Long-term Outcomes of Bilateral Lateral Rectus Recession Using a Modified Normogram for Targeting Small Overcorrection in Intermittent Exotropia

Abstract

Purpose: To evaluate the surgical outcomes of a modified normogram for bilateral lateral rectus recession in the surgical management of intermittent exotropia, with a focus on achieving small overcorrection.

Methods: A retrospective medical chart review of 242 patients who underwent surgery for intermittent exotropia between October 2014 and June 2020 was performed. Our modified normogram reducing amount of recession targeted for small postoperative overcorrection within 5 prism diopters (PD). Patients were observed for at least 3 years. Esodeviation was denoted by negative numbers and positive values indicated exodeviation. A satisfactory outcome was defined as if distant angle of deviation ranged between ≤10 PD of exotropia and ≤5 PD of esotropia. Recurrence was defined as an exodeviation of >10 PD at distance. Overcorrection was defined as an esodeviation of >5 PD at distance.

Results: The mean preoperative deviation angles were 29.32 ± 3.92 PD at distance and 29.88 ± 4.41 PD at near. At postoperative day 1, the mean deviation angles at distance and near were -6.22 ± 1.44 and -6.22 ± 1.49 PD, respectively. Overcorrection within 6 PD of esodeviation was seen in 168 patients (69.42%), undercorrection with exophoria was noted in 11 patients (4.55%), and overcorrection by more than 6 PD of esodeviation was seen in 63 patients (26.03%) at postoperative day 1. The long-term success rate at postoperative 3 years was 77.27% (187 of 242), with a recurrence rate of 19.83% (48 of 242) and an overcorrection rate of 2.89% (7 of 242). A positive correlation between the angle of deviation at postoperative day 1 and 3 years was observed (r = 0.22, p = 0.001). The final success rate at the final examination after a mean follow-up of 38.60 ± 7.99 months was 83.06%.

Conclusions: Our modified normogram for bilateral lateral rectus recession in intermittent exotropia surgery resulted in successful surgical outcomes with small overcorrection, reducing the risk of consecutive esotropia due to excessive overcorrection.

Keywords: Esotropia; Exotropia; Strabismus.

Fig. 1

The proportions of surgical outcomes for each postoperative time point after bilateral lateral rectus recession with a modified normogram for targeting small overcorrection.

Fig. 2

Kaplan-Meier survival curve for recurrence of more than 10 prism diopters after bilateral lateral rectus recession with a modified normogram for targeting small overcorrection.

Fig. 3

Linear regression analysis of angle of deviation at postoperative day 1 and 3 years. The angle of deviation at postoperative 3 years was statistically correlated with angle of deviation at postoperative day 1 (r = 0.22, p = 0.001). PD = prism diopters.