Some research suggests that cannabis may improve symptoms of glaucoma, primarily by reducing pressure in the eye, which experts call intraocular pressure (IOP). However, the data on using cannabis for glaucoma are not unequivocal.

The American Academy of Ophthalmology (AAO) claims that cannabis is not a practical treatment for glaucoma.

A 2019 review highlights some promising research indicating that cannabis may ease symptoms of glaucoma. However, many of the studies had a poor design, with a small sample size or inadequate controls. Hence, the review authors note that more research is necessary before experts can draw any conclusions about cannabis for glaucoma.

Some doctors recommend cannabis for glaucoma, and a minority of people with the condition take it and believe that it helps. Some cannabis dispensaries also routinely dispense cannabis for glaucoma in states where it is a qualifying condition.

Without more research, one cannot conclude that cannabis can treat glaucoma. There is no conclusive scientific evidence that it is superior to standard treatments. However, some people with glaucoma say that cannabis helped them when other treatments did not.

Read on to learn more about cannabis and glaucoma, including the main benefits and potential risks.

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Glaucoma is a group of conditions that cause increased IOP, which damages the optic nerve. Over time, this can weaken vision and potentially lead to blindness.

Glaucoma is the leading cause of vision loss among people over the age of 60 years.

Reducing IOP is the most important tactic for decreasing the risk of glaucoma. Lowering IOP can also help ease glaucoma symptoms.

Traditional glaucoma treatments aim to decrease IOP. Proponents of medical cannabis believe that it, too, may cause IOP reduction.

Animal studies suggest that cannabis might promote blood flow to the eye or offer neuroprotective effects that prevent nerve damage and reduce the effects of glaucoma.

Some studies support the idea that cannabis might play a role in treating glaucoma.

For instance, according to a 2019 review, five randomized controlled trials found some evidence that cannabis could lower IOP. It is of note, though, that no studies compared cannabis with standard glaucoma treatment. Also, sample sizes were small, and the data were conflicting.

However, an older study found that tetrahydrocannabinol could lower IOP, while CBD increased it.

Various ophthalmic organizations do not recommend cannabis, because the evidence supporting its use is insufficient and because cannabis may cause side effects.

The AAO states that even if cannabis does decrease IOP, the effect is too short-lived to help with glaucoma. A person would need to take enormous quantities of cannabis to get any benefit or to see consistent symptom improvement.

Additionally, the AAO cautions that there is evidence that cannabis may harm the optic nerve. It notes that research on cannabidiol (CBD) is ongoing and may eventually show some benefits.

Currently, however, there is insufficient scientific support for cannabis as a glaucoma treatment.

Some evidence indicates that cannabinoids, which are the chemicals in cannabis, have neuroprotective properties.

According to animal studies, cannabinoids may increase blood flow to important structures in the eye.

Proponents of medical cannabis for glaucoma argue that these findings suggest glaucoma might help reverse glaucoma or even cure it, not just manage symptoms.

Other potential benefits of medical cannabis for glaucoma include:

  • fewer side effects than with other treatments
  • a reduced need for surgery
  • better pain management
  • a treatment people perceive as “natural”

However, research on cannabis for glaucoma is equivocal.

If a person replaces conventional treatments for glaucoma with cannabis, their condition may get worse. Also, cannabis is potentially addictive.

Moreover, cannabis is illegal in many countries and at the federal level in the United States. That is why using cannabis may subject a person to legal risks, including jail.

All treatments, including natural and alternative remedies, can cause side effects. Some risks and side effects of cannabis use include:

A small body of research notes that cannabis products could damage cells in the eye.

Studies into cannabis use have also linked it to vision loss and decreased color perception, although the data are correlative. This means that researchers have not proven that cannabis causes these effects.

No treatment can reverse vision loss from glaucoma. Instead, treatment focuses on preventing further damage. When medication proves ineffective, a person may need surgery.

Some people choose alternative treatments instead. These include:

  • Ginkgo biloba: Some people believe that the anti-inflammatory effects of this herb improve glaucoma symptoms.
  • Dark leafy greens: A diet rich in dark leafy greens correlates with a lower risk of developing glaucoma.
  • Omega-3 fatty acids: Consuming omega-3 fatty acids may help prevent inflammation and oxidative damage. Some people think omega-3 fatty acids may also prevent glaucoma, although research is not conclusive.
  • B vitamin supplements: One study found a link between low levels of vitamin B12 and thinner retinal nerves.
  • Antioxidant supplements: Antioxidants such as vitamin C and vitamin A might help reverse oxidative damage or inflammation to manage or treat glaucoma.
  • Melatonin: Melatonin may help ease sleep symptoms associated with glaucoma.
  • Lifestyle changes: To manage glaucoma more effectively, some people may find it helpful to:
  • Alternative and complementary medicine: Some people turn to acupuncture, massage therapy, or other interventions to help with glaucoma.

While some research suggests alternative therapies might help, or offers theoretical or animal models to support their use, there is no conclusive scientific data that these interventions help.

There is also no evidence that alternative treatments are superior to conventional treatments.

Living with glaucoma can be difficult, and treatment is not effective for everyone. Moreover, it is impossible to reverse vision damage resulting from glaucoma.

Consequently, many people turn to alternative treatments. Science has not fully explored the potential risks and benefits of cannabis. It is possible that scientific research will eventually back up people’s anecdotal experiences. Currently, however, there is not enough evidence to support cannabis use as a glaucoma treatment.

People who still wish to try cannabis should seek guidance from a doctor who is knowledgeable about medical cannabis.

It is advisable to discuss the risks, benefits, and side effects and to learn about the potential legal risks.