Supplementary Material for: Optimal Timing for Idiopathic Epiretinal Membrane Peeling Surgery Based on a Preoperative Visual Acuity Threshold.

PURPOSE: To evaluate the efficacy and safety of vitrectomy-peeling for idiopathic epiretinal membrane (iERM) in patients with preserved preoperative best corrected visual acuity (BCVA) compared to those with reduced BCVA, and determine the optimal preoperative VA threshold for intervention. METHODS: This single-center retrospective cohort study analyzed 415 eyes from 368 patients who underwent iERM surgery between January 2019 and July 2023. Epidemiological, surgical, and spectral domain-optical coherence tomography (SD-OCT) data were collected preoperatively and at each follow-up visit. Patients were divided into three groups based on preoperative BCVA: poor (≤ 60 Early Treatment Diabetic Retinopathy Study (ETDRS) letters), moderate (61–76 ETDRS), and good (≥ 77 ETDRS). The primary outcome was final BCVA at the last visit, while secondary outcomes included analyzing surgical complications and preoperative predictive factors to develop a predictive model of postoperative BCVA. RESULTS: Median preoperative BCVA was 75 ETDRS letters (IQR 70–80), improving significantly postoperatively to 80 ETDRS (IQR 75–85) (p 75 ETDRS letters leads to optimal visual outcomes without increasing complications.