Electroretinographic components of the canine visual evoked response

Electroretinograms (ERG) and visual evoked responses (VER) were recorded from 2 anesthetized dogs before and after surgical manipulation. The ERG was recorded from a corneal contact lens, and the VET, from 9 different scalp sites. The recordings were made on a signal averager as done in clinical situations. Surgical manipulation consisted of an alcohol block of the stimulated eye and enucleation of the nonstimulated eye. The results indicated that under the conditions of making the recordings, the major and consistent waves of the VER from all scalp sites were a far-field ERG and were not of cortical origin.