JP2008113779A - Corneal endothelium photographing apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corneal endothelium photographing apparatus with a novel structure which can realize the facilitation and omission of selection work by examiners after photographing along with a reduction in burden on examinees and the examiners with the shortened examination time by evaluating the photographined state of a plurality of images acquired by successive shooting. <P>SOLUTION: The apparatus is provided with a luminance information acquisition means 144 for acquiring the luminance information of pixels in prescribed areas of the images 132 taken and also, image evaluation means 146 and 150 and 156 which evaluate the photographed state of corneal endothelium in the images 132 taken based on the luminance information acquired by the luminance information acquisition means 144. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a corneal endothelium imaging device and a corneal endothelium imaging method for imaging a corneal image by irradiating the eye to be examined with illumination light and receiving reflected light from the cornea of the eye to be examined.

  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.

  There is known a corneal endothelium imaging apparatus capable of imaging corneal endothelial cells in a non-contact manner with respect to an eye when observing the cell state of such corneal endothelium. This corneal endothelium imaging apparatus irradiates slit-shaped illumination light obliquely onto the cornea of an eye to be examined by an illumination optical system, and receives reflected light from the cornea with an imaging optical system to image corneal endothelial cells. ing.

  By the way, since the corneal endothelial cells are thin, the corneal endothelium imaging apparatus has a problem that it is difficult to obtain a clear focused image of the corneal endothelial cells. In particular, since the corneal endothelium imaging apparatus employs slit-shaped illumination light, in order to obtain a clear corneal endothelial cell image while avoiding the adverse effects of reflected light from the corneal epithelium or corneal stroma, illumination optics It is necessary to accurately align the system and the imaging optical system with the focus position of the endothelium in the approach / separation direction with respect to the corneal endothelial cell.

  Therefore, conventionally, as shown in Patent Document 1, for example, a line sensor that detects the light amount distribution of reflected light from the cornea is employed to detect and align the in-focus position of the corneal endothelial cells. What has been proposed is proposed. That is, by considering the distribution characteristics of the amount of reflected light in the cornea composed of the corneal epithelium, the corneal stroma, and the corneal endothelium, the focal position of the corneal endothelial cell is estimated from the peak position in the output value of the line sensor. Corneal endothelial cells are imaged with the illumination optical system and the imaging optical system aligned with the estimated in-focus position.

  However, the conventional corneal endothelium imaging apparatus as described in Patent Document 1 has a problem that it is difficult to stably detect the in-focus position of corneal endothelial cells with high accuracy. Specifically, for example, when the corneal thickness is reduced by refractive power surgery or the like, there are individual differences in the thickness of the cornea, and in the case of a thin cornea, the corneal epithelium and the corneal endothelium It may be difficult to detect both peaks, and the endothelium focus position may not be correctly identified. In addition, due to the properties of the corneal stroma, especially when the corneal stroma is clogged due to an eye disease or the like, it is impossible to detect the in-focus position due to the peak of the corneal endothelium due to antagonism of the reflection level of the corneal stroma and the corneal endothelium. There is also a possibility that it is possible or wrong position detection is performed.

  Furthermore, even if the in-focus position can be detected with high accuracy, imaging is performed after alignment with the in-focus estimation position detected by the line sensor, so that the in-focus position shifts due to fine movement of the eye to be examined. There is also a possibility that a clear image of focused endothelium cannot be obtained. If the desired clear in-focus image cannot be photographed, it is necessary to re-adjust to the in-focus inferred position, so that not only the examiner but also the subject by extending the photographing time. It was a big burden. Especially in the case of manual imaging, the subject's eye is constantly steadily moving with high magnification, and the corneal endothelial cell image shakes violently, making manual focusing difficult. It takes considerable skill to do so.

  Therefore, Patent Document 2 proposes a corneal imaging apparatus that continuously performs imaging near the corneal endothelium in-focus position. In the corneal imaging apparatus disclosed in Patent Document 2, a predetermined number of frames are continuously captured at a predetermined movement interval, and focused corneal endothelial cells can be obtained without requiring expert skill. The purpose is to shoot.

  However, with such a cornea photographing device described in Patent Document 2, it is possible to obtain a focused image relatively easily, while taking an image from a large number of photographed images obtained by the examiner after photographing. It is necessary to separately perform an operation for selecting a corneal endothelium focused image in a good state, which increases the burden on the examiner.

  In order to obtain a focused image of the corneal endothelium relatively easily by performing continuous imaging in the vicinity of the focal position of the corneal endothelium using the corneal imaging apparatus described in Patent Document 2, setting of the imaging interval of the image is performed. There is also a problem that is extremely difficult. That is, in order to easily obtain a focused image of the corneal endothelium by continuous imaging, it is necessary to continuously capture images over a relatively long period of time. It becomes a number. Therefore, the size of the imaging data exceeds the storable data capacity of the storage device before reaching the in-focus position, making it impossible to store the in-focus in-endothelium image, or the in-focus in-endothelium after imaging. There has been a problem that more labor is required for image selection. On the other hand, if the imaging interval is set long in consideration of the capacity of the storage device and the sorting work, it becomes difficult to reliably capture a focused image of the corneal endothelium, and in some cases, it is necessary to repeat the imaging. There was also a risk of becoming.

  Further, in Patent Document 3, in order to extract an appropriate image from a plurality of captured images continuously captured in the vicinity of the focal position of the corneal endothelium, all of the captured images are once stored in a memory, and then It has been proposed to detect the degree of focus of each photographed image and selectively extract those with a high degree of focus. However, even with the measure described in Patent Document 3, it is unavoidable that a very large memory is required in the end. In addition, when the memory is accessed and the degree of focus is detected and compared, It is inevitable that the burden will increase and a considerable amount of time will be required.

  In the first place, in Patent Document 3, it is only described as “detecting the degree of focus and extracting an image with a high degree of focus”, and what is the “degree of focus”? There is no technical disclosure even regarding how to detect the image, and how to extract an image with a higher degree of focus. In short, as described in Patent Document 3, the automatic selection and extraction of an in-focus image from a plurality of continuously photographed images is also merely desired or disclosed in Patent Document 3. Is merely disclosed as a purpose.

