Can Marijuana Effectively Treat Glaucoma?

Currently, 23 states have legalized recreational marijuana and some glaucoma patients are using the drug in lieu of their traditional medications–but does it help? Michigan Medicine ophthalmologist, Theresa M. Cooney, MD, says it is complicated.

In the 1970s, cannabinoids were used to reduce intraocular pressure (IOP). According to Cooney, marijuana can reduce IOP by 25% in 60% to 65% of people with or without glaucoma. The caveat is that the effects are not long lasting. In fact, the reduced IOP only lasts 3 to 3.5 hours. IOP must be continuously controlled in order to be an effective glaucoma treatment. Cooney notes, “You’d need to smoke eight to 10 marijuana cigarettes a day for them to have the same effectiveness as regular glaucoma drops.”

In conjunction with reduced IOP, marijuana results in reduced blood pressure. This in turn worsens glaucoma because reducing blood flow to optic nerves means increasing potential optic nerve damage.

In the past decade, studies have found receptors for active ingredients of marijuana in the tissues of the eyes. Cooney adds, “There have been no long-term studies demonstrating whether or not long-standing usage of marijuana maintains visual function, visual fields or stable optic nerves.” The latest question has been whether tetrahydrocannabinol (THC) could be beneficial to glaucoma patients, as it is not toxic to lungs like marijuana. However, there has not yet been an effective THC eye drop, and topical applications have resulted in corneal damage.

More studies are needed to explore the benefits and risks of marijuana for the treatment of glaucoma.

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