JP3406933B2 - Corneal examination equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corneal examination apparatus used in ophthalmic clinics and the like. 2. Description of the Related Art In a conventional corneal examination apparatus for measuring the shape of a cornea, a large number of ring light beams are projected on the cornea of an eye to be examined, and the light beam reflected on the cornea is received as a ring image. Is analyzed to determine the shape of the cornea. As a ring light beam projecting means of such an apparatus, a dish-shaped member as disclosed in Japanese Patent Application Laid-Open No. 4-44736 and a cylindrical member as disclosed in US Pat. No. 5,018,850 are often used. Are known. Furthermore, Japanese Patent Application Laid-Open No. 61-293424 discloses an apparatus provided with a plurality of ring mirrors as ring light beam projection means. Further, U.S. Pat. No. 4,597,648 discloses a corneal examination apparatus which detects a reflection image on the cornea due to a ring light beam, monitors the position of the apparatus, and automatically starts measurement when the apparatus is aligned. . [0004] However, the above-mentioned conventional ring light beam projecting means has a complicated structure, and the ring mirror type is also required to increase the number of ring mirrors in order to improve measurement accuracy. It gets complicated. An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a corneal examination apparatus including a projection unit having a simple configuration. A corneal examination apparatus according to the present invention for achieving the above object has a circular opening around an optical axis.
Has a mouth portion, a hemispherical or flat-shaped transparent light <br/> faculty member center and the plurality of concentric optical <br/> beam diffusing unit provided on the surface of the opening, the and a light source disposed on an end surface of the opening to illuminate the inner <br/> portion of the optical member, a ring-shaped light beam is diffused by the light beam diffusing unit repeatedly internally reflected within said optical member by said light source Illuminates the cornea of the eye as a light beam
Analyzing the plurality of ring-shaped corneal reflected image obtained by reflection, and measuring the corneal shape of the eye. In the corneal examination apparatus according to the present invention having the above-described structure, the light beam from the light source illuminates the inside of the optical member, and is diffused by a plurality of concentric light beam diffusing portions, and the cornea of the eye to be examined. Is projected as a ring-shaped light beam , and the corneal reflection image of this light beam on the cornea is analyzed to determine the shape of the cornea of the eye to be examined. The present invention will be described in detail with reference to an embodiment shown in the drawings. FIG. 1 is a configuration diagram of the first embodiment. A thin hemispherical shell-shaped transparent member 1 made of a transparent acrylic resin or the like is provided in front of an eye E to be inspected. The end face 1a has a mirror-like shape. A ring-shaped strobe light source 2 is mounted along an end surface 1b of a circular opening at the center of the transparent member 1, and a reflecting member 3 covers the periphery of the strobe light source 2 and opens on the end surface 1b side of the reflecting member 3. Is provided,
Further, a ring slit 4 is cut on the eye E side. On the rear surface of the transparent member 1, there are provided light beam diffusing portions 5 to 11 having concentric light beams. An aluminum film or the like may be attached to these light diffusion units 5 to 11 or the entire rear surface to increase the reflectance. In addition, the light beam diffusing unit 5
11 can be provided only on both side surfaces or the front surface of the transparent member 1. On the optical path O1 passing through the center of the opening of the transparent member 1, there are arranged a lens 12, an aperture 13, and an image sensor 14 composed of a CCD from the eye E side. On two optical paths O2 and O3 symmetrical with respect to the optical path O1, half mirrors 15, 16 and a lens 17,
18, four-lobed light receiving elements 19 and 20 each composed of four photodiodes are arranged,
6, an alignment light source 21,
22 are arranged respectively. The optical member shown in FIG. 1 is placed on a slide table (not shown). FIG. 2 is a block diagram of a control unit and an operation unit of the apparatus.
A mode selection means 24 provided with two input buttons A and M,
An operation rod 25 for operating a slide table (not shown) is connected, and the operation rod 25 is provided with a measurement button 26. When measuring the shape of the cornea Ec, the light beam from the ring-shaped strobe light source 2 is applied to the transparent member 1 from the end face 1b.
Incident on the end surface 1a by repeating total reflection, and is diffused by the light beam diffusing portions 5 to 11 and emitted from the front surface of the transparent member 1. Part of the incident light flux reaches the end surface 1a of the transparent member 1 and is totally reflected. The light is diffused by the light beam diffusing portions 5 to 11, travels inside the transparent member 1 and exits from the transparent member 1, and is again emitted by the reflecting member 3. The light is reflected inside the transparent member 1. The light beam from the strobe light source 2 is also emitted from the ring slit 4. Ring slit 4 and light beam diffusing portions 5 to 11
Is a cornea Ec of the eye E to be inspected.
