A 33-year-old female patient developed a hallucinogen-persisting perception disorder (HPPD) after lysergic acid diethylamide (LSD) abuse for a year at the age of 18. Specifically, she reported after images, perception of movement in her peripheral visual fields, blurring of small patterns, halo effects, and macro- and micropsia. Previous treatment with antidepressants and risperidone failed to...