JPH0956675A - Corneal endothelium photographing device with corneal thickness measuring function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corneal thickness-measurable corneal endothelium photographing device which is easily assembled and regulated with a simple structure requiring no separate sensor for corneal thickness except for an area sensor for corneal cell photographing in order to measure the corneal thickness together with the corneal endothelium cell photographing of a subject eye, and also advantageous in cost. SOLUTION: A pair of narrow slits are formed on the longitudinal end parts of the photographing slit diaphragm 41 of a lighting optical system for obliquely lighting the cornea C of a subject eye, and images having narrow slit images are formed on the endothelium image and epithelium image upper part mutually adjacent on the image pickup surface 13 of a magnifying photographing optical system on the basis of the slit illuminating light. On the basis of the endothelium focus detection signal from a PSD 10 set in the corneal endothelium reflected light receiving position of slit light on the optical axis of an objective lens 8, the space between parts corresponding to the narrow slit images of endothelium and epithelium on the image pickup surface, or the distance from the image pickup surface left end to the narrow slit image of epithelium is determined and converted into the corneal thickness to display the corneal endothelium cell magnified image and the corneal thickness on a monitor 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corneal endothelium imaging apparatus having a function of measuring corneal thickness together with corneal endothelial cell imaging.

[0002]

2. Description of the Related Art Conventionally, a corneal thickness measuring device called a pachometer for optically measuring the thickness of the cornea observes the reflected light from the eye to be inspected into which slit light is incident while rotating a parallel prism. It is known to measure the corneal thickness based on the rotation angle of the prism when the reflected light from the corneal epithelium / endothelium overlaps, and to the one improved in terms of measurement operation and measurement accuracy without using the prism, Japanese Patent Application Laid-Open No. 5-146409 discloses a device that photoelectrically converts a light flux reflected from the corneal epithelium / endothelium to measure the corneal thickness. On the other hand, the corneal endothelium imaging apparatus at present cannot generally measure the corneal thickness, and the pacometer, which is a separate device, is required for the corneal thickness measurement, and the corneal endothelial cells cannot be imaged by the pacometer.

The applicant previously described in Japanese Patent Application No. 5166132/1993 that a magnifying photographing optical system facing the spherical surface of the eye is moved in a non-contact state with respect to the spherical surface of the eye so that the slit light is incident on the cornea. While the corneal endothelium is imaged on the basis of the signal detected from the corneal endothelium focus of the reflected light from the
We proposed a device that can measure the corneal thickness by detecting the amount of movement of the photographic optical system from the focus position of the corneal epithelium to the focus position of the corneal endothelium detected respectively.

[0004]

As described above, in the conventional corneal cell imaging apparatus, generally, the corneal thickness cannot be measured at the time of imaging the corneal endothelium, and in the apparatus proposed by the applicant, the imaging optical system is used. The corneal thickness is calculated based on the amount of movement of the photographic optical system based on the sequentially detected epithelial signal and endothelium signal while moving in the direction of the eye to be inspected. There was a problem that an error would occur if it moved. In addition, when a pacometer is added to an existing corneal cell imaging apparatus to measure corneal thickness, it is necessary to newly install a sensor for pacometer (one-dimensional line sensor) and an optical system for guiding light to the position of the sensor. It is unavoidable that the device is complicated and expensive due to its configuration.

The present invention has been made in view of the above points, and since the corneal thickness is measured together with the corneal endothelium imaging of the eye to be inspected, there is no measurement error even if the eye moves. And an area sensor (CC
(D light receiving element), a separate sensor for corneal thickness measurement is not required, and a single sensor can simultaneously perform imaging of the endothelium and measurement of corneal thickness. Simple structure and easy assembly and adjustment. An object of the present invention is to provide a corneal endothelium imaging device having a thickness measuring function.

[0006]

In order to achieve the above object, the present invention provides, as a first invention of a corneal endothelium imaging apparatus having a corneal thickness measuring function, an illumination optical system for slit-illuminating an eye spherical surface C of an eye to be examined from an oblique direction. In a corneal endothelium imaging apparatus including a system and a magnifying and observing unit having a magnifying and photographing optical system for forming and observing a magnified image of a subject on the basis of the slit illumination light, an imaging plane of the magnifying and photographing optical system. When an image of the corneal endothelium is formed on the light receiving surface of the image pickup device 13 and the image pickup device 13 arranged so that the image of the corneal endothelium is formed and the image of the corneal epithelium is formed A focusing detection light receiving element 10 set at a position for receiving the corneal endothelium reflected light of the slit light through at least the objective lens 8, and the focusing detection light receiving element 10 detects the focusing of the corneal endothelium. Based on the signal to
From a predetermined position associated with the corneal endothelium image formed on the light receiving surface 13 of the image pickup device, and a position corresponding to the predetermined position of the corneal epithelium image formed on the light receiving surface 13 by the corneal thickness measuring means. It is configured to measure corneal thickness.

