Three other reports deal with the effects of hallucinogenic drugs on blind subjects. Alema reported that 50 micrograms of orally administered LSD induced elaborate visual hallucinations in a subject with bilateral enucleations of the eyeball. However, the effects of 50 micrograms of LSD are stated to have persisted for the incredibly long period of 5 days (they usually last 6 hours). This subject was noted to have spontaneous visual activity.

via Mind Hacks: Do blind people hallucinate on LSD?.