New Research on Marijuana Use for Glaucoma: Is Education Enough, or Is Emotional Support also Necessary?

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Photograph of a retina with cupping of the optic disc from glaucoma

New glaucoma research from The George Washington University in Washington, DC indicates that the factors associated with patients' intentions to use marijuana for glaucoma include their perceptions of the legality of marijuana use as well as satisfaction (or not) with their current standard of glaucoma care. The researchers conclude that patients need to be educated about marijuana and its specific effects on glaucoma, which they note is not supported by scientific evidence.

In an editorial response to the research, however, two physician authors emphasize that

...physicians must offer not only informational guidance but also emotional support to increase patient satisfaction levels. Clear, high-grade information and education were appreciated by patients, but among other equally important factors were a physician's ability to convey respect and empathy for the patient's needs and values, aptitude for appropriately engaging the patient's family members and friends, and capacity to provide emotional support and alleviate fear and anxiety.

This ongoing research and quality-of-care debate is detailed below.

Please note: While the use of marijuana can lower intraocular [i.e., within the eye] pressure, the Glaucoma Research Foundation does not recommend it for glaucoma treatment for several reasons: (a) its short duration of action (3-4 hours); (b) its side effects; and (c) lack of research-based evidence demonstrating that it can alter the course of the glaucoma disease process, which is different from providing a temporary lowering of eye pressure.

From JAMA Ophthalmology

The research, entitled Marijuana Use among Patients with Glaucoma in a City with Legalized Medical Marijuana Use, was published "online first" in the December 23, 2015 edition of JAMA Ophthalmology (formerly Archives of Ophthalmology). JAMA Ophthalmology is an international peer-reviewed journal, published monthly by the American Medical Association.

The authors are David A. Belyea, MD, MBA; Rashed Alhabshan, MD; Ana Maria del Rio-Gonzalez, PhD; Nisha Chadha, MD; Tania Lamba, MD; Cyrus Golshani, MD; Kunal Merchant, MD; Neena Passi, MD; and Jacob A. Dan, MD, PhD, from The George Washington University, Washington, DC.

About Glaucoma

Glaucoma is a group of eye diseases that damage the optic nerve and is one of the leading causes of vision loss and blindness. Open-angle glaucoma is the most common (but not the only) form of glaucoma.

The eye continuously produces a fluid, called the aqueous (or aqueous humor), that must drain from the eye in order to maintain healthy eye pressure. Aqueous humor is a clear, watery fluid that flows continuously into, and out of, the anterior (or front) chamber of the eye, which is the fluid-filled space between the iris and the cornea. It is the aqueous that helps to bring nutrients to the various parts of the eye.

Aqueous fluid drains from the anterior chamber through a filtering meshwork of spongy tissue along the outer edge of the iris (called the trabecular meshwork), where the iris and cornea meet, and into a series of "tubes," called Schlemm's canal, that drain the fluid out of the eye. Problems with the flow of aqueous fluid can lead to elevated pressure within the eye.

In primary open-angle glaucoma, the filtering meshwork may become blocked or may drain too slowly. If the aqueous fluid cannot flow out of the eye, or flow out quickly enough, pressure builds inside the eye and can rise to levels that may damage the optic nerve, resulting in vision loss.

Most eye care professionals define the range of normal intraocular [i.e., within the eye] pressure (IOP) as between 10 and 21 mm Hg [i.e., millimeters of mercury, which is a pressure measurement]. Most persons with glaucoma have an IOP measurement of greater than 21 mm Hg.

If you have been diagnosed with glaucoma, it is critical to maintain the treatment plan prescribed by your eye doctor. You can read more about glaucoma medication regimens and additional treatments at What Are the Different Treatments for Glaucoma? and What are the Different Types of Glaucoma? on the VisionAware website.

Vision Loss from Glaucoma

Glaucoma results in peripheral (or side) vision loss initially, and as this field loss progresses, the effect is like looking through a tube or into a narrow tunnel. This constricted "tunnel vision" effect makes it difficult to walk without bumping into objects that are off to the side, near the head, or at foot level.