Is irradiated. The reflected light flux here is the opening of the transparent member 1,
The light is received by the imaging device 14 as a concentric corneal ring image through the lens 12 and the aperture 13, and the received light signal is taken into a computer in the apparatus. The computer calculates the position of the corneal ring image to determine the shape of the cornea Ec.
If the distortion of the corneal ring image is only visually checked, a corneal ring image may be recorded by arranging a film in place of the image sensor 14. When observing the anterior segment Ef, the alignment light sources 21 and 22 are turned on. Light source for alignment 21, 2
The luminous flux from 2 is reflected by the half mirrors 15 and 16 and passes through the transparent member 1 to illuminate the cornea Ec of the eye E to be examined, thereby generating a corneal reflection image Pc which is a virtual image. The luminous flux reflected by the cornea Ec returns along the same optical path, and the half mirrors 15, 16 and the lens 1
The four-lobe light receiving elements 19 and 20 are received as corneal reflection images Pc 'each consisting of one small circle, passing through 7 and 18, respectively. Based on the received light signals, the control means 23 monitors the alignment state of the apparatus. If the alignment of the apparatus is appropriate, the corneal reflection image Pc 'is converted to a four-lobe light receiving element 1 as shown in FIG.
An image is formed at the center of the light receiving elements 9 and 20, but when the position of the apparatus is shifted, the corneal reflection image Pc 'is shifted from the center of the four-lobed light receiving elements 19 and 20 as shown in FIG. Is generated.
Therefore, the control means 23 sets the four-leaf light receiving elements 19 and 20 to 4
Corneal reflection image by comparing the amount of light received by two photodiodes
The degree of deviation of Pc from the center is calculated, and the position in the optical path O1 direction and a position in a plane orthogonal thereto are monitored. The anterior segment Ef by the illumination light sources 21 and 22
Is reflected by the imaging device 14 as an anterior ocular segment image Pf through the lens 12 and the aperture 13 and is displayed on an external television monitor 27 as shown in FIG. The examiner performs alignment while observing the television monitor 27. On the screen of the television monitor 27, an anterior segment image Pf is displayed.
In addition, a small circular reference mark SM indicating the position of the optical path O1 electronically synthesized and an alignment mark AM composed of two crosses are projected. On the other hand, the alignment mark AM indicates the three-dimensional relative position of the subject's eye E and the apparatus, and the deviation from the working distance in the optical path O1 direction is represented by two crosses separated from each other, and is in a plane perpendicular to the optical path O1. The deviation is represented by a deviation from the reference mark SM. Now, when actually performing the alignment,
The examiner grasps the operation rod 25 and adjusts a slide table (not shown) in a plane perpendicular to the optical path O1 so that the alignment mark AM matches the reference mark SM. Further, the slide table is adjusted in the optical path O1 direction so that the two crosses of the alignment mark AM match.
Then, after the alignment is completed, the strobe light source 2 emits light to start measurement. In the present embodiment, the mode selection means 24 can select two measurement modes: a manual mode in which the examiner manually inputs measurement timing, and an automatic mode in which the apparatus automatically starts measurement. ing. In the automatic mode, the examiner performs the alignment after pressing the button A of the mode selecting means 24. During this time, the control means 23 detects the position and aiming state of the corneal reflection image Pc based on the light receiving signals of the four-lobe light receiving elements 19 and 20, and monitors the alignment state. When it is determined that the alignment is appropriate, the strobe light source 2 is caused to emit light. Then, the corneal ring image obtained by the image sensor 14 is recorded on the computer of the apparatus and then displayed on the television monitor 27. The examiner observes the television monitor 27,
It is checked whether the corneal ring image is suitable for the measurement, and if the image is not a very good image, the measurement button 26 is pressed. In response to this input, the control means 23 displays the anterior eye image Pf on the television monitor 27 as shown in FIG. The examiner continues the alignment operation while observing the image on the television monitor 27. If there is no defect in the corneal ring image, the computer starts to analyze the shape of the cornea Ec based on the stored corneal ring image when waiting for several seconds, and the analysis result is displayed on the television monitor 27. . In the manual mode, the examiner presses the button M of the mode selecting means 24 to perform alignment. Then, the examiner presses the measurement button 26 after confirming that the alignment is appropriate. Then, in response to the input of the measurement button 26, the control unit 23 emits light from the strobe light source 2, obtains the shape of the cornea Ec from the recording of the corneal ring image of the imaging device 14 in the computer, and displays the measurement result on the television monitor 27. Put out. In this embodiment, one ring-shaped strobe light source 2 is used. However, a ring-shaped fluorescent lamp is used, or a plurality of point-like light sources are arranged in a circle around the optical path O1. Is also good. In addition, the light beam diffusing portions 5 to 11 are formed in a ring shape, but the ring may be cut out at several places. FIG. 5 is a structural view of the second embodiment. A disk-shaped transparent member 31 having a circular opening at the center is disposed in front of the eye E to be examined. Outer edge 3
1a and the inner edge portion 31b are formed in a mirror-like shape having a reflection surface toward the eye E to be inspected while being inclined with respect to the optical path O4 of the apparatus. The light beam reflecting portion 32 has an outer edge portion 31a and an inner edge portion 31b.
