The optokinetic uncover test: a new insight into infantile esotropia.

IMPORTANCE We devised the optokinetic uncover test to examine the role of peripheral retinal motion input in generating horizontal optokinetic responses in patients with infantile strabismus. OBJECTIVE To ascertain whether subcortical visual input contributes to the asymmetrical monocular optokinetic responses that characterize infantile esotropia. DESIGN AND SETTING Observational study in an academic research setting. PARTICIPANTS Ten patients with infantile esotropia. INTERVENTION Optokinetic uncover test. MAIN OUTCOME MEASURES Optokinetic testing was performed in 7 patients with isolated infantile esotropia (5 untreated and 2 previously treated) and in 3 patients with infantile esotropia syndrome associated with mild neurological disease. RESULTS All patients showed poor temporally directed optokinetic responses that instantaneously improved when the occluded esodeviated eye was uncovered, exposing it to nasally directed optokinetic motion. This improvement in optokinetic responses did not necessitate a fixation shift to the contralateral eye. CONCLUSIONS AND RELEVANCE Nasally directed optokinetic input to the esodeviated eye can supplement temporal monocular optokinetic responses in the fixating eye under binocular conditions. This nonfoveal optokinetic contribution suggests that monocular nasotemporal optokinetic asymmetry is partly attributable to subcortical visuovestibular responses mediated by nonfoveal retina.