Retinal fiber layer edema and visual field correlation after pars plana vitrectomy with internal limiting and epiretinal membrane peeling

Purpose:To analyze the relationship between retinal fiber layer (RNFL) edema and visual field (VF) defects in patients who underwent pars plana vitrectomy with internal limiting membrane (ILM) and epiretinal membrane peeling. Methods:In this retrospective, interventional consecutive case series, twenty-five eyes of 25 patients that underwent pars plana (23-25 Ga) vitrectomy with (ILM) peeling between December 2009 and May 2010 were studied. No patiens with glaucoma, retinal vein occlusion or diabetic retinopathy were included. Eyes were divided into two groups according to the use of indocianine green (ICG +/-) during surgery. Spectralis HRA + OCT( Heidelberg Engineering, Heidelberg Germany) was used for the evaluation of RNFL edema one and four weeks after surgery and (Humphrey Field Analyzer) to test VF a week, one, three and six months after surgery. Results:Fifteen patients (60%), 9 (36%) ICG+ and 6 (24%) ICG-, did not show postoperative RNFL edema. Ten patients (40%) had RNFL edema a week after surgery and only 7 (28%) of them underwent ICG assisted vitrectomy (chi square test, p=0.69). No edema was observed after four weeks in these patients but VF defects corresponding with previous edema areas were maintained at the end of the follow-up in all of them. Conclusions:Postoperative VF defects were observed in all the patients with temporary RNFL edema, suggesting that it is caused by a mechanical injury of the inner layer of the retina during the ILM peeling and probably does not depend on the use of intraoperative ICG.