Effect of Müller Muscle–Conjunctival Resection on Pupil Diameter Under Different Lighting Conditions: A Clinical Study

Objective: To evaluate the effect of Müller Muscle–Conjunctival Resection (MMCR) on pupil diameter under different lighting conditions and to evaluate whether MMCR is associated with measurable postoperative changes in pupil diameter under different lighting conditions in patients with blepharoptosis.Material and Methods: This retrospective clinical study included 34 eyes of 34 patients who underwent MMCR for mild-to-moderate ptosis with good levator function and a positive phenylephrine test. All surgeries were performed by a single experienced surgeon. Preoperative and postoperative (1 and 3 months) assessments included margin reflex distance-1 (MRD-1), comprehensive ophthalmic examination, and static pupillometry using an infrared-based device. Scotopic (0.04 lux), mesopic (4.0 lux), and photopic (40.0 lux) pupil diameters were recorded under standardized environmental conditions. Repeated measurements were analyzed using the Friedman test with Bonferroni-corrected post hoc comparisons. A p value < 0.05 was considered statistically significant.Results: The present study comprised 34 eyes from 34 patients, predominantly female (59%), with 20 (59%) of the patients undergoing right eyelid surgery and 14 (41%) undergoing left eyelid surgery. The etiology of ptosis was categorized as follows: congenital ptosis, 28 patients (82%); involutional ptosis, 4 patients (12%); and neurogenic ptosis, 2 patients (6%). The mean patient age was 30.82 ± 11.92 years. Mean levator function was 16.05 ± 2.32 mm. MRD-1 increased significantly from 2.35 ± 0.19 mm preoperatively to 3.52 ± 0.17 mm at 1 month and 3.82 ± 0.15 mm at 3 months postoperatively (p < 0.001). In contrast, no statistically significant differences were observed between preoperative and postoperative scotopic, mesopic, or photopic pupil diameters at any time point (all p> 0.05). No clinically relevant pupillary abnormalities or ocular surface complications were detected. One eyelid with inadequate correction underwent subsequent levator surgery. Conclusions: MMCR significantly improved eyelid height without detectable statistically significant changes in pupil diameter under varying lighting conditions. These findings may have implications for the surgical outcomes of refractive and ptosis surgeries. However, further prospective studies with larger patient populations are required to confirm these observations.