Torsional eye movements during psychophysical testing with rotating patterns

Abstract

Torsional eye movements were measured while subjects viewed a large, high contrast windmill pattern rotating at 53 degrees /s or a small (5 degrees diameter) dot pattern rotating at 115 degrees /s. Both stimuli generated rotational eye movements consisting of torsional optokinetic nystagmus (tOKN) superimposed on a slow torsional drift in the direction of pattern rotation. With the wide-field windmill stimulus, torsional drifts of up to 7 degrees over 20 s were found. The dot pattern produced drifts of up to 2 degrees over 5-20 s. In both cases, the slow-phase speeds during tOKN were low (0.5-1 degrees /s). We conclude that reductions in slip speed are minimal with rotating stimuli, so torsi..