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.’”
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.
Relevant financial disclosures—Dr. Seibold: None.
For full disclosures and the disclosure key, see below.
Full Financial Disclosures
Dr. Jeng EyeGate Pharmaceuticals: O; GlaxoSmithKline: C; Kedrion: C; Merck: C.
Dr. Jones University of Utah Research Foundation: P. Callahan SP et al, inventors; University of Utah, assignee. Microscopy visualization. US patent 20140126801 A1. May 8, 2014. Jones BW et al., inventors; University of Utah, assignee. Disease diagnosis and treatment using computational molecular phenotyping. US patent 20130023436 A1. Jan. 11, 2011.
Dr. Pfeiffer None.
Dr. Repka NEI: S.
Dr. Seibold Allergan: C; New World Medical: C.
Dr. Wang Beijing University-CMU: S; Ministry of Science and Technology of the People’s Republic of China: S; National Natural Science Foundation of China: S; Sanming Project of Medicine in Shenzhen: S.
||Consultant fee, paid advisory boards, or fees for attending a meeting.
||Employed by a commercial company.
||Lecture fees or honoraria, travel fees or reimbursements when speaking at the invitation of a commercial company.
||Equity ownership/stock options in publicly or privately traded firms, excluding mutual funds.
||Patents and/or royalties for intellectual property.
||Grant support or other financial support to the investigator from all sources, including research support from government agencies (e.g., NIH), foundations, device manufacturers, and/or pharmaceutical companies.
More from this month’s News in Review