Transient enhancing of cone electroretinograms following exposure to brighter photopic backgrounds.

Normal subjects were first light adapted to a standard photopic background and a control photopic ERG was obtained. The subjects were then light adapted to a brighter background for 5 min at the end of which the luminance was returned to the control background and ERGs were taken at regular intervals. Most of the ERG/OP components were transiently enhanced following the above procedure. Given that the previously reported photopic light adaptation effect occurred following an increase in the luminance of the adapting field (from dark adaptation to light adaptation) while that reported in the present study is triggered following a decrease in the level of light adaptation, the opposite effects noted might suggest that the two retinal events result from the same, not yet identified, cone adaptation mechanisms which are solicited in an opposite way.