JP4909108B2 - Corneal imaging device - Google Patents

Description

The present invention relates to a corneal imaging apparatus that irradiates a subject's eye with illumination light and receives reflected light from the cornea of the subject's eye, thereby capturing a corneal endothelial cell image, and in particular, a central portion of the cornea of the subject's eye. In addition, the present invention relates to a cornea photographing apparatus capable of taking a corneal endothelial cell image not only in a peripheral portion.

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

  When observing the cell state of such corneal endothelium, a corneal imaging apparatus that can image corneal endothelial cells in a non-contact manner with respect to an eye to be examined is known. This corneal imaging device irradiates slit-shaped illumination light (slit luminous flux) obliquely to the cornea of an eye to be examined by an illumination optical system, and receives reflected light from the cornea by an imaging optical system to image corneal endothelial cells. It is like that.

  By the way, when imaging the corneal endothelium, it may be desired to image not only the central part of the cornea but also the peripheral part of the cornea. For this purpose, the subject is fixed in an oblique direction away from the front to irradiate the peripheral portion of the cornea with a photographing slit light beam, and the reflected light beam is imaged by the photographing optical system.

  However, in that case, it is known that a clear corneal endothelium image cannot be obtained simply by setting the fixation direction of the subject obliquely. This is anatomically clear, and is well known not only by those skilled in the art of developing cornea photographing devices but also by users who use the cornea photographing devices. . That is, since the curvature of the corneal endothelium and the curvature of the corneal epithelium are different from each other as is known, XY alignment of the corneal endothelium can be performed at the central portion of the cornea using specular reflection light from the corneal outer skin, This is because, when the XY alignment is performed using the specular reflection light from the corneal outer skin in the same direction, the portion shifts from the optimum position of the corneal endothelium.

  That is, in a state in which the subject stares at the front in order to image the central part of the cornea, as shown in FIG. 12 (a), the optical axis (● mark) of the XY alignment light reflected by the corneal skin is reflected. Since the optical axes (× marks) of the endothelium reflected light coincide with each other, by performing XY alignment, the corneal endothelium and the corneal outer skin have the same optical central axis in the □ marks indicating the imaging region. It is possible to accurately perform the endothelium imaging. However, in a state in which the subject stares at an oblique direction in order to image the peripheral part of the cornea, as shown in FIG. 12B, the optical axis (● mark) of the XY alignment light reflected by the corneal skin is reflected. As a result, the optical axis of the corneal endothelium and the corneal outer skin are different in the □ mark indicating the imaging region even if XY alignment is performed. The imaging accuracy is greatly reduced.

  In short, in order to clearly image the corneal endothelium in the peripheral portion of the cornea, in FIG. 12B, from the center point (● point) where the XY alignment is performed, toward the corneal endothelium displacement direction (× direction), It is necessary to image the endothelium after moving and setting the imaging region (region marked by □) by a predetermined distance.

  Therefore, conventionally, when imaging a peripheral portion of the cornea using a corneal imaging device, if a clear image is not obtained by the imaging, the relative position of the imaging optical system with respect to the eye to be examined is set in an appropriate direction in the XY directions. The position of the examiner was shifted and the image was taken repeatedly until a satisfactory image was obtained. For this reason, the burden on the examiner and the subject is large, and the examiner with little experience, in particular, takes a lot of time for imaging, which may cause pain to the subject.

  Therefore, in order to cope with such a problem, in Patent Document 1 (Patent No. 2812421) and Patent Document 2 (Patent No. 3338529), the eye to be examined is based on the XY alignment signal obtained from the corneal epithelial reflected light. When performing the XY alignment of the imaging optical system with respect to the cornea, a correction amount of the XY alignment is set in advance corresponding to the position in the oblique direction where the eye to be examined is fixed, and the cornea is corrected by the correction amount corresponding to the selected fixation target. There has been proposed a cornea photographing apparatus that corrects an XY alignment position determined based on an XY alignment signal obtained by epithelial reflected light.

  In short, the techniques disclosed in Patent Documents 1 and 2 are based on the premise that the direction and amount to be corrected with respect to the oblique direction in which the subject's eye is fixed are substantially specified. To reduce the burden of Actually, the correction direction of the XY alignment, that is, the direction of the deviation direction line: α in FIG. 12B is an oblique direction in which the eye to be inspected is fixed based on the theory of the difference in curvature radius of the inner and outer corneal skin as described above. It is confirmed that it is determined with respect to the direction, and the correction amount is also a value corresponding to the inclination angle of the visual axis of the eye to be examined and the curvature radius difference between the corneal endothelium and the corneal outer skin. It can be identified from the above data.

  However, as a result of studies by the present inventor, there are several cases in which the peripheral portion of the cornea cannot be imaged with sufficient accuracy even if the XY alignment according to the techniques described in the preceding Patent Documents 1 and 2 is adopted. It also became clear that it exists. As a result of further investigation by the inventor about the cause, there are individual differences in the radii of curvature of the corneal endothelium and corneal outer skin, and the degree of this individual difference is the correction method described in Patent Documents 1 and 2. Then, it turned out that it may be so large that it may affect imaging accuracy. In particular, it should be noted that subjects who require imaging of the corneal endothelium should not be intended for all general people. It is a fact that there are many people who are required, and in such people, it must be noted that the curvature of the corneal endothelium and corneal outer skin often varies greatly.