Japanese Patent Publication No.7-112255 Japanese Patent No. 2831538 Japanese Patent Laid-Open No. 10-113335

  The present invention has been made in view of the above circumstances, and evaluates the imaging state of a plurality of images acquired by continuous imaging, reduces the burden on the subject and the examiner by shortening the examination time, and imaging by the examiner. It is an object of the present invention to provide a corneal endothelium imaging apparatus and a corneal endothelium imaging method having a novel structure capable of facilitating or omitting the subsequent sorting operation.

  Hereinafter, embodiments of the present invention made to solve the above-described problems will be described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible.

  That is, the first aspect of the present invention is to receive an illumination optical system including an illumination light source that irradiates a slit light beam obliquely with respect 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. An imaging optical system including a photoelectric element that captures a corneal image, a moving unit that moves the illumination optical system and the imaging optical system as a whole toward or away from the eye to be examined, and the photoelectric element In a cornea photographing apparatus including a storage unit that stores a captured image, the moving optical unit moves the illumination optical system and the imaging optical system as a whole by the moving unit, and the plurality of imaging optical systems at a plurality of different positions. While a corneal image is captured, a luminance information acquisition unit that acquires luminance information in a predetermined region in each of the captured images is provided, and the luminance information acquisition unit Corneal endothelium photographing apparatus based on the luminance information obtained is provided an image evaluation means for evaluating the imaging state of the corneal endothelium in the captured image Te, characterized.

  In the corneal endothelium imaging apparatus having the structure according to this aspect, the imaging state of the corneal endothelium can be automatically evaluated using the luminance information of the captured image. Therefore, for example, when the illuminating optical system and the imaging optical system are moved continuously or intermittently with respect to the eye to be inspected, and the imaging is performed by the examiner after the imaging, even when the imaging is continuously performed at different positions. There is no need to separately check the state and select an image, and the burden on the examiner can be reduced.

  In addition, the amount of information to be processed can be reduced by limiting the luminance information used for the evaluation of the imaging state to the luminance information of a predetermined area, that is, a portion (for example, a pixel) located in a predetermined area. The imaging state can be quickly evaluated in a short time.

  According to a second aspect of the present invention, in the corneal endothelium imaging apparatus according to the first aspect, the captured images are selected based on an evaluation result of an imaging state by the image evaluation unit. And

  In the corneal endothelium imaging apparatus having the structure according to this aspect, it becomes possible to preferentially store and display only a high-quality captured image with a good imaging state by the image selection means, Image handling can be more efficient and easier. In particular, as a third aspect of the present invention, in the corneal endothelium photographing apparatus having the structure according to the second aspect, the selected photographed image is stored in the storage means as a result of selection of the photographed image. A mode in which a photographed image that has not been selected is discarded before being stored in the storage means can be suitably employed.

  According to a fourth aspect of the present invention, in the corneal endothelium imaging apparatus according to any one of the first to third aspects, the storage means stores the imaging state evaluation result by the image evaluation means. The use priority order is set for each captured image.

  In the corneal endothelium imaging device structured according to this aspect, it is possible to easily discriminate a high-quality captured image with a good imaging state by setting the priority of use for the image in relation to the evaluation result of the image evaluation means, The convenience of using the captured image is improved.

  According to a fifth aspect of the present invention, in the corneal endothelium photographing apparatus according to the fourth aspect, an image display means for displaying the photographed image stored in the storage means based on the use priority order is provided. It is characterized by.

  In the corneal endothelium imaging apparatus configured according to this aspect, based on the priority of use, an image with a high priority, that is, a high-quality captured image with a good imaging state is preferentially or selectively imaged. It can be displayed on the display means. Therefore, the in-focus image can be automatically identified and confirmed by visual recognition, or used for diagnosis.

  According to a sixth aspect of the present invention, in the corneal endothelium imaging device according to any one of the first to fifth aspects, the luminance information acquisition means is a pixel located on at least one straight line on the captured image. The luminance information is acquired.

In the corneal endothelium imaging apparatus having the structure according to this aspect, by limiting the predetermined area for acquiring the luminance information by the luminance information acquisition unit to a straight line extending in the left-right direction of the image,
The amount of information to be processed can be more advantageously suppressed, and the processing speed can be further increased. Moreover, by acquiring luminance information for each pixel on a straight line extending in the left-right direction of the image, which is the direction in which the corneal endothelium image is taken with a shift before and after the in-focus position, the luminance information necessary for evaluation of the imaging state is secured. It is possible to achieve sufficient evaluation accuracy. In this aspect, the predetermined area for acquiring the luminance information does not necessarily need to be an area on a single straight line, and may be an area on a plurality of straight lines separated in the vertical direction of the image. According to this, it becomes possible to realize a more accurate evaluation of the imaging state. In this embodiment, the horizontal direction of the image is, as is apparent from the above description, the image (with the movement of the illumination optical system and the imaging optical system of the apparatus as a whole in the approach / separation direction with respect to the eye to be examined. In the screen, the image of the corneal endothelium moves.

  According to a seventh aspect of the present invention, in the corneal endothelium imaging device according to any one of the first to sixth aspects, the image evaluation unit obtains the luminance information of the pixel acquired by the luminance information acquisition unit. And a first imaging state determining means for obtaining the number of pixels having a luminance higher than a preset luminance threshold based on the above.

  In the corneal endothelium imaging device having the structure according to this aspect, the imaging state of the corneal endothelium captured at a relatively high luminance in the corneal structure is calculated by calculating the number of pixels having a luminance higher than a preset threshold value. It can be evaluated with simple processing. Note that the threshold in this aspect is set based on the luminance of corneal endothelium imaging at the in-focus position. For example, the presence of the corneal endothelium in the image can be identified by setting the luminance level to be lower than the luminance level of the corneal endothelium image and higher than the luminance level of the corneal substance or anterior chamber image.

  In addition, according to an eighth aspect of the present invention, in the corneal endothelium imaging device according to any one of the first to seventh aspects, the luminance information of the pixel acquired by the luminance information acquisition unit is acquired by the image evaluation unit. And a second imaging state determining means for detecting the horizontal position of the corneal endothelium on the image based on the above.

