How Medical Marijuana Treats Glaucoma

Many people are wondering about the possible use of marijuana instead of eye drops to treat glaucoma. Glaucoma is a disease of the optic nerve, the nerve cable that connects the eye to the brain. Glaucoma can cause significant vision loss and even blindness. Most types of glaucoma coexist with high pressure inside the eye. Limited research has shown that marijuana could potentially treat glaucoma because of its ability to lower the pressure in the eye.

Pharmacist holding bag of medical marijuana
Jupiterimages / Getty Images

Traditional Treatments

An eye doctor's main goal in the treatment of glaucoma is to lower eye pressure to a safe level in order to halt damage caused by the high-pressure levels. Treatment typically includes prescribing medications, using laser treatments, or surgery.

Most glaucoma patients are treated with topical medication eye drops that lower the pressure in the eye to a level where the glaucoma does not progress. Unfortunately, some people do not tolerate daily eye drops very well and additional glaucoma therapies are sought.

Marijuana's Effect on Glaucoma

As several more states attempt to legalize the use of marijuana for medicinal uses, it has become a hot topic for glaucoma patients as some studies have shown that smoking marijuana can lower eye pressure, both generally and in people that suffer from glaucoma. People who cannot tolerate typical glaucoma medications might be able to use marijuana to effectively lower their eye pressure.

Downsides of Smoking Marijuana

Scientists have found that marijuana does lower eye pressure but the effects only last for 3 or 4 hours. This means that to lower eye pressure adequately, marijuana would have to be smoked every 3 hours.

Because marijuana causes mood-altering effects, smoking it every 3-4 hours would be impossible for people who drive for a living, operate heavy machinery, or have jobs that require close attention to detail.

Also of great concern is that marijuana cigarettes contain chemical compounds that can damage the lungs similar to regular tobacco cigarette smoking. Studies also show that chronic use of marijuana can have unwanted and sometimes permanent effects on brain function.

Marijuana Eye Drops

If the harmful effects of marijuana are mainly caused by inhalation, could doctors administer the active ingredient, THC (tetrahydrocannabinol), in a different way? Scientists have conducted studies in which patients ingested THC through oral (by mouth) or sublingual (under the tongue) methods and also in topical eye drops.

Although oral or sublingual methods avoid lung problems, they have other unwanted side effects. Because glaucoma is a chronic disease, unwanted systemic side effects make THC a poor option for treatment.

While eye drops sound like the most logical method of taking the drug, THC is not very water-soluble. As a result, it has been difficult to develop an eye drop with high enough concentrations of THC to be effective.

Negative Effects

If oral THC could be tolerated, more long-term studies are needed to make sure that it will not worsen glaucoma. Research has shown that some glaucoma is worsened by a lack of proper blood flow to the optic nerve. Marijuana actually reduces blood pressure so it is possible that marijuana could worsen the glaucoma by making the optic nerve receive less blood flow.

On the other hand, recent research shows that marijuana may not only treat glaucoma by reducing eye pressure, but it may also act on certain receptors to provide a type of neuro-protection against damage to the optic nerve. This would treat glaucoma in a different way, and it is worth conducting further studies.

Until then, researchers are focusing on a better way to make a THC formulation that people can tolerate and that will have a longer duration of action. For now, glaucoma patients should stick with doctor recommended traditional glaucoma medications.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. NIH National Eye Institute. Glaucoma.

  2. Rapino C, Tortolani D, Scipioni L, Maccarrone M. Neuroprotection by (endo) cannabinoids in glaucoma and retinal neurodegenerative diseases. Curr Neuropharmacol. 2018;16(7):959-970. doi:10.2174/1570159X15666170724104305

  3. Sun X, Xu CS, Chadha N, Chen A, Liu J. Marijuana for glaucoma: A recipe for disaster or treatment?Yale J Biol Med. 2015;88(3):265–269.

  4. American Academy of Ophthalmology. Does marijuana help treat glaucoma or other eye conditions?

  5. Volkow ND, Baler RD, Compton WM, Weiss SR. Adverse health effects of marijuana use. N Engl J Med. 2014;370(23):2219-27. doi:10.1056/NEJMra1402309

  6. Glaucoma Research Foundation. Does blood pressure affect glaucoma?

Additional Reading

By Troy Bedinghaus, OD
Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association.