  Considering such facts, it is certain that the anatomical statistical data adopts a correction amount set in advance as the magnitude of the individual difference in the radius of curvature of the corneal / inner coat does not cause a problem in imaging accuracy, In the corneal imaging apparatus described in Patent Documents 1 and 2 described above, the correction amount becomes inappropriate when used in an actual site, and eventually the examiner needs to fine-tune the imaging position. In this sense, the cornea photographing apparatuses described in the prior patent documents 1 and 2 must be limited to a photographing apparatus having a semi-automatic alignment mechanism.

Japanese Patent No. 2812421 Japanese Patent No. 3338529

  Here, the present invention has been made in the background as described above, and the problem to be solved is the corneal imaging apparatus provided with the semi-automatic alignment mechanism described in Patent Documents 1 and 2 described above. In comparison, subjects with greater individual differences can be automatically aligned, and even in actual usage sites, the burden on the examiner and the subject can be greatly reduced, resulting in highly accurate endothelial cells. It is possible to take images quickly

  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 feature of the present invention relating to the corneal endothelium imaging apparatus is that (A) an illumination optical system including an illumination light source that irradiates a slit light beam obliquely to the eye to be examined, and (B) the above-described slit light beam. A corneal imaging optical system including a photoelectric element that receives a reflected light beam from the cornea of the eye to be imaged to capture a corneal image, and (C) the illumination optical system and the corneal imaging optical system are When moving in the Z direction, which is the separation direction, a focusing observation light receiving element for observing the in-focus state in the Z direction, and (D) XY alignment index light is irradiated from the front toward the eye to be examined XY alignment index light irradiating means, (E) an XY alignment light receiving element for receiving specular reflection light of the index light from the cornea of the eye to be examined by the XY alignment index light irradiating means, and (F) the XY alignment. Based on the light reception signal from the optical element, the illumination optical system and the cornea imaging optical system are moved in the XY direction orthogonal to the Z direction as a whole, and the eye to be examined is aligned in the XY direction with respect to the slit light flux. (G) a peripheral fixation target that selectively orients the visual axis of the eye to be examined in a plurality of directions inclined with respect to the front; and (H) a vision of the eye to be examined by the peripheral fixation target. XY alignment imaging control means for imaging an XY alignment corneal skin image by the corneal imaging optical system with the axis oriented in the tilt direction; and (I) the XY alignment imaging control means XY alignment reference position determination that determines an XY alignment reference position as a specific position in the XY direction by evaluating optical information in the corneal skin image for XY alignment And (J) information on the XY alignment reference position determined by the XY alignment reference position determining means and information on the Z-direction in-focus position observed by the focus observation light-receiving element. Corneal endothelium image capturing control means for controlling the relative position of the illumination optical system and the corneal imaging optical system with respect to the eye to be examined, and capturing a corneal endothelial image of the eye to be examined by the corneal imaging optical system, It is in the equipped cornea photographing device.

  In such a cornea photographing apparatus having a structure according to the present invention, as in the cornea photographing apparatus described in the prior patents 1 and 2, simply “the position of the fixation target (that is, the direction of the visual axis of the subject)”. Each time the position of the subject or the fixation target is changed, without setting the XY alignment correction amount at a predetermined position (that is, a predetermined (note: wide-angled position)). In addition, the appropriate position of the XY alignment is individually measured, calculated, and determined ". Therefore, in the corneal imaging apparatus according to the present invention, it is possible to avoid a decrease in measurement accuracy due to individual differences among individual subjects as much as possible, and to stably obtain an accurate corneal endothelium image. In this sense, unlike the so-called semi-automatic corneal imaging apparatus described in the prior patent documents 1 and 2, an automatic imaging apparatus that can truly reduce the burden on the examiner and the subject can be realized. It is.

  Here, in the present invention, for example, the following configuration can be adopted. That is, in the present invention, in the XY alignment imaging control means, the XY alignment index light irradiation means causes the XY alignment index light on the optical axis of the specular reflection light by the corneal outer skin of the eye to be examined. Based on the luminance information in the obtained corneal skin image for XY alignment obtained by capturing a corneal skin image, in the XY alignment reference position determining means, on a predetermined XY direction line corresponding to the inclination direction of the visual axis. A configuration in which the XY alignment reference position is determined as an amount of deviation of the specular reflection light from the optical axis can be employed.

  As such a configuration, more specifically, for example, an XY alignment corneal skin image obtained by imaging on the optical axis of the specular reflection light by the corneal skin of the eye to be examined of the XY alignment index light, By obtaining the brightness level as optical information, calculating the boundary position of a preset brightness level in the acquired image, and analyzing where the boundary position exists in the XY alignment outer skin imaging, By estimating the curvature of the outer skin and the curvature of the corneal endothelium, the reference position for XY alignment is determined, that is, the reference position for XY alignment is the optical axis of the specularly reflected light by the corneal skin of the eye to be examined for the XY alignment index light On the other hand, it is possible to adopt a configuration for estimating how far the position is away from the position. In this aspect, for example, when determining the direction of the reference position for XY alignment with respect to the optical axis of the specular reflected light of the corneal skin of the eye to be inspected for the XY alignment index light, for example, the position of the peripheral fixation target to be adopted, in other words, In this case, it is possible to determine the direction corresponding to the inclination direction of the visual axis of the eye to be examined. However, for example, the XY alignment index light is imaged on the optical axis of the specular reflection light by the cornea outer skin of the eye to be examined. It is also possible to determine the obtained XY alignment corneal skin image obtained based on the relative positional relationship between a portion with a high luminance level and a portion with a low luminance level located across the luminance level boundary.