  In the corneal endothelium imaging apparatus having the structure according to this aspect, the imaging state of the corneal endothelium can be effectively evaluated by determining the position of the corneal endothelium on the image. The second luminance information processing means is not particularly limited. For example, among the pixels having luminance exceeding the threshold set in the third aspect, right and left on the image It is realized by detecting the pixel located at either end and detecting the position in the left-right direction on the image of the pixel located at the end, thereby specifying the position in the left-right direction on the image of the corneal endothelium. I can do it.

  According to a ninth aspect of the present invention, in the corneal endothelium imaging device according to any one of the first to eighth aspects, the image evaluation unit obtains luminance information of a pixel acquired by the luminance information acquisition unit. And a third imaging state determination unit that calculates a sum of luminance value differences between pixels adjacent in the horizontal direction in the captured image.

  In the corneal endothelium imaging apparatus having the structure according to this aspect, it is possible to calculate the sum of luminance value differences between pixels adjacent in the left-right direction of the image and evaluate the imaging state of the corneal endothelium using the calculated value. In other words, since the difference in luminance value between pixels adjacent to the corneal endothelium is relatively large compared to other parts constituting the cornea, the imaging state of the corneal endothelium is calculated by calculating the sum of the luminance value differences. Can be effectively evaluated.

  Further, the present invention captures a cornea image by receiving an illumination optical system including an illumination 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. An imaging optical system including a photoelectric element, moving means for moving the illumination optical system and the imaging optical system as a whole toward or away from the eye to be examined, and a captured image captured by the photoelectric element A corneal endothelium imaging method for obtaining and acquiring a target endothelium-focused image using a cornea imaging device having a storage means for storing the illumination optical system and the imaging optical system by the moving means. As a whole, a plurality of cornea images are continuously captured by the imaging optical system at a plurality of different positions, and brightness information in a predetermined region is acquired in each captured image, and the acquired brightness is acquired. Based on the information to evaluate the imaging state of the corneal endothelium in the captured image, selectively storing and / or corneal endothelium photographing method in which displaying a plurality of corneal image by using such evaluation results, characterized.

  According to such a method of the present invention, various technical effects similar to those described in the above-described corneal endothelium imaging apparatus according to the present invention can be exhibited. In carrying out the method of the present invention, as described above, it is possible to select or selectively display a large number of images using the luminance information acquired for each image. Further, when implementing the method of the present invention, more specifically, as a method for evaluating the imaging state of the corneal endothelium based on luminance information, the luminance information of pixels located on a straight line extending in the horizontal direction is used or preset. The number of pixels having a luminance level larger than the luminance threshold value used, the information specifying the position of the corneal endothelium on the image based on the pixel position information of the luminance level corresponding to the corneal endothelium, etc. Aspects can be employed. These specific aspects can be made clearer from the description of the present invention and the dictated embodiment of the above-described apparatus.

  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 corneal endothelium imaging 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. Further, a plurality (two in the present embodiment) of observation light sources 30 and 30 are arranged in front of the eye E to be examined. As the observation light sources 30, 30, for example, infrared LEDs that emit infrared light beams 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 is converted into a slit light beam through the condenser lens 38 and the slit 36, reflected by the cold mirror 34, and then irradiated to the cornea C from the oblique direction through the projection lens 32. It has become so.

  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 visible light LED and an infrared filter, for example. 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, it is possible to reduce the burden on the subject when irradiating the light beam from the observation light source 54 such as alignment.

  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, and then converted into a parallel light beam by the slit 56. The light is reflected by the cold mirror 27 through the lens 60 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 index 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 corneal endothelium imaging apparatus 100 shown in FIG. The corneal endothelium imaging 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. In addition, the main body unit 104 accommodates each control circuit, which will be described later, and is provided with a display screen 110 as an image display unit including, for example, a liquid crystal monitor.

  Further, as shown in FIG. 3, the corneal endothelium imaging apparatus 100 is provided with a drive unit that moves the apparatus optical system 10 toward or away from the eye E by driving the case 106. Yes. 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.

  In addition, the corneal endothelium imaging apparatus 100 is provided with an imaging control circuit 117 as imaging control means for performing operation control of imaging of a corneal 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 corneal endothelium imaging 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 storage means.

  Next, in the corneal endothelium 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 apparatus optical system 10 is aligned in the X direction and the Y direction (XY alignment) with respect to 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 12 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 12 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 blinking, and the light source 82, 30 is recognized as being 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 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 focusing 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 from the time when the position reaches the rear position (P2 in FIG. 8) by a predetermined distance: D2 (see FIG. 7) from the corneal endothelial cell position. 40 light emission starts. In the present embodiment, the predetermined distance from the corneal endothelial cell: D2 is determined from a predetermined threshold at which the light amount distribution detected by the line sensor 44 is slightly smaller than the second peak portion 130. The separation distance is. Further, the specific value of the predetermined distance: D2 is preferably a value having a certain margin so that the corneal endothelial cells can be reliably captured in consideration of the detection accuracy of the line sensor 44 and the positional deviation of the eye E to be examined. However, when the predetermined distance: D2 increases, the light emission time of the imaging light source 40 becomes longer, increasing the burden on the subject. Therefore, the predetermined distance: D2 is preferably a value in the range of 200 to 500 μm. Is done. 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 performed, for example, as shown in FIG. 9, one or more (in this embodiment, five) appropriate horizontal lines in the image 132 taken by the CCD 28: 11 to 15 From the luminance value of the upper pixel, it is determined that the reflected light from the corneal endothelial cell is detected based on the number of pixels having a luminance value equal to or higher than a predetermined value. 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. In consideration of the above, the luminance values of the respective pixels on the five horizontal lines: l1 to l5 on the image 132 are detected. Then, the number of pixels having a luminance value of 25 to 255 in each pixel on the horizontal lines: l1 to l5 is counted. Note that the luminance values 25 to 255 are amounts of light that can recognize reflected light that is clearly visible. And the average value of the number of pixels counted in the horizontal lines: l1 to l5, or the maximum value of the number of pixels counted in the horizontal lines: l1 to l5 is approximately 30 μm in terms of the distance on the corneal endothelium. The position corresponding to the amount of reflected light is 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.

