SURGICAL OUTCOMES, VALIDATION OF GOVETTO STAGING, AND POSTSURGICAL MACULAR EDEMA IN IDIOPATHIC EPIRETINAL MEMBRANES

Purpose: To report surgical outcomes of (combined) pars plana vitrectomy with epiretinal membrane (ERM) and inner limiting membrane peeling, validate the Govetto OCT-based staging system for idiopathic ERM, and assess the prevalence of postsurgical macular edema (PSME) relative to Govetto stages. Methods: Retrospective study of 996 consecutive eyes undergoing (combined) pars plana vitrectomy with ERM and inner limiting membrane peeling for idiopathic ERM (2015–2023) at University Hospitals Leuven. Eyes with secondary ERM or significant ocular comorbidities were excluded. Visual outcomes were analyzed using Govetto optical coherence tomography stages. Clinically relevant PSME was defined as intraretinal cysts on optical coherence tomography requiring treatment. Results: The median best-corrected visual acuity improved from 20/40 preoperatively to 20/25 at final follow-up (median 15 months). Vision worsened (>0.1 LogMAR) in 6.49% of eyes. Preoperative best-corrected visual acuity strongly predicted postoperative vision (estimate = 0.22, P < 0.001). Significant interstage differences in best-corrected visual acuity existed preoperatively and at 2 months postoperatively; however, only stage 4 remained significantly worse at long-term follow-up. Epiretinal membrane foveoschisis (4.17%) outcomes resembled stage 2 ERM. Clinically relevant PSME occurred in 23.19% of eyes, strongly correlated with higher Govetto stages, especially stage 4 (44.12%). Combined phacovitrectomy significantly increased PSME prevalence (23.19% vs. 15.93%, P = 0.01) without affecting visual outcomes. Conclusion: (Combined) pars plana vitrectomy with ERM and inner limiting membrane peeling effectively improves visual acuity in idiopathic ERM. Govetto staging reliably predicts early postoperative outcomes, while PSME incidence correlates strongly with higher Govetto stages. Epiretinal membrane foveoschisis resembles stage 2 ERM, highlighting the importance of distinguishing it from lamellar macular holes.