Marijuana doesn't help much for glaucoma, but a research study finds many patients want it anyway. Where cannabis is legal, the authors warn,physicians should expect patients will use it to self-medicate.
Marijuana has limited therapeutic value in treating glaucoma, but patients appear ready to try it, a George Washington University School of Medicine and Health Sciences study has found.
Writing in JAMA, David Belyea, MD, MBA of the school’s ophthalmology department faculty, and colleagues surveyed patients. Washington, DC, where the university is located, has legalized both recreational and medical marijuana use.
“Understanding [patients'] intentions will become even more important as states continue to legalize marijuana for recreational use (currently Washington, DC, and 4 other states), as patients with glaucoma will then have access to marijuana without the need for a physician to prescribe this drug,” the authors wrote.
That means physicians, general ophthalmologists, and glaucoma specialists should talk to patients and give them accurate information on marijuana’s limited efficacy and its potential for adverse effects.
Cannabis does work to lower intraocular pressure, but only for a few hours, the team wrote.
Further, the authors note, in 2010, the American Glaucoma Society recommended against the use of marijuana in the treatment of glaucoma given its short duration of action, its documented adverse effects, and the lack of scientific evidence that its use could alter the course of glaucoma.
Of 204 patients with glaucoma who completed the survey, about 60% said they knew marijuana was sometimes used to treat the condition.
Half of the patients said they had used marijuana recreationally and 4.4% had used it for their glaucoma.
Patients were more likely to want to use the substance if they were less educated and younger.
“Another factor found to be associated with intentions to use marijuana for glaucoma treatment was false beliefs regarding the usefulness of this alternative therapy in the prevention or treatment of glaucoma,” they wrote.
Patients who were dissatisfied with their traditional treatments were also more likely to want to try cannabis as a therapy.
"Our findings suggest a need for more education on this topic to protect patients with glaucoma against the increased acceptability among the public toward using marijuana based on false perceptions of its therapeutic value in glaucoma therapy," the authors concluded.