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