A living room viewed through a constricted visual field

A living room viewed through a constricted visual field.
Source: Making Life More Livable. Used with permission.

Glaucoma is an especially dangerous eye condition because most people do not experience any symptoms or early warning signs at the onset. Glaucoma can be treated, but it is not curable. The damage to the optic nerve from glaucoma cannot be reversed.

About the Glaucoma and Marijuana Research

From Patient Factors ID'd for Intention to Use Marijuana for Glaucoma, via DoctorsLounge.com:

[Researchers] from the George Washington University School of Medicine and Health Sciences in Washington D.C. conducted a cross-sectional survey of 204 patients with glaucoma or suspected glaucoma (51 percent women; 40.2 percent white) to examine intention to use marijuana for treatment. Patients completed a self-administered survey assessing demographics, perceived glaucoma severity, and factors related to marijuana use in glaucoma.

[Editor's note: A cross-sectional study involves an analysis of a population of subjects at one specific point in time (rather than studied over a longer period of time), which is helpful to consider when evaluating this particular study. In contrast, a longitudinal study follows, and gathers information about, the same individuals or group of people over an extended period of time – often many decades.]

The researchers found that after controlling for demographic variables including disease severity, and previous marijuana use, the subjects' (a) perceptions of the legality of marijuana use, (b) false beliefs regarding marijuana, (c) satisfaction with current glaucoma care, and (d) relevance of marijuana and glaucoma treatment costs correlated with intentions to use marijuana for glaucoma treatment.

"This 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," the authors write.

Here is another, somewhat different, summation of the research from United Press International:

The perception of marijuana's effects on glaucoma significantly outpace what research has shown, according to a new study that researchers said suggests the public needs to be re-educated on medical uses for the drug.

Marijuana has been legalized for medicinal or recreational purposes in 23 states and Washington, D.C., in recent years, based largely on voter referendums.

Many of the votes have been passed on a 1999 Institute of Medicine report on marijuana's possibly therapeutic effects for a range of medical conditions, including glaucoma. Researchers note that while marijuana can relieve the effects of glaucoma for three or four hours, patients would need to be dosed eight to ten times per day for a "sustained therapeutic effect."

The researchers said many patients had inaccurate expectations or knowledge about the drug's effects on glaucoma. False perceptions of the efficacy of marijuana on glaucoma, satisfaction with current care, and relevance of costs for marijuana versus their current treatment all factored in heavily on whether to use the drug for their condition.

Marijuana legalization, for medicinal or recreational purposes, has grown, but researchers said there has been a disconnect between actual research-supported uses for the drug and popular expectation of what it can do.

More about the Study from JAMA Ophthalmology

From the article abstract, with the full article, including the limitations of the study, available online:

Importance: Previous research has shown several limitations associated with the use of marijuana as a treatment for glaucoma. However, little is known regarding patients' perceptions toward using marijuana for glaucoma and their intentions to use this therapeutic alternative.

Objective: To identify factors among patients with glaucoma that could lead to intentions to use marijuana for treatment.

Design, Setting, and Participants: This cross-sectional survey study of 204 patients with glaucoma or suspected to have glaucoma was conducted at an academic-based glaucoma clinic in Washington, DC, between February 1 and July 31, 2013. Patients completed a self-administered survey assessing demographics, perceived severity of glaucoma, prior knowledge about marijuana use in glaucoma, past marijuana use, perceptions toward marijuana use (legality, systemic adverse effects, safety and effectiveness, and false beliefs), satisfaction with current glaucoma management, relevance of treatment costs, and intentions to use marijuana for glaucoma.

