Pattern VEPs before and after idiopathic epiretinal membrane removal.

Pattern visual evoked potentials (pVEPs) were used to assess the visual function before, and 1 and 6 months after removal of an idiopathic epiretinal membrane (ERM) from eight eyes. All patients underwent a standard three-port pars plana vitrectomy to remove the ERM removal and cataract surgery. pVEPs were elicited by check sizes of 15', 30', 60', and 120' with a reversal rate of 2 reversals/s. One hundred responses were averaged with an analysis time of 300 ms. The amplitude ratio (affected eye/fellow eye) of the P100 component were significantly larger at 6 months with smaller check sizes, and the increase was accompanied by an improvement of the VA. The mean peak latency of P100 did not change significantly for all check sizes. We conclude that the improvement of the P100 amplitude with smaller check sizes resulted from the recovery of visual function after the ERM removal.