Vestibulo-ocular reflexes of adventitiously and congenitally blind adults.

The vestibulo-ocular reflex (VOR) was measured in congenitally blind, adventitiously blind, and normally sighted adults to determine how it was affected by loss of vision. VOR gain and phase were measured in subjects rotated sinusoidally in total darkness, while concentrating on an imaginary earth-fixed target. Gain was lower in adventitiously blind subjects than in sighted subjects. The gain reduction in blind subjects was accompanied by an increase in the amount of phase lead at low frequencies. The dominant time constant was typically 3 sec for adventitiously blind subjects and 16 sec for sighted subjects. No convincing vestibulo-ocular responses were measured in congenitally blind subjects except at the highest test frequencies. These findings demonstrate that vision is necessary early in life for development of the VOR, and that vision is also necessary throughout life for ongoing maintenance of the VOR.