Effect of Unilateral Lateral Rectus Recession for Intermittent Exotropia under 25 PD

ABSTRACT

PURPOSE: To investigate the surgical outcome of unilateral lateral rectus recesssion in the treatment of intermittent exotropia under 25 prism diopter (PD). METHODS: The 62 patients who had underwent unilateral lateral rectus recession and followed up for 6 months or larger, were reviewed. Following inferotemporal fornix incision, 8.5 mm or 9.5 mm recession from the insertion of lateral rectus was performed in 20 PD or in 25 PD intermittent exotropia respectively. RESULTS: Mean age of patients was 8.8 years (5-14 years) and follow up time was 11.5 months (6-34 months) on average. Postoperative deviation and success rate were as followings -0.2+/-2.1 PD, 91.9% at postoperative 1 day, 0.5+/-2.3 PD, 95.2% at postoperative 1 week, 2.5+/-3.9 PD, 96.8% at postoperative 1 month, 3.7+/-5.0 PD, 91.9% at postoperative 6 month and 4.3+/-5.5 PD, 85.7% at postoperative 1 year. The average divergent shift was 4.5 PD during whole examination period and this shift showed significant change during same period (Repeated measures, p=0.000). The occurrence rate of undercorrection was 1.6% at postoperative 1 week, 3.2% at postoperative 1 month, 8.1% at postoperative 6 month and 14.3% at postoperative 1 year. The occurrence rate of overcorrection was 8.1% at postoperative 1 day and 3.2% at postoperative 1 week. All cases of overcorrection were orthophoric after postoperative 1 month. The limitation of abduction was not discovered in all cases at postoperative 1 year. CONCLUSIONS: Unilateral recession of lateral rectus is an effective method in the treatment of intermittent exotropia under 25 PD. However long term follow up should be considered since undercorrection seems to be increasing.