Factors insuencing the outcome of intermittent exotropia surgery

Objective: This study aims at the evaluation of factors influencing the outcome of intermittent exotropia surgery. Material and Methods: Sixty-seven patients with intermittent exotropia were included. The patient files were retrospectively evaluated for the factors influencing the postoperative outcome. Among these evaluated factors are age, the age at onset of strabismus, type of deviation (convergence insufficiency, divergence excess or simple exotropia), age at operation, amount of preoperative misalignment, the time between the age of onset of deviation and age at operation, the refraction defect, presence of anisometropia or amblyopia and A-V pattern, hyperfunction of oblique muscles, binocular single vision and amount resection and recession. The outcome was assigned as successful operation (ortophoric or residual deviation below 10 pd) and unsuccessful operation (residual deviation above 10 pd). Results: Mean age of onset of deviation was 4.46 +/- 3.94 (min:0, max:15) and mean age at operation was 21.14 +/- 12.13 (min:2, max:47). At the last visit of their follow-up 42 patients (62.7%) were assigned as successful operation whereas 25 patients (37.3%) were as unsuccessful. There was no significant relation between the age at onset of strabismus, type of deviation, age at operation, the time between the age of onset of deviation and age at operation, the refraction defect, presence of amblyopia and A-V pattern, oblique muscle dysfunction and binocular single vision with postoperative outcome (p=0.121). Operational success was better for the patients without anisometropia (p=0.042). There was a negative relation between the exchanged muscle amount and the success (p=0.012). The success rate was lower as the amount of exchanged muscles elevated. Conclusion: It has been found that the most important factors influencing the outcome of strabismus surgery are the presence of anisometropia and the amount of preoperative deviation.