Effect of Congenital Lower Eyelid Epiblepharon Surgery on Asymmetric Margin Reflex Distance 1

Objectives: To investigate the characteristics of margin reflex distance 1 (MRD1) asymmetry in congenital lower eyelid epiblepharon and its resolution after surgical correction of epiblepharon. Methods: Among patients who underwent lower eyelid epiblepharon surgery from November 2015 to September 2017, patients with a preoperative MRD1 difference of more than 1.0 mm between the two eyes according to medical photographs were defined as having MRD1 asymmetry. A postoperative MRD1 difference of less than 1.0 mm between the two eyes was regarded as MRD1 asymmetry resolution. The preoperative MRD1 difference was compared between subgroups with resolved or sustained MRD1 asymmetry. Astigmatism and amblyopia were also assessed. Results: Among 432 patients, MRD1 asymmetry was observed in 24 patients (5.6%). MRD1 was always lower in the side with more extensive epiblepharon. At 6 months after surgery, the mean MRD1 difference between the two eyes was significantly decreased (1.8 +/- 0.7 mm to 0.5 +/- 0.8 mm, p < .001, paired t-test) and MRD1 asymmetry resolution occurred in 19 patients (79%). In the resolved MRD1 asymmetry group, the preoperative MRD1 difference was 2.0 mm or less and was significantly smaller than that in the sustained MRD1 asymmetry group (p = .010, Mann-Whitney U test). Six patients had preoperative aniso-astigmatism >= 1.50 D. Unilateral amblyopia presented in nine patients (38%) and improved within 1 year postoperatively. Conclusions: MRD1 asymmetry can be resolved after epiblepharon surgery, especially when the preoperative MRD1 difference is 2.0 mm or less. Unilateral amblyopia was frequent, but the treatment outcome was good.