Non-contact eye pressure meter

• US 4,825,873 A
• Filed: 07/09/1987
• Issued: 05/02/1989
• Est. Priority Date: 07/26/1986
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kohayakawa, Yoshimi
• Primary Examiner(s): Coven, Edward M.
• Application Number:
  US07/071,314
• Time in Patent Office: 663 Days
• Field of Search: 128/648, 128/652, 128/645
• US Class Current: 600/401
• CPC Class Codes: A61B 3/165 Non-contacting tonometers

Abstract

A non-contact eye pressure meter is provided with a cornea deforming system for blowing a compressed fluid of a pressure variable with time against the cornea of an eye to be examined from a nozzle provided in a predetermined optical member opposed to the eye to be examined, and a deformation detecting system for applying a light beam from a predetermined light source to the eye to be examined past only one area of the interior of the nozzle and the interior of the predetermined optical member which is in the outer peripheral portion of the nozzle and receiving the cornea-reflected light by a predetermined light-receiving element past only the other area. The light source and the light-receiving element are set optically substantially conjugately through corneal reflection when the cornea of the eye to be examined is deformed to a predetermined curvature.

Claims

1. A non-contact eye pressure meter comprising:

a cornea deforming system for blowing a compressed fluid of a pressure variable with time against the cornea of an eye to be examined from a nozzle opposed to the cornea of the eye to be examined; and

a deformation detecting system for projecting a light beam from a light source to the eye to be examined on a path located either on the side inside of said nozzle and the side outside of said nozzle and receiving said light beam reflected by the cornea of the eye to be examined by a light-receiving element past the side of said nozzle opposite that for the applying light beam;

said light source and said light receiving element being set substantially optically conjugate by way of both the cornea of the eye to be examined and an imaging optical system in the optical path when the cornea of the eye to be examined is deformed to a predetermined convex curvature before applanation.

2. A non-contact eye pressure meter according to claim 1, wherein said nozzle is provided in an objective lens opposed to the eye to be examined and said objective lens is contained in said imaging optical system.

3. A non-contact eye pressure meter according to claim 1, wherein said nozzle is provided in a transparent planar plate opposed to the eye to be examined.

4. A non-contact eye pressure meter according to claim 1, further including condensing means for condensing the light beam from said light source substantially at a location inside of said nozzle and for applying a divergent light beam from said location to the cornea of the eye to be examined.

5. A non-contact eye pressure meter according to claim 1, further including condensing means for condensing the cornea-reflected light beam substantially at a location inside of said nozzle when the cornea of the eye to be examined is deformed to said predetermined curvature.

6. A non-contact eye pressure meter according to claim 1, wherein said deformation detecting system includes parallel projection means for projecting parallel light beams through the interior of said nozzle and for irradiating the cornea of the eye to be examined.

7. A non-contact eye pressure meter according to claim 1, wherein said deformation detecting means includes means for forming the light beams reflected by the cornea of the eye to be examined parallel to an axis of said nozzle when the cornea of the eye to be examined is deformed to the predetermined curvature.

8. A non-contact eye pressure meter according to claim 1, wherein said light-receiving means is adapted to provide a maximum output signal, and the pressure meter further includes calculating means for calculating the eye pressure when said light receiving means provides the maximum output signal.

9. A non-contact eye pressure meter according to claim 1, wherein said light-receiving means is adapted to provide a maximum output signal, and

said deforming system is provided with a cylinder having a pressure sensor for sensing the eye pressure when said light-receiving element provides the maximum output signal.

10. A non-contact eye pressure meter comprising:

a cornea deforming system for blowing a compressed fluid of a pressure variable with time against the cornea of an eye to be examined from nozzle opposed to the cornea of the eye to be examined; and

a deformation detecting system for projecting a light beam from a light source to the eye to be examined on a path located in one of either the side inside of said nozzle and the side outside of said nozzle and receiving said light beam reflected by the cornea of the eye to be examined by a light-receiving element, said reflected light beam travelling on a path located on the side of said nozzle opposite that for the applying light beam, said light source and said light-receiving element being set substantially optically conjugate by way of both the cornea of the eye to be examined and an imaging optical system in the optical path when the cornea of the eye to be examined is deformed a predetermined shape.

11. A non-contact eye pressure meter comprising:

a cornea deforming system for blowing a compressed fluid of a pressure variable with time against the cornea of an eye to be examined from a nozzle opposed to the cornea of the eye to be examined; and

a deformation detecting system for projecting a light beam from a light source to the eye to be examined and receiving said light beam reflected by the cornea of the eye to be examined by a light-receiving element, said light source and said light-receiving element being set substantially optically conjugate by way of both the cornea of the eye to be examined and an imaging optical system in the optical path when the cornea of the eye to be examined is deformed to a predetermined convex curvature before applanation.