title: Persisting visual hallucinations and illusions in previously drug-addicted patients.
abstract: BACKGROUND
  Tetrahydrocannabinol (cannabis) and lysergic acid diethylamide (LSD) are psychomimetic agents that induce impairment of sensory perception. Illusions and hallucinations are mostly visual. Most frequently the visual phenomena occur in conjunction with drug abuse.
  
  
  METHODS
  Three previously drug-addicted patients were examined for either persisting or spontaneously recurrent visual phenomena. Two patients complained of persisting visual illusions (vibrations, dyskinetopsia and impaired depth perception) during more than 12 months after an excessive use of cannabis. The third patient was a multiple drug abuser (LSD for 6 years) and complained of visual hallucinations and palinopsia following heavy ethanol intake, 20 years after stopping the use of any drug.
  
  
  RESULTS
  Results from neuro-ophthalmic and neurological examinations were normal for the first two patients. The third patient presented abnormal visual fields with preserved visual acuity; electroencephalography was abnormal, suggesting an underlying toxic encephalopathy.
  
  
  CONCLUSIONS
  Persistent visual illusions or hallucinations can occur during several months after an intake of cannabis. Flash-back phenomena are frequent amongst LSD abusers. They rarely occur at long times after the last intake (20 years in the present case); when they do so, precipitating factors are often present (ethanol, medication, anesthesia). Such phenomena reflect the cortical dysfunctions that can be induced by illegal substances.
authors.affiliation: Hôpital Ophtalmique Jules Gonin, Lausanne, Switzerland.
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Gaillard
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Borruat
mesh_terms: D000293:Adolescent; D000328:Adult; D000428:Alcohol Drinking / Q000009:adverse effects; D002908:Chronic Disease; D013759:Dronabinol / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006212:Hallucinations / Q000139:chemically induced* / Q000175:diagnosis; D006213:Hallucinogens / Q000009:adverse effects*; D006801:Humans; D008238:Lysergic Acid Diethylamide / Q000009:adverse effects*; D008297:Male; D002189:Marijuana Abuse / Q000150:complications* / Q000534:rehabilitation; D009903:Optical Illusions / Q000187:drug effects*; D013375:Substance Withdrawal Syndrome / Q000175:diagnosis*; D019966:Substance-Related Disorders / Q000150:complications* / Q000534:rehabilitation
chemical_list: D006213:Hallucinogens; D013759:Dronabinol; D008238:Lysergic Acid Diethylamide