In this case, the positional relationship of the corneal endothelium image and the corneal epithelium image with respect to the corneal thickness on the light receiving surface (imaging surface) 13 of the image pickup device by the corneal reflection light of the slit light is the cornea C of the eye to be examined.
On the other hand, when the slit light having a certain width is obliquely incident on the eye axis Ea at a certain incident angle, the reflected light from the corneal epithelium and the reflected light from the corneal endothelium are at the same angle as the incident angle with respect to the eye axis Ea. The corneal endothelium image and the corneal epithelial image are adjacent to the light-receiving surface 13 of the image pickup device (with a gray zone between them normally).
Although an image is formed, the lateral shift of the epithelial image with respect to the endothelium image is proportional to the depth of the cornea, that is, the thickness of the cornea.

Therefore, in the first invention, when the corneal endothelial cells of the eye to be inspected are magnified and photographed, the illumination light from the illumination optical system is slit-illuminated from the oblique direction to the eye spherical surface C of the eye to be inspected E. The cornea C to be inspected based on this slit illumination light
The reflected light from the magnifying observation means is made to form a magnified image of the endothelium and epithelium of the examined cornea on the light-receiving surface 13 of the image pickup device through the magnifying photographing optical system of the magnifying observation means, and the corneal endothelial cells are displayed on the monitor TV 18 of the observing means. A magnified image can be displayed, and when the focus detection light receiving element 10 detects the focus of the corneal endothelium, when the corneal thickness measuring means measures the corneal thickness, the light receiving surface 13 of the image pickup element is displayed. The corneal thickness is always proportional to the distance (lateral displacement) between the predetermined position related to the image of the corneal endothelium image formed and the position corresponding to the predetermined position of the image of the corneal epithelium image similarly formed on the light receiving surface 13. Because of the relationship, the corneal thickness can be easily measured by converting from the distance. Specifically, a known thickness is measured at the time of assembling a machine in a factory, and the thickness is adjusted accordingly before shipping.

A second invention of the corneal endothelium imaging apparatus having a corneal thickness measuring function is the same as the first invention, and the eye spherical surface C of the eye E to be examined.
In a corneal endothelium imaging apparatus provided with an illuminating optical system for illuminating a slit from an oblique direction, and a magnifying observation means having a magnifying imaging optical system for forming and observing a magnified image of a subject based on the slit illumination light. The imaging element 13 is arranged on the imaging surface of the magnifying imaging optical system so that the corneal endothelium image is formed and the corneal epithelium image is formed, and the corneal endothelium is formed on the light receiving surface of the imaging element. When the image is formed in a focused state, the light receiving element for focus detection 10 is set at a position for receiving the corneal endothelium reflected light of the slit light through at least the objective lens 8. This second invention In the, based on the signal that the focus detection light-receiving element 10 detects the focus of the corneal endothelium,
The corneal thickness is measured by a corneal thickness measuring means from a predetermined position related to the corneal epithelium image formed on the light receiving surface 13 of the image pickup device.

In this case, the positional relationship of the corneal epithelium image on the light receiving surface 13 of the image pickup device by the corneal reflected light of the slit light with respect to the corneal thickness is as follows. When the endothelium images due to the reflected light from the endothelium are formed next to each other, the position of the epithelial image from the left end of the imaging surface 13 is (although the endothelium image is in a fixed position in the focused state and does not change), the corneal thickness. A horizontal shift is caused in proportion to. Therefore, when the distance from the left end of the imaging surface of the predetermined position related to the epithelium image changes, the corneal thickness can be converted from the distance from the left end of the imaging surface 13 corresponding to the predetermined position. That is, the first aspect of the present invention relates to a predetermined position related to the corneal endothelium image formed on the light receiving surface 13 of the image pickup device, and a position corresponding to the predetermined position of the corneal epithelium image similarly formed on the light receiving surface 13. In contrast to the idea of measuring the corneal thickness by applying a scale between the two, in the second invention, the light receiving surface (imaging surface) 13 of the image sensor is
At a predetermined position related to the image of corneal epithelium imaged on
This is based on the idea of measuring the corneal thickness from a scale converted from the distance from the left end of the image pickup surface 13.

Thus, in the second invention, as in the first invention, in enlarging and observing the corneal endothelial cells of the eye E to be inspected, an enlarged image of the endothelium and epithelium of the inspected cornea C is picked up by the image sensor 13.
A corneal endothelial cell magnified image can be displayed on the monitor TV 18 of the observing means, and the focus detection light receiving element 10 detects the focus of the corneal endothelium based on the signal for detecting the corneal endothelium. When measuring the corneal thickness, the predetermined position related to the corneal epithelium image formed on the light receiving surface (imaging surface) 13 of the image sensor is in a certain relation position to the corneal epithelium image, and Since the position of the surface 13 varies in proportion to the corneal thickness, the distance from the left end of the imaging surface 13 of the predetermined position related to the corneal epithelium image is converted (that is, from the scale converted from the left end of the imaging surface). ) The corneal thickness can be easily measured. In the case of the second invention as well, as in the first invention, specifically, the known thickness is measured at the time of assembling the factory of the machine, and the adjusted thickness is adjusted and shipped.

