Hyperopic refractive errors as a prognostic factor in intermittent exotropia surgery

Purpose To evaluate and compare surgical outcomes with respect to refractive errors in strabismus surgery for the treatment of intermittent exotropia (IXT). Methods The medical records of patients with IXT who were treated by one surgeon from January 2005 and June 2011 were reviewed. Three hundred and thirty-three IXT patients were included and divided into three groups according to preoperative refractive error: IXT with hyperopia (group I), IXT with emmetropia (group II), and IXT with myopia (group III). The surgical outcomes with respect to sensory and motor criteria were compared among the three groups. Results The surgical success rates according to motor criteria and sensory and motor criteria combined were higher in groups I (29 patients) and III (124 patients) than in group II (180 patients) at postoperative 3 and 6 months and at the last follow-up. Stereopsis was significantly better in groups II and III than in group I preoperatively (P=0.002 by one-way analysis of variance test); however, the difference was not significant postoperatively. Twenty patients in group I (69.0%) were prescribed undercorrected hyperopic spectacles postoperatively, while only 22 patients in group III (17.7%) were prescribed spectacles with more myopic power than their refractive errors. Conclusion In the surgical treatment of IXT, hyperopia was not an indicator of poor prognosis. Taking into consideration the age effect, follow-up period after IXT surgery, and stereopsis improvement, hyperopic refractive error is rather a good prognostic factor.