JP6643603B2 - Ophthalmic equipment - Google Patents

Description

The present invention relates to a corneal imaging device that irradiates illumination light to a subject's eye and receives reflected light from the cornea of the subject's eye to capture a corneal image.

2. Description of the Related Art Conventionally, when judging the presence or absence of an eye disease or diagnosing the postoperative course of an eye, the state of cells of the cornea, particularly the corneal endothelium, has been observed.

A corneal imaging device is known which can image a corneal endothelial cell without contacting an eye to be examined when observing such a cell state of the corneal endothelium. Patent Document 1 discloses, as an example of the corneal imaging apparatus, an illumination optical system that irradiates a slit light obliquely toward a cornea of an eye to be examined, and a corneal endothelial cell that receives reflected light from the corneal endothelial cell of the cornea. And a fixation target light projecting optical system for projecting fixation target light toward the subject's eye to fixate on 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 part displayed on the screen and the previously captured corneal endothelium image cannot be grasped. Therefore, it has been difficult to track changes over time of 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 an object of the present invention is to present information by real-time processing in an observation screen using data obtained in the past in observation of a corneal endothelial image of an eye to be examined. It is to provide a corneal imaging device that is possible.

In order to achieve the above object, an invention according to claim 1 includes an illumination optical system including an irradiation light source that irradiates a slit light beam obliquely to an eye to be inspected, and a reflected light beam from the cornea of the eye to be inspected due to the slit light beam. And an imaging optical system provided with a photoelectric element for receiving a corneal image to receive the corneal image. The illumination optical system and the imaging optical system as a whole are moved toward or away from the eye to be examined to focus. In a corneal imaging apparatus provided with a driving unit, an image storage unit that stores a captured corneal endothelial image together with subject information, an extraction unit that extracts a contour of a corneal endothelial cell, and a storage unit that observes the same subject when observing the same subject. Reference means for specifying and referring to the past image data stored by the means, and correlation between any observation region between the observed image and the past image data during the observation, and determining a matching region 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 corneal imaging apparatus according to the first aspect, the area specifying means extracts and / or extracts a characteristic pattern in the stored past image as a reference marker. Alternatively, there is provided reference marker storage means for designating and storing the same, and calculation means for calculating matching between the stored image and the observed image using the reference marker.

According to a third aspect of the present invention, in the corneal imaging apparatus according to the first or second aspect, a coincidence area between the stored past image and the observed image specified by the area specifying unit is provided. On the other hand, using a stored corneal endothelial cell contour of the past image, a change degree determining unit that determines the magnitude of the change degree by sequentially comparing the specified cell regions. .

According to a fourth aspect of the present invention, in the corneal imaging apparatus according to the third aspect, based on the determination result by the change degree determination unit, the corneal imaging apparatus displays a color by superimposing it on an image being observed or photographed. Is performed.

Further, according to a fifth aspect of the present invention, in the corneal imaging apparatus according to the third aspect, based on a determination result by the change degree determining means, when the change degree is equal to or less than a specified value, the stored image is stored. It is characterized in that the contour of the corneal endothelial cell of the past image is superimposed and displayed on the image under observation.

According to a sixth aspect of the present invention, in the corneal imaging apparatus according to the third aspect, based on the determination result by the degree-of-change determining means, when the degree of change is equal to or less than a specified value, the stored image is stored. Using the corneal endothelial cell contour region of the past image, the cell density of the stored past image is superimposed and displayed on the image under observation in real time.

As described above, the corneal imaging apparatus according to the present invention can identify an area captured in the past and obtain an image at the same position as the previous image acquisition position in the observation of the corneal endothelial image of the subject's eye. As a result, it is possible to track changes over time.

