Macular Function and Morphology after Idiopathic Epiretinal Membrane Surgery correlate with the Presence of Ectopic Inner Foveal Layers

Abstract Background: To evaluate how Ectopic Inner Foveal Layers (EIFL) affect macular morphology and function after idiopathic Epiretinal Membrane (ERM) and internal limiting membrane (ILM) peeling by the means of Best-Corrected Visual Acuity (BCVA), Optical Coherence Tomography (OCT), Microperimetry (MP-1) and Multifocal Electroretinogram (mfERG). Methods: 27 patients underwent pars plana vitrectomy with ILM and ERM peeling. They were retrospectively followed-up for 12 months and allocated into two groups basing on baseline EIFL presence (group 1) or absence (group 2). Central Retinal Thickness (CRT) and BCVA were measured and compared pre- and post-operatively at 1, 4 and 12 months, whereas Fixation Stability (FS), Macular Sensitivity (MS) and mfERG responses were confronted at baseline and 12 months. Results: In group 1 BCVA improved (p<0.05) at 4 and 12 months (Mean difference (MD)=0.14 (SE=0.04); MD=0.13 (SE=0.05), respectively) as well as in group 2 (MD=0.31 (SE=0.07): MD=0.41 (SE=0.08), respectively). CRT did not change in group 1, whereas it decreased (p<0.05) in group 2 at 4 and 12 months (MD=-73.13 – SE=23.56; MD=-76.20 – SE=23.56). MS showed no changes in both groups after surgery. FS did not change in group 1, whereas group 2 improved (p<0.05) in either FS2° (+8.91±13.97) and FS4° (+4.33±3.84) at 12 months. MfERG P1 wave did not improve in group 1, while group 2 improved (p<0.001) postoperatively (αP1-2: 27.97±27.62; αP1-3: 12.51±17.36; αP1-4: 10.49±17.19) except from the most central ring (αP1-1). Conclusion: EIFL presence resulted to negatively affect the outcomes of this procedure.