Macular oscillatory potentials in humans

Studies of the focal macular electroretinogram (ERG) have been made with special reference to oscillatory potentials (OPs) by using a fundus monitoring system in humans. Human macular OPs consist of 3 to 4 wavelets (mean peak interval, approximately 6.5 msec). The distribution of OPs in relation to those in a- and b-waves was studied. The amplitudes of a-waves, b-waves, and OPs of the upper macula were significantly larger than those of the lower macula. The distribution of OPs is relatively sparse in the fovea, becoming more dense than the a- and b-waves from the fovea toward the parafovea, and differing even more toward the perifovea. There was no statistical difference of amplitude in a- and b-waves between nasal and temporal macula. The amplitude of OPs in the temporal macula, however, was significantly larger than in the nasal macula. In some macular diseases, such as diabetic maculopathy, cystoid macular edema, or the convalescent stage of central serous chorioretinopathy, macular OPs were selectively reduced, leaving the a- and b-waves intact. Macular OPs can provide a new aspect of macular function and can be a sensitive indicator to assess that function in macular diseases.