JP3506780B2 - Corneal endothelial cell imaging system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corneal endothelial cell photographing apparatus for observing and photographing an image relating to the cornea of a subject's eye including a corneal endothelial cell image of the subject's eye. 2. Description of the Related Art Conventionally, as an apparatus for observing and photographing a corneal endothelial cell image, an infrared light is projected at the time of observation, and a visible light is projected toward the cornea of an eye to be examined at the time of photographing. It is known that a CCD camera is used as an image receiving means for photographing and one slit stop for projecting slit illumination light onto the cornea is fixed on the optical axis of an illumination optical system. [0003] Infrared light at the time of observation and visible light at the time of photographing are:
Since the imaging position of the slit stop on the cornea differs due to the difference in wavelength, a focal position correction lens or the like may be inserted into and removed from the optical axis according to the wavelength, or the wavelength of visible light at the time of imaging. The focus shift of infrared light at the time of observation was neglected as the corneal endothelial cell position as it was with the imaging position. [0004] By the way, in such a corneal endothelial cell photographing apparatus, for example, a lens for correcting a focal position can be inserted into and removed from the optical axis in accordance with the wavelength. In this case, the drive unit for inserting and removing the correction member is required, which not only complicates the structure of the entire apparatus, but also responds to the drive sound generated from the drive unit, and However, there has been a problem that the user may blink. Also, if the defocus of infrared light during observation is ignored, there is a problem that the reliability of positional accuracy is low because the alignment is determined based on the blurred image. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when a different wavelength is used for observation and photographing, a special driving means is used to reduce the deviation of the slit image position caused by the difference in wavelength. It is an object of the present invention to provide a corneal endothelial cell photographing apparatus that can perform correction without using a corneal endothelial cell, thereby improving reliability. [0007] In order to achieve the object, the invention according to claim 1 is directed to an illumination optical system for irradiating illumination light emitted from an illumination light source obliquely toward a cornea of an eye to be examined. And an observation optical system for receiving and reflecting the reflected light from the subject's eye to observe and photograph the subject's eye image including the corneal endothelial cell image, as well as illumination for observing the subject's eye. In a corneal endothelial cell photographing apparatus in which light and illumination light for photographing an eye image to be photographed have different wavelengths, the illumination light source is provided on an optical axis of the illumination optical system in correspondence with respective wavelengths for observation and photographing. The two types of slit diaphragms, which use the illumination light emitted from the lens as slit illumination light, are installed in a fixed state.
For the different types of apertures, the slit aperture width for observation is
It is characterized by being narrower than the aperture width. According to the first aspect of the present invention,
Illumination light of the observation wavelength, which is regarded as slit illumination light, is obliquely directed toward the cornea of the eye to be examined through a slit stop for the observation wavelength fixedly installed on the optical axis of the illumination optical system, and is observed by the observation imaging optical system. The reflected light from the optometry is received and the eye image of the cornea including the corneal endothelial cell image is observed, and is converted into slit illumination light through a slit stop for a photographing wavelength fixedly installed on the optical axis of the illumination optical system. Illumination light of an imaging wavelength is irradiated obliquely toward the cornea of the eye to be inspected, and reflected light from the eye is received by the observation and imaging optical system, and an image of the eye to be inspected relating to the cornea including the image of the corneal endothelial cells is captured. . An embodiment of a corneal endothelial cell photographing apparatus according to the present invention will be described below with reference to FIGS. (First Embodiment) FIGS. 1 to 8 show a first embodiment of a corneal endothelial cell photographing apparatus according to the present invention.
In (B), the corneal endothelial cell photographing apparatus S includes an eye E to be examined.
