Combined applanation tonometer and ultrasonic pachymeter
AssigneeSublase, Inc.
InventorFrancis E. O'Donnell, Jr.
Life of this patent
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Abstract
An improved apparatus and method of intraocular pressure determination is disclosed in which applanation tonometry is done with an ultrasonic transducer. The method allows for increased accuracy of intraocular pressure determination based upon adjustment of applanation tonometry for subjacent corneal thickness. The device allows for the operator to view the corneal surface and the pattern of dye to determine the precise endpoint of applanation.
Claims13
An applanation apparatus which allows for the determination of applanation pressure and membrane thickness of an eye having a fluid filled cavity comprising:
- a transparent transducer body having one or more generally longitudinal flat surfaces, a corneal contact surface for applanation of the cornea, and a posterior viewing surface opposite the corneal contact surface, the one or more generally longitudinal flat surfaces being so positioned as to enable viewing through the corneal contact surface from the posterior viewing surface by reflection in the one or more generally longitudinal flat surfaces;
- and,
- an ultrasonic transmitter and receiver within said transparent transducer body for sending and receiving an ultrasonic signal to said applanated cornea, said ultrasonic signal processed to determine the applanation pressure and membrane thickness of the eye.
A method of determining intraocular pressure of a human eye comprising:
- providing a transducer including a transparent body with one or more generally longitudinal flat surfaces and a corneal contact surface at a front end, an ultrasonic transmitter and receiver within said body, said ultrasonic transmitter and receiver being in communications with a microprocessor, said microprocessor being capable of correcting an intraocular pressure signal for a corneal thickness to determine a true intraocular pressure independent of corneal thickness,
- placing the corneal contact surface of the transducer against a cornea while viewing the cornea through the corneal contact surface by means of total internal reflection in one or more said generally longitudinal flat surfaces through a viewing surface at a rear end of the transparent body;
- creating an applanation point on the cornea with said corneal contact surface;
- viewing said applanation point by means of total internal reflection in said one or more generally longitudinal flat surfaces through said viewing surface at a rear end of the transparent body,
- measuring an intracavity pressure at said applanation point with said transparent transducer body;
- measuring a corneal thickness with said ultrasonic transmitter and receiver;
- and,
- correcting the measured intracavity pressure for the measured corneal thickness to determine the true intraocular pressure.
Dependencies are inferred from the claim text.