Marijuana and Glaucoma: Everything You Need to Know
Smoking or ingesting marijuana helps people with glaucoma because TCH, the key ingredient in marijuana, lowers eye pressure. However, its effectiveness is temporary, lasting eight hours after one dose.
Research suggests CBD has the opposite effect, raising eye pressure.
There are other alternative treatments besides marijuana for glaucoma.
THC, CBD, and Glaucoma
Many people have expressed interest in the idea of treating glaucoma (a group of degenerative eye disorders) with marijuana, THC or CBD. While CBD alone has no beneficial effects for glaucoma, marijuana and THC do lower eye pressure, which can help slow the progression of this condition.
Unfortunately, marijuana’s beneficial effects only last a short time. Marijuana use also comes with side effects that make it difficult to be considered a viable treatment.
There are other alternative treatments for glaucoma that are less risky than smoking, vaping or ingesting marijuana that can help manage glaucoma.
How Marijuana, CBD, and THC Affect Eyes
Marijuana and its primary active component, THC, affect your eyes in several ways.
The bloodshot eyes that often accompany marijuana use are the most noticeable of these effects. This happens because marijuana lowers your blood pressure and dilates the blood vessels in your eyes, making those vessels stand out more than usual.
You may also experience changes to your vision after smoking or consuming marijuana, including:
- Reduced contrast sensitivity (the ability to tell dark tones from light ones)
- Poor night vision
- Impaired depth perception
- Increased sensitivity to glare
- Infrequent blinking and dry eyes
All these effects are temporary. They go away gradually as marijuana leaves your system.
Evidence suggests that marijuana use may also affect peripheral vision and visual processing. These effects have not yet been studied enough for scientists to confirm their existence.
CBD alone does not produce any of these effects. You can take CBD in any form without worrying about how it will impact your vision.
Marijuana or THC and Glaucoma
People with glaucoma and medical researchers alike have shown interest in how marijuana can treat the group of disorders that, over time, can cause partial vision loss or even total blindness.
However, these findings do not mean you can ingest THC as a treatment for glaucoma. While THC does lower eye pressure temporarily, people glaucoma must keep their eye pressure low 24 hours a day to avoid permanent eye damage.
Given that, people would need three doses a day of THC oils to control eye pressure, each at precisely timed intervals. Smoking marijuana produces weaker effects and would have to be done even more frequently.
The 24-hour coverage is likely to disrupt everyday life, including sleep patterns. It would also be easy to miss a dose, which could have lasting consequences for someone living with glaucoma.
These factors make marijuana a sub-optimal treatment for glaucoma compared to other available treatments, such as conventional medications.
CBD and Glaucoma
Researchers have also studied CBD as a potential treatment for glaucoma. Research suggests CBD is not useful for treating glaucoma. In fact, it may worsen the condition and lead to worse outcomes overall.
A study by the University of Indiana found that applying moderate doses of CBD oil to rats’ eyes raised their eye pressure by 18 percent for approximately four hours. Sublingual CBD drops of similar strength have also been shown to produce similar effects. Lower doses had no observed effect on the subject’s eyes.
Risks of Using Marijuana with Glaucoma
Beyond impracticality, there are other reasons why vision care providers do not recommend marijuana as an alternative treatment for glaucoma. Marijuana use carries many risks for your overall health, including:
- Distressing psychological effects, such as hallucinations
- Increased risk of cardiac events
- Risk of brain damage and cognitive difficulties with prolonged use
- Lung damage if the marijuana is consumed by smoking
These side effects are particularly hard on older people. Since most people with glaucoma are over age 60, this makes marijuana a poor fit for treating this condition.
Prolonged marijuana use also creates difficulties in daily life. You cannot drive while under the influence of marijuana, and your judgement may be considered impaired. This limits what you can safely do and may cause you to make bad decisions with little ability to consider the consequences.
Finally, marijuana use has also been shown to lower blood pressure, which may impact blood flow to the optic nerve. This may cause damage to your retinal nerve and possibly lead to vision loss.
Myths About Marijuana/CBD/THC and Your Eyes
There are many myths about marijuana’s impact on eye health. To clear up these misconceptions, it is helpful to look at what marijuana and its cannabinoid components can and cannot do.
- Temporarily lower your eye pressure
- Provide these effects regardless of whether it is smoked, vaped, injected or ingested from pills or edibles
- Cure glaucoma
- Treat glaucoma on its own
- Be used safely on a 24/7 basis
CBD cannot lower eye pressure on either a temporary or ongoing basis. It may also increase your eye pressure in the short term.
Always check with your eye doctor if you have questions about how certain treatments or substances (including THC and CBD) can affect your eye health. They can tell you more about effective and safe ways to manage your eye conditions.
Alternative Treatments for Glaucoma
If you are interested in complementing your prescribed treatment for glaucoma with alternative treatments, there are many options beyond marijuana that you can explore. Among them:
- Omega-3 fatty acids
- Vitamins A, C and E
- Gingko Biloba
- Leafy Greens
- Green tea
- Adjusted sleeping positions
- Quitting smoking
Omega-3 Fatty Acids
Omega-3 fatty acids help regulate oxidative stress (the imbalance of free radicals and antioxidants) in the eyes of people with glaucoma. This may help to slow the development of the disease and prevent it from causing permanent damage to your eyes.