Is formed in the shape of a ring near the middle. Light beam reflection unit 3
As shown in FIG. 6 in which the vicinity of FIG.
Has a sawtooth shape on the rear surface of the transparent member 31, and a metal film having a high reflectance is deposited. An optical path O4 passing through the center of the opening of the transparent member 31
Light sources 33a, 3 such as LEDs arranged along the inner edge 31b of the transparent member 31 from behind the transparent member 31
3b, a lens 34, an aperture 35, and an image sensor 36 are sequentially arranged. The light sources 33a and 33b are arranged not only in two but also in a circle, but are not shown. Light beams from the light sources 33a and 33b are reflected by the inner edge 31b of the transparent member 31 and guided to the inside of the transparent member 31, and are totally reflected while being reflected by the outer edge 31 of the transparent member 31.
When the light reaches the point a, the light is reflected to the left and projected onto the cornea Ec of the eye E to be examined. At this time, a part of the light beam is reflected to the left by the serrated light beam reflecting portion 32 as shown in FIG. 6, exits from the front surface of the transparent member 31, and is projected on the cornea Ec of the eye E to be examined. That is,
The light beam using the outer edge 31a of the transparent member 31 or the light beam reflecting portion 32 as a secondary ring light source is projected on the cornea Ec of the eye E as a ring light beam. The light beam reflected by the cornea Ec travels along the optical path O4, passes through the lens 34 and the stop 35, is photographed by the image pickup device 36 as two corneal ring images, and is converted into an electric signal. The computer of the apparatus analyzes the shape of the corneal ring image based on the electric signal, and obtains the radius of curvature of the cornea Ec. As described above, the corneal examination apparatus according to the present invention projects a ring-shaped light beam onto the cornea of the eye to be examined by the light beam diffusing portion of the optical member, so that the configuration can be simplified. In addition, the size of the device can be reduced .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a first embodiment. FIG. 2 is a configuration diagram of a control unit and an operation unit. FIG. 3 is an explanatory diagram of a corneal reflection image received by a four-lobe light receiving element. FIG. 4 is an explanatory diagram of an observation anterior segment image. FIG. 5 is a configuration diagram of a second embodiment. FIG. 6 is a cross-sectional view of a transparent member in which the vicinity of a light beam reflecting portion is enlarged. DESCRIPTION OF SYMBOLS 1, 31 Transparent member 2 Ring-shaped strobe light source 3 Reflecting member 4 Ring slit 5-11 Light beam diffusing unit 14, 36 Image sensor 19, 20 Four-lobe light receiving device 21, 22 Alignment light source 24 Mode selection means 25 Operation stick 32 Light flux reflecting portions 33a, 33b Light source

Claims (1)

(57) [Claim 1] It has a circular opening centered on the optical axis.
A hemispherical or flat-shaped transparent optical member mainly including a plurality of concentric light beams diffusing unit provided <br/> the surface mouth portion, the opening
And a light source for illuminating the interior of the place on the end face of the mouth portion and the optical member, the light beam is a ring-shaped light flux diffused by the diffusion unit repeatedly internally reflected by the light beam within the optical member by the light source
Illuminate the cornea of the subject's eye
A plurality of analyzing the ring-shaped corneal reflected image, cornea inspection apparatus characterized by measuring the corneal <br/> shape of the eye.