JP3511406B2 - Ophthalmic equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmic apparatus for observing an eye image of a subject's cornea. 2. Description of the Related Art Conventionally, there is known an ophthalmic instrument in which illumination light emitted from an illumination light source by an illumination optical system is directed toward a cornea of a subject's eye to measure the thickness of the entire cornea. . In such an ophthalmic apparatus, an epithelial cell layer, Bowman's membrane, corneal stroma, Descemet's membrane, and endothelial cell layer are formed in this order from the corneal surface side. It is not possible to measure the thickness of each stratum of the corneal tissue, and as a method of measuring the thickness of each of these layers, a thin section of the examinee's eye removed after death is observed and measured with a microscope. There has been no device for measuring the thickness of each layer of corneal tissue with respect to a living eye. [0004] The present invention has been made in view of the above-mentioned circumstances, and is not obstructed by the reflected light flux of the illumination light from the cornea.
And to provide an ophthalmic apparatus capable of measuring the Ku layers each thickness of tissue of the cornea living eye. [0005] In order to solve the above-mentioned problems, an ophthalmologic apparatus according to the present invention has an anterior eye portion of an eye to be examined in front.
Anterior ocular segment observation optical system to observe from
An alignment index light projection optical system that projects the index light,
A fixation target light projection optical system that projects fixation target light onto the cornea,
For corneal endothelial cell illumination, which illuminates the cornea diagonally with illumination light
Illumination optical system, and light of the anterior ocular segment observation optical system on the cornea
Illuminates corneal tissue by irradiating illumination light from the direction coaxial with the axis
Through the illumination optical system and the optical axis of the anterior ocular segment observation optical system.
And a symmetrical angle with respect to the illumination optical system for illumination of the corneal endothelial cells.
For observing and taking an image of the eye to be examined with respect to the cornea
An observation and imaging optical system for shadowing,
Based on the scattered light flux from the cornea of the subject eye obtained through
And measuring means for measuring the thickness of at least one layer of the cornea of the eye to be examined. According to the ophthalmic apparatus according to the present invention , the anterior eye is placed on the cornea.
Irradiate the illumination light from the coaxial direction with the optical axis of the
Illumination emitted from illumination optics for illuminating membrane tissue
Light is directed at the cornea and is scattered and reflected by the cornea.
The scattered light is received by the observation and imaging optical system, and the thickness of at least one layer of the cornea of the subject's eye is measured by the measuring means. An embodiment of an ophthalmologic apparatus according to the present invention will be described below with reference to FIGS. 1A and 1B, an ophthalmologic apparatus S
Is an anterior segment observation optical system 1 for observing the anterior segment of the eye E to be examined
0, an alignment index light projection optical system 20 for projecting index light on the cornea C of the eye E, a fixation target light projection optical system 26 for projecting fixation target light on the cornea C, an apparatus main body (not shown), and An alignment pattern projection optical system 30 used for an alignment operation with the optometry E, a corneal tissue observation illumination optical system (illumination optical system) 40 for irradiating the cornea C with illumination light from the front,
A corneal endothelial cell observation illumination optical system (second illumination optical system) 50 for irradiating the cornea C with illumination light obliquely, and an observation imaging optical system (observation optical system) for observing and photographing an eye image of the cornea C to be examined. 60 are provided. The anterior eye observation optical system 10 directly illuminates the anterior eye of the eye E to be examined.
Half mirror 12, objective lens 13, half mirror 1
4. An optical path switching mirror 15 having a front surface 15a having a light shielding surface and a rear surface 15b having a total reflection surface, and a CCD camera 16, and O1 is an optical axis thereof. The images of the anterior segment of the eye E illuminated by the anterior segment illumination light sources 11 and 11 pass through the half mirror 12 and are converged by the objective lens 13 while the half mirror 1 is focused.
