Risk factors analysis of consecutive exotropia: Oblique muscle overaction may play an important role

To evaluate clinical factors associated with the onset of consecutive exotropia (XT) following esotropia surgery. By a retrospective nested case-control design, we reviewed the medical records of 193 patients who had undergone initial esotropia surgery between 2008 and 2015, and had follow-up longer than 6 months. The probable risk factors were evaluated between groups 1 (consecutive XT) and 2 (non-consecutive exotropia). Pearson chi-square test and Mann–Whitney U test were used for univariate analysis, and conditional logistic regression model was applied for exploring the potential risk factors of consecutive XT. Consecutive exotropia occurred in 23 (11.9%) of 193 patients. Patients who had undergone large bilateral medial rectus recession (BMR) (P = 0.017) had a high risk of developing consecutive XT. Oblique dysfunction (P = 0.001), adduction limitation (P = 0.000) were associated with a high risk of consecutive XT, which was confirmed in the conditional logistic regression analysis. In addition, large amount of BMR (6 mm or more) was associated with higher incidence of adduction limitation (P = 0.045). The surgical methods and preoperative factors did not appear to influence the risk of developing consecutive XT (P > 0.05). The amount of surgery could be optimized to reduce the risk of consecutive XT. The presence of oblique overaction and postoperative adduction limitation may be associated with a high risk of consecutive XT, which may require close supervision, and/or even earlier operation intervention.