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Krill AE, Alpert HJ, Ostfeld AM. 
“Effects of a hallucinogenic agent in totally blind subjects”. 
Arch. Ophthal.. 1963;69:180-185.
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 function.


Twenty-four totally blind subjects were studied. Four subjects were totally blind by age of 2 and were designated as congenitally blind. All of these subjects probably had some vision at birth.


14/20 non-congenitally blind (lost sight after birth) experienced visual hallucinations. 7/14 hallucinated in color, 7/14 in black and white. 0/4 congenitally blind (blind since birth) experienced visual hallucinations. There was also a higher incidence of auditory, tactile, gustatory, and olfactory hallucinations in both the non-congenital and congenital groups compared to sighted people.
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