Comparison between 20 and 25 Prism Diopters in Bilateral Rectus Muscle Recession for Intermittent Exotropia

ABSTRACT

PURPOSE: To compare the outcomes of bilateral lateral rectus recession between 20 and 25 prism diopters (PD) for intermittent exotropia. METHODS: A retrospective study was performed with a total of 584 patients who underwent surgery for intermittent exotropia and were followed up for more than 12 months. The patients were classified into either the 20 PD group (5 mm bilateral rectus muscle recession [BLR]) or the 25 PD group (6 mm BLR). Successful postoperative motor alignment was defined as within 10 PD of exotropia and 4 PD of esotropia. RESULTS: Cumulative probabilities of surgical success rates for 24 months were 77.9% in the 20 PD group and 54.8% in the 25 PD group, respectively (p < 0.001). Postoperative deviations in recurrence patients were 13.41 +/- 3.64 PD and 14.66 +/- 3.87 PD (p = 0.062) at postoperative 12 months. CONCLUSIONS: All patients with relatively small angle of exodeviation such as 20 PD had a higher success rate and small postoperative exodaviation at 12 months. Therefore, surgery could be considered when the eye is exodeviated with a relatively small angle. However, in the group with the exotropic drift, approximately 2/3 of the preoperative angle of deviation is measured with similar outcomes between preoperative and postoperative angles of deviation.