Functional and Cosmetic Outcomes of Müller Muscle–Conjunctival Resection in Selected Pediatric Ptosis Patients with a Positive Phenylephrine Test

Background/Objectives: To evaluate margin reflex distance-1 (MRD-1), inter-eyelid symmetry, functional visual parameters, and cosmetic outcomes following Müller Muscle–Conjunctival Resection (MMCR) in selected pediatric patients with mild-to-moderate blepharoptosis, good levator function, and a positive 2.5% phenylephrine test. Methods: This retrospective observational study included pediatric patients (<18 years) who underwent MMCR between 2018 and 2023. Surgical indications were based on functional or developmental criteria, including visual axis obstruction, abnormal head posture, significant eyelid asymmetry, or psychosocial concerns, rather than eyelid height alone. Preoperative and postoperative examinations at 1 week, and at 1, 3, and 6 months, included best-corrected visual acuity (BCVA), MRD-1, eyelid symmetry, levator function, lagophthalmos, and ocular surface findings. Outcomes were analyzed separately for unilateral and bilateral cases. Statistical analyses were performed using non parametric tests, with p < 0.05 considered statistically significant. Results: Fifty patients (55 eyes; mean age 13.16 ± 4.04 years) were included. Mean preoperative MRD-1 increased significantly from 1.83 ± 0.89 mm to 2.97 ± 0.83 mm at 6 months (p < 0.001). Postoperative MRD-1 at 6 months showed a significant correlation with the phenylephrine response. In unilateral cases, excellent or satisfactory postoperative symmetry was achieved in 83.6% of eyes. Bilateral cases demonstrated comparable MRD-1 elevation with satisfactory contour and high patient/parent satisfaction. Transient lagophthalmos improved over time. No overcorrection, exposure keratopathy, or significant ocular surface complications were observed. Revision surgery was required in 8.9% of unilateral cases. Conclusions: MMCR is a safe and effective option for appropriately selected pediatric patients, providing predictable eyelid elevation, good symmetry, and low complication rates when functional indications are present.