Variability of Visual Recovery with Time in Epiretinal Membrane Surgery: A Predictive Analysis Based on Retinal Layer OCT Thickness Changes

Purpose: To correlate postoperative optical coherence tomography (OCT) thickness changes of each retinal layer with different patterns of visual recovery after idiopathic epiretinal membrane (ERM) surgery in a cohort of patients showing no known risk factors for poor visual recovery at preoperative imaging. Methods: Best corrected visual acuity (BCVA) and OCT images were acquired preoperatively and 1 month, 3 months and 6 months postoperatively. Patients were divided into four groups according to postoperative BCVA improvement: improvement < 15 ETDRS letters (GROUP 1), immediate improvement of BCVA without further improvements at later follow-ups (GROUP 2), immediate improvement of BCVA with further improvements at later follow-ups (GROUP 3) and delayed improvement of BCVA (GROUP 4). Results: Eighty-five patients were included. GROUP1 was the only one characterized by retinal nerve fiber layer (RNFL) thickness increase and ganglion cell layer/central macular thickness (GCL/CMT) ratio decrease at 1 month and outer nuclear layer (ONL) thickness decrease at 3 and 6 months. GROUP 2 was the only one showing a decrease in GCL/inner plexiform layer (GCL/IPL) ratio at 1 month. GROUP 3 and 4 showed higher preoperative RNFL thickness compared to the other, and GROUP 4 manifested a late increase in RNFL thickness at 6 months. Conclusions: Different patterns of VA recovery are associated with specific layer thickness changes. If further confirmed, this would help detect those cases characterized by poor or delayed visual recovery despite the absence of other known imaging risk factors.