Tomographic prognostic factors for visual improvement after pars plana vitrectomy for epiretinal membrane

Abstract

Purpose: To evaluate postoperative changes and investigate tomographic prognostic factors of visual impairment after vitrectomy for epiretinal membrane (ERM). Methods: A retrospective observational study on patients who underwent pars plana vitrectomy for ERM by a single experimented surgeon. Best corrected visual acuity (BCVA) on the logMAR chart and optical coherence tomography (OCT) features were recorded before surgery and at the last visit. Tomographic parameters analysed were: central foveal thickness (CFT), foveal contour morphology, external limiting membrane (ELM), ellipsoid zone (EZ) and interdigitation zone (IZ) integrity, the presence of intraretinal fluid (IRF), subretinal fluid, disorganization of retinal inner layers (DRIL) and subfoveal deposits. Student's t‐test and Pearson's correlation coefficients were used for statistical analysis. p Values <0.05 were considered statistically significant. Results: Forty‐seven eyes of 43 patients were included. The mean age was 61.7 years (range 13–87). The ERM was idiopathic in 49% and secondary in 51%. The mean BCVA was 1.02 before and 0.5 after surgery and improved significantly (p < 0.001) with a mean gain of 5.2 lines. The postoperative BCVA correlated strongly with the preoperative one (R2 = 0,764, p < 0.001). Tomographic factors associated with worse final BCVA were higher baseline CFT (p = 0.004), abnormal foveal profile (p = 0.02), the presence of IRF (p < 0.001), DRIL (p = 0.01) and subfoveal deposits (p = 0.04). The disruption of ELM, EZ and IZ were as well associated with a poorer visual outcome (p < 0.001, p = 0.03 and p < 0.001 respectively). Conclusions: ERM surgery provides functional and anatomical improvement. Preoperative OCT is an essential tool to evaluate morphological retinal changes and identify prognostic factors for visual recovery.