4 and is formed on the CCD camera 16. The optical path switching mirror 15 is retracted from the optical path when observing the anterior ocular segment (in a dashed line in FIG. 1A). The alignment target light projection optical system 20 includes an alignment light source 21 for emitting infrared light, a pinhole plate 22, a half mirror 23, a dichroic mirror 24,
It has a projection lens 25 and a half mirror 12 arranged on the optical path so that the focus coincides with the pinhole plate 22. The alignment index light emitted from the alignment light source 21 and passing through the pinhole plate 22 is transmitted through the half mirror 23 and the dichroic mirror 24, and is reflected by the half mirror 12 through the projection lens 25 to be reflected by the anterior ocular segment. The light is guided to the optical path of the observation optical system 10. As shown in FIG. 2, the alignment index light K1 reflected by the half mirror 12 forms 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 is reflected by the corneal surface T. O2 is the optical axis of the eyeball perpendicular to the vertex P of the cornea C, that is, coaxial with the line connecting the vertex P 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 26 includes a fixation target light source 27 that emits visible light, a pinhole plate 28, a half mirror 23, a dichroic mirror 24, a projection lens 25,
It has a half mirror 12. The fixation target light emitted from the fixation target light source 27 passes through a pinhole plate 28, a half mirror 23, a dichroic mirror 24, and a projection lens 25, and the half mirror 1
2 reflected. The subject's gaze is guided by gazing at the fixation target light reflected by the half mirror 12 as a fixation target. The alignment pattern projection optical system 30 includes:
Alignment detection sensor 17 with half mirror 14 interposed
Pattern projection light source 31, alignment pattern plate 32, projection lens 3 provided at a position facing
3, half mirror 14, optical path switching mirror 15, CC
It is composed of a D camera 16. An annular pattern is formed on the alignment pattern plate 32.
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. As shown in FIG. 3, the image E 'of the anterior segment of the eye E to be inspected including the pupil Pu illuminated by the anterior segment illumination light source 11 is a half image. The luminescent spot image R ′ by the alignment index light transmitted through the mirror 14 and the annular pattern image 42 ′ by the alignment pattern light from the alignment pattern projection optical system 21 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 moving the apparatus body and the eye E in the front-rear direction (Z direction).
Here, the alignment adjustment means an adjustment including all the adjustments in the XYZ directions. The illumination optical system 40 for observing corneal tissue includes an illumination light source 41, a condenser lens 42, a slit plate 43, and an aperture stop 4.
4. It has a dichroic mirror 24, a projection lens 25, and a half mirror 12. The condenser lens 4 emitted from the illumination light source 41
The visible light condensed by 2 passes through the slit plate 43, passes through the aperture stop 44 arranged on the focal plane of the projection lens 25 in the same direction as the slit plate 43, and is reflected by the dichroic mirror 24. The light is reflected by the half mirror 12 via the projection lens 25, guided to the cornea C along the optical axis O1, and illuminates the inside of the cornea C from the vertex P of the corneal surface T. The illumination optical system 50 for observing corneal endothelial cells is an illumination light source for observation using a halogen lamp (second illumination light source).
51, condenser lens 52, slit plate 53, aperture stop 5
4. It has a light projection lens 55, and O3 is its optical axis. The infrared light emitted from the observation illumination light source 51 at the time of observation is guided to the slit plate 53 while being condensed by the condensing lens 52. Projection lens 55 in the same direction
The light projecting lens 5 passes through an aperture stop 54 disposed on the focal plane.
The light is guided to the cornea C by 5 and traverses from the corneal surface T toward the inside. The observation optical system 60 includes a wavelength selection filter 61, an objective lens 62, a half mirror 63, and a mask 6.