[0012] As the predetermined position associated with the corneal endothelial or epithelial cell image for measuring the corneal thickness is formed on the light receiving surface 13 of the imaging device by the imaging slit diaphragm 4 ₁ of the illumination optical system Either side edge of the corneal cell image can be used. In this case, in the first invention, from the distances d ₁ and d ₁ ′ (see FIG. 2) between the corresponding edges (for example, the left edge) of the corneal endothelium image and the epithelial image formed on the imaging surface 13, respectively, The corneal thickness can be measured by the corneal thickness measuring means. Further, in the second aspect, the corneal thickness can be measured by the corneal thickness measuring means from the distance between the left edge of the imaging surface and the left edge of the corneal epithelium image formed on the imaging surface.
When using either side of this corneal cell image,
Since the predetermined position can be formed by the side edge of the photographing slit diaphragm, it is not necessary to process the photographing slit diaphragm.

[0013] The predetermined location associated with the corneal endothelial or epithelial cell image for measuring the corneal thickness, a predetermined length in the longitudinal direction of the imaging slit to the outside of the imaging slit diaphragm 4 ₁ in the illumination optical system the Hosohaba slits 4 ₁ 'for measurement formed Hosohaba, it can be used the position of the corneal cells image outside the Hosohaba slit image formed on the light receiving surface 13 of the imaging element. In this case, in the first invention, the distances d ₁ and d ₁ 'between the narrow slit images corresponding to the outer side of the corneal endothelium image and the epithelium image formed on the imaging surface 13 (see FIGS. 2 and 3). ), The corneal thickness can be measured by a corneal thickness measuring means. In the second invention, the corneal thickness is measured by the corneal thickness measuring means from the distances d ₂ and d ₂ ′ (see FIG. 4) from the left end of the imaging surface 13 of the narrow slit image outside the epithelial image formed on the imaging surface. Can be measured. In the narrow slit for measurement formed on the outer side of these slits for photographing, the distance between the narrow slit images on the outer side of the endothelium or the epithelium or the imaging surface of the narrow slit image on the outer side of the epithelium image is measured by the corneal thickness measuring means. 13 When measuring the corneal thickness from the distance from the left end, it is possible to measure the corneal thickness by accurately picking up a signal from the edge of the cell image.

It is effective to use a pair of narrow slits spaced in the width direction of the photographing slit as the measuring narrow slits. That is, in the case where there is _one measurement narrow slit 41 'in the center of the photographing slit diaphragm (Fig. 2
4 Ref ₁₎ aperture imaging slit, when corneal thickness is too thick, the first invention, in any of the second invention, Hosohaba slit image formed on the outer epithelial image is determined to exit the outer imaging surface 13 becomes impossible [see (d ₁ ') shown in FIG. 2 (B)], when measuring Hosohaba slits of the pair in the width direction of the photographic stop slit (FIG. 3, imaging slit diaphragm 4 ₁ 4 If the corneal thickness is too thick (except when it is very thick), the first invention,
In each of the second inventions, the left narrow slit image formed on the outer side of the epithelium image is located within the imaging plane 13 [see FIG. 3 (B)].
d ₁ ', see d ₂ ' in FIG. 4 (B)] Preventing measurement failure. The narrow slit image on the right side is used when the corneal thickness is thin.

Further, in the width direction of this photographing slit,
For a pair of Hosohaba slits spaced wider spacing than the width of the imaging slit (see imaging slit diaphragm 4 ₁ of FIG. 5), be more advantageously used for corneal too thick in the case of the second invention You can That is, when the corneal thickness is too thick, it is possible to easily cope with a thick corneal thickness that cannot be measured on the imaging surface when there is a pair of narrow slits for measurement within the width of the photographing slit. For example, when a narrow slit on the left side of a pair of narrow slits is used, d ₂₁ 'in Fig. 5 (B) has a margin on the imaging surface 13 compared to Fig. 4 (B), and it is possible to measure even a thick cornea. Shows. On the other hand, when the corneal thickness is very thin, for example, when a narrow slit on the right side of the pair of narrow slits is used, d ₂₁ can be set large in FIG. 5 (A), and accurate measurement can be performed. In this case, even if the pair of measurement Hosohaba slits on either side of the photographic stop slit, (see imaging slit diaphragm 4 ₁ of FIG. 6), similar to the above, if the corneal thickness is very thick [Fig. 6 (B)], and when the corneal thickness is very thin [see FIG. 6 (A)], it can be measured and can be advantageously used.

Further, as the narrow slit for measurement,
A cell slit image is located outside one end in the longitudinal direction of the photographing slit diaphragm, and a horizontal blanking area outside one end in the longitudinal direction of the corneal cell image formed on the light receiving surface of the image sensor. It is more effective to use a narrow slit that forms the. That is, as a result, as shown in FIGS. 2 to 5, the narrow slit image for measurement is removed from the display screen 18a of the monitor TV, and the required corneal endothelial cell image is displayed in the display screen 18a. Can be the screen 18
Within the remaining epithelial image displayable area of a, the epithelial image signal can be removed to display the required data (corneal thickness, etc.), and the display screen of the monitor television can be effectively used.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a corneal endothelium imaging apparatus having a corneal thickness measuring function of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of the embodiment,
2 and 3 show a photographing slit diaphragm used in the illumination optical system of the embodiment.

