Patent ID: 7473231
Filing Date: 2009-01-06
Classification: A61B

Abstract:
1. A method of measuring an ocular pulse pressure (OPP) of an eye, the method using a tonometer having an actuator pressing a prism with a variable force against a cornea of the eye while a source directs light to reflect from an applanation surface of the prism to a detector producing a detected light signal received by a programmed microprocessor and representing an applanated area of the cornea, the method comprising: recognizing a preliminary value of the detected light signal occurring upon preliminary contact of the applanation surface with the cornea, the preliminary value varying from one eye to another based on specific corneal thickness and curvature of the eye being examined; pressing the prism applanation surface against the cornea with increasing force applied during a time interval to change the detected light signal from the preliminary value through a range of values including the preliminary value extending by a predetermined amount from the preliminary value; determining an intra ocular pressure (IOP) from changes in the detected light signal corresponding to prism pressure force changes in the range of values so that the IOP determination is substantially unaffected by thickness and curvature of the cornea of the eye being examined; pressing the applanation surface against the cornea long enough for at least two systolic pulses to occur within the eye being examined; and determining OPP from departures of the detected light signal from the determined IOP during the systolic pulses.