4, relay lens 65, mirror 66, variable power lens 67,
Focusing lens 68, optical path switching mirror 15, CCD camera 1
6 and O4 is its optical axis. The optical path switching mirror 15 is inserted into the optical path at the time of corneal tissue observation imaging and corneal endothelial cell observation imaging. Also, the mask 64
Is retracted from the optical path during corneal tissue observation and photography. The variable power lens 67 is set to a high magnification during corneal tissue observation and photographing, and is set to a low magnification during corneal endothelial cell observation and photographing. As shown in FIG. 4, the illuminating light from the corneal tissue observation illumination optical system 40 includes corneal epithelial cells U, Bowman's membrane B, corneal stroma M, and Descemet's membrane D whose slit light beam K2 forms the cornea C. Are scattered and reflected by each layer of the corneal endothelial cells N. The light scattered by the layers U, B, M, D, and N of the cornea C passes through the wavelength selection filter 61, is collected by the objective lens 62, passes through the half mirror 63, and forms an image once. The image is reflected by the optical path switching mirror 15 via the relay lens 65, the mirror 66, the variable power lens 67 in the high magnification state, and the focusing lens 68, and an image of the corneal cross section is formed on the CCD camera 16, and the screen 18 As shown in FIG. 5, images of a corneal epithelial cell image U ′, Bowman's membrane image B ′, corneal stromal image M ′, Descemet's membrane image D ′, and corneal endothelial cell image N ′ in the cross-sectional direction of the cornea C are displayed. . From the images U ', B', M ', D', and N 'formed on the CCD camera 16, the curvature of the cornea C,
The image processing device and the arithmetic device take into account the image magnification, the refractive index, the angle of the optical axis O3, the angle of the optical axis O1 (not considered when the optical axis O1 is perpendicular to the vertex of the cornea) and the like. The thicknesses F1, F2, F3, F4, F5 of each layer are measured. The image processing apparatus functions as a measuring means to measure the thickness by calculation. As another measuring means, as shown in FIG. 6, the thickness from the cornea C received by the line sensor 69 is measured. Based on the scattered light, a boundary portion between the images U ′, B ′, M ′, D ′, N ′ is detected from each peak value,
The interval between the peak values is determined by the thicknesses F1, F2, F3, and F of the respective layers.
It is also possible to calculate by judging as 4, F5. As another measuring means, a screen 1
For example, a scale corresponding to the display magnification on a one-to-one basis may be displayed on the display 8. However, the thickness measurement itself when this scale is displayed is a visual measurement. Further, the measurement can be performed by selecting or setting alone or in combination, for example, by observing at a higher magnification and measuring only the thickness of the endothelial cells N, instead of calculating all the layers. The slit light beam K3 guided to the corneal endothelial cell observation illumination optical system 50 shows the state of reflection of the slit light beam K3 on the cornea C as shown in FIG. A part of the slit light beam K3 is first reflected on a corneal surface T which is a boundary surface between the air and the cornea C. The amount of the reflected light beam k from the corneal surface T is the largest. The light amount of the reflected light beam n from the corneal endothelial cell N is relatively small, and the light amount of the reflected light beam m from the corneal stroma M is the smallest. The light beam reflected from the cornea C passes through the wavelength selection filter 61, is collected by the objective lens 62, and is guided to the half mirror 63. The reflected light beam that has passed through the half mirror 63 forms an image once at the position of the
By 4, an extra reflected light beam other than forming a corneal endothelial cell image is blocked. Further, the reflected light beam passing through the mask 64 is reflected by the mirror 66 via the relay lens 65,
The light is reflected by the optical path switching mirror 15 via the variable power lens 67 and the focusing lens 68 and is imaged on the CCD camera 16. 8, a corneal endothelial cell image N ″ is displayed on the screen 18, as shown in FIG. 8. In FIG. 8, a broken line 71 indicates a reflected light flux k from the corneal surface T if it is not blocked by the mask 64. Is an optical image formed by
Reference numeral 2 denotes an optical image formed by the reflected light beam m from the corneal stroma M. The hatched portions in FIG. 8 are portions shielded by the mask 64. On the other hand, the light beam reflected by the half mirror 63 is guided to a line sensor 69 for alignment detection at a position conjugate with the mask 64 at the image forming position. The line sensor 69 is arranged as shown in FIG. 9B with respect to the sectional direction of the cornea C, and the intensity distribution of the reflected light beam is as shown in FIG. 9A. . In FIG. 9A, reference numeral P1 denotes a peak portion caused by the reflected light beam k reflected on the corneal surface T, and P2 denotes a peak portion caused by the reflected light beam n reflected by the corneal endothelial cell N. The peak P1 corresponds to the light image 71, and the peak P