  In the present invention, the optical information of the XY alignment corneal outer skin image obtained by imaging the XY alignment index light on the optical axis of the specular reflection light by the corneal outer skin of the eye to be examined is used. In addition to performing XY alignment, for example, the following configuration can also be adopted. In other words, in the present invention, the XY alignment imaging control means moves the illumination optical system and the cornea imaging optical system as a whole toward the predetermined XY direction corresponding to the tilt direction of the visual axis. It is possible to employ a configuration in which the corneal skin images for XY alignment are picked up at a plurality of locations on the predetermined XY direction line.

  In this way, a plurality of XY alignment corneal skin images are captured and their optical information is used to obtain an XY alignment reference position based only on the optical information of a single XY alignment corneal skin image. Compared to the case, the target XY alignment reference position can be determined with higher accuracy by performing verification and reconfirmation using optical information in another corneal skin image for XY alignment. This makes it possible to obtain a target highly accurate corneal endothelium image more stably. Also, by comparing the optical information of a plurality of XY alignment corneal skin images taken by moving in the XY direction and analyzing the degree of change accompanying the movement in the XY direction, the curvature of the corneal skin is obtained, It is also possible to determine the reference position for XY alignment.

Furthermore, in such a configuration that images are taken at a plurality of locations on the predetermined XY direction line, for example, the following configuration (i) or (ii) may be employed.
(I) In the XY alignment reference position determining means,
Each time the XY alignment corneal skin image is imaged on the predetermined XY direction line by the XY alignment imaging control means, the captured XY alignment corneal skin image is sequentially evaluated, and the evaluation result is preset. A configuration in which the XY alignment reference position is determined by satisfying the predetermined condition and the imaging of the XY alignment cornea skin image is terminated.
(Ii) In the XY alignment reference position determining means,
A configuration in which the imaging of the corneal outer skin for XY alignment by the imaging unit for XY alignment on the predetermined XY direction line is performed up to a preset final position and is finished.

  In the present invention, for example, the following configuration may be employed. That is, in the present invention, in the imaging of the corneal outer skin image for XY alignment of the eye to be examined by the corneal imaging optical system, imaging is performed by irradiating weaker light than when the corneal endothelium image is captured by the corneal imaging optical system. A configuration can be adopted.

  Thus, the burden on the subject can be reduced by capturing the corneal outer skin image for XY alignment using the irradiation light weaker than that for capturing the corneal endothelium. Preferably, the amount of light at the time of XY alignment corneal skin image may be approximately 1/200 when corneal endothelium is imaged.

  In the present invention, for example, the following configuration may be employed. That is, in the present invention, in the corneal endothelium image capturing control means, the illumination optical system and the corneal imaging optical system are moved relative to the eye to be examined in the Z direction, and continuously at a plurality of locations on the Z direction line. In addition, it is possible to adopt a configuration that captures the corneal endothelium image.

  By acquiring a plurality of corneal endothelium images on the Z-direction line in this way, the best image can be selected from the plurality of corneal endothelium images, and as a result, focusing in the Z direction is stable. It is possible to obtain a target highly accurate corneal endothelium image more stably. Note that the configuration for continuous imaging includes both imaging when the optical system is continuously running with respect to the eye to be examined and imaging when the optical system is moved by a predetermined distance with respect to the eye to be examined. .

  In the present invention, for example, a line sensor can be employed as the focusing observation light receiving element. That is, as a light receiving element for focusing observation, a photodiode may be used to detect only the presence or absence of focusing in the Z-axis direction, but focusing is achieved in the Z-axis direction by employing a line sensor. It is possible to grasp even the front and rear positions, and focusing in the Z-axis direction can be stably performed with higher accuracy.

  In the present invention, the focus observation light-receiving element may be any element that can observe the in-focus state in the Z direction, and does not necessarily need to detect the focus position of the corneal endothelium. Specifically, for example, only the outer skin focus position may be detected. In this case, the inner skin focus position can be estimated based on the outer skin focus position. (For example, refer to the well-known techniques described in JP-A-6-63018, JP-A-8-71043, etc.) Or by adopting the above-described continuous imaging means in the Z direction, accurate A focus observation light-receiving element that does not detect the endothelium focus position can be employed.

  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 a cornea photographing apparatus as a first embodiment of the present invention. In this figure, in order to make the configuration easy to understand, the cornea photographing apparatus is shown as the apparatus optical system 10 in a state in which the housing and the like are removed.

  The apparatus optical system 10 is provided with an imaging illumination optical system 14 and a position detection optical system 16 as an illumination optical system on one side with an observation optical system 12 for observing the anterior eye part of the eye E to be examined. A position detection illumination optical system 18 and an imaging optical system 20 as a cornea imaging optical system are provided on the side of the lens.

  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 as the illumination light source 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 from an oblique direction through the projection lens 32. It is like that.

  A part of the optical axis of the position detection optical system 16 is matched with the optical axis of the imaging illumination optical system 14, and the projection lens 32, the cold mirror 34, and the light for focusing observation are received in order from the position close to the eye E. A line sensor 44 as an element is provided. A light beam irradiated from an observation light source 54 described later and reflected by the cornea 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 obliquely onto the cornea. 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 serving as the cornea imaging optical system 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 and the cold mirror 48 in order from the position close to the eye E to be examined. , A slit 56, a zoom 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 is reflected by the cold mirror 48 through the objective lens 46, and then converted into a parallel light beam by the slit 56, and the variable power lens 58 and the focusing lens. Through 60, the light is reflected by the cold mirror 27 and imaged on a CCD 28 as a photoelectric element.

