The use of part-time occlusion for early onset unilateral exotropia.

Eleven patients (9 months to 5 years of age) with intermittent or constant exotropia of predominantly one eye on distant gaze were studied to investigate the effect of part-time occlusion. No patient had constant exotropia on near fixation. Visual acuity was found to be equal in both eyes. All patients were treated by part-time patching of the non-deviating eye from four to six hours a day and tapered as appropriate. If exotropia recurred after conversion to a heterophoria, part-time occlusion was reinstated. With occlusion, all patients converted to hetero- or orthophoria, at least temporarily. Mean follow-up (to last visit or surgical intervention) was 22 months (range 3 to 37 months). Three patients (27%) later developed constant exotropia (mean 28.3 months after beginning occlusion) and underwent surgery. Three patients (27%) became and remain orthophoric without further patching. Part-time occlusion for preschool patients with exodeviations that are predominantly unilateral can postpone surgical intervention and convert exotropia to orthophoria or exophoria.