Müller muscle conjunctival resection: Impact on Hering's law and facial symmetry in unilateral ptosis repair.

Purpose: Ptosis is characterized by drooping of the upper eyelid, often requiring surgical intervention for functional and aesthetic purposes. Müller's muscle conjunctival resection is a commonly utilized surgical technique to correct mild to moderate ptosis. This retrospective study aimed to evaluate the impact of Hering's law on the outcomes of unilateral Müller's muscle conjunctival resection surgery, particularly eyelid and brow symmetry.

Methods: Thirty patients with unilateral ptosis underwent Müller's muscle conjunctival resection. Preand postoperative assessments included ipsilateral and contralateral side margin-reflex distance and brow position, measured through digital image analysis.

Results: We found significant improvements in postoperative margin-reflex distance measurements in the ipsilateral eyelid but not in the contralateral eyelid, indicating minimal influence of Hering's law. Brow position showed a statistically significant increase on the contralateral side but not on the ipsilateral side.

Conclusion: Müller's muscle conjunctival resection effectively restores symmetry in eyelid height and maintains brow symmetry. This is the first study to explore bilateral eyelid and brow symmetry after unilateral Müller's muscle conjunctival resection surgery for mild to moderate ptosis. Further research should be conducted to understand the long-term effects of Müller's muscle conjunctival resection on facial aesthetics, particularly in relation to brow position.