Childhood visual experience affects adult voluntary ocular motor control

To quantify the effects of childhood visual experience/chronic visual deprivation upon adult voluntary ocular motor control.

Eye movements of blind and sighted adults were elicited and videotaped in total darkness. The videotaped responses were digitized using an eye tracker, yielding data from 10 congenitally blind (infantile onset, blindness before age 1 year), 16 adventitiously blind, and 9 sighted persons.

Multivariate analysis of variance, trend analyses and post hoc tests revealed that primary position fixational stability and consistency of return to primary position were lowest in the congenitally blind vs. the adventitiously blind group, and highest in the sighted. Duration of adventitious blindness reduced primary position stability but not consistency of return to primary position. Secondary position maximum amplitudes: congenitally blind mean, 14 degrees; adventitiously blind mean, 40 degrees; sighted mean, 47 degrees. Average velocity (a form of Main Sequence) increased significantly with amplitude in all three groups.

Visual deprivation can greatly attenuate but does not abolish human voluntary eye movement. Adventitious blindness exerts minimal to profound effects, commensurate with age of vision loss.