The Surgical Outcome of Intermittent Exotropia with Type Conversion Subsequent to Preoperative Part-Time Occlusion Therapy

ABSTRACT

PURPOSE: To evaluate the effects of converted intermittent exotropia type with part-time occlusion therapy on final postoperative outcomes. METHODS: The present study included 140 consecutive intermittent exotropia patients. On the patient's first visit, the type of intermittent exotropia was determined according to the deviation angle. After preoperative part-time occlusion therapy, the type of intermittent exotropia was reevaluated. The surgical success rates of each group was compared retrospectively according to the converted type. RESULTS: At the first visit, the basic type was the most prevalent (n = 112), followed by convergence insufficiency type (n = 18) and pseudo-divergence excess type (n = 10). Mean deviation angle on the first visit was 25.42 +/- 6.05 PD at distance and 26.19 +/- 8.20 PD at near. There were significant changes in near deviation angle after part-time occlusion in patients with the basic and convergence insufficiency types (p = 0.045, 0.03, respectively). Twenty-seven patients who had converted from basic type to pseudo-divergence excess type and from convergence insufficiency type to basic type showed better surgical success rate (89%) than other patients (69%) (p = 0.033). CONCLUSIONS: Part-time occlusion therapy converts the type of intermittent exotropia by reducing near deviation angle and is related to a better surgical success rate.