FIG. 1 shows an illumination optical system for illuminating the cornea C of the eye E, a magnifying photographing optical system for magnifying and photographing the illuminated corneal cells, and means for observing the magnified photographed image. There is shown a corneal endothelium imaging apparatus provided with a magnifying observation means consisting of In the illumination optical system, a halogen lamp 2 used as a light source for illuminating the cornea C of the eye E to be inspected is used during focusing of the magnifying photographing optical system, and a strobe discharge tube 1 used for photographing magnified photographs of corneal endothelial cells is emitted from the halogen lamp 2. The light passes through a narrow slit slit 4 ₂ for detection, and the light emitted from the strobe discharge tube 1 is a wide slit slit 4 ₁ for photographing.
In order to irradiate the cornea C, which is the surface to be observed of the eye E to be inspected, through the projection lens 6 via the projection lens 6 at a predetermined angle from the oblique direction with respect to the eye axis Ea, the strobe discharge tube 1 is The halogen lamp 2 is provided at a predetermined position on the illumination optical axis 5 and on the optical axis perpendicular to the illumination optical axis 5 via the infrared light reflecting / visible light transmitting mirror 3 on the illumination optical axis 5. There is.

On the opposite side of the illumination optical axis 5 of the illumination optical system from the eye axis Ea of the eye axis E of the eye E to be examined, an oblique slit illumination light by the halogen lamp 2 or the strobe discharge tube 1 with respect to the eye spherical surface C is provided. A magnifying photographing optical system for magnifying and observing a corneal endothelium image of the observed portion by receiving reflected light from the cornea C on the image pickup surface (CCD light receiving surface) 13 of the television camera 14 is provided. , CCD light receiving surface 13 of TV camera 14
When the corneal endothelium image is imaged in a focused state, the optical system of the optical path of part 7 ₁ is set to a position extended been corneal endothelium if the focus detection light receiving element (PSD) 10 is the illumination optical system , The light-receiving element as the photographing system 20 including the magnifying photographing optical system advances.
The corneal endothelium reflected light moving on the front surface of 10 is detected, and the imaging signal processing device 15, which will be described later, detects the focus.

[0020] That is, a predetermined position on the optical axis ₇₁ of the enlarged image taking optical system in the illumination optical axis 5 and the symmetrical position of the illumination optical system across the axial Ea of the eye E, an objective lens on the eyeball surface side 8 but also the objective lens 8 and the infrared light transmission and visible light reflecting mirror 9 at a predetermined distance, the optical axis ₇₁ and the image light by the reflected light of the illumination light from a predetermined angle cross to the eyeball surface C, The eye axis
Is arranged to bending so as to be perpendicular to the predetermined position of the substantially axis of Ea, reflected from the mirror 9 an image ray of visible light (strobe light by) imaging the slit light, the eye from the optical axis 7 ₂ On the optical axis 7 ₃ bent by the mirror 11 intersecting the direction of the axis Ea by 45 °, the light is incident on the CCD light receiving surface 13 of the television camera 14 provided on the optical axis 7 ₃ through the magnifying lens 12. infrared light detecting slit 4 ₂ narrow width in to the infrared light reflected visible light transmissive mirror 3 through corneal endothelium focusing position detecting slit light from the halogen lamp 2 extends the optical path on the optical axis 7 ₁ Then, the corneal endothelium focus detection light receiving element (PS) provided at the image forming position of the cornea reflected image light beam by the objective lens 8
D) It is designed to be incident on 10. When a corneal endothelium image is focused on the CCD light receiving surface 13 of the television camera 14 by the objective lens 8 and the magnifying lens 12, a slit-shaped corneal endothelium reflected light (infrared light) for focus detection is formed. Is incident on the light receiving area of the focus detection light receiving element (PSD) 10, the corneal endothelium reflected light is detected by the light receiving element 10, and the signal is input to the image pickup signal processing device 15 and the photographing system 20 is suitable for photographing. The position (focus position) can be detected.

