The luminance–response function of the human photopic electroretinogram: a mathematical model

The luminance–response function of the brief flash full-field photopic electroretinogram (ERG) rises to a peak before falling to a sub-maximal plateau – the ‘photopic hill’. The combination of on- and off-responses inherent in the brief flash photopic ERG suggests that this luminance–response function could be modelled by the sum of a Gaussian function and a logistic growth function. Photopic ERGs to a luminance series of brief flashes against three different background luminances recorded from seven healthy adults showed the characteristic ‘photopic hill’ function for b-wave amplitudes which were satisfactorily fitted with the sum of a Gaussian curve and a logistic growth curve. As background luminance increased, both components shifted to the right on the luminance axis.