Abstract

The most fundamental deficit attributable to retinal disease is a reduction in sensitivity to light. Recently we suggested a simple physiological basis for this sensitivity loss (Hood and Greenstein, 1982, Greenstein et al., 1982.). Based upon psychophysical experiments performed on patients with a variety of retinal diseases we hypothesized that in the diseased retina all retinal cells are less responsive to light. That is because of anoxia, or decreased metabolic activity, or some other factor, retinal cells respond to all light intensities with a fraction of the response produced in a non-diseased retina. In fact, much of our data suggest that a simple form of this explanation can be applied to the retinal diseases we studied. It is not surprising that decreased cellular responsiveness occurs in a disease like diabetic retinopathy; it is surprising that the loss in foveal sensitivity found in a group of patients with retinitis pigmentosa (RP) was consistent with this explanation (Greenstein et al. 1984). If sensitivity loss in RP can be attributed entirely to decreased responsiveness then the effects of adding adapting lights are quantitatively predictable. In this paper this hypothesis is tested by collecting foveal data at two levels of steady adaptation on a selected group of RP patients.

© 1985 Optical Society of America