Cyclopean and disconjugate adaptive recovery from post-saccadic drift in strabismic children before and after surgery

Post-saccadic drift has been analyzed in strabismic children 11-18 yr old, before and after surgery. Before surgery all the subjects had a large multi-component post-saccadic drift. A disconjugate compensation of the drift was not active, but an optimized cyclopean compensation occurred, aimed at minimizing the drift size in both eyes, either with binocular or monocular vision. The drift was directed toward the static offset of the eyes. One week after surgery the drift increased in most cases but the cyclopean compensation still occurred. One week later, a partial disconjugate compensation decreased the drift to levels lower than before surgery. In one subject surgery produced very big three-component drift, exceeding 20 deg. One year after the drift was decreased to < 1 deg. A mathematical model is presented accounting for most of the results.