Abstract
A technique based on the method of differential fundus reflectometry is used to assess the availability of rhodopsin in the eye. A defined part of the dark adapted fundus is bleached by a short intense flash of light. The fundus is subsequently photographed in order to record the flux reflected from the bleached area, the optogram, and the surrounding unbleached region. This procedure requires only a few simple modifications to a Zeiss fundus camera before it can be used routinely in the clinic.