Postoperative minimal overcorrection in the surgical management of intermittent exotropia

Purpose To investigate the effect of initial postoperative minimal overcorrection on the result of the surgical management of intermittent exotropia based on long-term follow-up results. Methods 111 patients who underwent surgery for intermittent exotropia and were followed up for at least 5 years after surgery were retrospectively reviewed. The outcome was judged to be successful when there was 10 prism dioptres (PD) or less of exodeviation and less than 5 PD of esodeviation without any reoperation at the final follow-up visit. We evaluated the success, recurrence, overcorrection rate and the duration of diplopia according to their initial deviation. Results We divided patients into four groups based on their initial deviation: orthophoria or undercorrection (Ortho group, 31 patients), minimally overcorrected at 5 PD or less (MO group, 20 patients), usually overcorrected between 6 PD and 10 PD (UO group, 35 patients), and highly overcorrected at more than 10 PD (HO group, 25 patients). The success rate was 43-60% between the four groups (p=0.52). The recurrence rate was 28-57% (p=0.105), but post hoc analysis showed borderline p values between the Ortho and HO group (p=0.024). No overcorrection was noted in the Ortho and MO groups (p=0.04). The duration of diplopia was 0-2.5 weeks, showing statistically significant difference among groups (p<0.001). Conclusions The amount of initial postoperative overcorrection may not predict the long-term success rate. However, the MO group showed a lower recurrence rate than the Ortho group and also showed no overcorrection and a shorter duration of postoperative diplopia than the UO and HO groups.