Patent ID: 7909765

Claim:
A non-contact tonometer comprising: a fluid pump including a plenum chamber; a fluid discharge tube in communication with the pump for directing a fluid pulse at a cornea of a patient to cause reversible deformation of the cornea from an original state of convexity through a first state of applanation to a state of concavity, and back through a second state of applanation to the state of convexity; an applanation detector providing an applanation signal indicating a time of the first state of applanation and a time of the second state of applanation; a pressure sensor arranged to provide a pressure signal indicating fluid pressure in the plenum chamber as a function of time; a processor connected to the applanation detector and the pressure sensor for evaluating the applanation signal and the pressure signal to provide a first pressure value (P 1 ) coinciding with the first state of applanation and a second pressure value coinciding with the second state of applanation, and for calculating an intraocular pressure value using a predetermined function of the first pressure value (P 1 ) and the second pressure value (P 2 ), wherein the predetermined function is empirically derived to minimize cornea-related influence on the intraocular pressure value; and a memory connected to the processor, wherein the memory stores the empirically derived predetermined function; wherein the predetermined function is derived from empirical data measuring the first pressure value (P 1 ) and the second pressure value (P 2 ) both before and after surgical alteration of the cornea.