You may have heard that smoking marijuana can treat glaucoma. The truth? It’s a myth.

Experts at the John A. Moran Eye Center want patients to know that while cannabis can lower eye pressure for a short time, it’s not an effective or safe treatment for glaucoma. Here’s what researchers have discovered, why cannabis doesn’t work for this condition, and what your doctor recommends instead.*

Understanding Glaucoma and Treatment Options

Glaucoma is a chronic eye condition that damages the optic nerve over time. Left untreated, it can cause permanent vision loss or even blindness. The disease is driven by elevated intraocular pressure (IOP), which often fluctuates and makes it difficult to manage.

For decades, treatment has focused on:

• Prescription eye drops to lower eye pressure.
• Laser therapy or surgery to improve drainage and prevent further damage.

These methods are proven to protect vision when used consistently and monitored by a specialist.

Where the Cannabis Rumor Came From

In the 1970s, small studies showed that marijuana could temporarily reduce IOP. That led many patients to wonder if cannabis might be a natural alternative to medications or surgery.

But further research revealed a major problem:

• Cannabis only lowered pressure for three to four hours.
• To maintain protection, you’d need to smoke marijuana six to eight times a day, every day.

As glaucoma specialist Dr. Craig J. Chaya explained:

“Glaucoma needs to be treated 24 hours a day. Smoking that much marijuana would leave you unable to function normally. Obviously, that’s a problem.”

Why Cannabis Doesn’t Work for Glaucoma

Beyond its short duration, cannabis carries other side effects that make it unsuitable for glaucoma patients:

• Tachycardia (rapid heart rate)
• Lowered blood pressure, which reduces blood flow to the optic nerve, undoing any benefit from lowered IOP.

Researchers even tested THC-based eyedrops, but they found two problems:

1. The drops did not significantly lower eye pressure.
2. They caused severe eye irritation.

What Doctors Recommend

The American Glaucoma Society has a clear position:

“Although marijuana can lower the intraocular pressure, 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.” 

In short, cannabis isn’t a treatment. Patients should continue following their doctor’s prescribed plan, whether that’s drops, laser therapy, or surgery.

The Bigger Picture

With legalization expanding across the U.S. and research confirming benefits of cannabis for other conditions, calls for more study continue. In 2017, the National Academies of Sciences, Engineering, and Medicine published a major report on cannabis use, highlighting both potential benefits and risks, and urging more research.

But for now, the advice for glaucoma patients remains clear: stick with proven treatments prescribed by your eye doctor.

* University of Utah, Health. Glaucoma and Cannabis: What Ophthalmologists Want You to Know (May 7, 2025). healthcare.utah.edu

To ensure that we always provide you with high-quality, reliable information, The Glaucoma Community closely vets all sources. We do not, however, endorse or recommend any specific providers, treatments, or products, and the use of a given source does not imply an endorsement of any provider, treatment, medication, procedure, or device discussed within.