Anterior segment observation optical system 10 for observing the anterior segment of the eye, alignment index light projection optical system 20 for projecting index light on cornea C of eye E to be examined, fixation target light projection for projecting fixation target light on cornea C The optical system 30, an alignment pattern projecting optical system 40 used for an alignment operation between the apparatus body (not shown) and the eye to be examined, an illumination optical system 50 for irradiating the cornea C with illumination light obliquely, An observation photographing optical system 60 for observing and photographing an optometry image is provided. The anterior eye observation optical system 10 includes a plurality of anterior eye observation light sources 11, half mirrors 12, objective lenses 13, half mirrors 14, which are located on the left and right of the eye E and directly illuminates the anterior eye. A light shielding plate 15 and a CCD camera 16 are retracted from the optical path when observing the anterior ocular segment and inserted into the optical path when observing and photographing the cornea C, and O1 is an optical axis of the optical path. An image of the anterior segment of the subject's eye E illuminated by the anterior segment illumination light source 11 is transmitted through the half mirror 12 and then focused by the objective lens 13 while the half mirror 1 is focused.
4 and is formed on the CCD camera 16. The alignment target light projection optical system 20 is a projection light source that emits infrared light, a pinhole plate 22, a half mirror 23, and a projection disposed on the optical path so that the focal points coincide with the pinhole plate 22. It has a lens 24, an aperture 25, and a half mirror 12. The alignment index light K emitted from the alignment light source 21 and passing through the pinhole plate 22 is reflected by a half mirror 23, is converted into a parallel light beam by a projection lens 24, passes through a diaphragm 25, and is Mirror 1
2 and, as shown in FIG. 1 (C), is reflected by the corneal surface T so as to form a bright spot image R at an intermediate position between the vertex P of the cornea C and the center of curvature of the cornea C. . The light beam reflected from the cornea C is transmitted to the half mirror 1
2. It is guided to the half mirror 14 via the objective lens 13. A part of the reflected light beam guided to the half mirror 14 is reflected by the half mirror 14 and guided to an alignment detection sensor 17 such as a PSD capable of detecting a position. The fixation target light projection optical system 30 includes a fixation target light source 31 that emits visible light, a pinhole plate 32, a half mirror 23, a projection lens 24, an aperture 25, and a half mirror 12.
Having. The fixation target light emitted from the fixation target light source 31 passes through a pinhole plate 32 and a half mirror 23, is converted into a parallel light beam by a projection lens 24, and then passes through a stop 25 to the half mirror 12. Is reflected. The subject's gaze is fixed by gazing at the fixation target light reflected by the half mirror 12 as a fixation target. The alignment pattern projection optical system 40 includes:
Alignment detection sensor 17 with half mirror 14 interposed
Pattern projection light source 41, alignment pattern plate 42, projection lens 4 provided at a position facing
3 is comprised. An annular pattern is formed on the alignment pattern plate 42.
A part of the pattern forming light beam transmitted through the
Is reflected on the back surface of the camera and imaged on the CCD camera 16. The CCD camera 16 outputs an image signal to the monitor device, and as shown in FIG. 2, an image E 'of the anterior segment of the eye E to be examined including the pupil Pu illuminated by the anterior segment illumination light source 11, a half A bright spot image R ′ formed by the alignment index light transmitted through the mirror 14 and an annular pattern image 42 ′ formed by the alignment pattern light from the alignment pattern projection optical system 40 reflected by the half mirror 14 are displayed on the screen 18 of the monitor device.
Will be displayed. The apparatus main body is swung up and down (Y direction) and left and right (X direction) so that the light beam reflected by the cornea C and forming the bright spot image R 'is located at the center of the annular pattern image 42'. By doing so, the alignment of the apparatus main body and the eye E to be examined is adjusted in the X and Y directions, and the optical axis O2 of the eye E and the optical axis O1 of the eye E are matched. Further, the working distance is set by shifting the apparatus body and the eye E in the front-back direction (Z direction).
Here, the alignment adjustment means an adjustment including all the adjustments in the XYZ directions. The illumination optical system 50 includes an observation illumination light source 51 using a halogen lamp, a condenser lens 52, an infrared filter 53, a photographing illumination light source 54 using a xenon lamp,
It has a condenser lens 55, a dichroic mirror 56, a slit plate 57, a light projecting lens 58, and an aperture stop 59, and O3 is its optical axis. In addition, an infrared LED is used as the observation illumination light source 51.
