JPH04141135A - Ophthalmic apparatus - Google Patents

Abstract

PURPOSE:To enable accurate measurement of a distance to an apex of a cornea with a less restriction on the construction of the apparatus by arranging a display means which displays deviation information at least in a direction of an optical axis of an eye to be inspected detected by a position detecting means for the eye to be inspected to facilitate the implementing of a positioning. CONSTITUTION:When light sources 8a and 8b are lit in alignment of a working distance, luminous fluxes thereof are reflected with half mirrors 5 a and 5b respectively and projected onto a cornea Ec to form light source images Ma' and Mb'. The cornea reflection lights of the luminous fluxes return through the same optical path to be projected onto photo sensors 7a and 7b as cornea reflection Ma and Mb through the halfmirrors 5a and 5b and lenses 6a and 6b. On the other hand, a front eye part image of an eye E to be inspected in taken with a TV camera 3 through an objective lens 1 and a light splitting mirror 2 and the front eye part image is synthesized and projected onto a TV monitor 10 together with an alignment mark. This makes the working distance easy to recognize in sense thereby facilitating the alignment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to ophthalmological devices such as keratometers and air-pack type tonometers used in eye clinics and the like.

[Prior Art] Conventionally, for example, in a tonometer, it is necessary to accurately align the position of the corneal vertex with respect to the device. With conventional devices, light beams are projected onto the cornea from two directions symmetrically inclined to the optical axis of the device, and the reflected light beams from the cornea are guided from the same direction to the anterior eye observation/imaging surface and displayed on a TV monitor, etc. A photodetector has been proposed that is used for positioning by doing this, and that a photodetector receives light from two directions different from the projection onto the cornea.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, there are restrictions on the arrangement of optical members in order to guide the reflected light flux to the anterior segment observation imaging surface. Furthermore, since conventional devices capture the position of the corneal reflected image, it is not possible to accurately measure the distance to the corneal vertex. Furthermore, 2 on the TV monitor
Since three-dimensional information is expressed by the spot position of a point, it is difficult to intuitively determine the working distance and position of the eye to be examined, and there are disadvantages in that alignment is difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ophthalmological device that eliminates the above-mentioned drawbacks of the conventional example, allows easy alignment, has fewer restrictions on the device configuration, and can accurately measure the distance to the corneal vertex. .

[Means for Solving the Problems] In order to achieve the above-mentioned object, in the ophthalmological device according to the present invention, a light beam is projected onto the cornea from two directions symmetrically inclined to the optical axis of the optical system of the device, eye position detection means for detecting the position of the eye to be examined based on the position of the corneal reflected image received by an optical position detector disposed at the same angle as the projection light with respect to the corneal vertex in the two directions or in the vicinity of the two directions; The present invention is characterized by comprising a display means for displaying displacement information of the eye to be examined at least in the optical axis direction detected by the eye to be examined position detection means.

[Operation] The ophthalmological apparatus having the above-described configuration illuminates the cornea from two directions symmetrically inclined to the optical axis of the ophthalmic apparatus optical system, and determines the position of the eye to be examined based on the position of the corneal reflected image received by the optical position detector. Detects and displays positional deviation information of the eye to be examined.

[Example] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a configuration diagram of the first embodiment, in which an objective lens 1, a light splitting mirror 2, and a television camera 3 are sequentially arranged on the optical axis facing the eye E to be examined. A measuring device main body 4 is arranged in the direction of reflection. Further, on the optical axis 02a inclined with respect to the optical axis O1, there is a half mirror.
5a, a lens 6b, and a photosensor 7a composed of four elements, and a light source 8a is arranged in the direction of reflection of the half mirror 5a. Furthermore, optical axis 0 with respect to optical axis 01
On the optical axis 02b that is symmetrical to 2a, there is a half mirror 5b, a lens 6b, and a photosensor 7b that is the same as the photosensor 7a.
is arranged, and a light source 8b is arranged in the reflection direction of the half mirror 5b.
is located. Further, the outputs of the photosensor 7a and the photosensor 7b are connected to a controller 9, and the outputs of the measuring device main body 4 and the controller 9 are connected to a television monitor 10.

