Treatment of Unilateral Exotropia by Part-Time Occlusion

Exotropia has been treated by different means including orthoptics, early surgery, mild cycloplegia, myopic overcorrection, prisms and observation. In a previous series we investigated the effect of part-time occlusion on non-alternating exotropia in children, and found it to be effective. We then decided to study this technique in a group of patients which included older children.Eleven patients (17 months to 13 years) were studied. All had exotropia of predominantly one eye which was intermittent or constant on distant gaze. No patient had constant exotropia on near fixation. Visual acuity was either equal or showed a difference of only one line between the two eyes. Treatment consisted of part-time patching of the non-deviating eye from 4 to 8 hours a day and tapered as appropriate. Part-time occlusion was reinstated if exotropia recurred after conversion to a phoria.With occlusion, all patients converted to a phoria at least temporarily. Mean follow-up (to last visit) was 9 months (range 1.5 to 33 months). Four patients (36%) maintain good control and a phoria at distance without occlusion. Six still continue part-time occlusion and one is scheduled for surgery since the exo deviation on distance gaze is not adequately controlled.Part-time occlusion for patients with predominantly unilateral exo deviations at distance can postpone surgical intervention and convert the tropia to a phoria. This gives the patient more time to establish better binocularity and gives the ophthalmologist and the patient's family an opportunity to assess the situation in this often frustrating strabismus entity.