The Relation between the Intensity of Light and the Electrical Excitability of the Human Retina

Abstract

The electrical excitability of the human retina becomes supernormal after an illumination of the eye. The maximum increase ζ in electrical excitability expressed in percentage of the excitability in the dark varies with intensities of illumination. The relation between ζ and log intensity is represented by a single sigmoid curve at the fovea, but consists of two different sections outside the fovea.
The double nature of the peripheral measurements very likely represents. rod function for the low intensity section and cone function for the high intensity section. The data for both cones and rods are adequately described by Hecht's equation KI=ζ²/(α-ζ)².