Comparative Study of Unilateral and Bilateral Surgery in Moderate Exotropia

Purpose: To evaluate the surgical outcome of unilateral versus bilateral rectus recession for the correction of moderate exotropia. Methods: This was a prospective study of 20 consecutive cases of intermittent exotropia ranging from 15 to 25 prism diopters (PD) randomized into two groups and operated on by a single surgeon. In the unilateral group, a recession of 7.0 to 7.5 and 8.0 to 8.5 was done for 15 to 20 PD and 21 to 25 PD of exotropia, respectively. In the bilateral group, a recession of 5.0 to 5.5 and 6.0 to 6.5 mm was done for 15 to 20 PD and 21 to 25 PD of exotropia, respectively. Surgical results of both groups were compared 3 months postoperatively. Results: The mean age of patients was 8.5 years in the unilateral group and 11 years in the bilateral group. The mean preoperative exotropia was 21.0 +/- 3.77 PD in the unilateral group and 22.9 +/- 3.03 PD in the bilateral group. The mean postoperative deviation at 3 months was 5.5 +/- 4.03 PD in the unilateral group and 2.8 +/- 3.91 PD in the bilateral group. Consecutive persistent small-angle esotropia was seen in one patient in the bilateral group. There was no significant incomitance at 3 months in either group. Conclusion: Unilateral and bilateral rectus recession are equally effective in mild to moderate exotropia.