JPH0651027B2 - Tonometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is designed to blow compressed air to an eye to deform the cornea, and optically detect the deformed state to measure the intraocular pressure. The present invention relates to a contact tonometer.

[Prior Art] A conventional tonometer of this type detects compressed air pressure on the cornea from a central nozzle of an objective lens arranged in front of the eye to detect the air pressure when the cornea is flattened. In general, the optical system for detecting the deformation of the cornea is designed to project light from the oblique direction to the eye to be inspected and receive the reflected light in the oblique direction. .

As described above, in the conventional system, both the light projecting system and the light receiving system are arranged obliquely with respect to the eye to be inspected, and the optical system is located at a position different from the air chamber, which makes the structure complicated. It has the drawback of

For example, in U.S. Pat. Nos. 3,181,351 and 3,232,099, which are known examples, light is put in and out through an air chamber, but only the description is made that the deformation of the eye to be inspected is measured by a change in light amount due to defocusing at the time of deformation. Moreover, the measurement accuracy cannot be expected in the measurement due to the change in the light amount during defocusing.

[Object of the Invention] An object of the present invention is to improve the above-mentioned drawbacks of the conventional example, and use both the light projecting system and the light receiving system in the peripheral portion of the nozzle to simplify the conventional optical system in an oblique direction. To provide a tonometer having a simple structure.

[Summary of the Invention] A tonometer according to a first invention for achieving the above-mentioned object,
In a tonometer that deforms the cornea by blowing compressed air to the eye to be inspected from a nozzle provided in a position facing the eye to be inspected in the air chamber, and the tonometer that optically detects the deformed state, the eye to be inspected with respect to the nozzle in the air chamber An optical window member provided on the side opposite to the light source, a light source for projecting a light beam onto the cornea through the optical window member and the peripheral portion of the nozzle, and a light beam reflected by the deformed cornea around the nozzle. And a light-receiving element for receiving light through the optical window member and at a position where the amount of light is maximized when the cornea has a larger predetermined curvature, and an output signal of the light-receiving element, It is characterized in that the intraocular pressure value is obtained based on the air pressure.

The tonometer according to the second aspect of the invention is a tonometer that optically deforms the cornea by blowing compressed air onto the eye to be inspected from a nozzle provided at a position facing the eye to be inspected in the air chamber, and optically detecting the deformed state. In, in order to project an optical window member provided on the side opposite to the eye to be examined with respect to the nozzle of the air chamber, and a light flux from the oblique direction with respect to the nozzle to the cornea through the optical window member and the peripheral portion of the nozzle. And a light receiving element arranged at a position to receive a light beam reflected by the deformed cornea from an oblique direction with respect to the nozzle through the peripheral portion of the nozzle and the optical window member. It is characterized in that the intraocular pressure value is obtained based on the output signal and the air pressure.

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

FIG. 1 shows a first embodiment, in which a nozzle 2 is provided in the center of an objective lens 1 arranged in front of an eye to be inspected, and a piston 4 of a cylinder 3 is driven in a direction of arrow A. Compressed air extruded at the time of spraying is blown to the cornea C through the nozzle 2 to deform the cornea C as in the conventional example.

In the case of the present embodiment, the optical system for detecting the deformed state of the cornea C is arranged such that both the light projecting system and the light receiving system pass through the lens portion 1a around the nozzle 2 of the objective lens 1, and the cylinder 3 Is provided with a window 5 for passing a light beam. Then, the light splitting member 6 and the light source 7 are arranged behind the window 5,
A light receiving element 8 is provided on the reflection side of the light dividing member 7, and the light source 7 and the light receiving element 8 are conjugated with respect to the light dividing member 6.

The light beam B emitted from the light source 7 is projected onto the cornea C through the light splitting member 6 and the window 5 and the lens portion 1a around the objective lens 1. Further, the light beam B1 reflected by the cornea C passes through the lens portion 1a around the objective lens 1 again when the cornea C undergoes a predetermined deformation, and receives light that is arranged in a conjugate relationship with the light source 7 with respect to the light splitting member 6. An image is formed on the element 8.

That is, as described above, when the cornea C is deformed by the pressure of the compressed air and is deformed into a shape such as Ca having a larger curvature, the center of curvature also changes from the position O to the position Oa,
The image of the light source 7 formed by the objective lens 1 is at this position.
If it is installed so as to form an image on Oa, the signal of the light receiving element 8 becomes maximum when the cornea C is deformed like Ca. That is,
When the signal of the light receiving element 8 becomes maximum when the cornea C undergoes a predetermined deformation, it is possible to obtain the intraocular pressure from the pressure of the compressed air at that time.

The light beam B2 reflected by the cornea C before the cornea C is deformed is not diffused as shown in the figure and does not form an image on the light receiving element 8.

FIG. 2 shows a second embodiment of the present invention.
The same reference numerals as in the drawings represent the same or equivalent members. In the case of FIG. 2, the optical axis D of the objective lens 1 passes through the center of the nozzle 2, and the light source 7 is arranged at the focal position of the objective lens 1 at a position decentered from the center of the nozzle 2. The light receiving elements 8 are installed at symmetrical positions. This second
Also in this embodiment, the eye pressure can be obtained from the pressure at which the light beam B1 reflected by the cornea C due to the blowing of compressed air forms a light source image on the light receiving element 8 and the signal becomes maximum.

[Advantages of the Invention] As described above, the tonometer according to the first aspect of the invention is configured to detect that the amount of light returning from the front increases when the curvature increases due to deformation. As a result, the size of the air chamber is reduced, and the light flux with a larger angle of view is reflected and reflected than in the case of applanation, and high-precision measurement that can use a large amount of light becomes possible.

Moreover, since the tonometer according to the second aspect of the invention has a configuration in which the optical paths for oblique illumination and oblique detection are passed through the air chamber, it is possible to arrange the optical system for high-accuracy measurement without taking up a large space.

[Brief description of drawings]

The drawings show an embodiment of the tonometer according to the present invention, and FIGS. 1 and 2 are configuration diagrams, respectively. Reference numeral 1 is an objective lens, 2 is a nozzle, 3 is a cylinder, 4 is a piston, 5 is a window, 6 is a light splitting member, 7 is a light source, and 8 is a light receiving element.

Claims (2)

[Claims] 1. A cornea is deformed by blowing compressed air to a subject's eye from a nozzle provided at a position facing the subject's eye in an air chamber,
In a tonometer that optically detects the deformed state, an optical window member provided on the side of the air chamber opposite to the eye to be inspected with respect to the nozzle, and a light flux to the cornea through the optical window member and the peripheral portion of the nozzle. A light source for projecting and for receiving a light flux reflected by the deformed cornea through the peripheral portion of the nozzle and the optical window member, and a light amount when the cornea has a larger predetermined curvature. The tonometer is characterized in that it has a light receiving element arranged at a position at which the maximum value is obtained, and obtains an intraocular pressure value based on the output signal of the light receiving element and the air pressure. 2. A cornea is deformed by blowing compressed air to an eye to be inspected from a nozzle provided at a position facing the eye to be inspected in an air chamber,
In a tonometer that optically detects the deformed state, an optical window member provided on the side of the air chamber opposite to the eye to be inspected with respect to the nozzle, and a light flux to the cornea through the optical window member and the peripheral portion of the nozzle. A light source for projecting obliquely to the nozzle, and a position for receiving the light beam reflected by the deformed cornea from the oblique direction to the nozzle through the peripheral portion of the nozzle and the optical window member. The tonometer is characterized in that the tonometer value is obtained based on the output signal of the light receiving element and the air pressure.