ANOMALIES OF MOTION PERCEPTION IN INFANTILE ESOTROPIA

PURPOSE. TO quantify motion sensitivity in patients with infantile eso tropia who, as a subgroup, have been previously reported to have abnor mal oculomotor control. In addition, to probe abnormal binocular devel opment as a factor underlying abnormal motion perception in infantile esotropia (IE), motion sensitivity was compared among participants wit h and without stereopsis. METHODS. Monocular sensitivity to leftward a nd rightward motion was assessed across the horizontal meridian, using partially coherent random dot kinematograms. Participants included 11 observers with IE, 5 observers with acquired esotropial and 11 observ ers with normal eye alignment. RESULTS. Participants with IE showed no deficits in motion sensitivity to any visual field locations when mot ion thresholds were collapsed across direction. However, they showed a n abnormal variation in directional anisotropy. Although sensitivity t o centripetal motion was superior in both hemifields of control partic ipants and in the temporal hemifields of participants with IE, a centr ifugal bias was revealed in the nasal hemifields of LE. Stereoblind ob servers with acquired esotropia showed a normal centripetal directiona l anisotropy, whereas binocular observers with acquired esotropia show ed directional anisotropy similar to that in the IE group. CONCLUSIONS . Motion perception, like oculomotor function in IE, is characterized by a variation of directional anisotropy for stimuli presented to the nasal hemifields. This finding supports the hypothesis that abnormal o culomotor control and motion perception in IE reflect a common disrupt ion of the visual system. A similar variation of directional sensitivi ty in patients with acquired esotropia with normal stereopsis suggests that the interruption of binocularity is not the underlying cause of abnormal motion perception in IE.