FIG. 1 is an explanatory diagram illustrating an optical system according to an embodiment of the invention. FIG. 1 is an explanatory diagram for explaining a corneal imaging device as one embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining a control circuit and the like connected to the optical system shown in FIG. 1. 5 is a flowchart illustrating a photographing procedure of the corneal photographing apparatus. FIG. 3 is an explanatory diagram for explaining an anterior eye part displayed on a display screen. FIG. 3 is an explanatory diagram for explaining a reflected light beam in each layer of the cornea. FIG. 4 is an explanatory diagram illustrating a light amount distribution detected by a light amount detecting unit. FIG. 4 is an explanatory diagram showing a change in a moving speed of an apparatus optical system. FIG. 5 is an explanatory diagram for explaining a method of detecting corneal endothelium reflected light and a method of selecting images. FIG. 4 is an explanatory diagram for explaining a method of selecting images. Explanatory drawing for demonstrating the structure of each layer of a cornea. FIG. 4 is an explanatory diagram showing an example in which an area shot in the past is displayed on an 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 one embodiment of a corneal imaging apparatus according to the present invention. The apparatus optical system 10 is provided with an imaging illumination optical system 14 and a position detection optical system 16 on one side, and a position detection illumination system on the other side, with an observation optical system 12 for observing the anterior segment of the eye E to be examined interposed therebetween. It has a structure provided with an optical system 18 and an imaging optical system 20. In particular, in the present embodiment, an illumination optical system includes 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 of (two in this embodiment) observation light sources 30 are arranged in front of the eye E to be examined. As the observation light sources 30, 30, for example, an infrared LED that emits an infrared light beam is used. The cold mirror 27 transmits infrared light while reflecting visible light. The reflected light flux emitted from the observation light sources 30 and 30 and reflected by the anterior segment of the eye E to be examined is reflected by the cold mirror 27. An image is formed on a CCD 28 through an objective lens 24 and a cold mirror 27.

The imaging illumination optical system 14 is provided with a projection lens 32, a cold mirror 34, a slit 36, a condenser lens 38, and an imaging light source 40 in order from a position near the eye E. As the imaging light source 40, for example, an LED that emits a visible light beam is used. The cold mirror 34 is configured to transmit infrared light while reflecting visible light. The light beam emitted from the imaging light source 40 passes through the objective lens 38 and the slit 36 and irradiates the cornea C from an oblique direction.

The position detection optical system 16 has a part of the optical axis coincident 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 near the eye E to be examined. It 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 is provided with 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, an infrared light source such as an infrared LED is preferably employed. The cornea C is obliquely irradiated with the infrared light emitted from the observation light source 54. 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 does not necessarily need 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 using a visible light source, the illuminance is preferably 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 the optical axis coincident with the optical axis of the position detection illumination optical system 18, and the objective lens 46, the cold mirror 48, the slit 56, A lens 58, a focusing lens 60, a cold mirror 27, and a CCD 28 are provided. Then, the light beam emitted from the imaging light source 40 and reflected by the cornea C is reflected by the cold mirror 48 via 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 to form an image on the CCD 28.

Further, the half mirror 22 provided on the observation optical system 12 forms 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, for example, a light source that emits visible light such as an LED. The light flux 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 flux by the projection lens 68. Then, the light is reflected by the half mirror 22 and irradiated to the eye E to be inspected.

The alignment optical system 66 is provided with a half mirror 22, a projection lens 68, a half mirror 70, a stop 76, a pinhole plate 78, a condenser lens 80, and an alignment light source 82 in this order from a position close to the eye E. . The alignment light source 82 emits infrared light. The infrared light is condensed by the condenser lens 80, passes through the pinhole plate 78, and is guided to the stop 76. The light that has passed through the stop 76 is reflected by the half mirror 70, is converted into a parallel light beam by the projection lens 68, is reflected by the half mirror 22, and irradiates the eye E to be inspected.

The half mirror 26 provided on the observation optical system 12 forms a part of the alignment detection optical system 84.

The alignment detection optical system 84 includes the half mirror 26 and an alignment detection sensor 88 capable of detecting a 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 device optical system 10 having such a structure is housed in a corneal imaging device 100 shown in FIG. The corneal imaging apparatus 100 is provided with a main body 104 provided on a base 102, and a case 106 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 an operation stick 108. The operation stick 108 can be operated to drive the case 106. Further, the main body 104 accommodates control circuits and the like to be described later, and has a display screen 110 formed of, for example, a liquid crystal monitor.

