Simultaneous pattern-reversal electroretinograms and visual evoked potentials in diseases of the macula and optic nerve.

Although it is well established that the flash electroretinogram (ERG) is preganglionic in origin, conflicting evidence exists concerning the main source of the pattern-reversal ERG(PERG). In this study, PERGs were recorded simultaneously with visual evoked potentials (PVEPs) in a group of patients and controls. In those patients with obvious macular disease, both the PERG and PVEP were reduced, whereas the standard flash ERG was normal. This result is consistent with either a preganglionic or ganglion cell origin of the PERG. In those patients with obvious optic nerve disease (n = 7), normal or near-normal PERGs were recordable even when PVEPs were completely absent. If the PERG reflects ganglion cell activity, one would anticipate both abnormal PVEPs and PERGs in these patients. These results suggest a preganglionic origin of the PERG in humans.