as shown in FIG. 12 (f), in the analysis method in which the inside of the cell is designated one by one rather than the analysis method of extracting the corneal endothelial cell contour, the gray level of the cell image is determined in a predetermined overlapping region. Depending on the degree of correlation, intracellular point data captured and analyzed in the past may be displayed in different colors. In the example of FIG. 12F, the colors are divided into two colors.

As described above, according to the present embodiment, when a corneal endothelium image is captured again for a subject who has captured a corneal endothelium image in the past, the past image acquisition is performed using the image captured in the past. Since it becomes possible to acquire an image at the same position as the position, it is possible to track a change with time.

As mentioned above, although one embodiment of the present invention has been described in detail, the present invention is not limited by the specific description in the embodiment, and various modifications are made without departing from the spirit of the present invention. Is possible.

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, 28 .... CCD , 30 .. Light source for observation, 40 .. Light source for imaging, 44 .. Line sensor, 54 .. Light source for observation, 64 .. Fixation target optical system, 66 .. Alignment optical system, 74. Light source, 82..Alignment light source, 84..Alignment detection optical system, 88..Alignment detection sensor

Claims (6)

An illumination optical system having an irradiation light source that irradiates the slit light beam obliquely to the eye to be examined;
An imaging optical system including a photoelectric element that receives a reflected light beam from the cornea of the eye to be examined by a slit light beam and captures a cornea image;
In the cornea photographing apparatus provided with a driving unit that moves the illumination optical system and the imaging optical system as a whole toward or away from the eye to be in-focus,
Image storage means for storing the photographed corneal endothelium image together with the subject information;
A cell contour extracting means for extracting a corneal endothelial cell contour;
Reference means for specifying and referring to past image data stored by the storage means when observing the same subject,
A region specifying means for correlating an arbitrary gaze region between an observation image and past image data during observation and specifying a region where the two images match;
A cornea photographing apparatus comprising: display means for displaying the area specified by the area specifying means on the observation image in real time. The area specifying unit extracts and / or specifies a characteristic pattern in the stored past image as a reference marker, and stores the reference marker storage unit.
2. The cornea photographing apparatus according to claim 1, further comprising calculation means for calculating matching between the stored image and the observation image using the reference marker. Using the corneal endothelial cell contour of the stored past image, the specified cell region is sequentially compared with the matching region between the stored past image and the observed image specified by the region specifying means. The cornea photographing apparatus according to claim 1, further comprising: a change degree determination unit that determines the magnitude of the change degree by performing the operation. 4. The cornea photographing apparatus according to claim 3, wherein the corneal photographing apparatus performs color display using a gradation expression superimposed on an image being observed or photographed based on a determination result by the change degree determining means. The corneal endothelial cell contour of the stored past image is superimposed and displayed on the image being observed when the degree of change is less than or equal to a specified value based on a determination result by the change degree determination unit. Item 4. The cornea imaging device according to Item 3. Based on the determination result by the change degree determination means, when the change degree is less than or equal to the specified value, the cell density is measured in real time on the image being observed using the corneal endothelial cell contour region of the saved past image. 4. The cornea photographing apparatus according to claim 3, wherein the cornea photographing device is displayed in a superimposed manner.