Further, as shown in FIG. 3, the corneal imaging apparatus 100 is provided with a driving unit that moves the apparatus optical system 10 forward, backward, up, down, and left and right by driving the case 106. These driving means are constituted by, for example, a rack and pinion mechanism. In this embodiment, an X-axis driving mechanism 112 for driving the apparatus optical system 10 in the vertical X direction in FIG. A Y-axis drive mechanism 114 for driving in the vertical Y direction and a Z-axis drive mechanism 116 for driving in the horizontal Z direction in FIG. 3 are provided.

Further, the corneal imaging apparatus 100 is provided with an imaging control circuit 117 as imaging control means for controlling the operation of imaging the corneal image by the apparatus optical system 10. Then, the X-axis drive mechanism 112, the Y-axis drive mechanism 114, and the Z-axis drive mechanism 116 are respectively connected to the imaging control circuit 117, and are driven based on a driving signal from the imaging control circuit 117. I have. 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 a Z alignment detection circuit 120, and the Z alignment detection circuit 120 is connected to an imaging control circuit 117. Thereby, the detection information of the alignment detection sensor 88 and the line sensor 44 is input to the imaging control circuit 117. Although not shown, the imaging control circuit 117 is also connected to each of the illumination light sources 30, 40, 54, 74, and 82 so as to be able to control the light emission thereof.

Further, the corneal photographing apparatus 100 is provided with an image selection circuit 122 for receiving an image received by the CCD 28 and selecting the image, and storing the image selected by the image selection circuit 122. A storage device 124 as means is provided.

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

First, in S1, alignment of the apparatus optical system 10 in the X direction and the Y direction (XY alignment) is performed on the eye E to be inspected. During such XY alignment, fixation target light emitted from the fixation target light source 74 is guided to the eye E to be examined. Then, by fixing the fixation target light on 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. In this state, a light beam emitted from the observation light sources 30 and 30 and reflected by the anterior segment of the eye E is guided onto the CCD 28. Thus, the anterior segment of the eye E is displayed on the display screen 110 as shown in FIG.

Further, on the display screen 110, a rectangular frame-shaped alignment pattern 125 generated by, for example, a superimpose signal or the like is displayed so as to overlap the eye E to be examined. At the same time, a light beam emitted from the alignment light source 82 toward the subject's eye E is reflected by the anterior segment of the subject's eye E and guided to the CCD 28, so that a point-like alignment light 126 is displayed on the display screen 110. It is displayed. Then, the operator operates the operation stick 108 to drive the apparatus optical system 10, and adjusts the position of the apparatus optical system 10 so that the alignment light 126 enters the frame of the alignment pattern 125.

In addition, a part of the light beam emitted from the alignment light source 82 and reflected by the anterior segment of the eye E is reflected by the half mirror 26 and guided to the alignment detection sensor 88. In addition, the burden on the subject is reduced by irradiating infrared rays that are not recognized by the subject from the alignment light source 82. Here, when the alignment light 126 enters the frame of the alignment pattern 125, the alignment detection sensor 88 can detect the position of the alignment light 126 in the X direction and the position in the Y direction. 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 based on the position information in the X direction so that the optical axis O1 of the observation optical system 10 approaches the optical axis of the eye E to be inspected, and converts the position information in the Y direction into Then, the Y-axis driving mechanism 114 is driven such 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 appropriate timing even during imaging. In particular, 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. Thus, the infrared light flux of the observation light sources 30, 30 does not affect the XY alignment. The blinking of the alignment light source 82 and the observation light sources 30, 30 is performed at a higher speed than the conversion speed of the CCD 28 into light reception signals. 30 is not recognized by blinking, but is recognized as if the light sources 82 and 30 are continuously lit.