, The infrared filter 53 can be omitted. At the time of observation, the infrared light emitted from the observation illumination light source 51 is condensed by the condenser lens 52, passes through the infrared filter 53, is reflected by the dichroic mirror 56, and is guided to the slit plate 57. On the other hand, the visible light emitted from the photographing illumination light source 54 at the time of photographing is also transmitted through the dichroic mirror 56 while being collected by the condenser lens 55 and guided to the slit plate 57. The luminous flux passing through the slit plate 57 is guided to the cornea C through a light projecting lens 58 and an aperture stop 59 in the same direction as the slit plate 57, and is illuminated so as to traverse inward from the corneal surface T. . The slit plate 57 is formed of a plane-parallel optical glass plate. As shown in FIG. 3, the slit plate 57 is long in the Y direction and has a different slit width so as to pass infrared light for observation or visible light for photographing. Two types of slit diaphragms 57a and 57b
Are provided on the front and back, and can be installed in the optical path at the same time, and the alignment of the optical axes when the slit stops 57a and 57b are installed in the optical path is unnecessary. The slit diaphragm 57a is formed narrower than the slit diaphragm 57b by a film 57c provided on the surface of the slit plate 57 for blocking infrared light and transmitting visible light. At the time of observation, a slit image is formed substantially at the middle of the corneal surface T or the cornea C in the thickness direction (the middle between the corneal surface T and the corneal endothelial cell surface N). The slit diaphragm 57b is formed by a film 57d provided on the back surface of the slit plate 57 for blocking all light fluxes, and forms a slit image on the corneal endothelial cell surface N during photographing. The thickness of the slit plate 57 corresponds to the wavelength of the light beam used for observation or photographing and the slit imaging position. Alternatively, the slit stop 57b may be a thin plate such as a metal plate with a stop opening formed. The observation photographing optical system 60 includes an objective lens 61,
Half mirror 62, mask 63, total reflection mirror 64, relay lens 65, optical path (on optical axis O4) during anterior segment observation
A light-shielding plate 66 inserted into the camera and retracted from the optical path when observing and photographing the cornea C, is disposed at a position where it does not hinder the anterior segment observation light flux, and has an inclination angle θ on the object side (the eye E side).
, A total reflection mirror 67 and a CCD camera 16 inclined at the same angle, and O4 is the optical axis. The luminous flux reflected from the cornea C is supplied to the objective lens 61
And is guided to the half mirror 62. The reflected light beam that has passed through the half mirror 62 forms an image once at the position of the mask 63, and the mask 63 blocks an extra reflected light beam other than forming a corneal endothelial cell image. Further, the mask 6
3 is reflected by the total reflection mirror 64 and is focused by the relay lens 65 while being reflected by the total reflection mirror 67.
Then, an image of corneal endothelial cells is formed on the CCD camera 16 at high magnification. The position of the mask 63 is at the focal position of the corneal endothelial cell image with visible photographing light. Also, CC
The corneal endothelial cell image on the D camera 16 is also at the focal position with visible photographing light. FIG. 4 shows how the slit light beam L projected by the illumination optical system 50 is reflected on the cornea C. A part of the slit light beam L is first reflected on a corneal surface T which is a boundary surface between the air and the cornea C. The light quantity of the reflected light flux T ′ from the corneal surface T is the largest. The light amount of the reflected light beam N ′ from the corneal endothelial cell surface N is relatively small,
The light amount of the reflected light flux M ′ from the light source is the smallest. On the screen 18, a corneal endothelial cell image 70 is displayed as shown in FIG. In FIG. 5, 71 indicated by a broken line is an optical image formed by the reflected light flux T ′ from the corneal surface T if it is not blocked by the mask 63,
Reference numeral 72 denotes an optical image formed by the reflected light flux M ′ from the corneal stroma M. The hatched portions in FIG. 5 are portions shielded by the mask 63. On the other hand, the infrared reflected light beam that transmits visible light and is reflected by the half mirror 62 to infrared light is
The light is guided to a line sensor 68 for alignment detection at a corneal endothelial cell imaging position by infrared light. The line sensor 68 outputs a focus determination signal from a determination circuit 69 to a control circuit (not shown). The line sensor 68 detects the corneal endothelial cell image 7
0, it is arranged as shown in FIG. 6B with respect to the reflected light from the corneal surface T, and its light amount distribution is as shown in FIG. 6A. Then, the output of the line sensor 68 is output to the judgment circuit 69, and the judgment circuit 69 calculates the image center P2 of the intracorneal cell image 70 as shown in FIG.
