Pars Plana Vitrectomy for Idiopathic Epiretinal Membrane: OCT Biomarkers of Visual Outcomes in 322 Eyes

Abstract

To investigate OCT-based biomarkers of visual acuity (VA) in eyes with idiopathic epiretinal membranes (ERMs) undergoing surgical intervention. To assess the surgical outcomes of pars plana vitrectomy (PPV) and membrane peel (MP) surgery in eyes with idiopathic ERM and to identify potential imaging-based biomarkers of vision outcomes. Retrospective, consecutive case series of eyes with idiopathic ERM that underwent PPV and MP surgery between January 1, 2017, and January 1, 2019. A previously described ERM grading scale was utilized for OCT analysis. The primary outcome was VA at postoperative month 6 and at final follow-up. The secondary outcome was the association of OCT structural features, including ectopic inner foveal layers (EIFLs), inner microcystoid changes, and ellipsoid zone (EZ) disruption, with VA outcomes. A total of 322 eyes with idiopathic ERM were included. The mean (± standard deviation) follow-up was 506.6 ± 324.6 days after MP surgery. VA improved from logarithm of the minimal angle of resolution value of 0.49 ± 0.27 (Snellen 20/61) before MP surgery to 0.41 ± 0.30 (Snellen 20/51, P < 0.001) at 6 months after MP surgery and to 0.31 ± 0.29 (Snellen 20/41, P < 0.001) at the final follow-up. A total of 21 (6.5%) eyes were graded as stage 1, 38 (11.8%) as stage 2, 188 (58.4%) as stage 3, and 75 (23.3%) as stage 4, with higher ERM stages associated with worse pre-MP VA (P < 0.001). The presence of inner microcystoid changes was associated with worse pre-MP VA (P= 0.04). Stage 4 ERM characteristics (P= 0.03), the presence of EZ disruption (P= 0.01) at month 3, and the presence of inner microcystoid changes at month 3 (P= 0.02) were associated with worse VA at 6 months. The presence of EIFL was not associated with the 6-month or final VA on multivariate analysis. When analyzed within defined age groups, patients older than 80 years had worse final VA (P= 0.02) and were more likely to have inner microcystoid changes on OCT (P= 0.01). VA improvement was noted after surgery in eyes with idiopathic ERM across all stages. Preoperative stage 4 characteristics were associated with worse VA at 6 months. Postoperative inner microcystoid changes and EZ disruption at month 3 were additional OCT biomarkers associated with worse 6-month and final VA outcomes.