  The half mirror 22 provided on the observation optical system 12 constitutes a part of the central 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 central fixation target light source 74 in order from a position close to the eye E. The central fixation target light source 74 is a light source that emits visible light such as an LED, and the luminous flux emitted from the central fixation target light source 74 is transmitted through the pinhole plate 72 and the half mirror 70 and then parallel by the projection lens 68. The light beam is reflected by the half mirror 22 and applied 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. . The alignment light source 82 emits infrared light as index light for XY alignment. The infrared light is collected by the condenser lens 80 and passes through the pinhole plate 78 to the diaphragm 76. Led. 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. The XY alignment index light irradiating means is configured by such a light beam irradiation mechanism for the eye E to be examined.

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

  The alignment detection optical system 84 includes a half mirror 26 and an alignment detection sensor (profile sensor) 88 capable of detecting the position in order from a position close to the eye E. Then, the light is irradiated from the alignment light source 82 and projected onto the cornea of the eye E on the optical axis O1 of the observation optical system 12, which is a front view of the eye E, and is specularly reflected by the cornea. The emitted light beam is reflected as it is by the half mirror 26 on the same optical axis O1 as the irradiation light from the alignment light source 82 and guided to the alignment detection sensor 88 as an XY alignment light receiving element.

  Further, in front of the eye E, there are a plurality of optical axes around the optical axis O1 of the observation optical system 12 that coincides with the front visual axis of the eye E at a position that does not affect the optical path of each optical system. A fixation lamp 89 as a peripheral fixation target is arranged in an appropriate direction. Specifically, these fixation lamps 89 are, for example, as shown in FIG. 2, when assuming a clock scale, the upper 0 o'clock and the lower 6 o'clock, and the two left and right equally, 2 o'clock, 4 o'clock, A total of six fixation lamps 89a, 89b, 89c, 89d, 89e, 89f corresponding to the respective positions at 8 o'clock and 10 o'clock are equally installed on one circumference with the optical axis O1 as the central axis. The As each fixation lamp 89, for example, a visible light LED or the like is used so that the subject can visually recognize.

  The plurality of fixation lamps 89a to 89f are selectively selected and turned on when imaging the peripheral portion of the cornea, and any one of the fixed fixation lamps 89 is turned on. The specific peripheral portion of the cornea can be positioned on the portion that is irradiated with the slit light beam and imaged by the corneal imaging optical system, in other words, on the optical axis O1 of the observation optical system 12. It has become.

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

  Furthermore, as shown in FIG. 4, the cornea photographing apparatus 100 is provided with a driving unit that moves the apparatus optical system 10 toward or away from the eye E by driving the case 106. . These driving means are constituted by, for example, a rack and pinion mechanism. In this embodiment, the X-axis driving mechanism 112 that drives the apparatus optical system 10 in the vertical X direction in FIG. 4 and the paper surface in FIG. And a Y-axis drive mechanism 114 for driving in the horizontal Y direction perpendicular to the Z-axis, and a Z-axis drive mechanism 116 for driving in the horizontal Z direction (direction along the optical axis O1 of the observation optical system 12) in FIG. Yes.

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

  Further, the cornea photographing apparatus 100 is provided with an image selection circuit 122 that receives an image received by the CCD 28 and selects the image, and stores the image selected by the image selection circuit 122. A storage device 124 is provided as a means. The corneal imaging apparatus 100 also determines an XY alignment reference position from the corneal epithelial image received by the CCD 28, and outputs information about the XY alignment reference position to the imaging control circuit 117. Is provided.

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

  The case of performing endothelium imaging at the center of the cornea of the eye E will be described first.

  First, in S1, the alignment (XY alignment) of the apparatus optical system 10 in the X direction and the Y direction is performed on the eye E. During such XY alignment, the fixation target light emitted from the central 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 set to a front view state in which the direction of the optical axis O1 of the observation optical system 12 is matched. 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. 6, the anterior segment of the eye E is displayed on the display screen 110. Since the XY alignment in this case is a front view state, it is considered that the normal direction to the tangential line between the corneal endothelium and the outer skin (the central axis (visual axis) direction that is an extension of the radius of curvature) is the same. It is sufficient to perform XY alignment based on the reflected light of the corneal outer skin (that is, it may be considered that XY alignment of the corneal endothelium can be performed).

  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.

  In addition, a part of the light beam irradiated from the alignment light source 82 and reflected by the anterior eye part (corneal outer skin) of the eye E to be examined is reflected by the half mirror 26 and guided to the alignment detection sensor 88. Yes. 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 is clear from this, in the present embodiment, the XY direction drive unit is configured to include the X axis drive mechanism 112 and the Y axis drive mechanism 114.

  As will be described later, such XY alignment is performed at an 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 the alignment is performed in accordance with the timing when the observation light source 30 is turned off and the alignment light source 82 is turned on. Detection by the detection sensor 88 is performed. 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. 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 with respect to the cornea of the eye E, and the light beam reflected from the cornea is reflected on the line sensor 44. Receives light. 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.

  Then, the reflected light beam is detected by the line sensor 44, and the light quantity distribution signal is detected by the line sensor 44. The focal position of the corneal epithelium is detected based on the light quantity distribution signal, and the imaging control circuit 117 drives the Z-axis drive mechanism 116 with reference to the detected position, and the apparatus optical system 10 is moved by a predetermined distance. Is driven forward in the approaching direction with respect to the eye E. That is, based on the detection signal of the line sensor 44, the apparatus optical system 10 moves forward so that the in-focus position in the apparatus optical system 10 is a predetermined distance behind the endothelial cells in the cornea in the Z direction. It is driven. A position behind the corneal epithelium by a predetermined distance is set as an inversion position of the apparatus optical system 10. The moving distance in the forward direction is appropriately set within a range of 1000 to 1500 μm forward from the focal position in the Z direction of the corneal epithelium.

