Properties of the human cone system electroretinogram during light adaptation

Abstract

Changes in the response characteristics of the flash electroretinogram (ERG) of the human cone system were studied during the time course of adaptation to a cone-isolating ganzfeld background. During light adaptation, the amplitudes of the b- and i-waves increased, while the implicit time of the b-wave decreased. The amplitude of the a-wave and the implicit times of the a- and i-waves did not change systematically during light adaptation. Luminance-response functions for b-wave amplitude were obtained at discrete times following background onset and were analyzed using the hyperbolic equation R/R(max) = L(n)/(L(n) + K(n)). The increase in b-wave amplitude was characterized by increases in R(max), K, and n. The decrease in b-wave implicit time was of a similar magnitude at all flash luminances. The amplitude increase of the i-wave only occurred at moderate flash luminances. The results provide a basis for optimizing the clinical recording of cone-isolated single-flash ERGs.