It is determined whether or not the address p of the image center P2 moves by the alignment operation and matches the predetermined address Q on the line sensor 68. The apparatus optical system is set so that the corneal endothelial cell surface N is focused when the address of the image center P2 coincides with the predetermined address Q. In FIG. 6A, a graph value indicated by a dashed line indicates a state where alignment is not performed, a graph value indicated by a solid line indicates a state where alignment is performed, and P1 indicates a light flux reflected from the surface T. This is the peak value of T '. It should be noted that the width of the aperture stop 59 is the same as the width of the slit stop 57.
Since the width of the slit light beam is much wider than the width of the slit aperture 57a, the slit light beam has a wedge shape, and the width of the slit light beam at the position of the corneal surface T located before the image forming position of the slit diaphragm 57a is large. Although there was a defect in the accuracy, when the line sensor 68 detects the alignment, the imaging position of the slit diaphragm 57a is set to substantially the middle of the corneal surface T or the cornea C in the thickness direction, so that the position from the corneal surface T can be reduced. The width of the light image 71 of the reflected light flux T ′ becomes narrower, and the difference between the peak value P1 and the light amount distribution of the peripheral addresses becomes sharp, so that the peak value P2
Detection accuracy is improved. Further, as shown in FIG. 3B, the slit width D1 of the slit stop 57a for observation illumination by infrared light.
Is made narrower than the slit width D2 of the slit stop 57b for photographing illumination by visible light, so that the image on the line sensor 68 at the time of observation shown by the solid line in FIG. 7 (the same light amount distribution as in FIG. 6A). Images 70 and 71 on the line sensor 68 at the time of photographing in which the widths of 70 and 71 are indicated by broken lines in FIG.
, And the detection accuracy of the peak values P1 and P2 can be improved. The control circuit detects the alignment between the eye E to be inspected and the main body of the apparatus, and controls each part of the drive system as shown in FIG. That is, when the position detection value of the light beam imaged on the alignment detection sensor 17 and the line sensor 68 checks the alignment in the XYZ directions, and when the XYZ alignment is within the allowable range, the light shielding plate 15 is moved to the optical path. And the light shielding plate 66 is retracted from the optical path. By inserting the light-shielding plate 15 into the optical path and retracting the light-shielding plate 66 from the optical path, the display state of the screen 18 is changed from the display state of the anterior eye image E 'shown in FIG. The corneal endothelial cell image 70 is switched to the displayed state. Next, when the photographing of the corneal endothelial cells is selected, the alignment in the XYZ directions is checked again, and when the alignment in the XYZ directions is within the allowable range, each of the light sources 11, 21, 21 is checked. The corneal endothelial cell surface N is photographed by turning off the light sources 31 and 51 and turning on the photographing illumination light source 54. (Second Embodiment) FIG. 9 shows a second embodiment of the present invention.
Although the a and 57b are integrally formed on the front and back of the plane-parallel optical glass, the slit diaphragm is separately arranged in the second embodiment. In FIG. 9, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Since the substantial operation of the second embodiment is the same as that of the first embodiment, only the configuration of an optical system different from that of the first embodiment will be described. The illumination optical system 80 according to the second embodiment includes an observation illumination light source 81 using a halogen lamp and a condenser lens 8.
