METHOD AND APPARATUS FOR MEASURING INTRAOCULAR PRESSURE

• US 3,585,849 A
• Filed: 10/09/1968
• Issued: 06/22/1971
• Est. Priority Date: 10/09/1968
• Status: Expired due to Term

• Current Assignee: Cambridge Instruments Inc (Danaher Corporation)
• Original Assignee: Grolman Bernard
• Inventors: GROLMAN BERNARD
• Application Number:
  US04/766,189
• Time in Patent Office: 986 Days
• US Class Current: 600/401
• CPC Class Codes: A61B 3/165 Non-contacting tonometers

Abstract

An air pulse is directed at the cornea of a patient'"'"''"'"'s eye, causing it to deform from its normal convex shape through application and to a slight concavity. The intraocular pressure thereupon causes the return of the cornea from concavity through application to a normal or convex shape. The time interval between occurrences of application, or between a fixed point in time and either occurrence of application, is a measure of intraocular pressure. Apparatus for the practice of this invention includes an air pulse generator to provide a corneadepressing pulse of air, a source of light and means to direct the same onto the corneal surface, a photodetection means to sense specularly reflected flux from the cornea, and instrumentation to show, as a function of time, the occurrences of reflected light flux maxima.

Claims

1. A method of tonometry by which, without contact between apparatus and cornea, intraocular pressure is indicated, including the steps of:

directing a fluid force against a corneal surface area, such force being sufficient to transfigure said surface area from convexity to a concavity, directing a monitoring light beam at said corneal surface area, receiving the reflection of said beam in a detecting apparatus, and detecting the quantities of flux of said reflection as a function of the time during which said corneal surface area is transfigured from convexity, through applanation, to concavity, and back through applanation to convexity, whereby the time between the directing of the fluid force against said corneal surface and the occurring of the first applanation of said corneal surface or the time between the first and second applanations may be correlated to the intraocular pressure.

2. The method of tonometRy as defined in claim 1 in which said fluid force is directed toward said corneal surface area in a direction substantially normal thereto and said monitoring light beam is directed toward said corneal surface area in a direction other than normal thereto.

3. Apparatus for the measurement of intraocular pressure including:

means for directing a fluid pulse against a corneal surface area in order to transfigure said area from convexity, through applanation to concavity;

a light source to direct a light beam at said surface area; and

a reflection detection means to detect and indicate quantities of flux reflection as a function of the time during which said corneal surface is transfigured from convexity, through applanation, to concavity.

4. Apparatus according to claim 3 further including means to align said apparatus to direct said fluid pulse in a direction normal to said surface area.

5. Apparatus according to claim 3 in which:

said pulse generator comprises a solenoid actuated plunger operatively associated with an orificed pressure chamber to provide uniform pulses successively; and

said reflection detection means comprises a light detector and a detector readout instrument to indicate relative quantities of detected light as a function of time.

6. A method of noncontact tonometry including the steps of:

directing a fluid force along a first axis against a corneal surface, such force being sufficient to transfigure said surface area from convexity through applanation to concavity;

directing a monitoring light beam along a second axis angularly displaced from said first axis and at said corneal surface area;

receiving the reflection of said beam in a photosensitive detecting apparatus;

recording the quantities of flux of said reflection continuously during the foregoing steps; and

plotting the relative quantities thus recorded as a function of the time during which said corneal surface area is transfigured from convexity through applanation to concavity and back through applanation to convexity, whereby the time between the directing of the fluid force against said corneal surface and the occurring of the first applanation of said corneal surface or the time between the first and second applanations may be correlated to intraocular pressure.

7. Apparatus for measurement of the intraocular pressure including:

means for directing a fluid pulse against a corneal surface area along a first axis normal to said area in order to transfigure said area from convexity, through applanation to concavity;

a light source;

means to direct a beam from said light source along a second axis angularly displaced from said first axis and at said surface area;

a photosensitive reflection detection means to detect quantities of reflected light flux from said surface area;

said light source and said reflection detection means disposed on opposite sides of said pulse directing means and at equal angles from the normal to said surface area; and

recording means to continuously plot relative quantities of detected flux reflection as a function of time before, during and after which said fluid pulse directing means is operative relative to said corneal surface area.