JPH0360262B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a so-called non-contact type device that deforms the cornea by blowing air onto the eye to be examined, and detects the deformation to measure intraocular pressure. It relates to ophthalmological devices such as tonometers.

[Prior art] In this type of conventional tonometer, when aligning with the subject's eye, the alignment index is projected onto the polar center of the cornea, so only the reflected image is visible, and the If the axes of the optometrist and the device are misaligned, alignment is extremely difficult because the corneal reflected image may be out of the field of view and cannot be seen.

However, in the conventional tonometer, a virtual image of the corneal reflection is formed at the center of curvature C of the cornea Ec, as shown in FIG. 6a. Therefore, when the axis B of the apparatus is shifted by δ with respect to the axis A of the eye E to be examined, as shown in b, the moving distance D1 of the corneal reflection image is approximately 2δ.

The distance from the apex of the cornea Ec to the center of curvature C is approximately 7.7 mm in a normal eye, and the apparent distance from the apex of the cornea Ec to the iris surface is approximately 3 mm.

[Object of the Invention] In order to improve the above-mentioned drawbacks, the object of the present invention is to make the anterior segment of the eye visible together with the corneal reflection image, and to prevent the corneal reflection image from going out of the visual field even if axis deviation occurs. An object of the present invention is to provide an ophthalmologic apparatus that allows easy alignment operations.

[Summary of the invention] The gist of the present invention for achieving the above object is as follows:
In an ophthalmological apparatus that performs alignment by observing a corneal reflection image of an index light source, the light source is arranged at a position where a virtual image position due to the corneal reflection of the light source is formed on the iris surface of the eye to be examined when the working distance is appropriate. The ophthalmologic apparatus is characterized in that the corneal reflection image of the light source can be observed together with the iris surface.

[Embodiments of the Invention] The present invention will be described in detail based on illustrated embodiments.

FIG. 1 shows a first embodiment of the present invention, in which air compressed by a piston or the like is blown onto the eye E through a nozzle in an air compression chamber to deform the cornea Ec, and the deformation of the cornea Ec is optically measured. It is well known that the intraocular pressure is measured by detecting the intraocular pressure, and the illustration of the airflow generator and the measurement detection unit is omitted.

A nozzle 2 is provided at the center of the objective lens 1,
Further, a positioning light source 3 consisting of a light emitting diode, a lamp, etc. is installed around the objective lens 1.
The virtual image of the corneal reflection image P of the positioning light source 3 is formed approximately 3 mm from the apex of the cornea Ec when the distance between the positioning light source 3 and the apex of the cornea Ec is approximately 11 to 12 mm. It is becoming more and more common. A lens 4 and an observation surface 5 are provided behind the objective lens 1, and the iris Ei and the corneal reflection image P are in a conjugate relationship with the observation surface 5 due to the objective lens 1 and the lens 4. The virtual image of the corneal reflection image P corresponds to the apparent position of the iris Ei of a normal eye from the vertex of the cornea Ec, and the iris Ei is visible along with the corneal reflection image P on the observation surface 5 through the lens 4.

FIG. 2 shows an example of the visual field image on the observation surface 5. A mark 6 is displayed on the observation surface 5, and by aligning the corneal reflection image P with this and focusing, alignment is completed and the measurement is completed. become possible.

In the case of this embodiment, the distance that the corneal reflection image P moves with respect to the axis misalignment between the eye E and the device is approximately half that of the conventional one, so even if there is multiple axis misalignment, the corneal reflection image can be observed. It rarely disappears from view.
The reason for this will be explained below with reference to FIG.

As shown in FIG. 3a, the corneal reflection image P of the alignment light source 3 is formed near the iris surface Ei of the eye E to be examined. When the axis B is shifted by a distance δ, the movement distance D2 of the corneal reflection image P is also approximately the same as δ.

FIG. 4 shows a second embodiment, in which a light splitting member 7 is arranged between an objective lens 1 and a lens 4, and a lens 8 and a light source 9 are provided on the reflection side thereof. Note that in FIG. 4, the same reference numerals as in FIG. 1 represent the same or equivalent members.

The image Q1 of the alignment light source 9 is formed by the lens 8 through the light splitting member 7 near the center hole 2 of the objective lens 1, and the virtual corneal reflection image Q2 is formed near the iris surface Ei of the eye E to be examined. is formed. In this embodiment, since the image is formed on the optical axis, the mark 6 displayed on the observation surface 5 is also brought to the center. Furthermore, in this case, it is necessary to separately provide a light source that illuminates the entire external eye.

A third embodiment is shown in FIG. 5, in which the measurement light source 9 also serves as a positioning light source. An optical member 10 made of flat glass and having a nozzle 2 is arranged corresponding to an objective lens, and a lens 11 is provided behind it. In addition, a second
A light splitting member 12 is disposed, and a television camera 13 is provided on the reflection side of the television camera 1.
The output of 3 is connected to a monitor 14.

The light beam from the light source 9 passes through the lens 8, the light splitting member 7,
It is projected onto the eye E through the lens 11 and the nozzle 2. When the light source image Q3 is formed near the iris surface due to the reflection of the cornea Ec, it is transferred to the optical member 10 and the lens 1.
1. Television camera 1 via light splitting members 7 and 12
3 and display the extraocular image on the monitor 14. Alignment is performed by bringing the corneal reflected image P to a predetermined position on the monitor 14, air is blown onto the cornea Ec from the nozzle 2, and when the cornea Ec is deformed to a certain curvature, the amount of light incident on the observation surface 5 is determined. The intraocular pressure can be determined from the timing at which it reaches its maximum.

[Effects of the Invention] As explained above, according to the present invention, it is possible to observe the outer eye of the subject's eye together with the corneal reflection image of the alignment light source, so even if the device is held misaligned with the subject's eye, the reflected light is Even if it is not within the field of view, it is possible to determine in which direction it is off.
Furthermore, since the corneal reflection image is less likely to become invisible from the observation field due to axis misalignment, there is an advantage that the alignment operation becomes extremely easy.

[Brief explanation of drawings]

Figure 1 is an optical layout diagram of the first embodiment of the present invention, Figure 2 is an explanatory diagram of its observation field image, Figure 3 is an explanatory diagram of its operation, and Figure 4 is an optical diagram of the second embodiment. FIG. 5 is an optical layout diagram of the third embodiment, and FIG. 6 is an explanatory diagram of the operation of the conventional example. 1 is an objective lens, 2 is a nozzle, 3 and 9 are light sources for alignment, 5 is an observation surface, 6 is a mark, 7,
12 is a light splitting member, 10 is an optical member, 13 is a television camera, and 14 is a monitor.

Claims (1)

[Claims] 1. In an ophthalmological apparatus that performs alignment by observing a corneal reflection image of an index light source, the light source is arranged at a position where a virtual image position due to corneal reflection of the light source is formed on the iris surface of the eye to be examined when the working distance is appropriate. An ophthalmological apparatus characterized in that the corneal reflection image of the light source can be observed together with the iris surface.