Predictive Factors Affecting the Short Term and Long Term Exodrift in Patients with Intermittent Exotropia after Bilateral Rectus Muscle Recession and Its Effect on Surgical Outcome

Abstract

Purpose. To determine the predictive factors that affect short term and long term postoperative drift in intermittent exotropia after bilateral lateral rectus recession and to evaluate its effect on surgical outcome.Methods. Retrospective review of 203 patients with diagnosis of intermittent exotropia, who had surgical corrections with more than 3 years of followup. Different preoperative parameters were obtained and evaluated using Pearson’s correlation analysis.Results. The proportion of exodrift increased from 62% at 6 weeks to 84% at 3 years postoperatively. The postoperative drift was4.3±8.1 PD at 6 weeks,5.8±8.4 PD at 6 months,7.2 ± 8.3 PD at 1 year,7.4 ± 8.4 PD at 2 years, and7.7 ± 8.5 PD at 3 years. Preoperative deviation and initial overcorrection were significant factors affecting the postoperative drift at 3 years (r=0.177,P=0.011,r=-0.349, andP<0.001, resp.).Conclusions. Postoperative exodrift along three years occurs in a majority of patients after bilateral lateral rectus recession for intermittent exotropia. The long term surgical success is significantly affected by this postoperative exodrift. A larger preoperative deviation and a larger initial overcorrection are associated with a larger early and late postoperative exodrift.