Comparison of long-term surgical outcomes of 2-muscle surgery in intermittent exotropia: Bilateral vs Unilateral

Purpose To compare long-term surgical outcomes after bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession-medial rectus resection (RR) for the treatment of intermittent exotropia. Methods Consecutive patients who underwent BLR or RR for treatment of intermittent exotropia between 1999 and 2010 and had ≥ 5 years’ follow-up were recruited. Surgical outcomes were grouped according to postoperative angle of deviation as overcorrection (esophoria/tropia>5△), success (esophoria/tropia ≤5△ to exophoria/tropia≤10△), or undercorrection/recurrence (exophoria/tropia>10△), and were compared between the BLR group and the RR group at postoperative 1 week, 1 month, 6 months, 1 year, 2 years, 3 years, 4 years, 5 years, and at the final examination. Results Of 99 patients, 37 underwent BLR and 62 underwent RR. The mean follow-up period was 99.6 months in the BLR group and 96.2 months in the RR group. At 1 week, 6 months, 1 year, 2 years, 3 years, 4 years, 5 years and at the final examination the surgical outcomes in each group were not different (p > 0.05). The surgical success rate was 44.6% in the BLR group and 45.0% in the RR group (p = 0.27). The re-operation rate was 29.7% in the BLR group and 40.3% in the RR group (p = 0.67). Conclusions Surgical outcomes by 5 years after surgery for intermittent exotropia were comparable between the BLR and RR groups. The surgical success rate and the re-operation rate were not different between the BLR and RR groups.