JPH07194551A - Cornea examination device - Google Patents

Abstract

PURPOSE:To measure the form of cornea in the appropriate timing by projecting ring-forming beams of light onto the cornea of an eye to be examined. CONSTITUTION:Beams of light from alignment light sources 21, 22 are allowed to pass through a semispherical transparent member 1 and illuminate the front portion Ef of an eye E to be examined, forming an image on the cornea Ec. The beams of light reflected at the cornea are received by clover-shaped photoreceptors 19, 20, and a control means monitors alignment on the basis of these input signals. The beams of light reflected are received also by an image pick-up element 14 as an image of the frontal eye, which is then displayed on a TV monitor. Beams of light from a ring-shaped stroboscopic light source 2 go out of ring slits 4 or impinge on the transparent member 1 and are scattered by beam scattering portions 5-11 to illuminate the cornea Ec of the eye E to be examined. These beams of light reflected at the cornea Ec are received by the image pick-up element 14 as a ring image of the cornea. Based on this input signal, an external computer analyzes the form of the cornea Ec of the eye E to be examined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corneal examination apparatus used in an ophthalmological clinic or the like.

[0002]

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 fluxes are projected on the cornea of an eye to be examined, the light flux reflected by the cornea is received as a ring image, and this ring image is analyzed. Seeking 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 Laid-Open No. 4-44736 and a tubular member as disclosed in US Pat. No. 5,018,850 are preferable. Are known. Further, Japanese Patent Application Laid-Open No. 61-293424 discloses an apparatus provided with a plurality of ring mirrors as a ring light beam projection means. Further, US Pat. No. 4,597,648 discloses a cornea inspection device that detects a reflection image on a cornea due to a ring light flux to monitor the position of the device and automatically starts measurement when the position of the device is matched. .

[0004]

[Problems to be Solved by the Invention]

(1) However, in the above-mentioned conventional ring light beam projection means, the dish-shaped member has a complicated structure, and the ring mirror type also has a complicated structure when the number of ring mirrors is increased in order to improve the measurement accuracy.

(2) On the other hand, although the cylindrical member has the advantage of being small, the distance between the eye to be inspected and the ring light source is very short, so that it is easily affected by an error due to the working distance.

(3) In the device disclosed in US Pat. No. 4,597,648, the image processing is executed because the position of the device is monitored by performing image processing on the corneal reflection image by the ring light flux. If the eye to be inspected moves in the meantime, the timing of measurement may be missed.

The first object of the present invention is to solve the above-mentioned problem (1).
It is an object of the present invention to provide a corneal examination device including a dish-shaped ring projection means having a simple structure.

The second object of the present invention is to solve the above-mentioned problem (2).
It is an object of the present invention to provide a corneal examination device including a tubular ring projection unit that has a small error due to the working distance.

The third object of the present invention is to solve the above-mentioned problem (3).
The object of the present invention is to provide a cornea inspection device capable of automatically solving the above problems and automatically starting the measurement at the optimum timing.

[0010]

A cornea inspection apparatus according to a first aspect of the invention for achieving the above object is a thin transparent member having a light beam diffusion portion formed in a ring shape around the optical axis, and a thin transparent member around the optical axis. It is characterized in that it has a light source for illuminating the inside of the transparent member, and an image receiving optical system for receiving a corneal reflection image by a light beam from the light source.

A cornea inspection apparatus according to a second aspect of the present invention is a cylindrical reflecting member having a ring-shaped mirror that gradually changes in angle in an inclined portion inclined in the optical axis direction, and on a circumference around the optical axis. And a light receiving optical system for receiving a cornea reflection image formed by a light beam from the light source.

A corneal examination apparatus according to a third aspect of the present invention is a corneal examination apparatus that projects a shape analysis pattern onto a cornea of an eye to be inspected and receives a reflected image on the cornea. And a storage means for automatically storing a reflected image of the shape analysis pattern by the cornea based on a signal from the photoelectric sensor.

[0013]

In the cornea examination apparatus according to the first aspect of the present invention having the above-mentioned structure, the light flux from the light source illuminates the inside of the transparent member and is diffused by the ring-shaped light flux diffuser to form a ring light flux on the cornea of the eye to be examined. Projected. The reflected light beam from the cornea is received as a ring image, and the ring image is analyzed to obtain the shape of the cornea of the subject's eye.

In the cornea inspection device according to the second invention,
The light beam from the light source is reflected by a ring-shaped mirror whose angle changes along the optical axis of the cylindrical reflecting member, and is projected as a ring light beam on the cornea of the eye to be examined. The reflected light beam from the cornea is received as a ring image, and the ring image is analyzed to obtain the shape of the cornea of the subject's eye.

