Background: To investigate the incidence of and factors predisposing to consecutive esotropia after intermittent exotropia surgery, and to prevent the onset of consecutive esotropia.
Methods: We retrospectively surveyed 226 patients who had been followed up for more than 1 year after surgery for intermittent exotropia conducted between February 2005 and September 2010. Consecutive esotropia was defined as an esotropia of at least 10 prism diopters (PD) at distance or near at least once in 2 weeks after surgery. Presumed risk factors for consecutive esotropia were analyzed. Gender, age at surgery, average binocular spherical equivalent, anisometropia, high myopia, amblyopia, preoperative angle of deviation, vertical deviation, A-V pattern strabismus, exotropia type, type of surgery, stereopsis, and suppression were investigated to evaluate factors influencing the onset of consecutive esotropia.
Results: Consecutive esotropia occurred in 22 patients (9.7 %). Significant correlations with occurrence of the condition were found with high myopia (P = 0.013), amblyopia (P = 0.047), preoperative angle of deviation of 25-40 PD at distance (P = 0.016), deviation at distance - deviation at near > 10 PD (P = 0.041), lateral incomitance (P = 0.007), tenacious proximal convergence fusion type (P = 0.001), unilateral lateral rectus muscle recession and medial rectus muscle resection (P = 0.001).
Conclusions: High myopia, amblyopia, and lateral incomitance were predisposing factors for consecutive esotropia. Furthermore, the preoperative angle of deviation at distance, differences between the angle of deviation at near and at distance, the type of intermittent exotropia, and the type of surgery affected the incidence of consecutive esotropia. More attention must be paid to patients with such factors.