Preoperative OCT biomarkers and surgical outcomes after vitrectomy with epiretinal membrane and internal limiting membrane peeling for refractory diabetic macular edema: a retrospective cohort study

Abstract Background Vitrectomy with epiretinal membrane (ERM) and internal limiting membrane (ILM) peeling may provide anatomical and functional benefit in selected eyes with refractory diabetic macular edema, but predictors of postoperative outcome remain incompletely defined. This study aimed to evaluate the anatomical and functional outcomes of pars plana vitrectomy (PPV) combined with ERM and ILM peeling in eyes with diabetic macular edema (DME) and to investigate the prognostic value of preoperative OCT biomarkers for postoperative outcomes. Methods Thirty eyes of 30 patients with DME refractory to repeated intravitreal anti-VEGF and/or corticosteroid therapy underwent 25-gauge PPV with ERM and ILM peeling. Best-corrected visual acuity (BCVA), central subfield thickness (CST), postoperative treatment requirement, and preoperative OCT biomarkers were evaluated. Associations between baseline OCT biomarkers and 12-month anatomical and functional outcomes were assessed using unadjusted analyses and multivariable regression models. Results Mean BCVA improved from 1.08 ± 0.52 logMAR at baseline to 0.65 ± 0.42 logMAR at 12 months ( P < 0.001), while mean CST decreased from 533.80 ± 100.31 μm to 261.23 ± 34.31 μm ( P < 0.001). Baseline DRIL was independently associated with worse 12-month BCVA (β = 0.399, 95% CI 0.035–0.762; P = 0.032). Eyes with intact EZ showed greater numerical visual improvement than those with EZ disruption, although the difference was not statistically significant ( P = 0.093). Absence of baseline HRF was associated with greater CST reduction in the unadjusted analysis ( P < 0.001), but HRF was not independently associated with 12-month CST ( P = 0.309). During postoperative follow-up, 22 eyes (73.3%) required no additional intravitreal treatment. Conclusions PPV with ERM and ILM peeling was associated with significant anatomical and functional improvement in selected eyes with refractory DME. Among the preoperative OCT biomarkers evaluated, DRIL showed the most consistent prognostic association with postoperative visual outcome. Preoperative assessment of retinal microstructure may provide complementary information for visual prognostication and patient counseling.