Photic damage to the eye: selective extinction of the c-wave of the electroretinogram.

Albino rabbits were exposed to strong visible light that had passed several infrared-absorbing filters. Photic damage to the retina and pigment epithelium was studied by means of the direct current electroretinogram (dc-ERG) which allows stable registrations of the slow c-wave from the pigment epithelium as well as the relatively fast a- and b-waves from the neuroretina. The exposure to light for 4 h gave rise to striking changes in the ERG: there was only a 25% decrease in the b-wave but a total disappearance of the normally very large c-wave. At the site of the c-wave in the ERG there appeared a negative trough. The electroretinographic evidence of this study seems to indicate a profound injury to the pigment epithelium (pigment epithelial cells and/or tight junctions) after exposure to strong visible light.