In the cornea inspection device according to the third aspect of the invention, the photoelectric sensor receives the reflected image of the cornea by the index projection light beam for alignment, and the position of the device is detected based on this received light signal to detect the position of the device. When the positions match, the corneal reflection image of the shape analysis pattern is automatically stored.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiments. FIG. 1 is a configuration diagram of the first embodiment. A thin hemispherical shell-shaped transparent member 1 formed of a transparent acrylic resin or the like is provided in front of an eye E to be inspected, and an outer edge portion of the transparent member 1 The end surface 1a has a mirror surface shape. The ring-shaped strobe light source 2 is attached along the end face 1b of the circular opening at the center of the transparent member 1, and the reflecting member 3 covers the strobe light source 2 and opens toward the end face 1b side of the reflecting member 3. Is provided,
Further, a ring slit 4 is cut on the side of the eye E to be examined. On the rear surface of the transparent member 1, there are provided light flux diffusers 5 to 11 having concentric light flux diffusion properties. An aluminum film or the like may be attached to the light flux diffusion portions 5 to 11 or the entire rear surface in order to increase the reflectance. In addition, the luminous flux diffusion units 5 to 5
It is also possible to provide 11 on both sides or only 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, a lens 12, a diaphragm 13, and an image pickup device 14 composed of a CCD are arranged from the eye E side. Further, on the two optical paths O2 and O3 which are symmetrical with respect to the optical path O1, the half mirrors 15 and 16, the lens 17, and the lens 17 from the back of the transparent member 1, respectively.
Four-leaf-shaped light receiving elements 19 and 20 composed of 18 and 4 photodiodes are respectively arranged, and half mirrors 15 and 1 are provided.
On the optical path in the reflection direction of 6, the alignment light source 21,
22 are arranged respectively. The optical member shown in FIG. 1 is mounted on a slide table (not shown).

FIG. 2 is a block diagram of the control section and the operation section of the apparatus. The input of the control means 23 for controlling the entire apparatus is 2
Mode selection means 24 provided with two input buttons A and M;
An operation rod 25 for operating a slide base (not shown) is connected, and a measurement button 26 is provided on the operation rod 25.

When measuring the shape of the cornea Ec, the luminous flux from the ring-shaped strobe light source 2 is transmitted from the end face 1b to the transparent member 1.
Is incident on the end face 1a, is repeatedly reflected toward the end face 1a, is diffused by the light flux diffusers 5 to 11, and is emitted from the front face of the transparent member 1. A part of the incident light flux reaches the end face 1a of the transparent member 1 and is totally reflected. While being diffused by the light flux diffusing parts 5 to 11, it travels backward in the transparent member 1 and exits from the transparent member 1, and again by the reflecting member 3. It is reflected inside the transparent member 1. The light flux from the strobe light source 2 is also emitted from the ring slit 4.

Ring slit 4 and luminous flux diffusers 5-11
The light flux with the secondary ring light source is the cornea Ec of the eye E to be examined.
Irradiate. The reflected light flux here is the opening of the transparent member 1,
The light is received by the image sensor 14 as a concentric corneal ring image through the lens 12 and the diaphragm 13, and the received light signal is captured by a computer in the apparatus. In the computer, the position of the corneal ring image is calculated and the shape of the cornea Ec is obtained.
In addition, if only the distortion of the corneal ring image is to be visually confirmed, a film may be arranged instead of the image pickup device 14 to record the corneal ring image.

When observing the anterior segment Ef, the alignment light sources 21 and 22 are turned on. Alignment light sources 21, 2
The light 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 inspected, thereby generating a corneal reflection image Pc which is a virtual image. The reflected light beam from the cornea Ec returns to the same optical path, and the half mirrors 15 and 16 and the lens 1
Each of the four lobe light-receiving elements 19 and 20 is received as a corneal reflection image Pc 'consisting of one small circle through 7 and 18, and the control means 23 monitors the alignment state of the device based on the received light signal.

When the apparatus is properly aligned, as shown in FIG. 3 (a), the corneal reflection image Pc 'shows the four-lobed light receiving element 1.
Although images are formed in the centers of 9 and 20, the corneal reflection image Pc 'is deviated from the center of the four-leaf shaped light receiving elements 19 and 20 and blurred as shown in FIG. Cause
Therefore, the control means 23 controls the four-leaf shaped light receiving elements 19 and 20.
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 in the plane orthogonal thereto is monitored.