Results: Results Of the 334 patients who were invited to participate in the study, 204 (61.1%) completed the survey. About half the participants were women (104, or 51%), and 82 (40.2%) were white. Analysis of 204 respondents indicated that perceptions of legality of marijuana use; false beliefs regarding marijuana; satisfaction with current glaucoma care; and relevance of marijuana and glaucoma treatment costs were significantly associated with intentions to use marijuana for glaucoma treatment after controlling for demographic variables, disease severity, and previous marijuana use.

The study authors also concluded with the following observations:

This study contributes to filling the gap in our knowledge about patients' perceptions toward using marijuana for glaucoma and their intentions to seek this therapeutic alternative. Understanding these 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.

This survey study is a reminder for physicians, general ophthalmologists, and glaucoma specialists to educate patients with glaucoma on the efficacy and adverse effects of marijuana as it applies to treating glaucoma.

Intentions to use marijuana were not based on severity of disease but on false beliefs about the role of marijuana in the prevention and treatment of glaucoma, perceptions that marijuana should be legal, lower perceptions of the relevance of costs of treatment, and lower satisfaction with current glaucoma management. By educating our patients, we can perhaps increase their understanding of the disease process, increase satisfaction with treatment, and increase compliance with therapy.

A More Nuanced Approach in an Editorial Response

In an editorial response to the study, also published in JAMA Ophthalmology, Eve J. Higginbotham, MD, from the Scheie Eye Institute, University of Pennsylvania, and Lenora A. Higginbotham, MD, from Johns Hopkins Hospital, Baltimore, Maryland, urged physicians to give considerable weight to their patients' perception of this issue, along with providing empathy and emotional support to patients and their families:

In this issue of JAMA Ophthalmology, Belyea and colleagues provide insight into the perspectives of patients with glaucoma on the use of marijuana for the potential treatment of their disease. This insight is undoubtedly timely, given the recently expanding legalization of medical marijuana throughout the United States.

As Belyea and coworkers acknowledge, this strong public-driven shift toward legalization of medical marijuana seems to clash with the relatively weak scientific evidence supporting its therapeutic use, particularly for treatment of glaucoma. However, more than 20 states have now legalized medical marijuana, creating a supportive landscape for its use in growing segments of the population.

In this intricate health care landscape, Belyea and colleagues have identified the timeliness of highlighting patient perceptions about marijuana. Although, as the article suggests, it is not enough to simply uncover these perceptions; the physician must then respond and tailor his or her practice accordingly. This finding raises the question: What is the best response to the insights uncovered in the current study?

Arguably of most interest, patient satisfaction with current glaucoma management exhibited a strong negative correlation with the intention to use marijuana for glaucoma treatment, highlighting 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.

In the discussion, the authors focus on how best to alter these favorable perceptions of marijuana and shift patient focus back to evidence-based therapies. However, their strategies only minimally take into account the variable of patient satisfaction. Instead, Belyea et al focus heavily on altering perceptions of the alternative therapy itself via ample patient education.

The discussion primarily addresses the inaccurate beliefs patients harbor regarding marijuana; using an approach that knowledge gives patients the power to choose the best therapy, the authors outline several methods for providing patients with informational resources to guide them toward conventional treatments. However, this singular education-oriented approach fails to directly address patients' overall frustration with current care and treatment options. It seems most logical that, to effectively influence patients' intentions toward marijuana use, our ultimate strategy will need to stretch beyond patient education and address the roots of this dissatisfaction.

… the literature has well demonstrated that to take into account all these contributing factors, physicians must offer not only informational guidance but also emotional support to increase patient satisfaction levels.

Clear, high-grade information and education were appreciated by patients, but among other equally important factors were a physician's ability to convey respect and empathy for the patient's needs and values, aptitude for appropriately engaging the patient's family members and friends, and capacity to provide emotional support and alleviate fear and anxiety. Comprehensive attention to all of these factors forms the basis of patient-centered care and its promotion of patient satisfaction.

VisionAware will continue to report on glaucoma and marijuana research as results become available. What is your opinion on this topic? We'd like to hear from you in the comments.

Additional Glaucoma Information from VisionAware


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