2 corresponds to the light image 72. Known means is used for detecting the peak portions P1 and P2 and for detecting the center of the peak portions P1 and P2. On the other hand, the line sensor 69 outputs a focus determination signal to the control circuit 73. The control circuit 73 determines the center address p of the peak portion P2 of the reflected light beam n when observing and photographing corneal endothelial cells by storing the signals of the peak portions P1 and P2 and performing arithmetic processing. It is determined whether or not p coincides with the predetermined address Q of the line sensor 69 to detect the alignment between the eye E and the apparatus main body, and control each optical member of the drive system. That is, the control circuit 73 includes the line sensor 69
When the position detection value of the light beam imaged in the range falls within the allowable alignment range in the vertical and horizontal directions, the center address p of the reflected light beam n from the corneal endothelial cell N matches the predetermined address Q. The switching mirror 15 is inserted into the optical path. Note that the scattered light shown in FIG. At this time, it is also possible to calculate the thickness of each layer in the sectional direction based on the light amount on the line sensor 69. In the above configuration, first, each light source 1
The rough adjustment of the alignment is performed while the display of the screen 18 is confirmed by turning on the lights 1, 21 and 51. The determination circuit 73 determines that the position detection value of the alignment detection sensor 17 falls within the allowable alignment range in the X and Y directions, and that the center address p of the light beam k reflected from the corneal surface T is determined by the alignment operation.
When entering (coincident with) a predetermined address Q, which is a direction allowable range, the control circuit 74 outputs information relating to one of the corneal tissue observation mode and the corneal endothelial cell observation mode and the output of the line sensor 69 to the control circuit 74. When the corneal tissue observation mode is selected, the control circuit 74 turns off the light sources 11 and 51, retracts the mask 64 from the optical path, and controls the illumination light source 41.
Is turned on and the variable power lens 67 is set to a high magnification, and then the optical path switching mirror 15 is inserted into the optical path. When the optical path switching mirror 15 is inserted into the optical path, the display state of the screen 18 is switched from the anterior segment display state shown in FIG. 3 to the corneal tissue display state in the corneal sectional direction shown in FIG. Further, in the corneal tissue display state, fine adjustment of the alignment is further performed, and the alignment detecting sensor 1
7 and the control circuit 7 when the alignment in the XYZ directions falls within the allowable range as judged from the output of the line sensor 69.
4, an imaging execution signal is output, and the images formed on the CCD camera 16, that is, the images U ′, B ′, M ′, D ′, and N ′ as the corneal tissue images displayed on the screen 18 are output. Be photographed. On the other hand, when the corneal endothelial cell observation mode is selected, the control circuit 74 turns off the light source 11 and moves the variable power lens 67 along the optical axis O4 to a low magnification. Optical path switching mirror 15 and mask 6
4 is inserted into each optical path. When the optical path switching mirror 15 is inserted into the optical path, the display state of the screen 18 is switched from the anterior segment display state shown in FIG. 3 to the corneal endothelial cell display state shown in FIG. Then, in the corneal endothelial cell display state, the alignment is further finely adjusted, and the XY is determined based on the outputs of the alignment detection sensor 17 and the line sensor 69.
When the alignment in the Z direction is within the allowable range, a shooting execution signal is output from the control circuit 74 and the CCD camera 16
The corneal endothelial cell image N ″ displayed on the screen 18 is photographed. The photographed corneal endothelial cell image N ″ is used in addition to the diagnosis of its state and the like, as well as the unit. Area (for example, 0.1 mm × 0.1
The number of cells per mm) is confirmed. In the above embodiment, measurement and photographing are performed using visible light, but measurement and photographing may be performed using infrared light.
The optical axis of the corneal tissue observation illumination optical system 40 is coaxial with the eyeball optical axis O2 (in an alignment completed state).