Next, in S2, the Z-axis drive mechanism 116 is driven to move the apparatus optical system 10 forward in a direction approaching the eye E to be examined. As described above, in the present embodiment, the advance control unit before imaging includes the S2 and the Z-axis drive mechanism 116. Then, the observation light source 54 is caused to emit light, and the infrared light beam emitted from the observation light source 54 is irradiated obliquely to the cornea C of the eye E to be examined, and the light beam reflected from the cornea C is converted into a line. The light is received by the sensor 44. In particular, in the present 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 flux 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 shown schematically in FIG. 6, the infrared light beam L from the observation light source 54 is first reflected by the epithelial cell e which is the interface between the air and the cornea C. A part of the light flux transmitted through the epithelial cell e is reflected by the corneal stroma s and the corneal endothelium en. The light amount of the reflected light beam e 'reflected by the epithelial cell e is the largest, and the light amount of the reflected light beam en' reflected by the corneal endothelium en is relatively small. The light amount becomes the smallest. Further, since the anterior chamber a is filled with the 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 line sensor 44 detects a light amount distribution as shown in FIG. In FIG. 7, the first peak portion 128 having the largest amount of light indicates reflected light from the corneal epithelium. Next, the second peak portion 130 having the next largest amount of light indicates reflected light from the corneal endothelium. Then, the imaging control circuit 117 drives the Z-axis driving mechanism 116 to move the apparatus by a predetermined distance: D1 from the position of the corneal epithelium detected by the line sensor 44 in consideration of the physiological corneal thickness variation of the human eye. The optical system 10 is driven to move forward in a direction approaching the cornea C. In addition, the moving distance from the corneal epithelium is appropriately set within a range of, for example, 1000 to 1500 μm. Thereby, the focus position of the imaging optical system 20 in the apparatus optical system 10 is located behind the endothelial cells in the cornea C. Then, a position behind the corneal epithelium by a predetermined distance: D1 is set as a reversal position of the apparatus optical system 10.

Next, when the apparatus optical system 10 is positioned at the reverse position, in S3, the Z-axis drive mechanism 116 is driven in the opposite direction, and the apparatus optical system 10 moves in the direction away from the eye E on the Z axis. It is moved backward. As described above, in the present embodiment, the reversing operation control means and the image retreat control means include the S3 and the Z-axis drive mechanism 116. Here, in the apparatus optical system 10, the retreat speed is changed from the reverse position to the start of the retreat operation to the end of the imaging. FIG. 8 shows a change in the moving speed in the backward operation of the apparatus optical system 10.

First, as described above, the device optical system 10 starts the retreat operation from the reversal position (P1 in FIG. 8). Such retreating operation is performed at a relatively high speed of, for example, 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 at a point in time when it reaches a position (P2 in FIG. 8) posterior to the corneal endothelial cell position by a predetermined distance: D ₂ (see FIG. 7). Light emission of the light source 40 is started. 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 From the distance. 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 It is preferably adopted. Further, the imaging light source 40 is caused to blink and emit light at predetermined short intervals, and the XY alignment in S1 is performed simultaneously at the timing when the imaging light source 40 is turned off.

Then, while causing the device optical system 10 to retreat 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 is started. The detection of the reflected light from the endothelial cells in S5 is, for example, as shown in FIG. 9, as shown in FIG. 9, one or more (five in this embodiment) suitable horizontal lines: l ₁ to l in the image 132 captured by the CCD 28. 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 in 255 gradations from luminance value 1 to luminance value 255 (the luminance value 1 is the darkest and the luminance value 255 is the brightest), and the unevenness of the endothelial reflected light is detected. , The luminance value of each pixel on the _five horizontal lines: l _{1 to} l 5 on the image 132 is 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 light amounts at which clear reflected light can be visually recognized. 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 A position corresponding to the amount of reflected light at approximately 30 μm is set as a 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 a captured image (image) received by the CCD 28 to the image selection circuit 122 at predetermined time intervals (for example, 1/30 second). As a result, a plurality of corneal images with different times and positions are input to the image selection circuit 122. Then, along with the continuous imaging, the image selection circuit 122 performs selection of the input image and storage of the input image in the storage device 124. As described above, in the present embodiment, the continuous imaging unit and the image selection unit include S6 and the image selection circuit 122.

9 and 10 illustrate a method of selecting images in the image selection circuit 122. First, in the same manner as in the detection of the corneal endothelial cells in S5 described above, as shown in FIG. 9, one or more (five in this embodiment) horizontal lines: l ₁ to l in the image 132 acquired by the CCD 28. to obtain the luminance value of each pixel on the l _5.