  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, the range of 200 μm or more can be suitably adopted as the range for moving at low speed and performing continuous imaging in consideration of the fine movement of the eye E. 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. The acceleration may be started or acceleration may be started when a predetermined time has elapsed from the start of imaging, or may be used in combination as appropriate.

  Further, when the apparatus optical system 10 is accelerated and reaches a relatively high speed before the deceleration 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).

  10 to 14 show corneal endothelial cell images captured at each position in the process in which the apparatus optical system 10 is moved backward. First, FIG. 10 is an image of a corneal endothelial cell in the vicinity where the reflected light from the corneal endothelium is received by the CCD 28 (in the vicinity of P3 in FIG. 8). At such a position, the anterior chamber-corresponding portion 134 is imaged in almost all areas of the screen, and the corneal endothelial cells 136 are only slightly visible at the right end of the screen. The anterior chamber equivalent portion 134 is imaged dark because the irradiation light is transmitted through the anterior chamber and almost no reflected light is obtained. FIG. 11 is a corneal endothelial cell image in the vicinity of the start of low-speed movement (in the vicinity of P4 in FIG. 8). In such a position, the left end portion of the corneal endothelial cell 136 is positioned on the left side of the screen more than the vicinity of P3 (FIG. 10), and the corneal endothelial cell 136 is imaged larger. FIG. 12 is a corneal endothelial cell image in the vicinity of the in-focus position with corneal endothelial cells (in the vicinity of P5 in FIG. 8). At such a position, the corneal endothelial cell 136 is imaged most greatly. Note that the corneal stroma 138 is imaged darker than the corneal endothelial cell 136 at the right end of the screen. FIG. 13 is a corneal endothelial cell image near the end of low-speed movement of the apparatus optical system 10 (in the vicinity of P6 in FIG. 8). In such a position, the right end portion of the corneal endothelial cell 136 is positioned on the left side of the screen as compared with the vicinity of P5 (FIG. 12), and the corneal endothelial cell 136 becomes smaller and the corneal epithelium 140 is imaged on the right end of the screen. Is done. FIG. 14 is a corneal endothelial cell image in the vicinity of acceleration after the low-speed movement of the apparatus optical system 10 (in the vicinity of P7 in FIG. 8). At such a position, the corneal endothelial cell 136 is only slightly imaged at the left end of the screen, and the corneal epithelium 140 is imaged greatly. In this way, the corneal endothelial cell image is gradually imaged as it goes from the rear of the corneal endothelium to the in-focus position with the corneal endothelium, and is captured at the in-focus position with the corneal endothelium. Then, as the corneal endothelium is further moved backward from the focus position (endothelium focus position), the image is gradually made smaller.

  15 to 19 show the luminance distribution in each corneal endothelial cell image of FIGS. 10 to 14. According to the luminance distribution diagrams shown in FIGS. 15 to 19, the corneal endothelial cell 136 is imaged with a relatively high luminance, while the anterior chamber corresponding portion is positioned on both the left and right sides of the corneal endothelial cell 136 on the image. It is clear that both 134 and corneal stroma 138 are imaged with low brightness, and the corneal epithelium 140 is imaged with extremely high brightness.

  Furthermore, in continuous imaging, as described above, corneal endothelial cells 136 are gradually imaged as they approach the endothelium focus position, so that the focus position is reached as shown in FIGS. As it gets closer, the brightness of the image pickup becomes higher (the image pickup becomes brighter). Then, when the in-focus position is passed, as shown in FIGS. 17 to 19, the brightness of imaging once decreases and then increases rapidly. That is, the imaging of the corneal epithelium 140 is extremely high in luminance, and the corneal epithelium 140 is gradually increased in size after passing the endothelium in-focus position.

  Here, in this embodiment, paying attention to the correlation between the distance from the endothelium focus position and the change in the luminance value of the imaging, the imaging state of the corneal endothelial cell 136 in the captured image is evaluated, and the image selection is automatically performed. To be executed.

  Hereinafter, a method for selecting an image in the image selection circuit 122 in S6 will be described. Note that the image selection circuit 122 in this embodiment includes an image data acquisition circuit 142, a luminance information acquisition circuit 144 as luminance information acquisition means, and a first imaging state, as shown in a block diagram in FIG. A determination circuit 146; a boundary position confirmation circuit 148; a second imaging state determination circuit 150; a luminance value difference calculation circuit 152; a storage availability determination circuit 154; and a third imaging state determination circuit 156. Yes.

  FIG. 21 is a flowchart showing the process in S6. That is, in this embodiment, each process of selecting an image by the image selection circuit 122, storing the selected image by the storage device 124, and setting the priority order of the stored image by the priority order setting circuit 158 is performed in S6. Executed.

  More specifically, first, in S61, the number of times of photographing: X is set to 0 which is an initial value. Next, in S62, 1 is added to the number of times of photographing: X. Thereby, a natural number indicating the number of photographing is set as X. As will be described later, in the case of repeatedly performing shooting and image selection processing, the number of shooting times: X is added in S62 to indicate the number of shooting and selection processes.

  Next, in S 63, the cornea is imaged by the CCD 28, and the image data acquisition circuit 142 acquires image data of the cornea captured image 132 imaged by the CCD 28.

  Further, in S <b> 64, the luminance information acquisition circuit 144 acquires luminance information of each pixel in a predetermined region of the captured image 132 acquired by the image data acquisition circuit 142. In particular, in the present embodiment, as shown in FIG. 9, the luminance of pixels on one or more lines (in this embodiment, five horizontal lines 11 to 15) extending in the horizontal direction of the captured image 132. Get information. Thereby, the processing speed can be improved by suppressing the data amount of luminance information processed in the first imaging state determination circuit 146 described later. In this embodiment, the luminance information of the pixels located on the horizontal line extending in the left-right direction on the image is acquired. However, the luminance information is acquired for pixels on the line extending in other directions such as the vertical direction and the diagonal direction. You may come to get.

  In S65, the luminance information acquired by the luminance information acquisition circuit 144 is processed by the first imaging state determination circuit 146 as the first imaging state determination unit, and the imaging state of the captured image 132 is determined. Although the first imaging state determination circuit 146 is not particularly limited, in the present embodiment, for example, the luminance information of the captured image 132 acquired by the luminance information acquisition circuit 144 is used to set in advance before shooting. It is determined whether or not a pixel having a luminance value higher than the luminance value threshold value is present on the captured image 132. Note that the preset threshold value of the luminance value is set based on the luminance value of an image obtained by photographing corneal endothelial cells at the time of focusing.