[0021] The illumination light axis 5 Photo slit diaphragm 4 ₁ is provided on has a photographic slit diaphragm in a direction perpendicular to the paper surface. The imaging slit diaphragm 4 _1, the shape of the imaging slit diaphragm of a predetermined width of the rectangle provided in the conventional slit plate, as shown in FIG. 3 in this embodiment, in its one longitudinal end, a predetermined at intervals and a slit diaphragm 4 ₁ to the pair formed a predetermined length Hosohaba slit. As a result, the reflected light of the slit illumination light from the cornea C from the oblique direction of the eye axis Ea is captured by the imaging lens (objective lens) 8,
When a CCD camera light-receiving surface (imaging surface) 13 of the television camera 14 simultaneously captures a magnified endothelium image and an epithelial image via the magnifying lens 12, the imaging surface 13 has
A bright epithelium image is formed through the endothelium image and the narrow gray zone, but as described above, a pair of narrow slits for measurement formed on one side of the slit for photography with a narrow slit of a predetermined length.
4 ₁ ′, 4 ₁ ′, as shown in FIG. 3 (A) or (B), shows a pair of narrow slit images formed on the side portions (the upper portion in the embodiment) of the endothelium image and the epithelial image in the same direction, respectively. The center intervals d _{1 to} d ₁ 'of the corresponding narrow slit images on the left side or the right side can be obtained by counting the horizontal synchronization pulses for scanning the imaging surface 13. Since this interval is proportional to the corneal thickness as described above, the corneal thickness is calculated by converting the actual center distance by a predetermined calculation formula in the imaging signal processing device 15, and the monitor television 18 connected to the imaging signal processing device 15 On the display screen 18a, the endothelium image and the corneal thickness are combined and displayed except for the narrow slit image for measurement, and the corneal endothelium image taken by the printer 19 and the measured corneal thickness can be printed out. When simultaneously capturing the endothelium image and the epithelial image, an ND filter may be inserted in the optical path of the epithelial reflected light in order to image the epithelial reflected light that is very strong against the endothelium reflected light in a balanced manner.

In this case, an image in which the standard corneal thickness is displayed is obtained by measuring the interval between the left narrow slit images corresponding to the narrow slit images for measurement formed on the corneal endothelium image or the epithelium image. In the case of FIG. 3 (A) showing the surface 13, the distance is
While the corneal thickness can be measured by obtaining d ₁ , even if the corneal thickness is very large, there is no problem in the imaging surface 13 as shown in FIG. 3 (B) (the narrow slit image does not come off the imaging surface). The corneal thickness can be measured by obtaining the distance d ₁ '.

Next, the procedure for measuring and displaying the corneal thickness in the embodiment of the first invention will be described based on the block diagram of the corneal endothelium photographing apparatus shown in FIG. 1 and the flowchart shown in FIG. First, the corneal endothelium photographing apparatus is turned on (not shown), the halogen lamp 2 is turned on, and the photographing system 20 including the illumination optical system and the magnifying photographing optical system is manually aligned with the eye E to be inspected (a pupil center and a television image). Centering)
After that, the Z-axis drive mechanism 21 drives the Z-axis to move the Z-axis forward. When the focus detection light receiving element (PSD) 10 receives the endothelium reflected light during the forward movement of the photographing system 20 and the focus is detected by the detection signal of the corneal endothelium reflected light in the imaging signal processing device 15, A signal from the image pickup signal processing device 15 causes the Z-axis drive mechanism 21 to stop the forward movement of the photographing system 20 and at the same time, the strobe light emission circuit 16 operates to operate the strobe discharge tube 1.
Is emitted, and the reflected light from the spherical surface C of the eye passes through the optical paths 7 ₁ , 7 ₂ , and 7 ₃ of the magnifying imaging optical system, and narrow slit images are formed above the magnified images of the corneal endothelium and epithelium to be examined. Tv camera
An image is formed by imaging on the CCD light receiving surface 13 of the 14
The image signals of the endothelium and epithelial images from 14
Input to 15, and the device is loaded and stored in the built-in frame memory.

At this time, in the image pickup signal processing device 15,
From the image signal of the captured corneal endothelium / epithelium, only the narrow slit portion for measuring the corneal thickness in the upper portion of the image is extracted in the mask circuit in the imaging signal processing device 15. Then, using the horizontal synchronizing pulse signal that is always input to the counter in the imaging signal processing device 15 from the position signals of the narrow slit images of the extracted endothelium and epithelium, the endothelium left of the narrow slit image for measurement, or Distances d _{1 to} d ₁ ′ between the right image position and the corresponding left or right position of the epithelium of the measuring narrow slit image (FIG. 3
(Reference) is obtained by counting the pulses between the corresponding narrow slit images, and the counted signal is the image pickup signal processing device.
At 15, the corneal thickness is calculated by a predetermined formula. The signal of the calculated corneal thickness is used as an imaging signal processing device.
Input from 15 to the monitor 18, and on the monitor 18, the corneal thickness is combined and displayed on the display screen 18a together with the endothelium image. Then, an operation on the operation panel 17 causes the printer 19 to print out a paper on which the magnified image of corneal endothelial cells and the corneal thickness are displayed. Thereby, accurate measurement data of corneal thickness can be automatically obtained along with a magnified image of corneal endothelial cells by a simple operation. Further, in the above measurement, as shown in FIG. 3, even when the corneal thickness is very large, the left narrow slit image of the pair of narrow slit images at the upper part of the endothelium image and the epithelium image is used. The corneal thickness can be measured easily by using one area image receiving element (C
It is possible to provide a corneal endothelium imaging apparatus having a corneal endothelium imaging function and a cost-advantageous corneal endothelium measurement function that is easy to assemble and adjust, and is easy to assemble and adjust.

