Dark Adaptation is Impaired in Diabetics before Photopic Visual Losses Can be Seen

The main theme of this volume is the inherited retinal degenerations, but the most important causes of blindness have a different aetiology, not directly related to genetic defects. Diabetes is the greatest cause of blindness in younger people, and even con sidering all age groups is as common a cause of blindness as Glaucoma and Age Related Maculopathy. Diabetes causes a retinopathy (DR) which is basically a vasculopathy1,2 and the cellular biology of DR has been recently linked to cytokines.3 Starting from this fact, it has been proposed that techniques of molecular biology which might be of use in the treatment of inherited degenerative diseases could also be applicable to DR. This paper is however concerned with a far simpler method of controlling DR, which is based on the physiology of the eye, the particular features of which have been known for half a century but not exploited in this connection. The basic idea is that anoxia early in DR will only develop during dark adaptation, occuring in long periods every night in sleep.