  Here, when the first imaging state determination circuit 146 does not detect a pixel having a luminance higher than the threshold value, it is estimated that the corneal endothelium image is not captured in the captured image 132. Therefore, it is evaluated as an image with a poor imaging state (not useful) and discarded. In this case, the process after S6f mentioned later is performed.

  On the other hand, when the first imaging state determination circuit 146 detects a pixel having a luminance higher than the threshold value, it is evaluated that the imaging state is good. In this case, in S <b> 66, the boundary position confirmation circuit 148 detects the boundary between the area where the pixel having the luminance exceeding the threshold value and the area where the pixel does not exist on the captured image 132. That is, as shown in FIG. 22, by detecting the pixel located at the left end of the captured image 132 in the horizontal direction in the pixels having the luminance exceeding the threshold, the imaging having the pixel having the luminance higher than the threshold is present. A boundary on the image 132 can be detected. In the present embodiment, as shown in FIG. 23, position numbers (X1, X2, X3...) Indicating the number of pixels from the left side in the image with respect to each pixel on the line. Xn) is attached, and as shown in FIG. 22, the position number (Xa) of the pixel located at the leftmost end among the pixels having luminance higher than the threshold (La) on the captured image is acquired. By doing so, the boundary can be specified.

  Then, in S65, it is determined whether or not the pixel located on the detected boundary (Xa in FIGS. 22 and 23) is located within a preset area on the image (Rl in FIG. 22). The second imaging state determination circuit 150 makes the determination. Thus, the boundary between the anterior chamber a and the corneal endothelium en on the captured image 132 in the corneal structure can be detected, and the left-right position on the image of the corneal endothelium en captured can be determined. Note that the predetermined area: Rl is set so that the imaging is in the vicinity of the in-focus position when the left end of the corneal endothelium en is positioned in the area.

  Here, when it is determined by the second imaging state determination circuit 150 that the pixel located on the boundary (Xa in FIGS. 22 and 23) is positioned outside the predetermined region (Rl in FIG. 22). For example, it is estimated that the imaging of the corneal endothelial cell 136 is shifted in the left-right direction in the image (for example, the imaging shown in FIG. 10 and the luminance distribution as shown in FIG. 15). Therefore, when the left end boundary of the high brightness region is positioned outside the predetermined region, it is evaluated that the image looks bad (unusable image), and the captured image 132 is discarded. . In this case, the process after S6f mentioned later is performed.

  On the other hand, when it is determined by the second imaging state determination circuit 150 that the pixel located on the boundary (Xa in FIG. 22) is located within the range of the predetermined region (Rl in FIG. 22), The imaging of the corneal endothelial cell 136 is estimated to be a good image in the imaging state positioned at the approximate center in the image (for example, the imaging shown in FIG. 12, as shown in FIG. 17. Shows the luminance distribution). In this case, in S68, the average value of the sum of the luminance value differences between adjacent pixels is calculated for the newly captured image 132 and the captured image stored in the storage device 124.

  That is, in S68, the luminance value difference calculation circuit 152 performs the horizontal lines: l1 to l5 for the pixels (X1 to Xn) on the lines of the horizontal lines: l1 to l5 from which the luminance information is acquired in S64, respectively. Based on Equation 1, (i) the absolute value of the luminance value difference between adjacent pixels in the horizontal direction is obtained, and (ii) the sum of the luminance value differences is obtained. And the average value of the sum total of the luminance value difference calculated | required for every horizontal line: l1-l5 based on Numerical formula 1 is calculated.

  In S69, the storage possibility determination circuit 154 determines whether or not the number of photographed images stored in the storage device 124 is equal to the number of images that can be stored in the storage device 124. Note that the storage possibility determination circuit 154 does not necessarily determine the number of images. For example, the used capacity that already stores image data is subtracted from the total amount of data that can be stored in the storage device 124. Thus, the available capacity of the storage device 124 may be calculated, and it may be determined whether or not the data size of the captured image 132 is larger than the available capacity of the storage device 124. According to this, it is possible to accurately grasp the number of storable sheets and to secure a larger number of images.

  Then, when the number of images already stored in the storage device 124 is not equal to the number of images that can be stored in the storage device 124, the processing after S6c described later is executed.

  On the other hand, when the number of images already stored in the storage device 124 is equal to the number of images that can be stored in the storage device 124, in S6a, the difference in luminance value between adjacent pixels in the captured image 132 calculated in S68. The third imaging state determination circuit 156 determines whether or not the average value of the sum is larger than the minimum value of the average value of the sum of the luminance value differences in the images stored in the storage device 124.

  Note that the average value of the sum of luminance value differences is recognized as an image obtained by capturing a corneal endothelial cell image in a wider range as the value increases. That is, as schematically shown in FIGS. 24 and 6, for example, a photographed image of the anterior chamber a is a dark image as a whole because an irradiation light beam is transmitted through the aqueous humor and almost no reflected light beam is obtained. It becomes. Further, since the corneal 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 an overall dark image (for example, shown in FIG. 10). That is the image, and the luminance distribution is as shown in FIG. Furthermore, since the amount of reflected light is large in the corneal epithelium e, the entire image becomes bright and uniform (for example, the image shown in FIG. 12 has a luminance distribution as shown in FIG. 17). Accordingly, the images of these parts are adjacent to each other, but the difference in the luminance values is 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 becomes large. The sum of the luminance value differences becomes large (for example, the image shown in FIG. 14 has such a luminance distribution as shown in FIG. 19).

  Therefore, in the third imaging state determination circuit 156, it is determined that the average value of the sum of the luminance value differences of the newly photographed image 132 is less than or equal to the minimum value of the average value of the sum of the luminance value differences of the stored photographed images. If it is determined that the corneal endothelium image is captured in an inferior state (not an image photographed in the vicinity of the corneal endothelium in-focus position), the photographed image 132 is discarded and the processing after S6f described later is executed. .

