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

Abstract

Objective: To investigate OCT-based biomarkers of visual acuity (VA) in eyes with idiopathic epiretinal membranes (ERMs) undergoing surgical intervention.

Purpose: 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.

Methods: 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.

Results: 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).

Conclusions: 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.

Keywords: Epiretinal membrane; internal limiting membrane; optical coherence tomography; pars plana vitrectomy.