Next, an embodiment of the second invention of the corneal endothelium imaging apparatus having the corneal thickness measurement function of the present invention will be described with reference to the accompanying drawings. In the second invention, the illumination optical system, the configuration of the imaging system 20 provided with an enlarged imaging optical system is the same as the first invention, endothelium image formed on the imaging surface 13 of the television camera 14 by the imaging slit diaphragm 4 ₁ Therefore, there is a difference in how to take signals related to the epithelial image and their processing.

FIG. 1 is a block diagram showing an embodiment of the second invention. Since it is the same as the first invention, its detailed description is omitted. FIGS. 4 and 5 respectively show a photographing slit diaphragm used in the illumination optical system of the embodiment, and FIG.
It is a flow chart which shows the operation procedure of corneal endothelium photography, corneal thickness measurement, and display in the invention.

[0027] In the second invention, imaging slit diaphragm 4 ₁ is provided on the illumination optical axis 5 in the photographing system 20, like the one used in the embodiment of the first invention, for capturing a rectangular predetermined width in one longitudinal end of the slit diaphragm, the at a predetermined distance in the width direction by a predetermined length Hosohaba measuring Hosohaba slits 4 ₁ formed in the '(in a rectangular predetermined width) that a pair formed (see FIG. 4 ) it is possible to use, can be used to Said sub width slits 4 ₁ 'to a predetermined width outward of the rectangular those pair formed (see FIG. 5).

[0028] The calculation of the corneal thickness of the second invention, the pair formed in the upper portion of the epithelium image only of the endothelium image epithelial image formed on the imaging surface 13 by the measuring Hosohaba slits 4 ₁ ' Using the narrow slit image on the left side or the narrow slit image on the right side of the narrow slit image, the distances d ₂ and d ₂ '(see FIG. 4) from the left end of the imaging surface 13 to the narrow slit image, or d
₂₁ and d ₂₁ ′ (see FIG. 5) can be obtained by counting the horizontal synchronizing pulse for operating the image pickup surface. The distance from the left edge of this imaging surface to the narrow slit image does not change the position of the narrow slit image above the endothelium image in focus, but the position of the narrow slit image above the epithelial image is proportional to corneal thickness. Then, a horizontal shift is caused, and the horizontal synchronizing pulse from the left end of the image pickup surface 13 at the narrow slit image position is counted to obtain the image pickup surface 13
The distance from the left end to the narrow slit image can be obtained. The position of this narrow slit image fluctuates in proportion to the corneal thickness, but the distances d ₂ , d ₂ ', d ₂₁ ' counted at the narrow slit image position on the left side of the epithelium, or the narrow slit image on the right side of the epithelium The corneal thickness is calculated by converting it with a predetermined calculation formula corresponding to the distance d ₂₁ counted at the position, and the endothelium image and the corneal thickness are combined and displayed on the display screen 18a of the monitor TV 18 excluding the narrow slit image. The corneal endothelium image taken from the printer 19 and the measured corneal thickness can be printed out.

In the above, when using the narrow slit image on the upper left of the epithelium image, when the corneal thickness is the standard thickness, FIG.
Seek distance as the d _2, also as the d ₂ 'in FIG even if corneal thickness is very thick 4 (B), both from stable imaging plane left in the imaging surface 13 to Hosohaba slit image in , Corneal thickness can be calculated.

Further, corresponding to the case where the corneal thickness is much thicker and the thickness is very thin, as shown in FIG. 5, it is formed at one end (upper part) in the longitudinal direction of the rectangular slit slit for photographing. It is possible to use a photographing slit diaphragm 4 _{1 in} which a pair of narrow slits 4 ₁ 'for measurement are formed outside a predetermined width of a rectangle. That is, the imaging surface shown in FIG.
When the epithelial image is located at the same position as the epithelial image position with respect to 13, the distance d ₂₁ 'can be obtained using the narrow slit image on the left side of the epithelium as shown in FIG. 5 (B). Unlike the case of FIG. 4B, there is still a margin on the right side of the narrow slit image in the plane 13, so that it is possible to cope with even a very thick image. On the other hand, when the corneal thickness is very thin, the distance d ₂₁ is obtained by using the narrow slit image on the right side of the epithelium as shown in FIG. , The corneal thickness can be calculated by obtaining the distance from the left end of the imaging surface. In the above case, when calculating the corneal thickness by obtaining the distance from the left end of the imaging surface 13 to the narrow slit image, the narrow slit image corresponds to the position with respect to the epithelial right or epithelial left or the like epithelial image. , The scale (predetermined calculation formula) for measuring the distance is differently calculated.