  On the other hand, in the third imaging state determination circuit 156, it is determined that the average value of the sum of the luminance value differences of the newly photographed image 132 is larger than the minimum value of the average value of the sum of the luminance value differences of the stored photographed images. In this case, it is evaluated that the imaging state of the corneal endothelium image is a good image (an image taken in the vicinity of the corneal endothelium in-focus position). In this case, in S <b> 6 b, among the captured images stored in the storage device 124, the data of the image having the smallest average sum of luminance value differences is discarded, and a new captured image 132 is stored in the storage device 124. The free space to be stored is secured, and the captured image 132 is stored in the storage device 124 in S6c. As a result, an image in which the corneal endothelial cell image is effectively obtained and in a good imaging state can be preferentially stored in the storage device 124. In the present embodiment, the third imaging state determination unit includes a luminance value difference calculation circuit 152 and a third imaging state determination circuit 156.

  In the present embodiment, before performing the above determination, pixels having a luminance value of 240 or more continuously span a range of about 50 μm to 100 μm on a predetermined horizontal line (for example, the horizontal lines: 11 to 15). In such a case, such an image may be 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, it is possible to exclude an image in which a part of the corneal epithelium is shown by using the above-described determination criterion.

  In the present embodiment, the captured image 132 is stored in the storage device 124 to be a stored image. In S6d, the priority order setting circuit 158 performs the third imaging state determination circuit 156 on the stored image. Usage priorities are assigned based on the evaluation results. Using this priority order, for example, the order of image data is automatically changed (the image files are arranged in the order of priority), or the display order on the display means to be described later is automatically changed (priority). It is possible to realize priority or selective display based on the order of the order), automatic determination of necessity of printing (selectively printing an image with high priority), or the like. As a result, it is possible to easily grasp the more detailed imaging state based on the priority order of use for the stored images that have been evaluated as having a good imaging state. Note that the usage priority order set by the priority order setting circuit 158 is set for all images including the captured image 132 and the stored image, for example, between the processing of S68 and S69. May be. In this case, the priority order can be used for evaluation of the imaging state in the third imaging state determination circuit. That is, the third imaging state determination circuit may select an image with the lowest priority (an image evaluated as having the worst imaging state) and discard the selected image in S6b.

  In the present embodiment, the selection is executed by obtaining an average value for each image from the sum of the luminance value differences calculated for each of the horizontal lines: l1 to l5 in S68, and comparing the values between the images. However, it is not always necessary to use the average value. For example, the maximum value or the minimum value in the sum of the luminance value differences calculated for each of the horizontal lines 11 to 15 is obtained and compared between the images. You may make it discard the image which shows the minimum numerical value.

  As is clear from the above, the image evaluation means in this embodiment is configured including the first to third imaging state determination circuits 146, 150, and 156. In the present embodiment, the first to third imaging state determination circuits 146, 150, and 156 evaluate the imaging state of the image, and automatically select an image based on the evaluation result. .

  In S6f, it is determined whether or not the number of times of photographing: X is equal to the number of times of photographing (total number of times of photographing): A. Then, when X = A, the selection process of shooting and imaging is finished. On the other hand, if X <A, the processing after S62 is executed again, and the continuous shooting and imaging selection processing is continued. Note that the end of shooting is not necessarily determined based on the number of times of shooting, but the elapsed time from the start of shooting, the operating state of the apparatus optical system 10 (for example, the moving speed and acceleration of the apparatus optical system 10, the position of the apparatus, etc. ) Or the like.

  As described above, the image selection circuit 122 automatically selects the captured image. Note that the acquired captured image can also be displayed on the display screen 110. In this case, based on the sum of the luminance value differences calculated in S68, an image with a good shooting state is selectively or preferentially displayed from among a plurality of images stored in the storage device 124. Is also possible. In the present embodiment, a plurality of captured images are stored in the storage device 124, and these images are arranged in order from an image with a good determination result (an image with a large sum of luminance value differences) according to the determination result of the imaging state. Display on the monitor. Such display on the monitor is not essential. For example, a number is assigned to the file name of the captured image data stored in the storage device 124 in the order of the determination result of the captured state, and the captured state of each acquired captured image data is indicated. You may make it easy to grasp. In addition, for example, in the present embodiment, a plurality of corneal endothelium images stored in the storage device 124 are all acquired as image data, and an image determined to have a good imaging state is selectively and automatically selected. You may make it print.

  In the corneal endothelium imaging apparatus 100 having such a structure, the apparatus optical system 10 is moved from the back of the cornea C, and the position of the corneal endothelial cell is detected by the reflected light at the rear end of the endothelium of the cornea C. Therefore, the position of the corneal endothelial cell can be accurately detected without being affected by reflected light from the corneal stroma or the like. And since the reflected light from such corneal endothelial cells is actually reflected from the eye E, regardless of the corneal thickness difference for each subject, the position of the corneal subject cell can be accurately determined. Can be detected. Therefore, the corneal endothelial cell image can be reliably captured.

  Further, in this embodiment, since the image selection circuit 122 automatically selects a captured image, only an image with a good imaging state can be handled. As a result, it is possible to eliminate the work of the examiner selecting a plurality of images acquired by continuous imaging according to the state of reflection, thereby improving work efficiency and reducing the work load of the examiner. .

  In particular, in the present embodiment, the imaging state of a captured image can be quickly evaluated by using the luminance values of pixels located on specific horizontal lines: l1 to l5. Therefore, it is possible to prevent the photographing time from being significantly extended by sorting the photographed images together with the photographing, and to avoid an increase in the burden on the subject or the examiner at the time of photographing.

  In addition, the imaging state can be evaluated with high accuracy by using the luminance values of the pixels located on the plurality of horizontal lines: l1 to l5. Therefore, it is advantageously prevented that useful images are discarded or unnecessary images are stored due to misselection of imaging, and it is necessary to take another image, and the examiner does not have to perform image selection work separately. It is possible to advantageously avoid the occurrence of a situation that must not occur.

