Medical marijuana has been promoted as a treatment for many diseases, including glaucoma. With recreational marijuana on the verge of being legal in Canada, it's tempting to consider self medicating with this controversial drug without consulting your eye care professional. But is using marijuana really an effective way of managing glaucoma?
Glaucoma is a disease of the optic nerve in the back of the eye. It becomes damaged over time, reducing side vision and if left untreated, will lead to blindness. One cause of optic nerve damage in glaucoma is higher-than-normal pressure within the eye (intraocular pressure or "IOP").
Currently, the only way to control glaucoma and prevent vision loss is to lower IOP levels with medication, such as prescription eye drops, or surgery, depending on the type of glaucoma and the severity.
Early studies conducted in the United States examined whether marijuana or its active ingredient, THC, could be used to keep IOP lowered. The research found that when marijuana is smoked, it does lower IOP. However, it only lowers IOP for about three or four hours.
Because glaucoma needs to be treated 24 hours a day, 365 days a year, you would need to smoke marijuana up to eight times a day, everyday to receive the benefit of a consistent lowered IOP. This would not be practical for everyday, working individuals because smoking so much marijuana daily would leave you too impaired to drive, operate equipment or function at the peak of your mental ability.
The effect that marijuana has on your ability to function is not the only side effect of the drug.
Marijuana cigarettes contain hundreds of compounds that can damage the lungs. Long term marijuana smoking can lead to emphysema-like lung changes, and possible increase in the frequency of lung cancer.
Unfortunately, marijuana not only lowers IOP, but it lowers blood pressure throughout the body. Reduced flow of blood to the optic nerve may also cause further damage in patients with glaucoma. As a result of marijuana potentially lowering the blood flow to the optic nerve, it reduces or eliminates whatever beneficial effect that developed from lowering the IOP.
It's best to stick with tested and proven treatment methods to address glaucoma. Always ask your ophthalmologist what's the best glaucoma treatment option for your specific case.