Level of Light Adaptation and the Human Electroretinogram

This report deals with the effects of two adaptational variables upon the human electroretinogram. First, further investigation of a temporal increase in electroretinogram amplitude during light adaptation is reported. The effects of red and white test flashes were compared at several adaptation levels. The temporal increase was found only for high luminance adaptation levels and only for white test flashes. Second, the effects of constant luminance test flashes upon a wide range of adaptation levels were investigated. It was found that increasing levels of light adaptation produced decreases in the amplitudes of the components of the electroretinogram. Long latency components were affected by lower levels of light adaptation and to a greater extent than short latency components. The results are considered in relation to the duplicity theory and to the resting potential of the eye.