The luminance-response function of the dark-adapted human electroretinogram.
A hyperbolic equation of the form (R/Rmax) = Ln/(Ln + Kn) has been used to describe the b-wave luminance-response function of the dark-adapted human electroretinogram (ERG). However, this equation accurately describes the function only at low to moderate flash luminances. At high flash luminances, a second amplitude increase or "limb" appears in the function. The results of the present study demonstrate that this limb does not represent a cone system response. First, the spectral sensitivity of the entire luminance-response function is rod-determined in normal subjects. Second, the limb was present in a rod monochromat, in whom cone system ERGs were indistinguishable from noise. Instead, the nonmonotonic nature of the luminance-response function may result from a luminance-dependent algebraic summation of the components that underlie the ERG waveform of the rod system.
Peachey
N S
NS
UIC Eye Center, University of Illinois, College of Medicine, Chicago 60612.
Alexander
K R
KR
Fishman
G A
GA
D003117:Color Vision Defects / Q000503:physiopathology; D003623:Dark Adaptation; D004307:Dose-Response Relationship, Radiation; D004596:Electroretinography; D006801:Humans; D008027:Light; D008433:Mathematics; D010783:Photometry; D010786:Photoreceptor Cells / Q000502:physiology*