Results of large (8-9 mm) bilateral lateral rectus muscle recessions for exotropia

Commonly recommended maximum lateral rectus muscle recession for exotropia ranges from as little as 7 mm to as much as 11 mm. Published studies on recessions of 8 mm or more are scarce. Many ophthalmic surgeons still avoid recessions larger than 7 mm because of the fear of creating abduction deficits and surgical overcorrections. Therefore, we sought to determine the incidence of clinically detectable abduction deficits and their correlation with early surgical overcorrection in exotropic patients who had undergone large 8 to 9 mm lateral rectus muscle recessions.

A retrospective chart review identified 30 patients with exotropia ranging from 35delta to 65delta who were treated with 8 to 9 mm recessions of both lateral rectus muscles. Patients with concurrent oblique muscle surgery were included. Mean followup time was 15 months (range 3-30 mos).

Twenty-four patients (80%) required only one operation. The remaining 6 patients (20%) required a second operation, four for overcorrection and two for undercorrection. Nine patients (30%) had mild but persistent abduction deficits postoperatively. However, abduction deficits were not predictive of poor outcome (p=0.959). Other variables that did not significantly affect outcome included age (p=0.894), systemic anomalies (p=0.127), size of preoperative exotropia (p=0.987) and amount of rectus muscle recession (p=0.480). However, concurrent oblique muscle surgery was associated with a higher risk of a poor result.

8-9 mm lateral rectus recessions are not associated with a poor outcome, except in association with concurrent oblique muscle surgery.