HPPD meaning in General ?

Hallucinogen persisting perception disorder (HPPD) is a chronic and non-psychotic disorder in which a person experiences apparent lasting or persistent visual hallucinations or perceptual distortions after a previous hallucinogenic drug experience, usually lacking the same feelings of intoxication or mental alteration experienced while on the drug. The hallucinations and perceptual changes themselves are usually not intense or impairing and consist of visual snow, trails and after images (palinopsia), light fractals on flat surfaces, intensified colors or other psychedelic visuals. People who have never previously taken drugs have also reported some visual anomalies associated with HPPD (such as floaters and visual snow).

To be diagnosed, the disorder must cause distress or impairment in work or everyday life. Symptoms often get worse when focused on.