A previous study demonstrated that lysergic acid diethylamide (LSD) induced measurable changes in human retinal function while visual hallucinations and illusions were being experienced.1 The changes were evident in both dark-adaptation and electroretinographic studies and were interpreted as mildly hypoxic or toxic retinal effects of LSD. In the dark-adaptation curve, LSD delayed the rod-cone break and elevated the entire rod threshold. In the electroretinogram (ERG), the drug increased the scotopic bwave amplitudes and in some subjects also increased the scotopic a-wave amplitudes.
Because hallucinations and illusions were reported only when measurable ERG and dark-adaptation changes occurred, a possible retinal role in the induction of hallucinations was considered. Consequently, the present study was undertaken to clarify the role of a functioning retina in the induction of LSD-induced visual changes by studying subjects with total blindness (no light perception) and, insofar as could be determined, normal central nervous system