Further, the anterior ocular segment Ef by the illumination light sources 21 and 22.
The reflected light flux at 1 passes through the lens 12 and the diaphragm 13 and is captured by the image sensor 14 as the anterior segment image Pf, and is displayed on the 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, the anterior segment image Pf
At the same time, a small circular reference mark SM that represents the position of the optical path O1 that is electronically synthesized and an alignment mark AM that is composed of two crosses are displayed. On the other hand, the alignment mark AM represents the three-dimensional relative position between the eye E and the device, 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 the deviation from the reference mark SM.

Now, when actually performing the alignment,
The examiner holds the operating rod 25 and adjusts a slide base (not shown) in a plane perpendicular to the optical path O1 to align the alignment mark AM with the reference mark SM. Further, the slide base is adjusted in the direction of the optical path O1 to align the two crosses of the alignment mark AM.
Then, after the alignment is completed, the strobe light source 2 emits light to start the measurement.

In this embodiment, the mode selection means 24 can select two measurement modes, a manual mode in which the examiner manually inputs the measurement timing and an automatic mode in which the apparatus automatically starts the measurement. ing.

In the automatic mode, the examiner presses the button A of the mode selecting means 24 and then performs the alignment. During this period, 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-leaf shaped light receiving elements 19 and 20, and monitors the alignment state. When it is determined that the alignment is proper, the strobe light source 2 is caused to emit light. Then, the corneal ring image obtained by the image pickup device 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 confirmed whether the corneal ring image is suitable for measurement, and if the image is not so good, the measurement button 26 is pressed. In response to this input, the control means 23 displays the anterior segment 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. When 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 proper. Then, in response to the input of the measurement button 26, the control unit 23 causes the strobe light source 2 to emit light, the computer determines the shape of the cornea Ec from the recording of the corneal ring image of the image sensor 14, and the result of the measurement is displayed on the television monitor 27. Put out.

In this embodiment, one ring-shaped strobe light source 2 is used, but a ring-shaped fluorescent lamp is used, or a plurality of point-shaped light sources are arranged in a circle around the optical path O1. Good. Further, the light flux diffusion portions 5 to 11 are formed in a ring shape, but the ring may be cut out at several places.

FIG. 5 is a block diagram of the second embodiment, in which a disk-shaped transparent member 31 having a circular opening in the center is arranged in front of the eye E to be inspected. Outer edge 3
The lamina 1a and the inner edge portion 31b are formed in a mirror surface shape that is inclined with respect to the optical path O4 of the apparatus and has a reflection surface toward the eye E side. The light flux reflecting portion 32 includes an outer edge portion 31a and an inner edge portion 31b.
It is formed in the shape of a ring near the middle of. Light flux reflector 3
2, the light flux reflecting portion 32
The rear surface of the transparent member 31 is cut into a sawtooth shape, and a metal film having a high reflectance is deposited.

Optical path O4 passing through the center of the opening of the transparent member 31
Above the light sources 33a, such as LEDs, arranged from the rear of the transparent member 31 along the inner edge portion 31b of the transparent member 31,
3b, the lens 34, the diaphragm 35, and the image sensor 36 are sequentially arranged. The light sources 33a and 33b are not only two, but are also arranged circumferentially, but not shown.

Light fluxes from the light sources 33a and 33b are reflected by the inner edge portion 31b of the transparent member 31 and guided to the inside of the transparent member 31, and while being totally reflected, the outer edge portion 31 of the transparent member 31.
It reaches a and is reflected to the left, and is projected on the cornea Ec of the eye E to be examined. At this time, a part of the light flux is reflected to the left by the sawtooth light flux reflecting portion 32 as shown in FIG. 6, emitted from the front surface of the transparent member 31, and projected onto the cornea Ec of the eye E to be examined. That is,
The light flux having the outer edge portion 31a of the transparent member 31 or the light flux reflecting portion 32 as a secondary ring light source is projected on the cornea Ec of the eye E to be examined as a ring light flux.

The reflected light beam from the cornea Ec travels along the optical path O4, passes through the lens 34 and the diaphragm 35, is photographed by the image pickup device 36 as two corneal ring images, and is converted into an electric signal. In the computer of the device, the shape of the corneal ring image is analyzed based on this electric signal, and the radius of curvature of the cornea Ec is obtained.

