Can Marijuana Treat Glaucoma (Legally)?

As marijuana use becomes more accepted and increasingly legalized, glaucoma patients frequently ask if marijuana can be used to treat glaucoma. We need to explain some truths and dispel some myths. 

Marijuana is legal for medical use in 30 US states and for recreational use in 9 US States (at the time this was written). It’s legal across Canada for recreational use. Despite the relaxed attitude around marijuana, it is still classified by the Federal Drug Enforcement Agency as a Schedule I controlled substance (the same category as heroin and LSD). 

Does Marijuana Lower Eye Pressure?

Marijuana’s ability to lower intraocular pressure (IOP) was discovered in the 1970s. Elevated IOP is the major risk factor for developing glaucoma and for the progression of glaucoma.  Treatment is focused solely on reducing IOP. Many have wondered whether marijuana could be used as a therapy to lower IOP and prevent glaucoma from getting worse or causing blindness. 

While marijuana does lower IOP, it has major drawbacks as a treatment for a chronic, long-term disease like glaucoma:

• First, unlike glaucoma eye drops (some of which are effective for up to 24 hours), smoking THC reduces eye pressure for only 3-4 hours
• Marijuana would require 8-10 doses throughout the day
• This would cost more than typical glaucoma treatment
• The physical and mental side effects of frequent marijuana use would reduce one’s productivity
• Marijuana also impairs judgment and coordination, increases paranoia, elevates heart rate, and irritates the eyes

 What are the long term side effects?

Marijuana can cause permanent lung damage when smoked, and possible permanent adverse effects on cognition and mental health. With regular use, tolerance to the eye pressure-lowering effects develops, meaning that increasing drug levels would be required to prevent progression of glaucoma. Moreover, lack of regulation and quality control makes the efficacy and safety of marijuana unpredictable. Research efforts to develop THC eye drops that can effectively lower eye pressure while minimizing side effects are being studied, but have not yet been successful.

What About CBD (cannabidiol) Oil?

New evidence has emerged showing that parts of the cannabis plant, specifically cannabidiol (CBD), the non-intoxicating, trendy component, may actually worsen glaucoma symptoms. Researchers at Indiana University published a study in the journal Investigative Ophthalmology & Visual Science that shows CBD increases pressure in the eye. This is problematic, they say, considering that CBD has become such a household name in American culture that many people, some of which may have or be at risk for glaucoma, are using it haphazardly as a natural, harmless medicine. But in reality, CBD could be destroying their overall eye health.

The Final Verdict on Marijuana & CBD

For these reasons, smoking marijuana or using CBD oil is not recommended as a medical treatment for glaucoma. If you use marijuana or CBD oil, let your ophthalmologist know since it may have an impact on your eye pressure readings. Also, it is very important to continue the glaucoma treatment recommended by your ophthalmologist. This treatment and regular monitoring can help you maintain your vision for the rest of your life.