  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. It should be noted that the moving speed of the apparatus optical system 10 can be appropriately changed and set for each appropriate moving position in both forward and reverse.

  In S4, the observation light sources 30 and 30 are turned off and the imaging light source 40 starts to emit light when the retraction operation is performed by a predetermined distance from the reversal position. 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.

  In S5, continuous imaging of the corneal endothelium image detected by the CCD 28 is started when the CCD 28 detects the reflected light from the corneal endothelial cells at a predetermined level. 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.

  As an image selection method in the image selection circuit 122, for example, the brightness value of each pixel on a plurality of horizontal lines in the image acquired by the CCD 28 is acquired, and the contrast of the image is obtained using these values. By determining, it is possible to select only images for which corneal endothelial cell images are effectively obtained.

  Then, after being moved backward by a sufficient distance including the in-focus position of the corneal endothelial cell (that is, the distance exceeding the in-focus position), in S6, the backward operation is stopped and the imaging light source 40 is turned off. The imaging is finished.

  Next, a case where endothelium imaging of the cornea peripheral portion of the eye E is performed will be described. In addition, since the operation | movement of the endothelium imaging of the peripheral part of this cornea can be performed only by the operation | movement in S1-S2 differing substantially compared with the case where the endothelium imaging of the above-mentioned cornea center part is performed, here Then, only the operation | movement by this S1-S2 is demonstrated, referring FIG. 7 which shows the step corresponded to those processes.

  That is, after starting the endothelium imaging of the peripheral portion of the cornea, first, in step Q1, only one peripheral fixation lamp 89 is selected and turned on. The examiner instructs the subject to fixate the fixed fixation lamp 89. Thus, the visual axis of the eye E is in a specific direction corresponding to the selected peripheral fixation lamp 89 with respect to the visual axis O1 in the front vision state defined by the central fixation target optical system. It is fixedly set in a state where it is inclined by a specific angle.

  Next, in step Q2, substantially the same processing as the XY alignment in step S1 is performed, and (temporary) XY alignment is executed. That is, first, the alignment light 126 emitted from the alignment light source 82 to the eye E is reflected by the corneal outer skin of the eye E, and the XY position of the reflected light from the corneal outer skin is detected by the alignment detection sensor 88. Are input to the XY alignment detection circuit 118. Based on the XY position information, the optical axis O1 of the observation optical system 12 is aligned with the optical axis of the reflected light from the corneal outer skin of the eye E, and (temporary) XY alignment is executed. Note that (provisional) is expressed here, as is known, in the state where the visual axis of the eye to be tilted, the corneal outer skin and the corneal endothelium have different radii of curvature. The light from the alignment light source 82 for XY alignment projected on the optical axis O1 at the intersection with the axis O1 is specularly reflected on the same optical axis O1, but the corneal endothelium to be imaged Since the light beam from the alignment light source 82 for XY alignment projected on the optical axis O1 is not specularly reflected on the same optical axis O1 because it is not orthogonal to the optical axis O1 at the intersection with the optical axis O1. by. That is, the above (provisional) XY alignment is mainly an alignment with respect to the reflection optical axis of the corneal outer skin, and is difficult to say an accurate XY alignment state with respect to the reflection optical axis of the corneal endothelium that is the imaging target.

  Subsequently, in step Q3, substantially the same forward operation process as in step S2 is performed. That is, the Z-axis drive mechanism 116 causes the apparatus optical system 10 to move forward in the direction approaching the eye E, and the reflected light of the infrared light beam emitted from the position detection light source 54 is received by the line sensor 44. The Z alignment detection circuit 120 detects the focal position of the corneal epithelium. Based on this detection position, the Z-axis drive mechanism 116 adjusts the position of the apparatus optical system 10 in the Z direction so that the apparatus optical system 10 is focused on the corneal epithelial cells of the eye E to be examined.

  After such position setting, in step Q4, the observation light sources 30, 30 are turned off, the imaging light source 40 is turned on, and an XY alignment corneal skin image is captured by the CCD 28 of the imaging optical system 20. At this time, the amount of light emitted from the imaging light source 40 in the imaging illumination optical system 14 is significantly smaller than the amount of light during imaging of the corneal endothelium in step S4. Specifically, for example, it is desirable that the amount of light is approximately 1/200 when imaging the corneal endothelium in step S4. In this way, in the imaging of the corneal outer skin image for XY alignment, only weaker illumination light is required than when imaging the corneal endothelium, so that the burden on the subject at the time of imaging is reduced. In the present embodiment, an imaging control unit for XY alignment is configured including the imaging illumination optical system 14, the imaging optical system 20, and step Q4. In this embodiment, the XY alignment corneal skin image is captured on the reflected optical axis of the corneal skin after the (temporary) XY alignment in Q2.

  Next, in step Q5, the XY alignment reference position is determined based on the optical information of the XY alignment corneal skin image input from the CCD 28 to the XY alignment reference position determination circuit 121. In this embodiment, the optical axis of the specular reflection light of the corneal endothelium is determined by estimating the radius of curvature of the corneal skin from the optical information of the corneal skin image for XY alignment, and estimating the radius of curvature of the corneal endothelium therefrom. The reference position for XY alignment is determined by estimating how far it is from the optical axis of specularly reflected light by the corneal outer skin of the eye to be examined.

