JP3420630B2 - Non-contact tonometer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact tonometer for measuring intraocular pressure, and more particularly to an alignment optical system suitable for aligning an eye to be inspected with an apparatus.

[0002]

2. Description of the Related Art There is known a non-contact tonometer for measuring an intraocular pressure by blowing a gas onto a cornea of an eye to be inspected from a nozzle held by an optical member through which a light flux of an anterior segment image passes.

As an alignment optical system of this apparatus,
An index for alignment is projected from the rear side of the optical member holding the nozzle onto the cornea of the eye to be inspected, and the reflected image of the apex of the cornea is again received by the observation optical system such as a television camera via the optical member, and the same optical member is used. It is known that an alignment is made while observing the reflected image together with the anterior segment image received through the image.

In this type of alignment optical system,
The anterior segment image observed with the observation optical system is uniformly widely observed, and when the alignment index is projected, the reflected light from the optical member that holds the nozzle does not enter the imaging surface of the observation optical system. Need to be configured.

As an apparatus having an alignment optical system that enables this, there is, for example, one disclosed in Japanese Patent Publication No. 5-66805. The optical system shown here projects the light flux from the light source for alignment through the nozzle of the compressed gas blowing port onto the cornea of the eye to be inspected, and the reflection image of the corneal apex is passed through the flat glass around the nozzle together with the anterior segment image. The light is guided to the imaging optical system. .

[0006]

However, in the alignment in the optical system as in the above Japanese Patent Publication No. 5-66805, the imaging optical system can detect the projected image of the alignment light source from the cornea of the eye to be inspected. The apex is limited to a narrow area in front of the nozzle of the compressed gas blowing port. Therefore, when the corneal apex is not in front of the nozzle, the examiner relies on the image of the anterior segment of the subject's eye observed from a television monitor or the like to perform alignment at the examiner's discretion until the projection image of the alignment light source is detected. There must be. This has a drawback that the measurement cannot be performed quickly and efficiently when the examiner is unfamiliar with the alignment operation of the apparatus.

The present invention has been devised in view of the above-mentioned drawbacks, and an object of the present invention is to provide a non-contact tonometer capable of more rapid alignment operation.

[0008]

In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) In a non-contact tonometer for measuring eye pressure by blowing gas onto a cornea of an eye to be inspected through a nozzle to hold the nozzle, the non-contact tonometer is inclined with respect to a plane perpendicular to the axis of the nozzle. A flat light-transmissive member, index projection means for projecting an alignment index through the light-transmissive member and the nozzle onto the cornea of the eye to be inspected, and a corneal reflection image by the index projection means and an anterior segment of the eye to be inspected An observation optical system for guiding and observing the image again through the light transmissive member and the nozzle.

(2) The light transmissive member of (1) is composed of a plurality of flat glass plates, and at least two of the flat glass plates are tilted at angles opposite to each other with respect to a plane perpendicular to the axis of the nozzle. It is characterized by being.

(3) The light transmissive member of (1) is composed of two flat glass plates having the same refractive index and the same thickness and being inclined at the same angle opposite to each other with respect to the plane perpendicular to the axis of the nozzle. Characterizing

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an optical system of the apparatus of the embodiment.

Reference numeral 1 denotes a piston, which is driven by a drive mechanism (not shown) at the time of measurement to compress the gas inside the gas compression chamber 2. The compressed gas is ejected from the nozzle 3 to deform the cornea Ec of the eye E to be examined.

Numerals 4 and 5 are optical members made of transparent parallel plane glass for holding the nozzle 3. The optical members 4 and 5 have the same refractive index and the same thickness, and are opposite to each other with respect to the axis L of the nozzle 3. Are inclined at the same angle. Reference numeral 6 denotes a window made of flat glass that constitutes the rear side wall of the gas compression chamber 2, and is provided so as to be inclined with respect to the axis L. Reference numeral 7 is an alignment light source, and 8 is a light projecting lens. Reference numeral 9 denotes a half mirror, which makes the alignment light flux emitted from the light source 7 coaxial with the axis L of the nozzle 3.

Reference numeral 10 is an objective lens having an optical axis which coincides with the axis L, and 11 is a television camera which receives an image from the objective lens 10. An illumination lamp 12 illuminates the anterior segment of the eye E to be inspected. The anterior ocular segment image illuminated by turning on the illumination lamp 12 passes through the optical members 4, 5 and the window 6 and then is imaged on the image pickup device of the television camera 12 by the objective lens 11.
It is displayed on a display device (not shown).

The apparatus is also provided with a measurement optical system for detecting corneal deformation for measuring intraocular pressure and a fixation optical system for fixing the eye to be examined, but they are not related to the present invention. The description is omitted.

