National Eye Institute
Fact Sheet on theTherapeutic Use of
Marijuana for Glaucoma

Marijuana is a complex mixture of numerous chemical components, some of which have biological activity. Studies in the early 1970's showed that marijuana, when smoked, lowers the intraocular pressure in people with normal pressure and in those with glaucoma.

To follow-up on these findings in an effort to determine whether marijuana and/or its derivatives might be effective as a glaucoma treatment, the National Eye Institute (NEI), one of the federal government's National Institutes of Health, supported several research studies from 1976 to 1988. Studies using topical preparations containing marijuana derivatives did not demonstrate lowering of intraocular pressure in human subjects. Other studies demonstrated that one of marijuana's derivatives, delta-9-tetrahydrocannabinol (THC), as well as some other cannabinoids, lower intraocular pressure when administered by various routes: smoking, orally, or intravenously. However, none of these studies demonstrated that marijuana, or any of its components, could safely and effectively lower intraocular pressure enough to prevent optic nerve damage from glaucoma. Simply lowering intraocular pressure does not necessarily control the disease, as research with other potential glaucoma drugs has shown.

Furthermore, these studies have shown that smoking marijuana produces undesirable side effects for glaucoma patients, such as elevated blood pressure, dry eye, and euphoria in the majority of patients studied. Glaucoma patients who regularly and chronically smoke marijuana would also be at risk for respiratory system damage. In addition, the long-term ocular and systemic effects of marijuana use by glaucoma patients is unknown.

There is considerable variability in the composition and quality of marijuana from supply to supply. In addition, smoking is a less than optimal drug delivery system. Without a standardized product and method of assuring the bioavailability of its active ingredients, marijuana is problematic as a therapy for glaucoma.