  Here, the XY alignment corneal skin image obtained in the step Q4, for example, as shown in FIG. 10, causes each subject to similarly fix the direction of 0 o'clock (that is, in FIG. 2). Even when the corneal epithelium image for XY alignment is obtained by fixing the fixation lamp 89a, the degree of shading in the outer skin image is different for each subject. As a result of examination by the present inventor, it has been found that such individual differences in the degree of shading are mainly due to differences in the corneal epithelial curvature radius of each subject. That is, the radius of curvature of the corneal epithelium can be estimated from the degree of shading in the corneal epithelium images for XY alignment.

  More specifically, for example, the XY alignment corneal skin images of a plurality of subjects are collected in advance, and the luminance level of each pixel in each of the XY alignment corneal skin images is obtained to obtain a predetermined level. Find the boundary position between the above-mentioned luminance (bright part) and the part (dark part) that shows only the luminance below the specified level, and statistically calculate the correlation between the boundary position and the radius of curvature of the corneal skin Keep it. After that, the corneal skin image for XY alignment of the subject is taken, and the boundary position between the bright part and the dark part in the acquired image is analyzed, so that the radius of curvature of the corneal skin is estimated according to statistically obtained data. It can be done. Note that the boundary position is actually a specific reference position (for example, a position in the image corresponding to the center point of the XY alignment) in a state where XY alignment is optically performed, for example, on the corneal skin, and the boundary position. It can be handled as a distance between and the like.

  Further, as a result of the study by the present inventors, it has been found that the curvature radius of each individual corneal skin and the curvature radius of the corneal endothelium have a substantially constant correlation. For example, the curvature radius of the corneal skin and the corneal endothelium By calculating statistically the data of the correlation with the curvature radius of the corneal skin, the curvature radius of the corneal endothelium of the eye E is determined based on the curvature radius of the corneal skin obtained from the corneal skin image for XY alignment described above. You can ask. From the radius of curvature of the corneal endothelium thus obtained, the amount of deviation in the XY direction of the specular reflection optical axis of the corneal endothelium from the optical axis of the specular reflection light of the corneal outer skin can be estimated. In this way, the reference position for XY alignment at the time of target corneal endothelium imaging is obtained from the optical information of the corneal skin image for XY alignment.

  Thus, in the present embodiment, the XY alignment reference position determining means is configured including the step Q5 and the XY alignment determining circuit 121. Further, as the optical information of the corneal skin image for XY alignment used for estimation of the curvature radius of the corneal skin, in addition to the boundary position of the brightness described above, for example, the number of pixels showing brightness of a certain value or more, The radius of curvature of the corneal skin may be estimated using the number of pixels that have reached luminance saturation. Further, the radius of curvature of the corneal skin may be obtained from the rate of change in brightness within a predetermined area.

  Subsequently, in step Q6, the apparatus optical system 10 set at the corneal epithelium in-focus position is further advanced to the inversion / retraction operation start position at the time of further advance operation to the inversion position in steps S2 to S3. Let At this time, simultaneously with the forward movement in the Z direction, the apparatus optical system 10 set to the (provisional) XY alignment position in the XY direction in the step Q2 is moved in the XY direction, and the alignment optical system determined in the step Q5 is performed. Guide to the reference position. As described above, by performing the movement in the XY direction to the reference position for XY alignment simultaneously with the alignment in the Z direction, the time required for imaging the corneal endothelium is shortened, and the burden on the subject is reduced. ing.

  Thereafter, in step Q7, an alignment completion signal is output, and on the condition that this completion signal is output, the same operation as the apparatus backward / imaging operation after step S3 is performed to image the target corneal endothelium. Further, even during imaging of the corneal endothelium, XY alignment by the alignment detection sensor 88 is appropriately performed. That is, substantially in the same manner as the imaging of the corneal endothelium in steps S4 to S5, the position of the reflected light from the corneal outer skin of the alignment light source 82 is detected by the alignment detection sensor 88 when the imaging light source 40 is blinking off. Then, based on the detected position information of the reflected light and the information on the alignment reference position output from the XY alignment reference position determination circuit 121 to the imaging control circuit 117, the imaging control circuit 117 performs XY alignment. That is, with respect to the detection position of reflected light from the corneal outer skin ((temporary) XY alignment position), the reference position for XY alignment shifted in a specific XY direction by the amount of deviation calculated in step Q5, XY alignment is performed so that the imaging optical system 20 is always located. Thus, in the present embodiment, the corneal endothelial image capturing control means is configured including the imaging control circuit 117 and the steps S3 to S5.

  By performing the corneal endothelium imaging by the reference position determining means for XY eyement and the corneal endothelium image capturing control means using the reference position determined thereby, the visual axis of the eye E is in the front view state. Even in the inclined state deviating from the optical axis O1, the imaging optical system 20 is positioned at a position where the optical axis O1 is orthogonal to the corneal endothelium based on the detection signal of the reflected light of the corneal outer skin by the XY alignment light receiving system. Can be combined.

  Therefore, it is possible to automatically and stably obtain a high-accuracy and clear endothelial image even after the same imaging operation as that in the front view state, that is, without requiring special processing or operation. It is.

  In this embodiment, it should be particularly noted that, as is clear from the above description, the XY alignment of the apparatus optical system 10 is automatically and accurately adjusted not only in the direction but also in the movement distance. It becomes possible to set. In addition, since the movement distance is adjusted based on the measurement value according to each eye to be examined, a sharp endothelial image can be stably compared with the movement setting based on statistical data as in the prior art. It becomes possible to obtain.

