Hallucinogens; Methadone; Narcotics; PCP (Phencyclidine) 

Drug abuse has a range of definitions, all of them suggesting disaproval at the use or overuse of a drug for a nontherapeutic effect . Leon Wurmser goes as far as to say "The term is so wide and imprecise, contains such a hodgepodge of clinical and social phenomena, and is so dependent on the bias of the observer, that a systematic study of its etiology would be as vast and comprehensive as an inquiry into the etiology of fever" . ...

Corneal injury as related to Drug Abuse