Surgical outcomes of symmetric and asymmetric surgery for intermittent exotropia with postoperative large early overcorrection

To compare surgical outcomes between bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession-medial rectus resection (RR) for intermittent exotropia with overcorrection of 20 prism diopter (PD) or more on postoperative day 1. A retrospective chart review identified 319 patients who underwent either BLR or RR for primary surgical treatment of intermittent exotropia between July 2008 and June 2011. The patients with basic type intermittent exotropia and overcorrection of 20 PD or more, at either near or distance, on postoperative day 1 and had more than 6 months of follow-up were included. Patients with simultaneous vertical and/or oblique muscle surgery and those with paralytic or restrictive strabismus were excluded. The pre- and post-operative deviation, visual acuity, and near stereoacuity were analyzed. Twenty-four patients were included. The mean postoperative day 1 alignment was 21.5 +/- A 6.2 PD esotropia at distance, and 13.8 +/- A 8.0 PD at near. Fourteen patients underwent BLR and 10 underwent RR. Three patients were wearing the base out prism below 15 PD at the last follow-up. The mean duration from the surgery to esotropia below 10 PD was 2.9 +/- A 1.1 weeks and 8.0 +/- A 7.1 weeks in the BLR and RR groups, respectively (p = 0.030). All three recurrent patients underwent RR. None of the patients completely lost stereoacuity, postoperatively. In basic type intermittent exotropia with overcorrection of 20 PD or more on postoperative day 1, the overcorrection resolved faster and recurrence rates were lower in BLR group than in the RR group. Consecutive esotropia over 15 PD did not occur in both groups.