The Effects of Part-Time Occlusion Therapy Shortened to One or Two Hours in Intermittent Exotropia

ABSTRACT

PURPOSE: To evaluate the compliance level of therapy and the change in exo-angle after 1 or 2 hours of part-time occlusion therapy in intermittent exotropia. METHODS: This retrospective study included 97 patients with intermittent exotropia who were followed-up for more than 6 months after their initial visit. We evaluated the exo-angle and prescribed either 1 hour or 2 hours of part-time occlusion therapy for the fixating eye. After 6 months, the exo-angle was reevaluated and compliance was examined. Patients were divided into 2 groups according to the occlusion therapy time the 1-hour patching group (33 patients) and the 2-hour patching group (64 patients). Compliance and deviation angle were retrospectively reviewed and compared between the 2 groups. We evaluated the exo-angle of patients with compliance over 50% (1-hour patching group (31 patients), 2-hour patching group (51 patients)). RESULTS: The mean exo-angles on the first visit were 22.61 +/- 5.78 PD (prism diopters) at distance and 22.88 +/- 8.11 PD at close-range in the 1-hour patching group, and 26.17 +/- 4.55 PD at distance and 25.27 +/- 8.54 PD at close-range in the 2-hour patching group. The proportion of patients with compliance over 50% was higher in the 1-hour patching group (93.94%) than in the 2-hour patching group (79.69%, p = 0.013). There were significant decreases in distant and close- range deviation angles after part-time occlusion in patients with compliance over 50% in both groups (1-hour patching group distant p = 0.042, close-range p = 0.002; 2-hour patching group distant p < 0.001, close-range p < 0.001). The magnitude of deviation angle decrease was not statistically significant between the 2 groups (ANCOVA; distant p = 0.461, near p = 0.761). CONCLUSIONS: One or 2 hours of part-time occlusion therapy in intermittent exotropia provided beneficial effects, including decreasing the deviation angle. The magnitude of deviation angle decrease, however, was not different between the 2 times of therapy. Compliance was higher in the 1-hour part-time occlusion therapy group. Therefore, 1-hour part-time occlusion therapy could be effective in patients with poor cooperation.