Is single-stage two-muscle surgery of 7-11 mm enough for large-angle exotropia?

Purpose: To report the effectiveness of single-stage two-muscle surgery of 7-11 mm in patients with large-angle exotropia.

Methods: A retrospective analysis of 34 patients with a large-angle comitant exodeviation was conducted. Patients were classified as severe (group 1) if the average deviation was ≥ 50 prism diopters (PD) and moderate (group 2) if their deviation ranged from 30 to 49 PD. A successful outcome of surgery was defined as deviation within 12 PD of orthophoria/tropia for both distance and near.

Results: The mean exodeviation was 49.5 ± 11.6 (range, 30-85) PD at distance and 50.3 ± 13.5 (range, 18-85) PD at near preoperatively. All patients underwent a recess/resect procedure. At the last visit, 25 (71%) of 34 patients in the entire group achieved successful alignment; it was higher in group 2 (81%) than in group 1 (67%); but the difference was not statistically significant (p = 0.45). Twelve patients had very poor vision (≤ counting fingers at 1 m) in one eye with a success rate of 83% in the short-term. Two patients had minimal asymmetrical abduction deficit and no patients reported permanent diplopia at the final postoperative evaluation.

Conclusion: Large-angle exodeviations can be successfully corrected with a two-muscle surgical procedure without causing significant abduction deficiency. This choice has the advantage of 2 horizontal rectus muscles remaining untouched.