A New Microprocessor-Assisted Objective Refractor

Abstract

Automated objective optometers (or refractors) enabling ophthalmic practitioners to measure ocular refraction automatically appeared within the last decade [1–4]. Bausch and Lomb’s ophthalmetron seems to have been the first of these instruments, soon followed by Acuity System’s Autorefractor and Coherent Radiation’s Dioptron [5,6,7]. With this type of instrument, the operator looking at the patient’s eye sets the eye-instrument distance and places the pupil in a central position. Then ocular refraction is automatically measured by the instrument which gives the prescription relative to the patient’s eye as a print-out on a paper roll. An exhaustive review of automatic refraction instruments was published recently by GUYTON [8] and SASIENI [9]. Automated refractors are convenient for they make it possible to find which corrective lenses should be prescribed; but their purchase and maintenance costs are high. Moreover they deprive specialists of the opportunity to observe the ophthalmoscopic image that would enable them to spot possible ocular diseases. That was why we decided to conceive a simpler refractor assisted by a microprocessor which avoids such drawbacks.