Changes in lower eyelid positions after Müller's muscle-conjunctival resection with tarsectomy for the correction of upper eyelid ptosis.

Objective: This study aims to evaluate the effect of Müller's muscle-conjunctival resection (MMCR) with tarsectomy on lower eyelid position in patients with unilateral aponeurotic ptosis in the East Asian population.

Methods: A retrospective review was conducted on patients undergoing unilateral MMCR surgery. Margin reflex distance (MRD) 1 and 2 were measured preoperatively and three months postoperatively. The primary outcome was the change in MRD2 following surgery. Additionally, we investigated the relationship between the relative change of MRD1 and that of MRD2. The secondary outcome was the influence of factors including age, sex, and preoperative MRD on the change in MRD2.

Results: Sixty-one patients were included. In the ptotic eye, postoperative MRD1 increased from 1.47 ± 0.88 mm to 3.57 ± 1.00 mm (p < 0.001), while MRD2 decreased from 5.53 ± 0.97 mm to 5.31 ± 0.96 mm (p = 0.007). A negative correlation was observed between the relative change of MRD1 and MRD2 in the ptotic eye (r = -0.335, unstandardized coefficient [B] = -0.016, 95% confidence interval [CI] -0.028 to -0.004, p = 0.009). Additionally, a positive correlation was found between the relative change in MRD2 in the ptotic and normal eyes (r = 0.818, B = 0.760, 95% CI 0.621 to 0.899, p < 0.001). Preoperative MRD2 in the ptotic eye was a predictor of postoperative MRD2 reduction (B = -0.189, 95% CI -0.327 to -0.051, p = 0.008).

Conclusions: This study demonstrates that MMCR alters lower eyelid position, with reductions in MRD2 correlating with the degree of upper eyelid correction. It is important to inform patients of this potential alteration preoperatively.