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

Then, based on (Equation 1), the average value of the sum of the luminance value differences obtained for each horizontal line: l _{1 to} l ₅ is obtained. The larger this value is, the more the corneal endothelial cell image is recognized as an image captured in a wider range. That is, as schematically shown in FIG. 11 and FIG. 6 described above, for example, the captured image of the anterior chamber a is entirely transmitted because the irradiation light beam is transmitted by the aqueous humor and the reflected light beam is hardly obtained. It becomes a dark image. In addition, the captured image of the corneal stroma s is transparent as in the anterior chamber a because the corneal stroma s is transparent, and becomes a dark image as a whole. Further, since the corneal epithelium e has a large amount of reflected light, a uniform bright image is obtained as a whole. Therefore, in the images of these parts, the difference between the luminance values of adjacent pixels is small. On the other hand, in the corneal endothelium en, the contrast between the central portion 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 cells en are imaged over a wide range. In such an image, the sum of the luminance value differences becomes large. Therefore, by storing only the image in which the average value of the sum of the luminance value differences obtained for each of the horizontal lines: l _{1 to} l ₅ is equal to or more than the predetermined value in the storage device 124, the corneal endothelial cell image can be effectively obtained. You can select only images that have been deleted.

In particular, in the present embodiment, before the above determination is made, pixels having a luminance value of 240 or more on a predetermined horizontal line (for example, the horizontal line: l _{1 to} l ₅ ) continuously have a luminance value of about 50 μm to 100 μm. If present over a range, such an image is excluded. That is, when a part of the corneal epithelium is captured in the image, a large difference in luminance value occurs on the boundary between the corneal epithelium and the corneal stroma. Therefore, if the sum of the luminance value differences in the corneal endothelium becomes small due to, for example, an in-focus position with the corneal endothelial cells not being obtained correctly (out of focus), the luminance value difference due to the influence of the boundary line with the corneal stroma is obtained. May increase, and an image obtained by imaging the corneal epithelium may be selected. Therefore, by using the above criterion, an image in which a part of the corneal epithelium is captured can be excluded.

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

Here, the relatively slow moving speed at which the deceleration in S5 is completed is determined in consideration of a range in which continuous imaging is performed while moving at a low speed (P4 to P6 in FIG. 8), an image capturing time by the CCD 28, the number of captured images, and the like. Is determined as appropriate. For example, a range of 200 μm or more can be suitably adopted as a range in which continuous imaging is performed while moving at a low speed in consideration of, for example, fine movement of the eye E to be inspected. If the image capturing time of the CCD 28 is 1/30 second per image and the range of continuous imaging is 200 μm, 600 μm / sec for 10 images, 300 μm / sec for 20 images, and 30 μm for 30 images. The imaging speed is set to 200 μm / sec for capturing 40 images, 150 μm / sec for capturing 40 images, and 100 μm / sec for capturing 50 images. Therefore, in order to reliably obtain a corneal endothelium photographed image by continuous imaging, a speed of 100 to 300 μm / sec is suitably adopted. 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 to adjust the number of images captured by continuous imaging. It is also possible to make the moving speed of the apparatus optical system 10 constant and vary the interval of the image capturing time by the CCD 28 based on the detection of the reflected light from the corneal endothelium in S5, thereby adjusting the number of images to be captured. Alternatively, both the moving speed and the capturing time may be controlled.

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

When the apparatus optical system 10 is accelerated to reach a relatively high speed before the deceleration is started (P7 in FIG. 8), in S8, for example, 100 μm in consideration of the fine movement of the eye E to be examined. After being retracted to the extent, the retraction operation is stopped, the imaging light source 40 is turned off, and the imaging ends (P8 in FIG. 8).

Next, a method of ascertaining the positional relationship between two corneal endothelial cell images acquired by the same subject at different times in a corneal endothelial cell image captured by such an imaging procedure will be described.

It is assumed that a corneal endothelial cell image has been taken in the past, and a subject in which both the corneal endothelial cell image and the subject information have been stored is taken again.

First, during the observation of the corneal endothelium, the same site as the previously photographed corneal endothelial cells is specified. As a method therefor, 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. Alternatively, a matching point may be found in a region including a marker by setting a characteristic region as a marker in past imaging instead of an arbitrary region. As the characteristic region, for example, a region having a shape and luminance distribution that is clearly different from the surroundings, such as the size and shape of a cell or a gutter that is scattered in a cell group, is used.

Then, based on the identification result of the matching part, the contents of the result of observation and analysis in the past are displayed on the observation image in real time.

