Unilateral versus bilateral lateral rectus recession for correction of small to moderate angle exotropia.

Purpose: To compare the effect of unilateral versus bilateral lateral rectus (LR) recession for correction of small to moderate exotropia.

Methods: Records of all patients with exotropia 14-35 prism diopters (∆), operated upon by the authors, were included in a retrospective study to compare the effect of unilateral (Group 1) versus bilateral (Group 2) LR recession. The study end-point was the last follow-up visit scheduled at least 3 months postoperatively. A successful outcome was defined as 0-10∆ of horizontal tropia.

Results: The study included 154 patients (47 in Group 1 and 107 in Group 2). Patients were followed up for 3-120 months (26.7 ± 24.88). A successful outcome was achieved in 83% in Group 1 and 82.2% in Group 2 (p = .976), with higher success in group 1 for surgical target angles up to 25∆. All failures in Group 1 were due to undercorrections., while the 17.8% failure rate in Group 2 comprised 15% undercorrections and 2.8% overcorrections (p = .419). Persistent lateral incomitance was seen in 29.5% in Group 1 versus 2.3% in Groups 2 (p < .001). Lateral incomitance was encountered in 71% of those undergoing 10 mm unilateral recessions, versus 20% of those who had smaller recession doses. Limited ductions were mild, and exceeded -1 in only 4 cases: 3 had had 10 mm and 1 had had 9 mm unilateral LR recession.

Conclusions: Unilateral and bilateral LR recessions offer essentially equal success rates. Unilateral recessions are advised for angles up to 25∆, without exceeding 10 mm.