Predictive factors for visual acuity and metamorphopsia after epiretinal membrane surgery

PURPOSE: To identify predictive parameters of best-corrected visual acuity (BCVA) and metamorphopsia following epiretinal membrane (ERM) surgery. METHODS: In this prospective consecutive case series, BCVA, vertical (VM-score) and horizontal M-Charts scores (HM-score) were measured preoperatively and at 2, 6 and 12 months postoperatively. Optical coherence tomography (OCT) features analyzed included central subfoveal thickness (CSFT), ectopic inner foveal layer thickness (EIFLT), inner macular cysts (IMC), ellipsoid zone (EZ) disruptions, the presence of a cotton ball sign (CBS), and the absence of the foveal pit (AoFP). RESULTS: Seventy-two eyes with primary idiopathic ERM were included. With reference to 12 months, improvements in BCVA, VM-score and HM-score were greatest between baseline and 2 months (all p<0.001), smaller between 2 and 6 months (all p<0.05), and not significant thereafter (all p≥0.12). Across all timepoints, higher EIFLT, and the presence of IMC and EZ disruptions (all p<0.001) were associated with worse BCVA, while none of the OCT parameters assessed demonstrated a significant association with VM-score or HM-score.BCVA at 12 months was significantly associated with preoperative BCVA (p=0.02), EZ disruption (p=0.04) and CBS (p=0.02) at baseline. Both VM-score and HM-score at 12 months were significantly associated with preoperative VM-score and HM-score (p<0.01 and p<0.001) but not with any of the baseline OCT parameters analyzed. CONCLUSIONS: Worse preoperative BCVA and metamorphopsia were associated with worse respective postoperative outcomes. Baseline photoreceptor-related abnormalities, i.e. EZ disruption and cotton ball sign, were associated with worse postoperative BCVA, whereas none of the OCT parameters assessed predicted postoperative metamorphopsia.