Comparison of Surgical Outcomes of Two-muscle Surgery in Children with Large-angle Intermittent Exotropia

Purpose: To evaluate the long-term results of 2-muscle surgery in children with large-angle intermittent exotropia (IXT), comparing bilateral lateral rectus recession (BLR) with unilateral lateral rectus recession & medial rectus resection (RR). Methods: Ninety-two children with IXT of 40 prism diopter or more, who underwent BLR or RR were included in this retrospective study. Final successful alignment rates, and cumulative probabilities of surgical success at 3 years postoperatively were analyzed and compared using Kaplan-Meier survival analysis between the two groups. Results: At 3 years after surgery, 37 (67.3%) of 55 patients in the BLR group achieved successful alignment; 18 (32.7%) had undercorrection, and none of them had overcorrection. In the RR group, 34 (92%) of 37 patients were successfully aligned, two (5%) had undercorrection, and one (3%) had an overcorrection at 3 years after surgery. There was a statistically significant difference in postoperative results between the two groups ( p = 0.0012). The cumulative probabilities of surgical success at 3 years postoperatively analyzed using the Kaplan-Meier survival curve were 63% in the BLR group and 92% in the RR group. Postoperative mean recurrence time was 45 months in the BLR group and 50 months in the RR group, showing a significant difference between the two groups ( p = 0.0006). Conclusions: The unilateral RR procedure demonstrated more favorable long-term postoperative outcomes than BLR procedure in patients with large-angle IXT.