To evaluate the effects of converted intermittent exotropia type with part-time occlusion therapy on final postoperative outcomes.

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.

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).

Part-time occlusion therapy converts the type of intermittent exotropia by reducing near deviation angle and is related to a better surgical success rate.