FIG. 7 is a configuration diagram of the third embodiment, in which a cylindrical shape having six ring mirrors 41a to 41f on the inner side from the eye E side is provided on the optical path O5 extending in front of the eye E to be examined. A reflection member 41, a ring-shaped reflection member 42 having a ring mirror 42a on the inner surface, a ring-shaped strobe light source 43, a ring-shaped reflection member 42, and a cylindrical light-shielding member 44 inserted through the opening of the strobe light source 43 are arranged. The ring slit 4 is formed along the outer edge of the front opening of the light shielding member 44.
5 is provided, and an objective lens 46 is attached to the rear opening. Further, behind the objective lens 46, a diaphragm 47 and an image pickup device 48 are arranged.

Here, the six ring mirrors 41a to 41f of the tubular reflecting member 41 have different reflection angles. The angle gradually increases from the eye E side to 29 ° to 35 ° with respect to the optical path O5, and as the angle increases, the inner diameter of the tubular reflecting member 41 also increases.

When the strobe light source 43 emits light, the measuring light from the strobe light source 43 is projected on the cornea Ec of the eye E through the ring slit 45. Further, the measurement light beam illuminates the inner side surfaces of the ring-shaped reflecting members 42 and 41, and is reflected by the ring mirrors 42a and 41a to 41f, respectively, and the eye E
Is projected on the cornea Ec. That is, the images of the light sources 43 of the ring slit 45, the ring mirror 42a of the ring-shaped reflecting member 42, and the ring mirrors 41a to 41f of the tubular reflecting member 41 serve as secondary ring light sources, and eight ring light beams are used as the eye to be inspected. It is projected on the cornea Ec of E. The light blocking member 4
Reference numeral 4 is for blocking the light flux from the strobe light source 43 so that the light flux is not scattered and reflected by the objective lens 46.

The reflected light beam from the cornea Ec travels along the optical path O5, passes through the inside of the light shielding member 44, and the objective lens 46 and the diaphragm 4
The image passes through 7 and is picked up by the image pickup device 48 as eight corneal ring images, and the shape of the cornea is analyzed by the computer.

In this embodiment, the ring mirrors 41a to 41f of the reflecting member 41 are arranged in the vicinity of the eye E to be inspected, but the image of the ring-shaped strobe light source 43 serving as an actual light source is separated from the eye E to be inspected. Therefore, it is unlikely to be affected by the error in working distance.

FIG. 8 is a configuration diagram of the fourth embodiment, in which a cylindrical transparent member 51, a ring-shaped strobe light source 52, and an objective lens are provided on the optical path O6 extending forward from the eye E to be inspected from the eye E side. 53, a diaphragm 54, and an image sensor 55 are arranged, and ring mirrors 56 and 57 are provided outside and behind the strobe light source 52.
Are arranged respectively. The rear surface of the cylindrical transparent member 51 is inclined with respect to the optical path O6, and the outer surface is composed of six ring mirrors 51a to 51f having different angles with respect to the optical path O6. The angles of the ring mirrors 51a to 51f are gradually increased from the side of the eye E to be inspected, and the cylindrical transparent member 51 is accordingly increased.
The outer diameter of has also been increased.

A part of the luminous flux from the strobe light source 52 is reflected by the ring mirrors 56 and 57, respectively, and projected onto the cornea Ec of the eye E to be examined. Further, the light flux emitted from the strobe light source 52 to the front enters the cylindrical transparent member 51 from the rear surface, is refracted, is reflected by the ring mirrors 51a to 51f on the outer surface and is emitted from the inner surface, and the cornea of the eye E to be inspected. Projected to Ec. That is, the ring mirrors 56 and 57, the tubular transparent member 5
Reference numeral 1 is a secondary ring light source, which projects a ring light flux onto the cornea Ec. The light flux reflected by the cornea Ec passes through the objective lens 53, the diaphragm 54, and the image sensor 55, and is captured by the image sensor 55 as a cornea ring image.

FIG. 9 is a block diagram of a modified example of the alignment detection optical system, in which the objective lens 61 facing the eye E to be inspected.
A dichroic mirror 62, a diaphragm 63, and an image pickup device 64 are arranged on an optical path O7 behind the optical path O7, and a half mirror 65, a cylindrical lens 66, and 4 as shown in FIG. 3 are provided on an optical path O8 in the reflection direction of the dichroic mirror 62. A four-leaf light receiving element 67 composed of one photodiode is arranged, and an alignment light source 68 is arranged in the incident direction of the half mirror 65. The optical path between the eye E to be inspected and the objective lens 61
A ring light beam projection optical system (not shown) is provided on O7.

At the time of alignment, the light flux from the alignment light source 68 is reflected by the half mirror 65 and the dichroic mirror 62, respectively, passes through the objective lens 61 and illuminates the anterior segment Ef of the eye E to be virtual image on the cornea Ec. Is formed as a corneal reflection image Pc. The reflected light beam from the cornea Ec returns through the same optical path, passes through the cylindrical lens 66, and is received by the four-lobed light receiving element 67 as a corneal reflection image. The state of alignment is monitored based on this received light signal.

