Marijuana & Glaucoma: Risks, Alternatives & More

Marijuana and glaucoma have a complicated relationship. Marijuana can lower pressure within the eye, but the effects only last for a few hours. To produce a meaningful change in eye pressure, the American Academy of Ophthalmology (AAO) estimates that people would need to ingest up to 20 mg of THC six to eight times per day. That amount is far too high for many people.

Additionally, marijuana can lower blood pressure. The optic nerve depends on a constant flow of blood. Marijuana users could effectively cancel out the vision benefits of lower eye pressure by damage to the optic nerve due to reduced blood flow.

As a result, the AAO and others do not recommend marijuana for the treatment of glaucoma.

If you’re considering a marijuana and glaucoma combination, talk to your doctor first. Together, you can explore the risks and potential benefits and develop a plan that’s right for you and your health.

What Is Glaucoma?

Glaucoma is a disease involving fluid buildup within the eye. As the pressure builds, the optic nerve at the back of the eye is compressed. Eventually, that nerve stops transmitting visual information to the brain.

The AAO says glaucoma is a leading cause of blindness for people older than 60. However, blindness can be prevented with the proper treatment.

Typically, treating glaucoma involves using medications (like eye drops) to lower pressure within the eye by reducing the amount of fluids the eyes create. Some people also need surgery to help excess fluids drain.

How Does Marijuana Affect the Eyes

Marijuana can lower intraocular pressure (IOP) within the eyes and reduce blood pressure, which by extension can reduce the amount of blood flowing through the eye. Lower IOP is considered good for overall eye health, but reduced blood flow is not good, especially for eye health conditions where blood flow is already a concern. 

This reduction in IOP lasts about three to four hours.

Why Marijuana Is Not a Good Treatment for Glaucoma

In the official position statement about marijuana and glaucoma from the American Glaucoma Society, experts say the following: “Although marijuana can lower the intraocular pressure (IOP), its side effects and short duration of action, coupled with a lack of evidence that its use alters the course of glaucoma, preclude recommending this drug in any form for the treatment of glaucoma at the present time.”

Marijuana also has various side effects that must be accounted for when considering it as a treatment option. It affects mood and motor function and prevents users from being able to safely perform many tasks, such as driving. It can also affect lung and brain health over time.

To get the full benefit of marijuana on eye pressure, you must use a lot of it. Doing so could increase your risk of substance use disorder or addiction. The Centers for Disease Control and Prevention summarized research on the topic and found that people who use cannabis have about a 10% likelihood of getting addicted.

Perhaps most importantly, no study has found it to be a sufficient glaucoma treatment. Considering the above, and without further evidence supporting its use to treat glaucoma, marijuana can’t be medically justified as a glaucoma treatment, even if one argues further studies should be conducted on its use for that purpose.

Origins of This Treatment Myth

The origin of the internet myth that marijuana can treat glaucoma is understandable. IOP is known to be a major component of glaucoma, and marijuana has been proven to lower IOP temporarily. 

Furthermore, it is touted fairly often as an alternate treatment to a variety of health conditions, the support for which varies depending on the particular use case being discussed. Since marijuana has proven useful for some health conditions, people are eager to tout its benefits for glaucoma, but these claims are currently unfounded.

Eye Risks Associated With Marijuana

A 2021 study of cannabis found that smoking cannabis impairs vision, linking habitual cannabis use to lower visual acuity. Notably, that study was reluctant to make too many conclusions based on their findings, suggesting a number of ways follow-up studies could improve on its findings and produce more definitive conclusions. 

Perhaps more importantly, the fact marijuana can lower blood pressure reduces or completely negates any small benefit it may provide as a glaucoma treatment. This reduction in blood pressure has the potential to affect blood flow to the eye enough that it may actually worsen a person’s glaucoma, although this potential hasn’t been significantly studied.

Does THC or CBD Help With Glaucoma?

The risks of marijuana and glaucoma treatment can involve the lungs. Smoking large amounts of marijuana leaves and stems could be harmful to the delicate structures used in breathing. Some people wonder if THC or CBD products might work better.

In 2020, researchers examined multiple published studies involving cannabis in glaucoma, including several involving eye drops. They point out that cannabis molecules need lipids (fat cells) to stay active when they’re stored. Cannabis eye drops are often made of oils as a result, which can be uncomfortable for patients.

In addition, no studies published between the 1980s and the 2000s found that these drops had a meaningful impact on eye pressure.

The AAO says CBD eye drops can raise eye pressure, making them harmful (not helpful) for people with glaucoma. They say this means more research is required before people should consider CBD as a glaucoma treatment.

With this said, researchers are interested in the ability of marijuana to lower IOP. The hope is that they may be able to isolate this property and remove or reduce the associated side effects of marijuana. Whether this research results in the development of a new, evidence-based glaucoma treatment remains to be seen, but it is possible a treatment derived from marijuana may exist in the future.

Marijuana Addiction

Important to this discussion is the possibility of marijuana addiction. While many people who smoke marijuana don’t develop an addiction, some mistakenly believe it isn’t possible to develop a marijuana addiction, which isn’t true. The CDC notes that different studies have placed the rate of cannabis use disorder (CUD) among people who use marijuana between about 10 and 30 percent.

This risk of addiction is another reason to avoid using marijuana as a glaucoma treatment. Even if cannabis isn’t the most destructive drug a person can misuse, it still can have detrimental effects on a person’s health and well-being, especially if they lose control of their drug use. This is combined with the fact marijuana simply doesn’t treat glaucoma.

When to Seek Help

Whether you started using marijuana in an effort to improve health conditions or not, use can spiral out of control. If you feel you’ve lost control of your marijuana use, or it has started to impact your health or quality of life, you should seek help. By talking to an addiction specialist, you can develop a treatment plan to regain control over your life and stop your drug use. 

Addiction of any kind is a serious issue and can damage a person’s relationships, finances, and more. The good news is that recovery is possible. In the case of marijuana, withdrawal symptoms tend to be mild, which is what many people consider one of the more difficult parts of the recovery process.

Medically Reviewed By Dr. Alison Tarlow

Dr. Alison Tarlow is a Licensed Clinical Psychologist in the States of Florida and Pennsylvania, and a Certified Addictions Professional (CAP). She has been a practicing psychologist for over 15 years. Sh... Read More