Risk factors associated with poor outcome after medial rectus resection for recurrent intermittent exotropia

Purpose To describe characteristics of recurrent intermittent exotropia after bilateral lateral rectus (BLR) recession, and identify factors associated with poor outcome after unilateral medial rectus (MR) resection for recurrent intermittent exotropia. Methods We retrospectively reviewed 124 patients who have undergone unilateral MR resection for recurrent intermittent exotropia after BLR recession. Patients were followed for at least 2 years after MR resection. Clinical characteristics and risk factors associated with poor outcome after unilateral MR resection were evaluated. Successful outcome was defined as distant deviation within the range of 4 prism diopters (PD) esotropia and 10 PD exotropia at last visit after MR resection. Results Among 124 patients, 50 patients (41.1%) were male, and the mean age at the time of MR resection was 9.5 +/- 3.1 years. The average follow-up period after MR resection was 43.8 +/- 23.7 months. Forty-seven patients (37.9%) were classified to have poor outcome at last visit, and 29 patients (23.4%) underwent third operation. None of the patients was overcorrected after MR resection. Multiple logistic regression analyses showed that distant deviation at post-operative 3 months and male gender were associated with poor outcome (OR 1.49; 95% CI 1.27-1.73; P < 0.001, and OR 5.19; 95% CI 1.42-18.98; P = 0.013, respectively). Conclusion Ocular deviation at 3 months after unilateral MR resection for recurrent intermittent exotropia may play a valuable role in anticipating poor outcome. Patients whose exotropia exceeded 9 PD at distance at 3 months' follow-up tended to recur while those whose exotropia remained below 9 PD at distance showed a stable disease course.