Here, the cylindrical lens 66 is arranged such that the generatrix line forms an angle of 45 ° with the dividing line of the four-leaf shaped light-receiving element 67, and the four-leaf shaped light-receiving element 67 is arranged in the middle of the astigmatic difference generated by the cylindrical lens 66. ing. Therefore, when the position of the device is correct, the corneal reflection image Pc is imaged at the center of the four-lobed light receiving element 67 and becomes a perfect circle. When the device is displaced in the optical path O7 direction, the corneal reflection image Pc becomes an ellipse from a perfect circle, and when it is displaced in the plane perpendicular to the optical path O7, the corneal reflection image is shown.
Pc deviates from the center of the four-leaf shaped light receiving element 67. Therefore, by obtaining the shape and position of the corneal reflection image Pc, it is possible to detect the three-dimensional position of the device even with one four-leaf shaped light receiving element 67.

Therefore, while the examiner is performing alignment, the received light amounts of the four photodiodes of the four-leaf shaped light receiving element 67 are compared, the shape and position of the corneal reflection image Pc are obtained, and the alignment state is monitored. ing. When the alignment is properly performed, the light source of the ring light beam projection means (not shown) emits light, and the ring light beam emits the cornea Ec of the subject's eye E.
Projected on. The light flux reflected by the cornea Ec is the objective lens 61,
The light passes through the dichroic mirror 62 and the diaphragm 63 and is captured as a corneal ring image. A computer (not shown) stores the corneal ring image and then analyzes the shape of the corneal ring image to determine the radius of curvature of the cornea Ec.

[0046]

As described above, the cornea examination device according to the first aspect of the present invention is configured to project the ring light flux onto the cornea of the eye to be inspected by the light flux diffusion portion of the transparent member, so that the structure can be simplified.

Further, in the cornea inspection apparatus according to the second aspect of the invention, since the angle of the ring mirror of the cylindrical reflecting member is changed stepwise along the optical axis, even if the light source is arranged at a position away from the eye to be inspected Can be projected onto the eye to be examined,
The measurement error due to the working distance can be reduced, and the number of ring mirrors can be easily increased.

In the cornea inspection apparatus according to the third aspect of the invention, the alignment pattern is projected onto the cornea of the eye to be examined separately from the ring light flux, and the corneal reflection image is detected photoelectrically. Therefore, the measurement can be started at a suitable timing.

[Brief description of 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-leaf shaped light receiving element.

FIG. 4 is an explanatory diagram of an anterior ocular 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 flux reflecting portion is enlarged.

FIG. 7 is a configuration diagram of a third embodiment.

FIG. 8 is a configuration diagram of a fourth embodiment.

FIG. 9 is a configuration diagram of a modified example of the alignment detection optical system.

[Explanation of symbols]

1, 31 Transparent member 2, 43, 52 Ring-shaped strobe light source 3 Reflecting member 4, 45 Ring slit 5-11 Light flux diffuser 14, 36, 48, 55, 65 Image sensor 19, 20, 67 Four-leaf light-receiving element 21, 22, 68 Alignment light source 24 Mode selecting means 25 Operation rod 32 Luminous flux reflecting portion 33a, 33b Light source 41, 42 Reflecting member 51 Cylindrical transparent member 41a to 41f, 42a, 51a to 51f, 56, 57
Ring mirror 66 Cylindrical lens

Claims (3)

[Claims] 1. A thin transparent member having a ring-shaped light flux diffuser formed around the optical axis, a light source provided on a circumference around the optical axis and illuminating the inside of the transparent member, and the light source. Corneal examination apparatus having an image receiving optical system for receiving a cornea reflection image due to a light flux from the. 2. A cylindrical reflecting member provided with a ring-shaped mirror whose angle is changed stepwise in an inclined portion inclined in the optical axis direction,
A cornea inspection apparatus comprising: a light source provided on a circumference having an optical axis as a center; and an image receiving optical system for receiving a corneal reflection image by a light flux from the light source. 3. In a cornea inspection apparatus for projecting a shape analysis pattern onto the cornea of an eye to be inspected and for receiving a reflected image on the cornea, a light receiving optical for receiving a corneal reflected image by an index projection light beam for alignment on a photoelectric sensor. A corneal examination apparatus comprising: a system; and a storage unit that automatically stores a reflected image of the shape analysis pattern by the cornea based on a signal from the photoelectric sensor.