Modulation of the human photopic ERG luminance-response function with the use of chromatic stimuli

In response to progressively brighter flashes, the amplitude of the photopic b-wave of the human electroretinogram (ERG) first increases, then saturates at a maximal value (Vmax) to finally decrease with the brightest flashes. The purpose of this study was to investigate if this “photopic hill” could be modulated with the use of stimuli of different wavelengths. ERGs were evoked to flashes of white, blue, green and red light presented against a white background in 30 normal subjects. Each chromatic stimulus produced a photopic hill. Findings indicate that the amplitude of Vmax was essentially identical except for that measured in response to the red stimuli, where it was 20% smaller than the others.