Effects of Involuntary Eye Movements on Visual Acuity*

Abstract

This research was conducted to evaluate the effect of involuntary eye movements on visual acuity. Three types of acuity target—vernier, fine line, and grating—were observed for varying exposure durations under two viewing conditions. One was the “stabilized image” condition where a mirror on the eye was used to reflect the target beam in such a way as to stop the motion of the retinal image that would otherwise accompany the eye movements. The other viewing condition was optically the same except that the eye movements produced normal motions of the retinal image. Acuity was defined in terms of a minimum angle of resolution, i.e., the threshold value of the angle subtended by the critical dimension of the target. Acuity was found to improve with increasing exposure time up to about 0.2 sec under both viewing conditions. The main conclusion is that acuity is neither enhanced nor impaired by the involuntary eye movements that are present during the inspection of a test object.