2. It has an infrared filter 83, a slit diaphragm 84, a dichroic mirror 85, a photographing illumination light source 86 using a xenon lamp, a condenser lens 87, a slit diaphragm 88, a light projecting lens 58, and an aperture diaphragm 59. The optical axis. The infrared light emitted from the observation illumination light source 81 at the time of observation is transmitted through an infrared filter 83 while being condensed by a condenser lens 82, guided to a slit diaphragm 84, and passed through the slit diaphragm 84 to be dichroic. The light is reflected by the mirror 85 and guided to the light projecting lens 58. On the other hand, the visible light emitted from the photographing illumination light source 86 at the time of photographing is guided to the slit diaphragm 88 while being condensed by the condenser lens 87, passes through the dichroic mirror 85 through the slit diaphragm 88, and is projected. Optical lens 58
It is led to. The light beam guided to the light projecting lens 58 is guided to the cornea C through an aperture stop 59 optically in the same direction as the slit stops 84 and 88, and crosses from the corneal surface T toward the inside. Light up. The slit diaphragms 84 and 88 are formed of a parallel plane optical glass plate similarly to the above-described slit plate 57, and are long and slit in the Y direction so as to pass infrared light for observation or visible light for photographing. The width is slit aperture 84,
A light-shielding film is provided on the front surface or the back surface so as to be different from 88 (the slit diaphragm 84 is narrower), or a thin metal plate formed with slit diaphragms 84 and 88 is used. . The slit diaphragm 84 forms a slit image through the light projecting lens 58 substantially at the center of the corneal surface T or the cornea C in the thickness direction (the middle between the corneal surface T and the corneal endothelial cell surface N) during observation. The slit stop 88 forms a slit image on the corneal endothelial cell surface N at the time of photographing via the light projecting lens 58. As described above, in the above-described first embodiment, the film 5 with the wide slit aperture 57b using visible light
Although the portion where the film 57c is projected is slightly dark when the cut line 7c is reflected as a line, the structure is complicated in the second embodiment, but the dark image is eliminated. . As described above, in the corneal endothelial cell photographing apparatus of the present invention, the illumination light source corresponding to each wavelength for observation and photography is provided on the optical axis of the illumination optical system. Emitted from
Types of slit diaphragms using slit illumination light as slit illumination light
Is fixed, and two types of apertures are used for observation.
I made the aperture width narrower than the slit aperture width for shooting
In the case of using a different wavelength in the wavelength for capturing the wavelength for observation, can be corrected without using a special drive means the deviation of the slit image position due to the difference in wavelength, thus reliability Performance can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a corneal endothelial cell photographing apparatus according to the present invention, wherein (A) is an explanatory view of a main optical system, and (B) is an alignment index light projection optical system and a fixation target. Explanatory drawing of a projection optical system, (C)
FIG. 4 is an explanatory diagram showing a corneal reflection state of the index light. FIG. 2 is a front view of the monitor device in an anterior segment image display state. FIG. 3A is a perspective view of a slit plate, and FIG.
Is a front view of the slit plate, and (C) is a cross-sectional view of the slit plate. FIG. 4 is a diagram showing a reflection state of a slit light beam on the cornea. FIG. 5 is a front view of the monitor device in a corneal endothelial cell image display state. FIG. 6A is a graph showing a relationship between a light amount distribution of a reflected light beam received by a line sensor and alignment detection, and FIG. 6B is an explanatory diagram showing a relationship between the line sensor and a corneal endothelial cell image. is there. FIG. 7 is a graph showing a light amount distribution of a reflected light beam received by the line sensor when the slit width of the slit stop during observation is reduced. FIG. 8 is a flow chart showing the operation. FIG. 9 is a view showing a second embodiment of a corneal endothelial cell photographing apparatus according to the present invention, and is an explanatory view of a main optical system thereof. [Explanation of Symbols] E: eye to be examined C: cornea 50: illumination optical system 51: illumination light source for observation (illumination light source) 54: illumination light source for illumination (illumination light source) 57: slit plate 57a: slit aperture 57b: slit aperture 60 … Observation optical system

Claims (1)

(57) [Claim 1] An illumination optical system for obliquely irradiating illumination light emitted from an illumination light source toward a cornea of an eye to be inspected, and a cornea receiving reflected light from the eye to be inspected. An observation and imaging optical system for observing and photographing the eye image of the cornea including the endothelial cell image is provided, and illumination light for observing the eye to be inspected and illumination light for photographing the image of the eye to be inspected are provided. In a corneal endothelial cell photographing apparatus having different wavelengths, two types of illumination light emitted from the illumination light source on the optical axis of the illumination optical system corresponding to each wavelength for observation and imaging are used as slit illumination light. With fixed slit aperture
The two types of diaphragms have different slit diaphragm widths for observation.
A corneal endothelial cell photographing apparatus characterized in that it is narrower than a slit aperture width for shadow .