Misperceptions Drive Pot Use Among Patients With Glaucoma

Diana Phillips
Perceptions about marijuana, including its legality and therapeutic value, strongly influence the intention of patients with glaucoma to use it as a treatment alternative, a cross-sectional survey study has shown.

The study's findings "suggest a need for more education on this topic for ophthalmologists to be able to protect patients with glaucoma against the increased acceptability among the public of using marijuana based on false perceptions of its therapeutic value in glaucoma therapy," write David A. Belyea, MD, MBA, from the Department of Ophthalmology, George Washington University School of Medicine and Health Sciences, Washington, DC, and colleagues.

The researchers published their findings online December 23 in JAMA Ophthalmology.

"When used for treatment of glaucoma, marijuana has been shown to lower intraocular pressure but its effects are limited to 3 to 4 hours, requiring dosing 8 to 10 times per day for sustained therapeutic effect," the authors explain. "Furthermore, only 60% to 65% of individuals experience intraocular pressure reduction with the use of marijuana."

The investigators surveyed a consecutive sample of patients with glaucoma visiting a glaucoma clinic between September 1, 2013, and September 30, 2015, to identify factors that could lead to their intention to use marijuana for treatment. The survey included questions about patients' perceived diagnosis, perceived severity of glaucoma, previous knowledge about the use of marijuana for glaucoma treatment and the sources of such information, history and frequency of marijuana use in the past, intentions to use marijuana, and factors associated with those intentions.

Of the 204 patients ranging in age from 23 to 87 years who completed the study, more than half (59.8%) reported knowing about the possible use of marijuana for glaucoma therapy before the study, and half (50.0%) reported previous recreational use of marijuana. Few patients reported use of the substance for glaucoma (4.4%) or other medical condition (3.0%). The intentions to use marijuana in the sample were modest, at a mean of 2.36 on a 5-point scale.

A multiple linear regression model identified significant associations between intentions to use the substance for glaucoma treatment and perceptions of the legality of its use, false beliefs about its value in the prevention and treatment of glaucoma, satisfaction with current glaucoma care, and relevance of the costs of marijuana and glaucoma treatment, the authors report.

"While the intentions to use marijuana in our sample of patients were generally low, we suspect that this figure will change dramatically given increased public support for legalizing marijuana for medical and recreational purposes and the wider media coverage of this topic in recent years," the authors write.

Given the relationship between intention to use marijuana and false beliefs regarding its therapeutic value and dissatisfaction with current glaucoma treatment, educational efforts should focus on "changing the unrealistic beliefs that patients might have regarding the efficacy of marijuana and improving their satisfaction toward their current glaucoma management," the authors write. "Although it is true that marijuana does lower intraocular pressure, we must educate our patients on the limited effects, the frequent dosing required for therapeutic effect, and the unacceptably high number of adverse effects that come with this frequent dosing."

In addition, "we must also instill hope for future alternative therapies" and inform patients about ongoing research, the authors write.

The negative correlation between patient satisfaction with current glaucoma management and intention to use marijuana is a particularly notable finding, Eve J. Higginbotham, MD, from the Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, and Lenora A. Higginbotham, MD, from the Department of Neurology, Johns Hopkins Hospital, Baltimore, Maryland, write in an invited commentary.

The findings highlight "an important aspect of patient perception in the medical marijuana landscape that has relatively little to do with opinion or knowledge of the drug itself."

The proposed strategy of altering favorable perceptions of marijuana and shifting patient focus back to evidence-based therapies "only minimally take into account the variable of patient satisfaction" and "fails to directly address patients' overall frustration with current care and treatment options," the editorialists argue.

To effectively influence patients' intentions to use marijuana for glaucoma, "our ultimate strategy will need to stretch beyond patient education and address the roots of this dissatisfaction," they write, advocating for a more comprehensive, patient-centered approach that includes open patient–physician dialogue that investigates and addresses issues driving patient satisfaction or dissatisfaction with care.