a non - contact tonometer is improved by providing a non - telecentric applanation detection system enabling relaxation of instrument alignment requirements during testing . in a preferred embodiment , the applanation detection system comprises an emitter for directing an obliquely incident beam of light for reflection by the cornea , and a detector array having a plurality of photosensitive detector array elements located to receive corneally reflected light . the detector array generates a plurality of signal curves for light energy received at different locations on the array as a function of time , and the signal curves are evaluated to determine an optimal signal curve which best indicates the moment of applanation .