Longitudinal Changes in Retinal Nerve Fiber Layer Thickness After Vitrectomy for Epiretinal Membrane

PURPOSE. We investigated longitudinal changes in retinal nerve fiber layer (RNFL) thickness following vitrectomy for epiretinal membrane (ERM). METHODS. Thirty-one patients who underwent pars plana vitrectomy with internal limiting membrane (ILM) peeling for ERM were included. Average thickness and four quadrants of RNFL thicknesses were determined before and at 1, 3, 6, and 12 months after surgery by spectral-domain optical coherence tomography (SD-OCT). As macular lesions could affect RNFL thickness, we evaluated changes in RNFL thickness by dividing the RNFL into 12 o'clock hourly positions, defining pathologic area adjacent to the lesion and nonpathologic area. RESULTS. Retinal nerve fiber layer thickness of the affected eyes increased at 1 month after vitrectomy and later decreased compared to baseline values. Temporal quadrant RNFL thickness was statistically significantly thicker in affected eyes at baseline and at 1 month after surgery and thinner after 12 months than fellow eyes. Retinal nerve fiber layer thickness in pathologic area decreased after surgery, and the RNFL was statistically significantly thinner at 3, 6, and 12 months postoperatively, compared to the baseline thickness. The RNFL thickness of pathologic area of affected eyes compared to fellow eyes was thicker both at baseline and 1 month after surgery but thinner at 12 months compared to baseline values. CONCLUSIONS. Postoperative RNFL thickness after vitrectomy combined with ERM removal tended to decrease postoperatively. Retinal nerve fiber layer thicknesses in temporal pathologic area were significantly reduced at 3, 6, and 12 months postoperatively compared to baseline values, whereas RNFL thicknesses in nasal nonpathologic area exhibited no significant postoperative changes. We found that ERM itself and the removal procedure resulted in decreased RNFL thickness.