Non-contact type tonometer

• US 4,947,849 A
• Filed: 07/20/1987
• Issued: 08/14/1990
• Est. Priority Date: 06/12/1984
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Topcon 1-GO 75-Ban Hasunuma-Cho Itabashi-Ku Tokyo-To
• Original Assignee: Tokyo Kogaku Kikai Kabushiki Kaisha
• Inventors: Ohtomo, Fumio, Takahashi, Susumu
• Primary Examiner(s): Sykes, Angela D.
• Application Number:
  US07/075,543
• Time in Patent Office: 1,121 Days
• Field of Search: 128/645,646-647, 128/648, 128/748, 128/649-652, 73/81, 73/78-79
• US Class Current: 600/401
• CPC Class Codes: A61B 3/165 Non-contacting tonometers

Abstract

A non-contact type tonometer is disclosed. It has an arrangement for transfiguring a cornea to be tested by discharging a fluid to it. This first arrangement comprises a rotary solenoid, a cylinder, and a rotary solenoid driving circuit. It also has a second arrangement for detecting the physical quantity showing the transfiguration of the cornea. The second arrangement comprises a radiating optical system and a detecting optical system. It also has a circuit serving as a third arrangement for detecting the flow pressure of the fluid which has a correlation with an intraocular pressure. It has a fourth arrangement for establishing a correlation function curve between the physical quantity and the flow pressure of the fluid based on the information from the second and third arrangements, deducing a flow pressure value corresponding to the preset value of the physical quantity from the correlation function curve, and converting such deduced flow pressure value of the fluid to an intraocular pressure value.

Claims

1. A non-contact type tonometer comprising:

fluid generating means for generating a pulse of pressurized fluid, and for discharging said pulse of pressurized fluid toward a cornea of an eye to be tested to transfigure the cornea from convexity to a predetermined transfiguration shape, said fluid generating means including a cylinder, said cylinder having a nozzle with a tip portion extending toward the cornea, a piston reciprocally disposed within said cylinder, and driving means for reciprocally moving said piston to pressurize said fluid and discharge said pressurized fluid through said nozzle toward the cornea;

cornea transfiguration detecting means for opto-electrically detecting the occurrence of said predetermined transfiguration shape of the cornea;

pressure detecting means, responsive to said cornea transfiguration detecting means, for directly detecting the pressure of said pulse of fluid when the cornea assumes said predetermined transfiguration shape; and

intraocular pressure deducing means for determining the intraocular pressure of the eye in accordance with said detected pressure of said fluid pulse;

wherein said driving means includes linear motor and a source of electrical current for powering said motor, and said pressure detecting means includes means for measuring the level of said source of electrical current and means for determining said detected fluid pressure in accordance with said measured level of electrical current.

2. A non-contact type tonometer comprising:

fluid generating means for generating a pulse of pressurized fluid, and for discharging said pulse of pressurized fluid toward a cornea of an eye to be tested to transfigure the cornea from convexity to a predetermined transfiguration shape;

cornea transfiguration detecting means for opto-electrically detecting the occurrence of said predetermined transfiguration shape of the cornea;

pressure detecting means, responsive to said cornea transfiguration detecting means, for directly detecting the pressure of said pulse of fluid when the cornea assumes said predetermined transfiguration shape; and

intraocular pressure deducing means for determining the intraocular pressure of the eye in accordance with said detected pressure of said fluid pulse;

wherein said cornea transfiguration detecting means includes radiating optical means for projecting a light flux toward the cornea, and detecting optical means for forming an image of said light flux reflected from the cornea, and position detecting means for detecting an image position at which said image of said reflected light flux is formed and for measuring displacements of said image position from a reference position, said displacements of said image position corresponding to the transfiguration of the cornea, and wherein said pressure detecting means includes means for detecting the fluid pressure when said measured displacement of said image position reaches a predetermined value.

3. A non-contact type tonometer comprising:

fluid generating means for generating and discharging a pulse of pressurized fluid toward a cornea of an eye to be tested to transfigure the cornea;

cornea transfiguration detecting means for opto-electrically detecting transfiguration of the cornea;

pressure detecting means for detecting the pressure of said pulse of pressurized fluid when the cornea assumes a predetermined transfiguration shape; and

intraocular pressure deducing means for determining the intraocular pressure of the eye in accordance with said detected fluid pressure;

said fluid generating means including first and second nozzles;

said first nozzle having a tip portion extending toward the cornea;

said second nozzle having a tip portion; and

said pressure detecting means including a pressure sensor disposed in such a manner that the distance between said tip portion of said second nozzle and said pressure sensor is equal to the distance between said tip portion of said first nozzle and the cornea.