DETERMINATION AND SIGNIFICANCE OF THE SCOTOPIC RETINAL VISIBILITY CURVE

Abstract

For the past half century the relation between visual purple and vision has been realized to be of fundamental importance. Many investigators¹have compared the absorption spectrum of visual purple with the scotopic visibility curve. Some of the more recent comparisons have been made by Hecht and Williams,²Dartnall and Goodeve³and Blum.⁴The comparisons made by Hecht and Williams and by Blum are inadequate because the absorption spectrum of visual purple was compared with the scotopic ocular visibility curve, which means that no corrections were made for the selective absorption of light by the refractive media of the human eye. These comparisons are also inadequate because the absorption spectrum of visual purple used was that determined by Koettgen and Abelsdorff,^1cwhereas the more recent work of Lythgoe,⁵of Krause and Sidwell⁶and of Bayliss, Lythgoe and Tansley⁷has shown that