Automatic Optometer for Use with the Undrugged Human Eye

Abstract

An automatic optometer that relies on phase detection as opposed to amplitude detection offers the advantage of relative independence of refractive measurements from changes in photodetector signal amplitude. Thus, phenomena that affect signal amplitude such as changes in test source output, variations in pupil size, eye movements, and photodetector and amplifier instabilities have negligible or greatly reduced effects on refractive measurements. The foregoing properties permit high resolution refractive measurements without the need for a pupil dilating drug and also allow the recording of pupil size changes in the same eye with minor additions to the existing apparatus.