Objective To discuss the clinical effects, including toxicological data, of marijuana and its many constituent compounds on the eye and the remainder of the body. A perspective is given on the use of marijuana and the cannabinoids in the treatment of glaucoma.
Results Although it is undisputed that smoking of marijuana plant material causes a fall in intraocular pressure (IOP) in 60% to 65% of users, continued use at a rate needed to control glaucomatous IOP would lead to substantial systemic toxic effects revealed as pathological changes.
Conclusions Development of drugs based on the cannabinoid molecule or its agonists for use as topical or oral antiglaucoma medications seems to be worthy of further pursuit. Among the latter chemicals, some have no known adverse psychoactive side effects. Smoking of marijuana plant material for the reduction of elevated IOP in glaucoma is ill-advised, given its toxicological profile.
PREVIOUS REVIEWS of the ocular and toxic effects of marijuana1–6 have provided considerable background on general human responses. Use of marijuana for medicinal purposes decreased markedly in Western civilizations during the 1930s and 1940s, due to the variable potency of these herbal preparations and the parallel development of specific medications that were more potent and targeted toward specific symptoms. This philosophical alteration in medical therapy reflected changes that occurred in all branches of medicine.7 Only in the latter part of this century has marijuana been used as a pleasure-inducing substance during liberalization of ethics and social behavior in many cultures.8–10 After tobacco, alcohol, and caffeine, it is probably the most widely used drug in society.
More recently, legislation has been passed by certain states (with subsequent revocation in 1 state) that has led to a resurgence of interest in the evaluation of possible medical uses of marijuana. Extensive evaluations have resulted in 1 report to the director of the National Institutes of Health,11 and will result in another from the Institute of Medicine of the National Academy of Sciences. Furthermore, a meeting on this topic held in March 1998 at New York University School of Medicine, New York, will result in publication of a book in the spring of 1999.12 In many areas of interest, there is little but anecdotal material on which to rely, but in the area of glaucoma, there exists a substantial literature.