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 was 4.3 ± 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, and 7.7 ± 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, and P < 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.
Highlights
Intermittent exotropia is the most common form of childhood exotropia [1]
We identified 203 patients with intermittent exotropia who had operations done from 1993 to 2008, with a minimal postoperative followup of three years
One hundred and seventy-eight (87.3%), twenty (9.8%), and five (2.5%) of them were classified as basic type, simulated divergence excess type, and true divergence excess type intermittent exotropia, respectively, according to the Burian classification [9]
Summary
Intermittent exotropia is the most common form of childhood exotropia [1]. Some patients progress into constant exodeviation, while others remain stable or improve; the natural history of this disorder remains obscure [2,3,4]. Patients with intermittent exotropia tend to develop an exotropic drift following surgical correction over time [5]. Because of this exotropic drift, many authors suggested an initial overcorrection for intermittent exotropia may be required for better long term motor alignment. Other authors suggested that initial overcorrection cannot inhibit the long term recurrence [8]
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