To assess macular function before and after vitrectomy and membrane removal in epiretinal membranes by means of multifocal electroretinogram (mfERG).

The mfERGs (RETIscan®, Roland, Germany) of 28 consecutive patients (28 eyes) with idiopathic epiretinal membranes were recorded before epiretinal membrane surgery and 3 to 6 months after surgery. The average retinal response density and implicit time of each local response were estimated as anatomic macular areas corresponding roughly to 5 rings. Preoperative and postoperative responses of mfERG were compared. The correlation of the change of retinal response density and postoperative macular configuration on optical coherent tomography (OCT) was statistically analyzed.

The postoperative value of P1 amplitude and implicit time were not statistically correlated with the preoperative value (p>0.05). There were no significant correlations between the changes of rings 1 and 2 with regard to the retinal response density of the mfERGs and visual acuity. There was no significant correlation between the change of retinal response density and postoperative macular configuration according to OCT.

The use of mfERGs does not seem useful for predicting clinical prognosis after epiretinal membrane surgery. Further studies of influence of internal limiting membrane removal on mfERG response should be conducted.