More specifically, as shown in FIG. 12A, the specified area is represented by a frame 201 on the observation screen 200, thereby indicating that the previously captured area is recognized on the current screen. Can be displayed. When a matching region is specified using a characteristic region without using an arbitrary region, only the cell outline 202 of the specific region may be highlighted as shown in FIG. Cells may be colored.

Further, the entire region frame captured in the past from the specified gaze region may be displayed as a frame 203 on the currently displayed observation screen.

Furthermore, for the identified overlapped portion, the previously captured image is compared with the image under observation using the previously captured and analyzed corneal endothelial cell contour, and the degree of change in the corneal endothelial cell contour is determined. judge. Then, by using the determination result of the degree of change, information photographed and analyzed in the past can be displayed on the observation image.

For example, when the matching of the cell outline region is high between the image captured in the past and the image under observation, that is, the degree of change is small, the reference cell outline 204 is displayed on the observation image as shown in FIG. You may. If only a few years have passed since the previous imaging, this display method is effective because it is common that corneal endothelial cells do not significantly change.

At this time, by using the cell contour of the image photographed in the past and combining it with a superimposed region frame that matches the past photographed region on the display screen, the cell density in that frame is calculated, thereby obtaining the cell density shown in FIG. As described above, the cell density 205 may be displayed on the observation screen. Thus, the approximate cell density can be confirmed in real time on the observation screen.

In addition, as shown in FIG. 12F, in the analysis method in which the inside of the cell is specified one by one instead of the analysis method in which the contour of the corneal endothelial cell is extracted, the gray level of the cell image in the predetermined overlapping region is determined. Intracellular point data captured and analyzed in the past may be displayed in different colors according to the degree of correlation. In the example of FIG. 12F, the colors are classified into two colors.

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

As described above, one embodiment of the present invention has been described in detail. However, the present invention is not limited to the specific description in the embodiment, and various modifications may be 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, light source for imaging, light source for imaging, 44, light source for observation, light source for 64, fixation target optical system, 66, alignment optical system, 74, fixation target Light source, 82 alignment light source, 84 alignment detection optical system, 88 alignment detection sensor

Claims (6)

An illumination optical system including an irradiation light source that irradiates the slit light beam obliquely to the subject's eye,
An imaging optical system including a photoelectric element that receives a reflected light beam from the cornea of the subject's eye by the slit light beam and captures a corneal image,
In a cornea imaging apparatus including a driving unit that moves the illumination optical system and the imaging optical system as a whole toward or away from the subject's eye in a direction away from the eye to focus,
Image storage means for storing the captured corneal endothelium image together with subject information,
Cell contour extraction means for extracting a corneal endothelial cell contour,
Reference means for identifying and referencing past image data stored by the storage means when observing the same subject,
Area specifying means for obtaining a correlation of an arbitrary gaze area between the observed image and the past image data during the observation, and specifying a matching area between the two images,
Display means for displaying the area specified by the area specifying means on an observation image in real time. A reference marker storage unit configured to extract and / or specify a characteristic pattern in the stored past image as a reference marker and store the extracted characteristic pattern;
The corneal imaging apparatus according to claim 1, further comprising a calculation unit that calculates matching between the stored image and the observation image using the reference marker. Using the corneal endothelial cell contour of the saved past image, sequentially compare the identified cell region with the matched region of the saved past image and the observation image identified by the region identifying means. The corneal imaging device according to claim 1 or 2, further comprising a change degree determining unit that determines the magnitude of the change degree by performing the operation. 4. The cornea imaging apparatus according to claim 3, wherein a color display is performed using a gradation expression by superimposing the color image on an image during observation or photographed based on a determination result by the change degree determination unit. When the change degree is equal to or less than a specified value based on the determination result by the change degree determination unit, a corneal endothelial cell contour of the stored past image is superimposed and displayed on an image being observed. Item 8. A corneal imaging device according to item 3. Based on the determination result by said change degree determination unit, wherein when the degree of change is defined below, using the conserved corneal endothelial cells contour region of the previous image was, the stored past on an image under observation The corneal imaging apparatus according to claim 3, wherein the cell density of the image is superimposed and displayed in real time.