1 is disclosed, but the light beam emitted from the illumination light source 41 is obliquely illuminated on the eye E, and the optical axis at that time is set to the observation optical axis with respect to the eyeball optical axis O2. The angle is not particularly limited as long as it is different from O4. As described above, the illumination optical system 4 for corneal tissue observation
Since the optical axis of 0 and the optical axis of the observation optical system 60 are asymmetric with respect to the optical axis O2 of the eyeball, the luminous flux with a high light quantity emitted from the illumination light source 41 and reflected on the corneal surface T of the eye E to be examined Is not guided to the observation optical system 60, so that the corneal tissue can be observed based on the scattered light in the corneal cross-sectional direction having a low light amount. Therefore, for example, for finding a disease in the cross-sectional direction, measuring and confirming the thickness of each layer of the cornea C which differs depending on individual differences and disease, or in myopia surgery for correcting by shaving the corneal surface with a laser scalpel. Before and during laser scalpel power setting / change and confirmation of shaving amount,
Observation and imaging of each layer in the cross-sectional direction that could not be achieved with the living eye can be performed, such as thickness measurement and inspection in the cross-sectional direction after myopia surgery including myopia surgery to correct and correct the corneal surface with a scalpel. . As described above, in the ophthalmologic apparatus according to the present invention, the anterior segment for observing the anterior segment of the eye to be examined from the front is described.
An observation optical system, and an aerial for projecting the index light onto the cornea of the eye to be examined.
Lightment target light projection optical system and fixation target light on the cornea
A fixation target light projection optical system for projecting, and an oblique illumination of the cornea.
An illumination optical system for illuminating corneal endothelial cells that emits bright light;
The cornea is illuminated from the same axis as the optical axis of the anterior ocular segment observation optical system.
Illumination optics for illuminating corneal tissue with bright light
And the corneal endothelium through the optical axis of the anterior ocular segment observation optical system
The illumination optical system for cell illumination is provided at a symmetrical angle and
Observation for observing and photographing the eye image of the cornea to be examined
Before being obtained through the photographic optical system and the observation photographic optical system
Serial was a measuring means for measuring a thickness of at least one layer of the eye of the cornea based on the scattered light beam from the eye
And that the illumination light is disturbed by the reflected light from the corneal surface
Instead, the thickness of each layer of the corneal tissue of the living eye can be measured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of an ophthalmologic apparatus according to the present invention, in which (A) is an explanatory view of a main optical system, and (B) is an explanatory view of an illumination optical system for corneal tissue observation. FIG. 2 is also an explanatory diagram showing a corneal reflection state of an index light. FIG. 3 is a front view of a screen in an anterior segment observation state. FIG. 4 is an explanatory view showing the state of reflection of a slit light beam on the cornea during corneal tissue observation and imaging. FIG. 5 is a front view of a screen in a corneal tissue observation and imaging state. FIG. 6 is a graph showing the amount of light received by a line sensor during corneal tissue observation and imaging. FIG. 7 is an explanatory view showing a reflection state of a slit light beam on the cornea at the time of corneal endothelial cell observation and imaging. FIG. 8 is a front view of a screen in a corneal endothelial cell observation and imaging state. FIG. 9A is a graph showing the amount of light received by a line sensor during precise alignment in corneal endothelial cell observation and imaging, and FIG. 9B is an explanatory diagram showing a light receiving state of an eye image on the line sensor at that time. It is. [Description of Signs] E: Eye to be inspected C: Cornea 40: Illumination optical system for observing corneal tissue (illumination optical system) 41: Illumination light source 60: Observation photographing optical system (observation optical system)

Claims (1)

(57) Claims 1. An anterior eye for observing an anterior eye part of an eye to be examined from the front
Part observation optical system and alignment index for projecting index light to the cornea of the eye to be inspected
A light projection optical system, a fixation target light projection optical system for projecting fixation target light onto the cornea, and a corneal endothelial cell illumination for irradiating the cornea with illumination light obliquely
Illumination optical system, and the cornea from the coaxial direction with the optical axis of the anterior ocular segment observation optical system
Illumination optical system for illuminating corneal tissue by illuminating light
And the corneal endothelial cells via the optical axis of the anterior ocular segment observation optical system
The cornea is provided at a symmetric angle with respect to an illumination optical system for illumination.
Observation for observing and photographing the eye image of the subject
An optical system, and a cornea of the subject's eye obtained through the observation and imaging optical system.
A measuring means for measuring the thickness of at least one layer of the cornea of the subject's eye based on the scattered light flux from the eye.