  Next, a cornea photographing apparatus as a second embodiment of the present invention will be described. Each of the following embodiments shows another specific example of determining the reference position for XY alignment, and the operations shown in steps Q1 to Q7 of FIG. 7 in the first embodiment are performed. Since it can be executed only by different steps, here, description will be made with reference to the process diagram of FIG. 8 corresponding to FIG. 7 in the first embodiment.

  First, according to steps R1 to R3, the apparatus optical system 10 is aligned to the (provisional) XY alignment position in the XY direction and to the corneal epithelial in-focus position in the Z direction in the same manner as in steps Q1 to Q3. Then, based on the loop operation of steps R4 to R6, as shown in FIG. 9, a specific XY corresponding to the gaze direction of the subject from the XY (temporary) alignment position indicated as P0, as shown in FIG. In P1, P2, P3,... Moved by a predetermined distance in the direction, corneal skin images for XY alignment are respectively taken a plurality of times. After that, when the final arrival position Pend which is set in advance is finally reached, the XY alignment corneal skin imaging is finished.

  In step R7, the radius of curvature of the corneal skin is estimated from the optical information in the obtained corneal skin images for XY alignment. For the estimation of the radius of curvature, for example, as in step Q5, the boundary position between the bright part and the dark part during each imaging is obtained, the boundary position in each imaging is compared, and a certain amount of movement in the XY direction at the time of imaging On the other hand, it is possible to estimate the radius of curvature of the corneal outer skin by analyzing how the boundary position has changed. Further, the radius of curvature may be estimated using the amount of change in luminance of each pixel being imaged during movement in the XY directions. The curvature radius of the corneal endothelium is estimated from the curvature radius of the corneal outer skin thus obtained in the same manner as in Step Q5, and the alignment reference position is determined.

  In Steps R8 to R9, the same processes as those in Steps Q6 to Q7 in the first embodiment are performed to complete the XY alignment.

  In the XY alignment corneal skin imaging in steps R4 to R6 in the present embodiment, each time imaging is performed at a point such as P1, P2, etc., optical information of the XY alignment corneal skin imaging is sequentially analyzed, and Imaging may be terminated when a predetermined condition for determining the alignment reference position is satisfied. Such conditions include, for example, the sum of the absolute values of the luminance levels of the pixels in a predetermined area of the CCD 28, the number of pixels whose luminance has reached a certain value such as a saturation value, and a certain value such as the luminance being a saturation value. Various conditions can be set such that the area of the pixel that has reached the predetermined area is satisfied.

  Incidentally, in order to see individual differences in the amount of deviation in the XY direction during imaging of the endothelium around the cornea, which is considered to be caused by variations in the curvature difference between the inner and outer corneas, some of the results of experiments conducted by the present inventor were referred. To mention. FIG. 10 shows the corneal for XY alignment in step Q4 in the first embodiment in a state where the right eye of each of eight persons with different A to H is fixed in an inclined direction facing upward (0 o'clock direction). The image obtained by imaging the outer skin image, that is, the image obtained by imaging the outer skin from the front on the optical axis O1 ((temporary) XY alignment position) which is the visual axis of the front view.

  When the obtained images are compared with each other, it can be seen that the ratio of the size of the bright and dark areas varies greatly among individuals. This means that the radii of curvature of the corneal outer skin and corneal endothelium are greatly different between individuals, and therefore a certain amount of correction is applied in the XY direction as shown in the prior arts 1 and 2. It is understood that a clear endothelial image is not always obtained by an individual alone.

  As mentioned above, although each 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.

  In the above-described embodiment, the imaging operation in the backward direction that separates the apparatus optical system 10 from the eye to be examined has been described. However, after performing XY alignment, the apparatus optical system 10 advances toward the eye to be examined. For example, if a detection mechanism capable of detecting the position of endothelium focusing with high accuracy is employed, continuous or multiple endothelium imaging operations are not required, and the in-focus position can be performed. It is of course possible to obtain a target endothelium image by imaging the endothelium at only one point.

  Instead of the line sensor 44, for example, a simple light receiving element as shown in the prior patent 1 may be used, or a focusing determination may be performed using a CCD.

  In the above embodiment, the XY direction for performing the XY alignment is specified as the XY direction corresponding to the lighting direction of the peripheral fixation target (fixation lamp 89), but instead, the visual axis is set obliquely. It is also possible to determine the direction in which the XY alignment is performed based on the image data obtained by imaging the outer skin on the optical axis O1 that is the front visual axis in the set peripheral fixation state.

  Specifically, image data obtained by imaging the outer skin on the optical axis O1 serving as the front visual axis in a state in which the image is fixed in each oblique direction corresponding to six directions of 0:00 to 10:00 in the clockwise direction, FIG. 11 shows the arrangement at corresponding positions around the axis O1.

  As can be seen from the image shown in FIG. 10, the different directions of the luminance level appear corresponding to the oblique direction to be fixed. Therefore, it is also possible to determine the direction in which the XY alignment is performed based on the obtained luminance level of each outer skin imaging.

  In the first and second embodiments, the XY alignment reference position is calculated by estimating the curvature of the corneal skin from the captured XY alignment corneal skin image. In determining the position, the reference position for XY alignment may be determined by analyzing not only the curvature of the corneal skin but also the thickness of the cornea from the optical information of the corneal skin image. This makes it possible to determine a more accurate XY alignment reference position and to advantageously capture a corneal endothelium image.

