Noncontact type tonometer

Abstract

A noncontact type tonometer comprising with a nozzle for directing fluid into a cornea of a patient's eye and for deforming the cornea from a normally convex state, through a flat state, to a concave state, a detector for detecting fluid pressure within the nozzle and for generating pressure data corresponding to the fluid pressure, an optical detector for optically detecting corneal deformation and for generating optical data corresponding to a deformation state from the normally convex state to the concave state, a generator for generating predetermined time interval data according to a predetermined time interval, a clock, cooperable with the optical detector for optically detecting corneal deformation, for detecting an elapsed time interval for the cornea to deform to the flat state from the normally convex state and for generating elapsed time interval data corresponding thereto, a predictor for predicting an optimal time interval for the cornea to deform from the normally convex state to the flat state based upon the optical data and the predetermined time interval data and for generating optimal time interval data corresponding thereto, a comparator for comparing the elapsed time interval data with a predetermined range of the optimal time interval data, a pressure calculator for calculating the fluid pressure according to the pressure detected by the detector for detecting fluid pressure at the elapsed time interval where the cornea deforms to a flat state if the elapsed time interval lies within the predetermined range of the optimal time interval, and a controller for driving the nozzle.