Risk factors and predictive cutoff values for new-onset microscotoma following vitrectomy with internal limiting membrane peeling for epiretinal membrane

PURPOSE: To identify the risk factors and predictive cutoff values for new-onset microscotoma following vitrectomy with internal limiting membrane (ILM) peeling for epiretinal membrane (ERM). METHODS: This retrospective study included patients who underwent vitrectomy with ERM and ILM peeling. Visual acuity, metamorphopsia, and visual field (Humphrey Field Analyzer 10-2 program) were evaluated preoperatively and at 3-6 and 12 months postoperatively. New-onset microscotoma was defined as any test points decreasing from ≥10 dB preoperatively to <10 dB at 3-6 months. Risk factors, vulnerable regions, and preoperative threshold cutoff values for new-onset microscotoma were analyzed. RESULTS: New-onset microscotoma was observed in 31 (17.8%) of 174 eyes (174 patients; 67.7 ± 8.2 years). Visual acuity and metamorphopsia improved significantly at 12 months postoperatively (both p<0.0001). A multivariate analysis identified glaucoma (odds ratio [OR]=8.18), secondary ERM (OR=4.45), indocyanine green usage (OR=3.70), and male sex (OR=2.46) as significant risk factors. Vulnerable regions corresponded to the temporal and inferior macula (p<0.01). The overall preoperative threshold cutoff value was 27.5 dB (area under the curve [AUC] = 0.85, p < 0.001), whereas in eyes with glaucoma (n = 18), it was 26.5 dB (AUC = 0.90, p < 0.001). Both analyses demonstrated a negative predictive value (NPV) exceeding 99%. CONCLUSION: The identified risk factors, vulnerable regions, and cutoff values may guide preoperative patient counseling and development of safe strategies to prevent postoperative microscotoma. The high NPVs highlight reliable identification of low-risk areas, contributing to ILM peeling approach optimization.