A new applanation tonometer (NCT) measures intraocular pressure without touching the eye. A central area of the cornea is deformed by an air-pulse of linearly increasing force and the instant of applanation is determined by a monitoring system that senses light reflected from the corneal surface. Clinical evaluation has demonstrated good correlation between NCT and Goldmann tonometer readings, thereby validating this new method of tonometry.
Forbes M, Pico G, Grolman B. A Noncontact Applanation TonometerDescription and Clinical Evaluation. Arch Ophthalmol. 1974;91(2):134-140. doi:10.1001/archopht.1974.03900060140012