Long-term Surgical Outcomes of Initial Postoperative Overcorrection in Adults with Intermittent Exotropia

To evaluate the relationship between initial postoperative overcorrection and long-term surgical success in exotropia patients.

The medical records of 46 patients who underwent surgery for intermittent exotropia after the age of 18 were enrolled. Enrolled patients also had at least 2 years of postoperative follow-up. Based on the initial postoperative deviation at distance measured by prism and the alternating cover test at 1 week, patients were assigned to one of the following groups: group A included patients who demonstrated any esodeviation, while group B included patients who showed orthophoria to exodeviation of 10 prism diopters. The records were analyzed to determine the preoperative deviation with stereoacuity and postoperative deviations with stereoacuity at the follow-up examinations at the following intervals: 1 week; 1, 3, and 6 months; and 1 and 2 years. A comparison between groups for demographic data and preoperative and postoperative angles of deviation was performed using analysis of variance.

Of the 46 patients with intermittent exotropia included in this study, 18 (39%) belonged to group A, while 28 (73%) belonged to group B. The postoperative angle of deviation for distant fixation until 2 years of follow-up showed statistically significant differences in each group (p < 0.003 in all comparisons). The amount of exodrift until 2 years in group A (from ?9.7 ± 6.1 to 1.6 ± 3.7) was greater than that in group B (from 2.0 ± 2.7 to 6.8 ± 5.6). The long-term surgical success rate within 2 years of surgery was significantly better in group A than in group B (p = 0.027). The number of patients with intermittent diplopia and the duration of diplopia were greater in group A (n = 8) than in group B (n = 2).

Long-term surgical success was achieved in 89% of patients who were initially overcorrected. Overcorrection of an average of 10 prism diopters at the first postoperative week was found to be associated with a more favorable long-term surgical outcome.