Anomalies of motion perception in infantile esotropia

To quantify motion sensitivity in patients with infantile esotropia who, as a subgroup, have been previously reported to have abnormal oculomotor control. In addition, to probe abnormal binocular development as a factor underlying abnormal motion perception in infantile esotropia (IE), motion sensitivity was compared among participants with and without stereopsis.

Monocular sensitivity to leftward and rightward motion was assessed across the horizontal meridian, using partially coherent random dot kinematograms. Participants included 11 observers with IE, 5 observers with acquired esotropia, and 11 observers with normal eye alignment.

Participants with IE showed no deficits in motion sensitivity to any visual field locations when motion thresholds were collapsed across direction. However, they showed an abnormal variation in directional anisotropy. Although sensitivity to centripetal motion was superior in both hemifields of control participants and in the temporal hemifields of participants with IE, a centrifugal bias was revealed in the nasal hemifields of IE. Stereoblind observers with acquired esotropia showed a normal centripetal directional anisotropy, whereas binocular observers with acquired esotropia showed directional anisotropy similar to that in the IE group.

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 oculomotor control and motion perception in IE reflect a common disruption of the visual system. A similar variation of directional sensitivity 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.