SUPPRESSION OF FIXATIONAL SACCADES IN STRABISMIC AND ANISOMETROPIC AMBLYOPIA

Individuals with strabismus frequently exhibit large fixational saccadic pairs (saccadic intrusions) during monocular fixation with the amblyopic eye in the light. We found two conditions in which the saccadic intrusion frequency could be markedly reduced. When instructed to ‘hold the eye steady’ in the presence of a visible target in the light, saccadic intrusions were suppressed and eye position maintained within a few degrees of the target. These results suggest that corrective drift was used by the amblyopic eye to aid in position maintenance. When instructed to ‘fixate’ in complete darkness, the intrusive pattern was replaced by a jerk nystagmus-like pattern. These results clearly demonstrate that saccadic intrusions in amblyopic eyes require the presence of a visible target for their generation, and additionally, that ‘extraretinal signals’ were involved in maintenance of eye position under this condition. Saccades could also be suppressed during the ‘hold’ command in the light by patients having amblyopia without strabismus or constant strabismus amblyopia with intermittent jerk nystagmus. © 1979 S. Karger AG, Basel.