Marijuana as Tx: What Are Your Patients Thinking?

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Researchers in Colorado, where recreational and medical marijuana both are legal, report that glaucoma patients are receiving conflicting infor­mation regarding the therapeutic use of medical marijuana.¹ Few glaucoma specialists in the state recommend marijuana, in keeping with a statement from the American Glaucoma Society (AGS) advising against its therapeu­tic use.² Yet most marijuana vendors endorse its use, without supporting scientific evidence.

SURVEY RESULTS. Many Colorado dispensaries routinely recommend marijuana to glaucoma patients, despite lack of supporting evidence.

Perspectives from three populations. In a cross-sectional study, Leonard K. Seibold, MD, and his colleagues at the University of Colorado surveyed three groups: AGS members, patients at the university’s glaucoma clinic, and ven­dors at marijuana dispensaries.

Physicians. Of the nearly 300 AGS members who responded, only 22 had recommended marijuana for glaucoma—and done so rarely. Their decisions typically were influenced by patient requests or failed prior treatments. Those who had not recommended marijuana cited lack of research, followed by con­cerns regarding safety and legality.

Patients. Of the 231 patients sur­veyed, 58% had heard of marijuana’s use for treating glaucoma and 36.9% had used it recreationally, yet only 2.6% had used it therapeutically.

Patients who knew of marijuana’s purported therapeutic use or had used it recreationally were more willing to try it as a glaucoma treatment, and younger patients were more likely to regard it as effective. In addition, those with moderate glaucoma were more likely to be interested in marijuana therapy than those with mild disease.

Vendors. Callers assuming the role of glaucoma patients contacted 203 randomly selected dispensaries to ask whether they recommended marijuana to treat glaucoma and whether it was safe and effective. While 49% of vendors deferred answering or said that they were unsure, 51% of dispensary em­ployees recommended marijuana to the callers. Of these, 91% agreed it was a safe alternative treatment for glaucoma.The 16% who stated that scientific evidence existed to support marijuana’s efficacy could not cite any evidence.

A need for research. An early study suggested that marijuana could lower intraocular pressure (IOP) by as much as 30%.³ But given the dearth of research, “We still do not fully under­stand which component of marijuana is responsible for an IOP reduction, which method of consumption works best, and duration of effect from each [method],” said Dr. Seibold.

For now, he advised physicians to be aware of the information that patients may be receiving—and to tell patients that our current knowledge does not support its regular use for glaucoma. “My favorite line to patients who ask me about marijuana for glaucoma is, ‘The most likely thing it will do is make you forget to take the medications that we know will help you.’”

—Miriam Karmel

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1 Weldy EW et al. Ophthalmol Glaucoma. 2020;3(6):3(6):453-459.

2 Jampel H. J Glaucoma. 2010;19(2):75-76.

3 Helper RS, Frank IR. JAMA. 1971;217:1392.

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Relevant financial disclosures—Dr. Seibold: None.

For full disclosures and the disclosure key, see below.

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