When the light sources 8a and 8b are turned on during alignment of the working distance, their light beams are reflected by the half mirrors 5a and 5b and projected onto the cornea Ec, forming a light source image Ma'
, Mb' are formed, and the corneal reflected light returns along the same optical path via the half mirrors 5a, 5b and lenses 6a, 6b to form corneal reflected images Ma, Mb on the photosensors 7a, 7b as shown in FIG. projected as. In this optical system, the corneal reflection images Ma, &lb are adjusted so as to reach the center of the photosensors 7a, 7b when the cornea Ec is at a predetermined working distance position. These corneal reflection images Ma,
Mb shifts symmetrically on the photosensors 7a, 7b when the eye E moves in the direction along the optical axis O1, and when the eye E moves in a plane perpendicular to the optical axis 01, the Mb shifts symmetrically on the photosensors 7a, 7b.
Since the position of the eye E is shifted asymmetrically on the photo sensor 7b, the position of the eye E can be detected by the computer in the controller 9 using this principle from the ratio of the amount of light received by each element of the photosensors 7a and 7b.

On the other hand, an anterior segment image of the eye E to be examined is imaged by a television camera 3 through an objective lens 1 and a light splitting mirror 2, and an electric current is generated based on the position signal of the eye E detected as described above. The anterior eye segment image is combined and displayed on the television monitor 10 together with the generated alignment mark. Third
The figure shows cross-shaped alignment marks P1 and P2 as an example.
Show.

When the working distance is a predetermined value, alignment marks Pi and P2 are displayed overlapping each other as shown in FIG. 3 (al), and when it deviates from the predetermined value, alignment marks PL, By displaying P2 at a distance proportional to the distance of the shift, it is possible to create a natural feeling for the blur caused by one working distance.Since the working distance and direction can also be detected, if these are displayed together, the front and back can also be seen. In addition, the deviation of the eye E in the plane perpendicular to the optical axis O1 is determined by the alignment mark P1 from the mark fixed at the center of the television monitor 10. , P2. Therefore, after roughly aligning by observing the anterior segment image on the television monitor 10, aligning is performed based on the position information of the alignment marks PI and P2. After completion of the measurement, the measuring light beam passing through the light splitting mirror 2 and the objective lens 1 automatically starts measuring the eye E using the measuring device main body 4.

The alignment mark P1.
P2 is different from the conventional example in which the corneal reflected images Ma and Mb are directly displayed on the television monitor 10 because the display magnification of the deviation in the direction along the optical axis and in the plane perpendicular thereto can be determined arbitrarily. Therefore, restrictions on the arrangement of the working distance detection optical system are relaxed.

Although there are individual differences in the reflectance of the cornea Ec, if we use the photosensors 7a and 7b composed of four elements to handle the ratio of the amount of received light, we can accurately determine the working distance without being affected by the reflectance. can be detected.

Note that these photosensors 7a and 7b may be semiconductor photodetectors or CCDs, and the television monitor IO can also be used to display measured values.

FIG. 4 shows a main part configuration diagram of another embodiment, and FIG.
is its side view, (bl is its front view).

As a working distance detection optical system, a lens lla and four elements 12A, 1 are provided on an optical axis 03a inclined with respect to the optical axis O1.
Photo sensor 12 composed of 2B, 12C, and 12D
a is arranged, and the optical axis 03a is located near the photosensor 12a.
A light source 13a is arranged on the optical axis 04a apart from the optical axis 04a. On the optical axis 03b, which is symmetrical to the optical axis 03a with respect to the optical axis O1, the same lens itb and four elements 12E% 12F
, 12G, and 12H is arranged symmetrically with the odometer 12a, and a light source 13b is arranged symmetrically with the light source 13a on the optical axis 04b off the optical axis 03b near the photosensor 12b. Therefore, the angle between the optical axes 04a and 04b of the light emitting system and the corneal vertex is equal to the angle between the optical axes 04a and 04b of the light receiving system and the corneal vertex. Note that the other configurations are the same as in the first embodiment.

