ERG assessment of the functional activity of the retina in following the surgical closure of idiopathic macular holes

Abstract

Twenty patients with stage 3 or 4 idiopathic macular holes were evaluated with standard cone ERG, photopic flicker ERG at 8,3-30-Hz, to study the function of cone photoreceptors, bipolar cells, and Muller cells after the surgical correction of their macular hole. The correlations between the ERG parameters and the microperimetry and optical coherent tomography data were evaluated. IMH has been associated with the general reduction in the function of the cone photoreceptors and bipolar cells and with the sharp increase in the activity of Muller cells and their functional relationships with some bipolar cells. The nature of the changes in photopic standard and flicker ERGs demonstrated the dependence of the central retinal function on the dynamics of cone bipolar cells’ recovery. In the early period after the surgery of IMH, a sharp reduction in the flicker ERG at 24 Hz was found, to be followed by a progressive increase, which indicated a pronounced reduction in the bipolar cell function with the formation of the IMH and its substantial decrease after the vitreoretinal surgery. A significant increase in the glial index for flicker ERG at 24 Hz may be associated with a compensatory overreaction of retinal Muller cells in the preoperative and in the recovery period after the closure of IMH.