Glaucoma patients ask for marijuana prescriptions because they have false notions of its effectiveness in treating the eye disease, a new survey has found.
And the trend toward legalization of marijuana has lent additional weight to those misconceptions, the results suggested.
Recent research has shown that prescription eye drops are much more effective than marijuana in treating glaucoma, an eye disease that afflicts more than 2 million Americans, said survey author Dr. David Belyea. He is director of glaucoma services at the George Washington University School of Medicine & Health Sciences, in Washington, D.C.
Eye doctors need to step up their education efforts and make sure that people understand that marijuana is an impractical option, Belyea and colleagues conclude in their report, which is published Dec. 23 in the journal JAMA Ophthalmology.
Glaucoma causes blindness by increasing the fluid pressure inside the eyeball, squeezing and damaging the optic nerve, according to the U.S. National Institutes of Health.
Early research showed that smoking marijuana can reduce fluid pressure inside the eye, but it’s of limited value because the drug’s effects are short-lived, said Dr. Eve Higginbotham, a professor of ophthalmology and a vice dean of the University of Pennsylvania’s Perelman School of Medicine in Philadelphia.
Marijuana only relieves eye pressure for three to four hours, meaning that people would have to smoke pot eight to 10 times a day to sustain its beneficial effects. “You have to smoke it continuously, and you just can’t live that way,” said Higginbotham, who wrote an accompanying editorial.
At the same time, new eye drops have come onto the market that are much more effective than marijuana at reducing eye pressure and have longer-lasting effects, said Mitch Earleywine, an advisory board member for NORML, which advocates for reform of marijuana laws.
“Legendary case studies from 30 years ago consistently support medical cannabis as a potential treatment for glaucoma, but subsequent research has identified potentially better treatments,” said Earleywine, a professor of psychology at the State University of New York at Albany.
Despite this, glaucoma patients continue to ask eye doctors for a marijuana prescription to treat their condition, Belyea said. To find out why, he and his colleagues surveyed 204 patients being treated at a glaucoma clinic in Washington, D.C., which legalized medical marijuana in 2010.
The researchers found that patients ask for a marijuana prescription based on the fact that states are legalizing pot for medical uses, which gives them the idea that it must be an effective treatment.
“As states have passed this, patients were feeling that legalization gave the treatment credibility,” Belyea said.
Patients also are likely to ask for marijuana based on false beliefs regarding its effectiveness, the researchers found.
Their glaucoma care also mattered greatly — people were more likely to ask for marijuana if they were not satisfied with the quality of their care or if they felt their medications were too expensive.
Interestingly, the severity of a person’s glaucoma did not influence whether they wanted to try marijuana. “It didn’t seem to be a motivator for the intention to use it,” Belyea said.
Higginbotham said the study underscores “how important it is for providers to understand patients’ concerns about their treatment, and if patients are not tolerating their current treatment, to address those concerns. Because I think that’s what drives patients to explore other options.”
The American Academy of Ophthalmology has put out a statement that says there is “no scientific benefit” for marijuana use in glaucoma, compared to other widely available medications, Belyea noted.
He has found that providing a copy of the statement to patients is very helpful in clearing the air. “It seems to be effective, and patients seem to understand it,” he said. “They don’t ask again for this therapy once they’ve read it and we’ve discussed it with them.”
But Higginbotham said patients may need more than just an evidence review.
“There is a lot of fear, when patients are diagnosed with glaucoma, and that has to be addressed,” Higginbotham said. “It’s not just educating people about what’s evidence and what’s not evidence, but dealing with the emotions involved with having a disease that could lead to blindness.”
For more information on marijuana and glaucoma, visit the American Academy of Ophthalmology.