Should I Use Marijuana to Treat My Glaucoma?
By St. George Eye Center
Glaucoma is an ugly disease. It damages the optic nerve, the communication pathway between eye and brain, resulting in permanent, progressive loss of vision. There is no cure. For decades, physicians and scientists have worked diligently to solve the problem of glaucoma. Still, the only effective treatment is to lower eye pressure (referred to as intraocular pressure or IOP) with eye drops, laser procedures, or surgery.
In 1971, scientists first reported that smoking marijuana could lower IOP.1 This led some to view cannabis and its derivatives, cannabidiol (CBD) and tetrahydrocannabinoid (THC), as potential treatments for glaucoma. As excitement grows around shifting marijuana laws, many patients are wondering if cannabis is a safe and effective treatment for glaucoma. The short answer is a resounding NO! The longer answer provides insights for the larger debate about medical marijuana.
Effect on Pressure(s)
As mentioned above, studies of cannabis and THC performed in the 1970s and 1980s did show a reduction in IOP. However, the effect was very short-lived, lasting only three to four hours.1 In order to reduce the risk of vision loss from glaucoma, IOP must be consistently lowered twenty-four hours per day. Cannabis use also lowers the blood pressure. Low blood pressure can reduce blood flow to the optic nerve, resulting in further damage.2 Finally, a recent study reported that CBD use actually increases IOP, making glaucoma-related vision loss more likely.3
Cost and Other Side Effects
Due to the short IOP-lowering effect of cannabis, a glaucoma patient would need to ingest eighteen to twenty mg of THC six to eight times daily in order to have the effect of one drop of latanoprost (a common glaucoma medication).4 Depending on the potency of pot available, that is the equivalent of smoking eight to ten marijuana joints per day.5 This level of cannabis use would affect a patient’s mental clarity and mood, impairing their ability to work, drive, operate machinery, and perform many functions of daily living. If smoked, lung health would be impacted. Aside from the health risks, the financial impact would be prohibitive. According to Oxford Treatment Centers, the average cost per joint of “medium quality” marijuana in Utah is $5.68, making the annual cost of this regimen over $20,000.4
More research is needed in order to determine the safety and efficacy of cannabis in the treatment of human disease in general and glaucoma specifically. Unknowns include teratogenicity (birth defects), carcinogenicity (cancer-causing effects), levels excreted into breast milk, and many others. Currently approved medications have undergone extensive vetting. Marijuana and its derivatives have not seen this level of scrutiny.
The Bottom Line
Current formulations and delivery vehicles for cannabis and its derivatives are NOT effective or safe in the management of glaucoma or other eye diseases. They are Not endorsed or recommended by the American Academy of Ophthalmology or the American Glaucoma Society.6,7 Do not attempt to self-medicate glaucoma with marijuana or its derivatives.
It is important to note that patients who suffer from glaucoma have never had more options for safe and effective treatment. Talk with your ophthalmologist about which therapies are right for you.
Works Cited: 1. Hepler RS, Frank IR. Marihuana smoking and intraocular pressure. JAMA 1971;217(10):1392. 2. Novack GD. Cannabinoids for treatment of glaucoma.Curr Opin Ophthalmol.2016;27(2):146-150. 3. Miller S, Daily L, Leishman E, Bradshaw H, Straiker A. Δ9-Tetrahydrocannabinol and Cannabidiol Differentially Regulate Intraocular Pressure. Investigative Opthalmology & Visual Science, 2018; 59 (15): 5904. 4. The average cost of marijuana by state. Oxford Treatment Center. https://www.oxfordtreatment.com /substance-abuse/marijuana/average-cost-of-marijuana/. Accessed July 30, 2019. 5. Barreda A, De Leon K, Urmas S. A simple guide to pot, thc and how much is too much. Los Angeles Times. 2018; https://www.latimes.com/projects/la-me-weed-101-thc-calculator/. Accessed July 30, 2019. 6. American Academy of Ophthalmology. Marijuana in the Treatment of Glaucoma CTA – 2014. https://www.aao.org/complimentary-therapy-assessment/marijuana-in-treatment-of-glaucoma-cta–may-2003. Accessed July 30, 2019. 7. Jampel H. American glaucoma society position statement: marijuana and the treatment of glaucoma. J Glaucoma. 2010;19(2):75-76.