Next, the procedure for measuring and displaying the corneal thickness in the embodiment of the second invention will be described based on the block diagram of the corneal endothelium photographing apparatus shown in FIG. 1 and the flowchart shown in FIG. First, after turning on the power supply of the corneal endothelium photographing apparatus, turning on the halogen lamp 2, the photographing system 20 including the illumination optical system and the magnifying photographing optical system is manually aligned with the eye to be inspected, and then Z The Z-axis is driven by the axis drive mechanism 21 to move the Z-axis forward. When the focus detection light receiving element (PSD) 10 receives the endothelium reflected light during the forward movement of the photographing system 20 and the focus is detected by the detection signal of the corneal endothelium reflected light in the imaging signal processing device 15, The Z-axis drive mechanism 21 stops the forward movement of the photographing system 20 by the signal from the image pickup signal processing device 15, and at the same time, the strobe light emitting circuit 16 is activated to cause the strobe discharge tube 1 to emit light, and the reflected light from the eye spherical surface C is enlarged and photographed. optical path 7 ₁ of the optical system, 7 _2, 7 ₃ an image formed of Hosohaba slit image in each upper portion of the enlarged image of the object part corneal endothelium, epithelium via is formed on the CCD light-receiving surface 13 of the television camera 14 The image signals of the endothelium image and the epithelial image from the television camera 14 are input to the image pickup signal processing device 15, and are captured and stored in the frame memory incorporated in the device.

At this time, in the image pickup signal processing device 15,
In the image signal of the captured corneal endothelium / epithelium, only the narrow slit image portion for measuring the corneal thickness in the upper portion of the image is extracted by the mask circuit in the image pickup signal processing device 15. Then
From the position signal of the narrow slit image of the extracted epithelium, by using the horizontal synchronizing pulse signal that is always input to the counter in the imaging signal processing device 15, the epithelial left of the narrow slit image for measurement is left from the left end of the imaging surface 13. Or the distance to the right position d ₂ '~
d ₂ ', d ₂₁ ' or d ₂₁ (see FIGS. 4 and 5) is obtained by counting the pulses between them, and the counted signal is
In the image pickup signal processing device 15, the corneal thickness is calculated by a predetermined calculation formula corresponding to the left or right narrow slit image. The signal of the calculated corneal thickness is input from the image pickup signal processing device 15 to the monitor 18, and the corneal thickness is combined and displayed on the display screen 18a of the monitor 18 together with the endothelium image. Then, a button operation on the operation panel 17 causes the printer 19 to print out a paper on which the enlarged image of corneal endothelial cells and the corneal thickness are displayed. As a result, it is possible to automatically obtain accurate measurement data of corneal thickness together with a magnified image of corneal endothelial cells with a simple operation. As described above, when measuring the corneal thickness, the narrow slit image on the left side of the epithelium is used among the pair of narrow slit images on the upper part of the endothelium image / the epithelium image as shown in FIGS. The corneal thickness can be easily measured even if the thickness is very thick. With a structure that enables corneal endothelium imaging and corneal thickness measurement with one area light receiving device (CCD), easy assembly and adjustment is easy and cost effective. Can also provide an advantageous endothelium imaging apparatus.

[0033]

According to the corneal endothelium imaging apparatus having the corneal thickness measurement function of the first invention of the first aspect of the present invention, the corneal endothelium is imaged and the corneal thickness is measured using a single area image receiving element. Since there is no need to provide a light receiving element for corneal thickness measurement separately from the corneal endothelium imaging, the structure can be simplified, and the cost of corneal thickness measurement function can be reduced by reducing the number of assembly and adjustment steps. It is possible to provide a corneal endothelium imaging apparatus having the following.

According to the corneal endothelium imaging apparatus having the corneal thickness measuring function of the second invention of the second aspect of the present invention, the first
As in the invention, since the imaging of corneal endothelium and the measurement of corneal thickness can be performed simultaneously by using a single area image receiving element, it is not necessary to provide a light receiving element for measuring corneal thickness separately from the imaging of corneal endothelium. It is possible to provide a corneal endothelium imaging apparatus having a low-cost corneal thickness measurement function such that the structure can be simplified and the number of steps for assembly and adjustment can be reduced.

According to the third aspect of the present invention, since the side edge of the corneal cell image on the imaging surface is used for measuring the corneal thickness, the rectangular shape of the slit stop for photographing in the illumination optical system is used for measuring the corneal thickness. There is an effect that it is not necessary to perform a specific processing for

According to the fourth aspect of the invention, for measuring the corneal thickness, a narrow slit for measurement, which is formed outside the photographing slit in the illumination optical system to have a predetermined narrow width in the longitudinal direction of the photographing slit. By using an elongated slit image formed on the image pickup surface by, the signal for measurement can be easily obtained, and the position of the narrow slit for measurement can be freely set, so that the degree of freedom to obtain the signal can be increased. it can.

According to the fifth aspect of the present invention, a pair of narrow slits are provided as the measuring narrow slits and are spaced in the width direction of the photographing slit, so that the narrow slit is formed on the imaging surface of a predetermined width. When a signal for measuring corneal thickness is taken from, unlike a single narrow slit, it is possible to easily take a signal corresponding to a wide range of corneal thickness such as when the corneal thickness is too thick. It is possible to widen the corneal thickness measurement range on the imaging surface having a predetermined width.

According to the sixth aspect of the invention, the narrow slit image formed on the image pickup surface by the measuring narrow slit formed outside the photographing slit is formed in the horizontal blanking area of the television screen. It is possible to prevent unnecessary narrow slit images from entering the TV screen, and prevent the narrowed visual field of the imaged corneal endothelium image on the TV screen.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a relationship diagram between a photographing slit diaphragm and a corneal thickness calculation distance on an imaging surface in the first invention.