The light beams from the light sources 13a and 13b are projected onto the cornea Ec of the eye E to be examined to form light source images a'' and Mb', and these corneal reflected images Ma and Mb are projected onto the photosensors 12a and 12b by lenses lla and llb. The optical axis 01 is projected when the corneal reflected images Ma and Mb reach the center of the four elements, as shown in FIG.
When the ophthalmological apparatus approaches the eye E in the direction along the optical axis O1, (cl is the direction along the optical axis O1). (dl indicates a case in which the eye E to be examined moves downward within a plane perpendicular to the optical axis 01, and tel indicates a case in which the eye E to be examined moves laterally within that plane. These amounts directly proportional to the distance of the deviation of the eye E are a proportional amount Δ3 of the deviation in the direction of the optical axis 01, a proportional amount Δ1 of the deviation in the vertical direction in a plane perpendicular to the optical axis O1, and a proportional amount Δ1 of the deviation in the vertical direction within the plane perpendicular to the optical axis O1. The proportional amounts Δ of the directional deviations are given by the following equations, and when these become zero, it is the end of alignment.

Δ+ = (Qa+ Q11+QF+QO1(Qa+Q
c+Qz+QJΔ! = (QA+Qo+Qt+QH)
-CQm+Qc+CIW+QQ)6m =(QA+Qs
+Qt+(61(QC+QD+Q(++QH)) where,
Qn (n=A, B, . . . , H) represents the amount of light received by the element 12n. Similar to the first embodiment, alignment marks PL, P are created based on these proportional amounts Δ1, Δ2, and Δ3.
2 will be presented.

Although FIG. 6 shows a case where the reflectance of the cornea Ec of the eye E to be examined is different, after the alignment is completed, the proportional amounts Δ1, Δ2 . Since all Δ□ are zero, there is no problem.

In this way, the light sources 13a, 13b, the photosensor 12a
, 12b are arranged slightly away from the optical axes 03a, 03b, it is not necessary to use the half mirrors 5a, 5b (and the configuration becomes easier. Note that the light sources 13a, L
3b can also function as an illumination system for observing the anterior segment of the eye.

Furthermore, although manual alignment has been described in the above-described embodiments, signals from a photosensor can be used for an electric alignment device.

[Effects of the Invention] As explained above, the ophthalmological device according to the present invention illuminates the cornea from two directions symmetrically inclined to the optical axis of the optical system of the ophthalmological device, and is provided in or near the two directions. The optical position detector receives the corneal reflected image and accurately detects and displays the distance from that position to the corneal apex of the eye being examined, making it easy to intuitively understand the working distance and aligning the position. can.

In addition, since the corneal reflection image is received on the optical position detector, there are fewer restrictions on the arrangement of the optical system, and the configuration of the apparatus is simplified.

[Brief explanation of drawings]

The drawings show an embodiment of an ophthalmological device according to the present invention. Fig. 1 is a configuration diagram of the first embodiment, Fig. 2 is an explanatory diagram of the corneal reflection image on the photosensor, Fig. 3 is an explanatory diagram of the alignment mark on the television monitor, and Fig. 4 is an illustration of the second embodiment. The main part configuration diagram of the example, FIGS. 5 and 6, are explanatory views of the corneal reflection image on the photosensor. Reference numeral 3 is a television camera, 4 is the measuring device main body, 6a, 6b
are lenses; 7a, 7b, 12a, 12b are photosensors; 8a, 81.13a; 13b is a light source, 9 is a controller, and 10 is a television monitor. Figure 1 Figure 3 Figure 4 Figure 5 (a) (b) (c) (cl) (e) Figure 6

Claims (1)

[Claims] 1. Light beams are projected onto the cornea from two directions symmetrically inclined to the optical axis of the optical system of the device, and a light position is placed at the same angle as the projected light with respect to the corneal apex in or near the two directions. An eye position detection means for detecting the position of the eye to be examined based on the position of the corneal reflection image received by the detector, and a display means for displaying displacement information of the eye to be examined at least in the optical axis direction detected by the eye position detection means. An ophthalmological device comprising: