Comparison of postoperative morphological changes and retinal displacement in diabetic and idiopathic epiretinal membranes

Purpose: To compare the postoperative retinal displacement by optical coherence tomography (OCT) in idiopathic epiretinal membranes (iERM) and diabetic epiretinal membranes (dERM). Methods: This retrospective study included 36 iERM and 22 dERM cases. In cross-sectional OCT images (B-scan) the presence of foveal pit, subfoveal fluid, cotton ball sign (CBS), intraretinal cystic changes (ICC), disorganization of retinal inner layers (DRILs) and ectopic inner foveal layer (EIFL) were recorded. Central macular thickness (CMT) and EIFL thicknesses were calculated. Retinal displacement was quantified using infrared image of OCT approach consisting of the fovea to disc margin, interarcade distance and perimacular distances. Results: The presence of subfoveal fluid (p = 0.014) and DRIL (p = 0.02) was significantly higher in the dERM group. CMT decreased significantly in both groups (p<0.001). The EIFL was significantly thicker in the iERM group compared to the dERM group (p = 0.049), and it decreased significantly in the iERM group postoperatively. In the iERM group, while the fovea-disc margin distance decreased, the interarcade and perimacular distance increased significantly (p<0.001). In the dERM group, the disc-fovea distance change was not significant (p = 0.082). Significant visual improvement was achieved with vitrectomy in both groups (p<0.001). In the dERM group, the presence of DRIL was associated with lower pre and post-op visual acuity (VA) (r = 0.596 and p = 0.004 for pre-operative and r = 0.567 and p = 0.007 for post-operative). Conclusion: Significant retinal displacement occurs after vitrectomy in both iERM and dERM. The low VA in the dERM group may be related to the presence of DRILs.