Risk factors for consecutive exotropia after esotropia surgery

To evaluate the risk factors in development of postoperative exotropia following bilateral medial rectus (BMR) recession for esotropia. 108 patients who underwent BMR recession for esotropia between November 1996 and July 2010 were enrolled. 54 patients who required surgery for consecutive exotropia were compared to 54 controls whose angle of deviation showed less than five prism diopters of esotropia at all periods after BMR recession. Amblyopia, dissociated vertical deviation (DVD), refractive error, inferior oblique overaction, and multiple surgery history were evaluated as risk factors for the development of consecutive exotropia. The postoperative changes of angle of deviation were calculated. Amblyopia was found in 27 patients (50.5 %) in the exotropia group, and in six patients (11.1 %) in the control group (P < 0.001) before esotropia surgery. DVD was detected in 16 (29.06 %) patients in the exotropia group as compared to 4 (7.4 %) in the control group (P = 0.003). With logistic regression analysis, the odds ratio of DVD was 5.27 (95 % CI 1.63-17.03; P = 0.006) and of amblyopia, 8.00 (95 % CI 2.94-21.80; P < 0.001). There were no significant differences between the two groups with regards to the pre-operative deviation, follow up periods, degree of hyperopia, presence of anisometropia or inferior oblique overaction, and history of multiple surgery. Using linear mixed model analysis, the exotropic shift across time was higher in the consecutive exotropia group relative to the controls (P < 0.001). The presence of amblyopia before esotropia surgery and DVD correlated with risk of consecutive exotropia.