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Purpose

To evaluate contralateral upper and lower eyelid changes following unilateral Müller’s muscle–conjunctival resection (MMCR) in patients without preoperative Hering’s effect.

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Methods

This retrospective study included 60 patients who underwent unilateral MMCR for mild to moderate ptosis between January 2024 and December 2025. Patients with preoperative Hering’s effect or additional eyelid procedures were excluded. Margin reflex distance 1 (MRD1) and MRD2 were measured from standardized digital photographs using ImageJ software. Preoperative and 3-month postoperative values were compared using nonparametric tests. Patients were also stratified based on the presence of paradoxical contralateral eyelid elevation.

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Results

Median MRD1 of the operated eye increased significantly from 2.00 mm (IQR, 0.76) to 3.00 mm (IQR, 0.70) postoperatively (p < 0.001), while MRD2 showed no significant change (p = 0.287). No statistically significant change was observed in contralateral MRD1 (p = 0.222) or MRD2 (p = 0.401). However, contralateral MRD1 responses varied individually, with a decrease in 27 patients, paradoxical elevation in 20 patients (33.3%), and no change in 13 patients. The inter-eye difference in MRD1 decreased significantly from 1.31 mm (IQR, 0.82) to 0.26 mm (IQR, 0.57) (p < 0.001), indicating improved postoperative symmetry. Paradoxical contralateral eyelid elevation was associated with lower preoperative contralateral MRD1 values (p = 0.005). A trend toward higher rates of paradoxical elevation was observed with increasing MMCR resection amounts.

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Conclusion

Unilateral MMCR effectively improves eyelid position and symmetry. Although no significant overall change is observed in contralateral eyelid position, individual responses vary considerably, including both decreases and paradoxical elevations. Lower preoperative contralateral MRD1 appears to predict paradoxical elevation, and resection amount may also influence contralateral eyelid behavior. These findings suggest that contralateral eyelid response cannot be fully anticipated by preoperative Hering testing alone.

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Additional Authors

First name	Last name	Base Hospital / Institution
Feyza	Çukurova	Beyoglu Eye Training and Research Hospital
Derya	Özkan Tellioğlu	Beyoglu Eye Training and Research Hospital
Ayşe	Çetin Efe	Beyoglu Eye Training and Research Hospital
Mehmet Göksel	Ulaş	Beyoglu Eye Training and Research Hospital
Ayşe Burcu	Dirim	Beyoglu Eye Training and Research Hospital

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