  In the present embodiment, the presence of high-luminance pixels exceeding the threshold value by the first imaging state determination circuit 146, the horizontal position on the image of the high-luminance pixels by the second imaging state determination circuit 150, the third The imaging state determination circuit 156 determines the contrast between the pixels, and evaluates the imaging state (image quality) of the image based on the result. Therefore, it is possible to more advantageously avoid erroneous selection of the photographed image and to evaluate the reflected state of the photographed image with higher accuracy. In addition, the capacity of the storage device 124 can be reduced more advantageously.

  As mentioned above, although one embodiment of the present invention has been described in detail, the present invention is not limited in any way by the specific description in the embodiment, and various changes, modifications, and modifications based on the knowledge of those skilled in the art. Needless to say, the present invention can be implemented in a mode with improvements and the like, and all such modes are included in the scope of the present invention without departing from the gist of the present invention.

  For example, the apparatus optical system 10 is merely an example, and the configurations and arrangement positions of lenses and slits constituting each optical system are not limited to the configurations described above. For example, in the above-described embodiment, the cold mirror 27 is disposed on the optical axis O1 of the observation optical system 12. However, for example, instead of the cold mirror 27, a mirror that totally reflects the received light beam is used as the optical axis O1. The light beam from the imaging light source 40 may be disposed at a position deviated from the top and reflected to the CCD 28. Here, the observation light sources 30 and 30 are not necessarily infrared light sources, and visible light sources may be used. Alternatively, a mirror that totally reflects the received light beam is movably disposed on the optical axis O1 of the observation optical system 12, and the light beam of the imaging optical system 20 is guided to the CCD 28 while shielding the light beam of the observation optical system 12. Alternatively, it may be moved to a position deviated from the optical axis O1 of the observation optical system 12 so that any one of the states in which the light beam of the observation optical system 12 is guided to the CCD 28 may be alternatively expressed. Further, the positions of the observation light source 54 and the line sensor 44 may be exchanged.

  The line sensor 44 in the above-described embodiment is not necessarily required. For example, after detecting the corneal epithelial position using the CCD 28, the position advanced toward the eye E by a predetermined distance is set as the inversion position. The reverse operation may be started from the reverse position. Specifically, reflected light from the eye E to be examined by the imaging light source 40 is received by the CCD 28 while the apparatus optical system 10 is advanced toward the eye E to be examined. The apparatus optical system 10 is advanced until the reflected light from the corneal epithelium is detected by the CCD 28. Here, the detection of the reflected light from the corneal epithelium can be performed, for example, in substantially the same manner as in the case of detecting the reflected light from the corneal endothelial cells (S5 in FIG. 4). That is, the luminance value of a predetermined number (for example, five) of pixels on the horizontal line is acquired from the image received by the CCD 28, and the number of pixels having a luminance value equal to or higher than the predetermined value corresponding to the reflected image from the corneal epithelium. It is determined that the reflected light from the corneal epithelium has been detected when the number exceeds the predetermined number.

  Then, from the position where the reflected light from the corneal epithelium is detected, the corneal thickness is taken into consideration, and a predetermined distance that can reach the back of the corneal endothelial cell (for example, the distance shown in FIG. 7 in the above embodiment: D1), The apparatus optical system 10 is further advanced. Thereby, the apparatus optical system 10 can be positioned at substantially the same position as the inversion start position in the above-described embodiment. Then, the reversing operation is started from this position, and imaging is started. In such an embodiment, the imaging light source 40 has already started to emit light at the start of the backward operation since the light emission is started from the start of the forward operation in order to detect the reflected light from the corneal epithelium. You will be harassed.

  According to such an aspect, since the line sensor 44 is also unnecessary, an accurate corneal endothelial cell image can be captured with a simpler configuration. Further, since the configuration is simplified, the corneal endothelium imaging apparatus can be downsized.

  In the embodiment, the first to third imaging state determination circuits 146, 150, and 156 are employed as the image evaluation unit. However, as the image evaluation unit, the pixels located in a predetermined region on the image are used. Any device using luminance information may be used.

  That is, in the above embodiment, an example in which the imaging state is evaluated using the presence / absence of a high luminance pixel, the position of the high luminance pixel, and the contrast of the pixel is shown. The imaging state can also be evaluated using the ratio of the left and right lengths (x in FIGS. 12 to 14) of the luminance pixel existing area. In addition, for example, it is possible to calculate the ratio of the number of high-luminance pixels to the total number of pixels in the entire image, and to evaluate the imaging state based on the calculation result.

  In the embodiment, in S65, the boundary position between the anterior chamber a and the corneal endothelium en in the corneal structure is detected, and the position of the corneal endothelium en in the left-right direction of the captured image is determined using the boundary position. However, the means for determining the position of the corneal endothelium en in the left-right direction is not limited to that specifically shown in the embodiment.

  Specifically, for example, the boundary between the corneal endothelium en and the corneal stroma s in the corneal structure can be detected, and the position of the corneal endothelium en in the left-right direction of the captured image can be determined using the boundary position. . That is, as shown in FIG. 22, in S66, the position number (Xb) of the pixel located at the right end in the photographed image among the pixels having the luminance value exceeding the preset luminance threshold: Lb is defined as the boundary. It is acquired as position information, and it is determined whether or not the pixel (Xb) located at the right end is located within a predetermined region: Rr in the left-right direction of the image. Thereby, the imaging state can be determined by detecting the left-right direction position on the image of the corneal endothelium en. It should be noted that in step S65, the determination of the appearance of the corneal endothelium en using the boundary position between the anterior chamber a and the corneal endothelium en, and the determination of the appearance of the corneal endothelium en using the boundary position between the corneal endothelium en and the corneal stroma s described above. In combination, it is possible to determine the degree of reflection with high accuracy. Alternatively, only one of them may be determined to quickly determine the degree of reflection of the corneal endothelium en.

  Further, for example, as shown in FIG. 25, a lower limit threshold value: Lmin and an upper limit threshold value: Lmax are respectively set as luminance threshold values, and based on the number of pixels having luminance values intermediate between Lmin and Lmax. It is also possible to evaluate the image quality. That is, if the ratio of the luminance information of the pixel having a luminance value between Lmin and Lmax to the total number of pixels acquired is large, it can be determined that the appearance of the corneal endothelium en is good. Note that Lmin, which is the lower threshold value of the luminance value, is set based on the luminance value when the corneal endothelium en is imaged at the time of focusing, and Lmax, which is the upper threshold value of the luminance value, is acquired when the corneal epithelium e is imaged. The luminance value is set as a reference. In addition, by using the sum of the horizontal lengths of pixel groups that are continuously positioned between Lmin and Lmax, the region where the corneal endothelium en is reflected on the captured image can be more accurately grasped, It is also possible to increase the accuracy of determining the image quality. Furthermore, by detecting the number and continuity of pixels having a luminance value of Lmin or less and pixels having a luminance value of Lmax or more, it is possible to grasp the reflection of each part of the corneal structure on the image more accurately. Could be possible.

