The Relationship between Velocity of Early Exotropic Drift and Recurrence

1. Ja Young Lee
2. Moon Sun Jung
3. So Young Kim

Soonchunhyang University Cheonan Hospital, Cheonan, Korea

Purpose: To evaluate the relationship between velocity of early exotropic drift and recurrence after surgical correction of intermittent exotropia.

Methods: The alignments of 133 patients with surgical correction of intermittent exotropia were retrospectively reviewed pre- and post-operation at the following time periods: postoperative 1 week, 1, 3, 6, and 12 months. More specifically, we measured the monthly change of alignment velocity(Δ) from postoperative 1 month to 12 months in patients who demonstrated tendencies of exotropic drift. Furthermore, we analyzed the correlation between each data and the total velocity (1 week to 12months). We divided 3 groups according to angle deviation at postoperative 1 week and analyzed the effect on motor success rates at postoperative 12 months.

Results & Conclusions: 121 patients (90.98%) exhibited to exotropic drift tendencies. The mean postoperative monthly change of alignment velocities were as follows: 1 week-1month, 3.60±4.56PD; 1-3months, 0.43±1.69PD; 3-6months, 0.12±0.66PD; 6-12 months, 0.17±0.51PD; and 1 week-12month, 0.49±0.56PD. Each time point was correlated with the total velocity (1 week to 12months), with postoperative 1 month showing the highest correlation (Pearson, r=0.60, p<0.01). There were no significant differences in motor success rates between groups that were divided according to the velocity of early exotropic drift (Fisher's Exact, p=0.08), except among patients with exotropia at immediate post-operation (Mann-Whitney, p=0.03). The velocity of exotropic drift at early postoperative 1 month best reflected the total velocity, but could not influence the recurrence rate. However, patients with exotropia and high exotropic drift velocities may develop a greater likelihood of recurrence.