Effect of stimulation parameters.

(A) Peak eye velocity as function of current strength for stimulation at a site corresponding to R = 15 (light), 21 (medium) and 31 (dark) deg, for 100 ms stimulation duration. Beyond the threshold at 140 pA, the evoked eye velocity is virtually independent of the stimulation current. (B) Total eye displacement as function of microstimulation strength for stimulation at a site corresponding to R = 15 (light), 21 (medium) and 31 (dark) deg for 100 ms stimulation duration. Beyond the threshold at 90 pA, the total eye displacement is independent of the stimulation current. (C) Peak eye velocity as a function of microstimulation duration from the same locations at a fixed stimulation strength of 150 pA.