The operation of the apparatus having the optical system configured as described above will be described. The alignment light flux emitted from the light source 7 is made into a substantially parallel light flux by the light projecting lens 8, and then is reflected by the half mirror 9 to be coaxial with the axis L of the nozzle 3. After passing through the flat glass window 6, the alignment light flux reflected by the half mirror 9 passes through not only the inside of the nozzle 3 but also the optical members 4 and 5 around it and the cornea E.
It is projected on c.

The alignment light flux passing through the optical members 4 and 5 will be described in detail with reference to FIG. The alignment light flux parallel to the axis L entering the optical member 5 in the optical path A causes an optical axis shift due to the inclination of the optical member 5 when passing through the optical member 5, and exits the optical member 5 as an optical path A ′. . The alignment light flux on the optical path A ′ also causes an optical axis shift due to the inclination when passing through the optical member 4, and is emitted as the optical path A ″. Here optical members 4, 5
Is composed of flat glass having the same refractive index and the same thickness as described above, and is tilted in the opposite directions by the same angle, the optical axis shifts generated in the optical members 4 and 5 are offset to cancel the optical path A. And the optical path A ″ are the same, and the light is projected onto the cornea Ec without any difference from the light flux passing through the inside of the nozzle 3.

A part of the alignment light flux passing through the optical members 4 and 5 becomes reflected light when entering and exiting the optical members 4 and 5, but is reflected as shown by B and B'in FIG. The light largely deviates from the axis L due to the inclinations of the optical members 4 and 5. Therefore, the incidence on the television camera 11 is blocked, and unnecessary and harmful flare can be avoided. The inclination of the optical members 4 and 5 is so designed and arranged.

When the alignment light flux passing through the inside of the nozzle 3 and the optical members 4 and 5 is projected onto the cornea Ec, the index image i of the light source 1 is formed by the specular reflection of the cornea Ec.
The reflected light of the cornea Ec that appears as if it were emitted from the index image i returns to the optical system of the apparatus again and passes through the inside of the optical members 4, 5 and the nozzle 3. At this time, as in the case of projecting the alignment light flux, the cornea Ec passing through the optical members 4 and 5 is also used.
The reflected light of (1) passes through without any optical axis deviation from the light flux passing through the inside of the nozzle 3.

The reflected light of the cornea Ec which has passed through the insides of the optical members 4 and 5 and the nozzle 3 passes through the flat glass window 6 and then the objective lens 10 forms an image of the index image i on the television camera 11 for display. It is displayed on the device. The examiner operates a well-known sliding mechanism such as a joystick based on the relationship between the index image and the anterior segment image on the display device while observing this image and the anterior segment image of the subject's eye E illuminated by the illumination lamp 10. And align.

[0022]

As described above, according to the present invention,
Since the alignment light flux can be projected onto the eye to be inspected not only from the inside of the nozzle that ejects air but also from the peripheral portion of the nozzle, it is possible to further widen the projection range of the alignment light flux to the eye. Thereby, even if the corneal apex of the eye to be inspected is not placed in front of the nozzle, the alignment index image can be detected early and the alignment operation can be speeded up.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an optical system of an example apparatus.

FIG. 2 is a diagram illustrating an alignment light flux when passing through optical members 4 and 5.

[Explanation of symbols]

Ec cornea 4, 5 Optical member 7 Alignment light source 8 Projection lens 9 Half mirror 10 Objective lens 11 TV camera 12 Lighting

Claims (3)

(57) [Claims] 1. A non-contact tonometer for measuring eye pressure by blowing gas onto a cornea of an eye to be inspected through the nozzle to hold the nozzle by inclining with respect to a plane perpendicular to the axis of the nozzle. A flat light-transmissive member, index projection means for projecting an alignment index through the light-transmissive member and the nozzle onto the cornea of the eye to be inspected, and a corneal reflection image by the index projection means and an anterior segment image of the eye to be inspected And an observation optical system that guides light through the light-transmissive member and the nozzle again for observation, and a non-contact tonometer. 2. The light transmissive member according to claim 1, comprising a plurality of flat glass plates, and at least 2 of the plurality of flat glass plates.
The non-contact tonometer is characterized in that the two are inclined at angles opposite to each other with respect to a plane perpendicular to the axis of the nozzle. 3. The light transmissive member according to claim 1, wherein the light transmissive member is composed of two flat glass plates having the same refractive index and the same thickness, which are opposite to each other and inclined at the same angle with respect to a plane perpendicular to the axis of the nozzle. Non-contact tonometer.