Retrospective Analysis of the Effect of Hering's Law on Outcomes of Surgical Correction of Ptosis

INTRODUCTION Several factors may influence aesthetic outcomes of ptosis surgery, especially in patients with asymmetrical ptosis. We retrospectively assessed the effect of Hering's law on surgical outcomes of patients with asymmetrical ptosis. METHODS Patients with mild to moderate asymmetrical ptosis (N = 300) who underwent advancement or plication of upper eyelid aponeurosis between January 2014 and July 2016 were enrolled. Fifty patients (group A) underwent surgery without taking into consideration the impact of Hering's law. Of these, 35 patients with unilateral ptosis (subgroup A1) underwent standard surgery on the contralateral side, whereas 15 patients with bilateral ptosis (subgroup A2) were first operated on the milder side followed by the more severely affected side.In 250 patients (group B), surgery was performed taking cognizance of the implications of Hering's law. These included 100 patients with unilateral ptosis (B1) and 150 with bilateral ptosis (B2). Difference in bilateral palpebral fissure symmetry by less than 0.5 mm was considered as satisfactory outcome. RESULTS Duration of postoperative follow-up ranged from 3 to 24 months. Satisfactory outcomes were achieved over 60% of patients in group A (A1, 60.6%; A2, 66.67%) and in 96% of patients in group B (B1, 95%; B2, 96.67%). Patients with unsatisfactory outcomes underwent repair according to Hering's law after 3 months and obtained good results. CONCLUSIONS Application of Hering's law may improve outcomes of corrective surgery in patients with asymmetric ptosis.