Measurement of the applanated diameter of ocular cornea using a novel optical probe

Abstract

A precise measurement of the applanated diameter of the ocular cornea with the optical probe is very important in applanation tonometry. A novel optical probe with a common path configuration is presented. The optical probe mainly consists of a cone-shaped prism and a photodetector. The former serves as a measuring body touching the ocular cornea to shape the area to be measured, and the latter converts the quantity of the luminous flux returning from the cone-shaped prism into one electronic current signal. Laboratory experiments are carried out on a simulated eyeball, followed by an enucleated porcine eyeball specimen. Experimental results show that there is a significant rise of the normalized variational current with increasing the applanation diameter of the ocular cornea, and the sensitivity is 0.2111/mm with an error of 0.00263/mm. Measurements of the normalized variational current on the porcine eyeball have good agreement with those on the simulated eyeball.

Keywords

Optical Probe / Variational Current / Applanation Tonometry / Luminous Flux / Applanation Tonometer

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This work has been supported by the Natural Science Foundation of Anhui Provincial Education Department (Nos. KJ2008B262, KJ2008A146 and KJ2011z060).