Surgical Outcomes of Unilateral One-muscle Surgery in Basic Intermittent Exotropia with Larger Near Deviation

Purpose: To compare the postoperative changes between unilateral medial rectus resection and lateral rectus recession and evaluate surgical outcomes of unilateral one-muscle surgery in basic intermittent exotropia under 25 prism diopters (PD) with a larger near than distance deviation.Methods: This study was conducted on patients with basic intermittent exotropia under 25 PD and a larger near than distance deviation. A retrospective analysis was conducted on 23 patients who underwent unilateral medial rectus resection (Group 1) and 32 patients who underwent unilateral lateral rectus recession (Group 2) as primary surgery. The angle of deviation at near and distance was measured at 1 week, 1 month, 3 months, 6 months, and 1 year postoperatively. Surgical success was defined as within 4 PD of esophoria or 10 PD of exophoria at 1 year after surgery.Results: The mean preoperative deviation angle was 20.18 ± 2.55 PD for Group 1 and 19.30 ± 2.77 PD for Group 2, while the mean near-distance disparity was 6.83 ± 2.67 PD for Group 1 and 5.18 ± 1.56 PD for Group 2. At 1 year postoperatively, the mean distance deviation angle was 9.43 ± 5.82 PD for Group 1 and 5.94 ± 6.49 PD for Group 2. The mean near-distance disparity at 1 year was 0.91 ± 3.96 PD for Group 1 and 0.81 ± 2.07 PD for Group 2. The success rates at 1 year were 65.2% for Group 1 and 72.7% for Group 2 (<i>p</i> = 0.362). Both groups showed effective reductions in the postoperative angle of deviation and near-distance disparity with no significant difference between the groups.Conclusions: Unilateral medial rectus resection and lateral rectus recession both effectively manage basic intermittent exotropia under 25 PD with larger near than distance deviation as the primary surgery.