  In the above embodiment, it is determined whether or not the boundary position of the pixel having the luminance exceeding the threshold is positioned on the predetermined region Rl, and the imaging state is evaluated. As shown in FIGS. 15 to 19, a threshold value (Xs) in the left-right direction may be set, and the imaging state of the image may be evaluated based on the numerical value | Xa−Xs |. That is, it can be recognized that the smaller the numerical value of | Xa−Xs |, the better the image in the imaging state that is captured at a position closer to the corneal endothelium in-focus position.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing for demonstrating the optical system as one Embodiment of this invention. Explanatory drawing for demonstrating the corneal endothelium 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 corneal endothelium 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 a change in 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. The corneal endothelial cell image corresponding to the position of P3 in FIG. The corneal endothelial cell image corresponding to the position of P4 in FIG. The corneal endothelial cell image corresponding to the position P5 in FIG. The corneal endothelial cell image corresponding to the position of P6 in FIG. The corneal endothelial cell image corresponding to the position P7 in FIG. Explanatory drawing which shows the luminance distribution of the corneal endothelial cell image shown by FIG. Explanatory drawing which shows the luminance distribution of the corneal endothelial cell image shown by FIG. Explanatory drawing which shows the luminance distribution of the corneal endothelial cell image shown by FIG. Explanatory drawing which shows the luminance distribution of the corneal endothelial cell image shown by FIG. Explanatory drawing which shows the luminance distribution of the corneal endothelial cell image shown by FIG. The block diagram which shows an image selection circuit. The flowchart which shows the selection selection procedure of a picked-up image. Explanatory drawing for demonstrating the luminance distribution waveform and threshold value setting of an endothelium focusing 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 for demonstrating the luminance distribution waveform and threshold value setting of the endothelium focus image in another one Embodiment of this invention.

Explanation of symbols

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: imaging light source, 44: line sensor, 54: observation light source, 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 110: display screen 122: image selection circuit 124: storage device 132: image 142: image data acquisition circuit 144: luminance information acquisition circuit 146: first imaging state determination circuit 148: boundary position confirmation circuit, 150: second imaging state determination circuit, 152: luminance value difference calculation circuit, 154: storage possibility determination circuit, 156: third imaging state determination circuit, 158 Priority setting circuit

Claims (10)

An imaging optical system including an illumination optical system that irradiates a slit light beam obliquely to the eye to be examined, and a photoelectric element that receives a reflected light beam from the cornea of the eye to be examined by the slit light beam and images a corneal image A moving unit that moves the illumination optical system and the imaging optical system as a whole toward or away from the eye to be examined, and a storage unit that stores a captured image captured by the photoelectric element. In a cornea photographing device equipped with
The illumination optical system and the imaging optical system are moved as a whole by the moving means so that a plurality of corneal images can be captured by the imaging optical system at a plurality of different positions, while brightness in a predetermined region in each of the captured images A cornea characterized by comprising luminance information acquisition means for acquiring information and image evaluation means for evaluating the imaging state of the corneal endothelium in the captured image based on the luminance information acquired by the luminance information acquisition means Endothelial imaging device.   The corneal endothelium imaging apparatus according to claim 1, wherein the captured image is selected based on an evaluation result of an imaging state by the image evaluation unit.   The cornea according to claim 2, wherein the selected photographed image is stored in the storage means as a result of selection of the photographed image, and the unselected photographed image is discarded before being stored in the storage means. Endothelial imaging device.   The corneal endothelium imaging apparatus according to any one of claims 1 to 3, wherein a use priority order is set for a captured image stored in the storage unit based on an evaluation result of an imaging state by the image evaluation unit.   The corneal endothelium imaging apparatus according to claim 4, further comprising an image display unit configured to display a captured image stored in the storage unit based on the use priority order.   The corneal endothelium imaging device according to any one of claims 1 to 5, wherein the luminance information acquisition unit acquires luminance information of pixels located on at least one straight line on a captured image.   The image evaluation unit includes a first imaging state determination unit that obtains the number of pixels whose luminance is higher than a preset threshold of luminance based on the luminance information of the pixels acquired by the luminance information acquisition unit. The corneal endothelium imaging device according to any one of claims 1 to 6.   The said image evaluation means is comprised including the 2nd imaging state determination means which detects the horizontal direction position of the corneal endothelium on an image based on the luminance information of the pixel acquired by the said luminance information acquisition means. The corneal endothelium imaging device according to any one of 1 to 7.   The image evaluation unit includes a third imaging state determination unit that calculates a sum of luminance value differences between pixels adjacent in the horizontal direction in the captured image based on the luminance information of the pixels acquired by the luminance information acquisition unit. The corneal endothelium imaging apparatus according to any one of claims 1 to 8, which is configured by: An imaging system including an illumination optical system including an illumination light source that irradiates a slit light beam obliquely to the eye to be examined, and a photoelectric element that receives a reflected light beam from the cornea of the eye to be examined by the slit light beam and captures a corneal image A moving unit that moves the illumination optical system and the imaging optical system as a whole toward or away from the eye to be examined, and a storage unit that stores a captured image captured by the photoelectric element. A corneal endothelium imaging method for obtaining and acquiring an image of a focused endothelium using a corneal imaging device comprising:
The illumination optical system and the imaging optical system are moved as a whole by the moving means, and a plurality of corneal images are continuously captured by the imaging optical system at a plurality of different positions, and brightness in a predetermined region in each of the captured images. The information is acquired, the imaging state of the corneal endothelium in the captured image is evaluated based on the acquired luminance information, and a plurality of corneal images are selectively stored and / or displayed using the evaluation result. And corneal endothelium imaging method.