Explanatory drawing which shows the apparatus optical system as 1st embodiment of this invention. Explanatory drawing which shows the arrangement | positioning form of the periphery fixation target (fixation lamp) in the apparatus optical system as 1st embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing for demonstrating the cornea imaging device as 1st 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 basic imaging | photography procedure of a cornea imaging device. Explanatory drawing for demonstrating the to-be-tested eye image displayed on a monitor screen. The flowchart which shows the process including XY alignment according to 1st embodiment of this invention. The flowchart which shows the process including XY alignment according to 2nd embodiment of this invention. Explanatory drawing for demonstrating the specific operation | movement of the reference position according to the flowchart shown in FIG. An outer skin photographed image as a reference diagram for explaining a difference between individuals of reference positions at the time of XY alignment, which is considered to be caused by the curvature radius of inner and outer skins. Explanatory drawing which arranged the outer_capture | photographing image for demonstrating the action | operation of XY alignment as another embodiment of this invention. Explanatory drawing for demonstrating the subject in an endothelium imaging device.

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: central central fixation target optical system, 66: alignment optical system, 74: central fixation target light source, 82: alignment light source, 84: alignment detection Optical system 88: Alignment detection sensor 89: Fixation lamp 112: X axis drive mechanism 114: Y axis drive mechanism 117: Imaging control circuit 118: XY alignment detection circuit 121: XY alignment reference position determination Circuit, E: Eye to be examined

Claims (8)

An illumination optical system including an illumination light source that irradiates the slit light beam obliquely to the eye to be examined;
A corneal imaging optical system including a photoelectric element that receives a reflected light beam from the cornea of the eye to be inspected by the slit light beam and images a corneal image;
When moving the illumination optical system and the corneal imaging optical system in the Z direction, which is an approach / separation direction to the eye to be examined, a focus observation light receiving element for observing a focus state in the Z direction;
XY alignment index light irradiation means for irradiating index light for XY alignment from the front toward the eye to be examined;
An XY alignment light-receiving element that receives specular reflection light of the index light from the cornea of the eye to be examined by the XY alignment index light irradiation unit;
Based on a light reception signal from the XY alignment light receiving element, the illumination optical system and the cornea imaging optical system are moved in the XY direction orthogonal to the Z direction as a whole, and the eye to be examined is in the XY direction with respect to the slit light flux. XY direction driving means for aligning with
A peripheral fixation target for selectively directing the visual axis of the eye to be examined in a plurality of directions inclined with respect to the front;
XY alignment imaging control means for capturing an XY alignment corneal skin image by the corneal imaging optical system under a state in which the visual axis of the eye to be examined is directed in the tilt direction by the peripheral fixation target;
XY alignment reference position determining means for determining an XY alignment reference position as a specific position in the XY direction by evaluating optical information in the XY alignment cornea skin image imaged by the XY alignment imaging control means; ,
Based on the information on the XY alignment reference position determined by the XY alignment reference position determining means and the information on the focus position in the Z direction observed by the focus observation light receiving element, the illumination optical system And a corneal endothelium imaging control means for controlling the relative position of the corneal imaging optical system with respect to the eye to be examined and capturing a corneal endothelium image of the eye to be examined by the corneal imaging optical system. Cornea photographing device. The XY alignment imaging control means captures the XY alignment corneal skin image on the optical axis of the specular reflected light of the XY alignment index light by the XY alignment index light irradiation means by the corneal skin of the eye to be examined. ,
Based on the luminance information in the obtained corneal skin image for XY alignment, in the XY alignment reference position determining means, the XY alignment reference position on a predetermined XY direction line corresponding to the inclination direction of the visual axis is determined. The cornea photographing apparatus according to claim 1, wherein the cornea photographing device is determined as a deviation amount of the specular reflection light with respect to the optical axis.   The imaging control unit for XY alignment drives the illumination optical system and the cornea imaging optical system as a whole by the XY direction driving unit in a predetermined XY direction corresponding to the tilt direction of the visual axis, The corneal imaging apparatus according to claim 1, wherein the XY alignment cornea skin image is captured at a plurality of locations on a predetermined XY direction line. In the XY alignment reference position determining means,
Each time the XY alignment corneal skin image is imaged on the predetermined XY direction line by the XY alignment imaging control means, the captured XY alignment corneal skin image is sequentially evaluated, and the evaluation result is preset. 4. The cornea photographing apparatus according to claim 3, wherein the XY alignment reference position is determined by satisfying the predetermined condition, and the imaging of the XY alignment cornea skin image is terminated. In the XY alignment reference position determining means,
The corneal imaging according to claim 3, wherein imaging of the XY alignment corneal outer skin image by the XY alignment imaging means on the predetermined XY direction line is performed up to a preset final position, and is finished. apparatus.   The imaging of the corneal outer skin image for XY alignment of the eye to be examined by the corneal imaging optical system irradiates light that is weaker than that during imaging of the corneal endothelium image of the eye to be examined. The corneal imaging apparatus described.   In the corneal endothelium image capturing control means, the illumination optical system and the corneal imaging optical system are moved relative to each other in the Z direction with respect to the eye to be examined, and the corneal endothelium image is continuously displayed at a plurality of locations on the Z direction line. The cornea photographing apparatus according to any one of claims 1 to 6, wherein the cornea photographing apparatus is configured to pick up an image.   The cornea photographing apparatus according to any one of claims 1 to 7, wherein a line sensor is employed as the focus observation light receiving element.