Application of a Low-Cost Optical Probe with a Cone Prism in Applanation Tonometry

Applanation tonometry is the widely accepted method of measuring intraocular pressure (IOP). The optical probe in applanation tonometer is responsible for the measurement of the applanation diameter or area of the ocular cornea. In this paper, we introduce a novel optical probe in which a fabricated cone prism is employed and use it to detect the flattened diameter and area of the simulated eyeball with a curvature radius of ocular cornea, 7.8 mm. Experimental results show that the present optical probe can measure the flattened diameter of the ocular cornea; moreover, it can directly detect the flattened area by means of a circular modulating flake of light intensity. The present optical probe has a compact structure, easy use and low cost advantage over the existing optical probes in several applanation tonometer.