Study Examines Patient Perceptions of Marijuana as Glaucoma Treatment

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Research shows patients with glaucoma are likely to encounter conflicting opinions on marijuana’s role in glaucoma therapy, especially from dispensaries.

Glaucoma specialists have fielded inquiries about marijuana’s use against the disease for decades. Now, with the drug’s legalization spreading, a study published in Ophthalmology Glaucoma in a partnership with the American Glaucoma Society, is showing what kind of information patients are gathering regarding its use in managing their condition. The research aims to define the differing perceptions among glaucoma specialists, medical marijuana dispensaries, and patients in Colorado, a state with legalized marijuana.

 The researchers wanted to learn, specifically, if marijuana use was being recommended as a possible alternative treatment and if patients were actually using it. 

The investigation shows that specialists rarely recommend marijuana, while dispensaries frequently do. Physicians need to be aware of the conflicting opinions their patients might receive so that they can provide safe guidance. 

Investigators randomly selected medical marijuana dispensaries from the registry and called using a mystery caller approach. They used a basic script and assumed the role of a patient with glaucoma when talking with dispensary employees. 

Of their findings, the investigators write, “a total of 203 of the 300 medical marijuana dispensaries called were successfully contacted (68%). Of these, 103 respondents (51%) recommended marijuana products for the treatment of glaucoma. The remaining 100 (49%) deferred making a recommendation or were unsure. No dispensary explicitly recommended avoiding marijuana use for the treatment of glaucoma.”

The dispensary employees who did recommend marijuana, most frequently suggested using tinctures (topical marijuana concentrates ) followed by smoking and edibles. Cannabidiol (CBD)-based products were more frequently recommended than tetrahydrocannabinol (THC) products. Use was recommended either multiple times a day or daily, however while a large majority stated that marijuana is a safe alternative treatment for glaucoma, few could cite evidence beyond anecdotal examples.  

Glaucoma specialists, all of which are members of the American Glaucoma Society (AGS), were surveyed. The authors write, “of the 1308 AGS members, 290 (22%) responded to the survey. Among the respondents, 22 (7.6%) reported that they had recommended marijuana for the treatment of glaucoma, with the majority of these (86.4%) having done so rarely (1 to 2 times in their career) or occasionally (1 to 3 times per year),” the study says. “The remaining 268 providers who had not recommended marijuana cited concerns with lack of evidenced-based research (80.6%), safety (52.2%), and legality (39.2%).” 

“Regardless of whether the physician had recommended marijuana, a majority of specialists agreed further research is warranted (87.8%), and most would prescribe marijuana if proven effective and legal (77.4%),” according to the survey results.

In addition to polling physicians and dispensary workers, the researchers included the views of 231 patients from the glaucoma clinic at the Sue Anschutz-Rodgers Eye Center in the study. Most (58.9%) had heard about the possible use of marijuana for glaucoma, but only 2.6% had personally used marijuana as a treatment for glaucoma. 

The survey results between the marijuana dispensaries and the glaucoma specialists highlights the need for additional research to dispel or confirm anecdotal experiences as evidence, according to the researchers. “For the medical marijuana dispensary component of the study, approximately half of the employees surveyed explicitly recommended marijuana-derived products for the treatment of glaucoma. Surprisingly, CBD was the most frequently recommended agent, and topical application and tinctures were the most commonly recommended method of consumption. Unlike the previously demonstrated relationship between smoking marijuana and the transient lowering of intraocular pressure (IOP), the effect of CBD alone and topical application on IOP is unclear, and limited studies of the IOP effects of CBD taken in isolation are available. Those few studies show that CBD does not alter IOP or transiently increases it. Topical application of THC or CBD is limited by poor aqueous solubility and has not demonstrated a difference in IOP when compared with placebo.”

The study also points out that physicians should be aware that patients could be supplementing their glaucoma care with methods that are ineffective or harmful. This highlights a need to better educate patients around marijuana use as treatment. 

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Weldy E, Stanley J, Koduri V, et al. Perceptions of marijuana use for glaucoma from patients, cannabis retailers, and glaucoma specialists. Ophthalmol Glaucoma. 2020;3(6):453-459. doi: 10.1016/j.ogla.2020.06.009