FIG. 3 is a relationship diagram between another photographing slit diaphragm and a corneal thickness calculation distance on an image pickup surface in the first invention.

FIG. 4 is a relationship between an imaging slit diaphragm and a corneal thickness calculation distance on an imaging surface in the second invention.

FIG. 5 is a relationship diagram of another photographing slit diaphragm in the second invention and a corneal thickness calculation distance on an imaging surface.

FIG. 6 is a relationship diagram of still another photographing slit diaphragm and a corneal thickness calculation distance on an image pickup surface in the second invention.

FIG. 7 is a flow chart showing a procedure for measuring corneal thickness according to the embodiment of the first invention.

FIG. 8 is a flowchart showing a procedure for measuring corneal thickness according to the embodiment of the second invention.

[Explanation of symbols] 1 ... Strobe discharge tube, 2 ... Halogen lamp, 3 ... Infrared light reflecting / visible light transmitting mirror, 4 ₁ ... Shooting slit diaphragm, 4 ₂ ... Detection slit diaphragm, 5 ... Illumination optical system light Axis, 6 ... Projection lens, 7 ₁ , 7 ₂ , 7, ₃ ... Enlarged imaging optical system optical axis, 8 ... Objective lens, 9 ... Infrared light transmitting / visible light reflecting mirror, 10 ... Focus detection light receiving element (PSD) ), 12
… Magnifying lens, 13… CCD light receiving surface (imaging device), 14
... TV camera, 15 ... Imaging signal processing device, 16 ... Strobe light emitting circuit, 18 ... Monitor, 20 ... Shooting system, 21 ... Z-axis drive mechanism, E ... Eye to be examined, C ... Corneal (eyeball).

Claims (6)

[Claims] 1. An illuminating optical system for slit-illuminating an eye spherical surface of an eye to be examined from an oblique direction, and a magnifying observation having a magnifying photographing optical system for forming and observing a magnified image of a subject based on the slit illumination light. In the corneal endothelium imaging apparatus equipped with means,
An imaging element arranged on the imaging surface of the magnifying imaging optical system so that a corneal endothelium image is formed and a corneal epithelium image is formed, and the corneal endothelium image is focused on the light receiving surface of the imaging element. A focusing detection light receiving element set at a position to receive the corneal endothelium reflected light of the slit light through the objective lens at least when the image is formed in the state, and the focusing detection light receiving element is connected to the corneal endothelium. A predetermined position associated with the corneal endothelium image formed on the light-receiving surface of the image sensor based on a signal for detecting focus, and a position corresponding to the predetermined position of the corneal epithelium image similarly formed on the light-receiving surface. A corneal endothelium imaging apparatus having a corneal thickness measuring function, characterized in that the corneal thickness is measured by a corneal thickness measuring means. 2. An enlargement observation having an illumination optical system for slit-illuminating an eye spherical surface of an eye to be examined from an oblique direction, and a magnifying photographing optical system for forming and observing a magnified image of the subject on the basis of the slit illumination light. In the corneal endothelium imaging apparatus equipped with means,
An imaging element arranged on the imaging surface of the magnifying imaging optical system so that a corneal endothelium image is formed and a corneal epithelium image is formed, and the corneal endothelium image is focused on the light receiving surface of the imaging element. A focusing detection light receiving element set at a position to receive the corneal endothelium reflected light of the slit light through the objective lens at least when the image is formed in the state, and the focusing detection light receiving element is connected to the corneal endothelium. The corneal thickness measuring function is characterized in that the corneal thickness measuring means measures the corneal thickness from a predetermined position related to the corneal epithelium image formed on the light receiving surface of the image pickup device based on the signal for detecting the focus. Corneal endothelium imaging apparatus having a. 3. A corneal cell image formed on a light-receiving surface of the image pickup device by a photographing slit of the illumination optical system at a predetermined position related to the corneal endothelium or epithelial cell image for measuring corneal thickness. A corneal endothelium imaging apparatus having a corneal thickness measurement function according to claim 1 or 2, wherein the side edge is one of the side edges. 4. A predetermined position related to the image of corneal endothelium or epithelial cell for measuring corneal thickness is a narrow line having a predetermined length in the longitudinal direction of the photographing slit outside the photographing slit in the illumination optical system. The corneal thickness measurement according to claim 1 or 2, which is a position of the narrow slit image outside the corneal cell image formed on the light receiving surface of the image pickup device by the formed narrow slit for measurement. A corneal endothelium imaging device having a function. 5. The corneal endothelium having a corneal thickness measuring function according to claim 4, wherein the narrow slit for measurement is a pair of narrow slits spaced in the width direction of the slit for photographing. Imaging device. 6. The narrow slit for measurement is located outside one end in the longitudinal direction of the slit for photographing, and one of the longitudinal direction of a corneal cell image formed on the light receiving surface of the image pickup device. 6. A corneal endothelium imaging apparatus having a corneal thickness measurement function according to claim 4, wherein the slit is a narrow slit that forms a narrow slit image in a horizontal blanking area outside the end portion.