However, researchers have not yet fully investigated how this protective effect works or how strong it is. Since there are some risks associated with overconsumption of omega-3s (including an increased risk of sudden hemorrhage), eye doctors do not recommend this treatment for glaucoma at this time.
Vitamins A, C and E
Vitamins A, C and E are potent antioxidants that have been shown to have some beneficial effects on glaucoma patients. However, scientists are not sure how this effect is produced or whether it could be replicated with sufficient doses of supplements. This topic requires further investigation before any of these vitamins can be recommended as part of glaucoma treatment.
Gingko biloba is an herbal supplement that is often used to improve brain health and cognitive function. It is a powerful antioxidant that can also improve your circulation and protect your optic nerve from damage. All of these effects can help treat glaucoma.
Taking gingko biloba supplements for glaucoma is considered a low-risk alternative treatment. Researchers have not had the chance to study its effects fully, but it has few side effects and has the potential to help fight glaucoma from several different angles.
Leafy greens have been shown to help lower eye pressure and control glaucoma. The reason for this effect is not clear, but the prevailing theory is that the nitric oxide in these greens significantly lowers oxidative stress within the eye.
Leafy greens also contain a multitude of vitamins that are beneficial to eye health and overall health. They are also non-toxic unless consumed in impossibly large quantities. This makes them a low-risk alternative treatment that many eye doctors are happy to recommend in addition to conventional treatment.
Turmeric is an earthy-tasting spice that contains curcumin, a compound with antioxidant and anti-inflammatory properties. Studies show that it may help to protect the eye’s cells from the impact of reduced blood flow, a common problem for glaucoma patients.
Like nitric oxide, turmeric only produces negative side effects in very large doses. Turmeric consumption and supplements are generally considered a low-risk alternative glaucoma treatment that can help a patient’s overall health.
Green tea has antioxidant properties that can help fight the effects of glaucoma. However, it also contains small amounts of caffeine. Since caffeine has been shown to raise eye pressure in people at high risk for glaucoma, this may negate the team’s beneficial effects.
Sleeping with your head propped at a 20-degree incline has been shown to help regulate eye pressure at night. There are no side effects associated with doing this, and taking measures to keep your eye pressure low at night when you cannot actively control it can significantly slow the progression of glaucoma.
Glaucoma patients are also advised to avoid sleeping on one side. In some people, this can significantly raise eye pressure. For best results, try sleeping on your back as much as possible.
Regular moderate exercise has been shown to lower eye pressure and blood pressure, both of which lead to better outcomes with glaucoma. Exercise can also help to control systemic diseases like diabetes which can make glaucoma worse.
Quitting smoking has been linked to lower eye pressure and a lower risk of developing glaucoma. It also lowers inflammation in your body and is beneficial for your eye health overall.
Talk to your doctor for advice before beginning any alternative treatment.
Does CBD help with glaucoma?
CBD has not been shown to provide any benefit for people with glaucoma. Some studies have shown that it may increase eye pressure, potentially leading to a greater risk of eye damage from glaucoma.
What cannabinoid helps with glaucoma?
THC can be used to moderately reduce pressure in your eyes for a short period (usually around 8 hours). However, it is not recommended for use in treating glaucoma due to its many side effects and the need for frequent, carefully timed doses.
Glaucoma. (2022). American Optometric Association.
Glaucoma and Marijuana: What Ophthalmologists Want You to Know. (January 2019). University of Utah Health.
Cannabinoids for Glaucoma. (November 2021). American Academy of Ophthalmology EyeWiki.
Ginkgo biloba: An adjuvant therapy for progressive normal and high tension glaucoma. (February 2012). Molecular Vision: Biology and Genetics in Vision Research.
Alternative Treatments for Glaucoma. (October 2021). American Academy of Ophthalmology EyeWiki.
Marijuana and Glaucoma. (2001). Marijuana as Medicine? The Science Beyond the Controversy.
Effect of sublingual application of cannabinoids on intraocular pressure: a pilot study. (October 2006). Journal of Glaucoma.
Marijuana Smoking vs Cannabinoids for Glaucoma Therapy. (November 1998). Clinical Sciences.
Δ9-Tetrahydrocannabinol and Cannabidiol Differentially Regulate Intraocular Pressure. (December 2018). Investigative Ophthalmology and Visual Science.
CBD Oil May Worsen Glaucoma. (February 2019). American Academy of Ophthalmology.
Cannabinoids and glaucoma. (April 2004). British Journal of Ophthalmology.
Effects of cannabis on visual function and self-perceived visual quality. (January 2021). Scientific Reports.
Targeting Oxidative Stress for Treatment of Glaucoma and Optic Neuritis. (February 2017). Oxidative Medicine and Cellular Longevity.
Cannabis and Glaucoma. (August 2020). Glaucoma Today: Therapeutics Update.
Effects of different sleeping positions on intraocular pressure in secondary open-angle glaucoma and glaucoma suspect patients. (August 2018). Clinical Ophthalmology.
How does marijuana affect vision? (2022). Canadian Association of Optometrists.
A Review of Nitric Oxide for the Treatment of Glaucomatous Disease. (December 2017). Ophthalmology and Therapy.
Therapeutic potential of curcumin in eye diseases. (July 2019). Central European Journal of Immunology.
Last Updated April 19, 2022
Note: This page should not serve as a substitute for professional medical advice from a doctor or specialist. Please review our about page for more information.