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Marijuana As Medicine?: The Science Beyond the Controversy (2001)

Chapter: Marijuana and Glaucoma

9

MARIJUANA AND GLAUCOMA

Glaucoma ranks among the most frequently cited reasons for using medical marijuana and is one of the indications for which the federal government once granted permission for compassionate marijuana use (see Chapter 2 and Chapter 11). Research findings from as early as the 1970s show that both marijuana and THC reduce intraocular pressure, a key contributor to glaucoma. The first such reports generated considerable interest because at the time conventional medications for glaucoma caused a variety of adverse side effects. But, as will be described, other treatments for the disorder have since eclipsed marijuana-based medicines. Conventional therapies for intraocular pressure outperform cannabinoids, and the next generation of glaucoma drugs is expected to treat the disease more directly or even reverse its progress.

After cataracts, glaucoma is a leading cause of blindness worldwide, affecting more than 60 million people. Its most common form, primary open-angle glaucoma (POAG), is a slowly progressive disorder that destroys cells in the eye’s retina and degrades the optic nerve. These losses constrict the visual field, which eventually disappears, along with the patient’s sight.

Researchers have not yet learned what triggers POAG, but they have identified three factors that place individuals at risk for developing the disease: age, race, and elevated intraocular pres-

FIGURE 9.1 The anatomy of the human eye. (Drawing by Roberto Osti.)

sure. One percent of people age 60 have POAG, while more than 9 percent of people over 80 develop the disease. For African Americans the figure rises to 10 percent and is up to 25 percent among Caribbean people of African origin (who are less racially mixed than their American counterparts).

The third risk factor, elevated intraocular pressure, results from blockage in the flow of fluid that helps the eye maintain its rigid shape (see Figure 9.1). Normally this clear fluid, called the aqueous humor, circulates between the front of the lens and the back of the cornea. In people with elevated intraocular pressure the outflow of fluid from the anterior chamber of the eye becomes restricted, causing pressure to build up like water behind a dam. Increased pressure in the eye contributes to glaucoma by decreasing the flow of nutrients to the optic nerve, scientists suspect. Because elevated intraocular pressure is the only significant risk fac-

tor for glaucoma that can be controlled, most treatments to date have been designed to reduce it. Unfortunately, reducing intraocular pressure does not always stop or even slow the progress of glaucoma toward blindness.

Drugs can alter intraocular pressure by acting on different circulation routes of the aqueous humor (see Table 9.1). One important outflow route is the trabecular meshwork, a latticework of connective tissue and cells. The fluid flows through this tissue, into a little canal, and out of the eye, where it joins the blood-stream. Such drugs as epinephrine or dipevefrin work by chang-

TABLE 9.1 Treatments for Glaucoma

How it reduces IOP

Beta-2 adrenergic agonists

Eases flow through trabecular meshwork

Beta-2 adrenergic antagonists

Supresses production of aqueous fluid

Eases flow through trabecular meshwork

Alpha-2 adrenergic agonists

Reduces production of aqueous fluid

Carbonic anhydrase inhibitors

Reduces production of aqueous fluid

Helps drain excess fluid

How it reduces IOP

Laser modification of trabecular meshwork

Improves flow through meshwork

Drainage tube insertion

Helps drain excess fluid

Destruction of ciliary epithelium

Reduces fluid production

ing the shape of certain cells, resulting in improved flow through the trabecular meshwork. Pilocarpine, another type of drug, contracts the muscle that controls the shape of the trabecular meshwork making it easier for fluid to pass through, whereas timolol, yet another type of drug, interferes with fluid manufacture by the ciliary epithelium. Other drugs, such as apraclonidine and brimonidine, also reduce the amount of fluid produced. Finally, an additional type of drug simulates the production of agents that ease the passage of aqueous humor from the eye.

There are also surgical options for controlling elevated intraocular pressure. The trabecular meshwork can be cut with a laser, allowing the fluid to move out of it more easily. Alternatively, a surgeon can remove a piece of the eye wall and allow fluid to drain out under the conjunctiva. Doctors can also insert tiny drainage tubes, similar to those used for middle-ear problems, inside the eye to allow fluid drainage to the outer layers of the eye. Lastly, laser, heat, or cold can be used to destroy the ciliary epithelium, which secretes the aqueous humor.

Several clinical studies have found that cannabinoids or marijuana reduce intraocular pressure (IOP) as well as do most conventional glaucoma medications. 1 This is true whether the cannabinoids are administered orally, intravenously, or by inhalation but not when they are applied directly to the eye. Smoked or eaten marijuana, THC and synthetic cannabinoids in pill form, and intravenous injections of several natural cannabinoids have all been shown to reduce IOP significantly in both glaucoma patients and healthy adults with normal IOP. In most trials a single dose of marijuana or cannabinoid maintained this effect for three to four hours.

Researchers have yet to explain how marijuana and cannabinoids reduce IOP. But while clearly effective in reducing IOP, marijuana-based treatments for glaucoma have numerous drawbacks. Marijuana reduces blood pressure and produces psychological effects that some people —particularly the elderly—find intolerable. Several patients in these studies also reported that their hearts pounded or raced and that they felt uncomfortably anxious after taking cannabinoids. All of these effects could prove especially problematic for people at risk for cardiovascular disease and stroke; moreover, reduced blood pressure could decrease

blood flow to the optic nerve, counteracting the benefits of reducing IOP. Finally, their short duration of effect means that marijuana-based medicines must be taken up to eight times a day, which most patients are unlikely to do; other medicines reduce IOP equally well and need only be taken once or twice a day. This is an important difference because patients need to control IOP continuously due to the progressive nature of glaucoma.

It is possible that future research could reveal a therapeutic effect for isolated cannabinoids other than THC or produce synthetic cannabinoid analogs that last longer and have fewer side effects. But the most promising line of research for treating glaucoma lies in the development of therapies that can protect or rescue the optic nerve from damage or that can restore its blood supply. There is some evidence that a synthetic cannabinoidlike compound known as HU-211 has nerve-protecting properties, although it does not reduce IOP. HU-211 is chemically similar to THC, but it is not found in the marijuana plant and does not bind to the cellular receptor in brain cells that THC activates.

There is no question that marijuana-based medicines can be used to lower IOP. But like several other glaucoma medications that have fallen into disuse, their drawbacks outweigh their benefits. This was not the case when the first reports of marijuana’s effects on IOP were published in the 1970s, a time when relatively few drugs —all of which caused troubling side effects—were available to treat the condition. Those drugs have since been superseded by more effective and less problematic medications. That seems the likely fate of marijuana-based treatments for glaucoma as well.

NOTE

1. Institute of Medicine. 1999. Marijuana and Medicine: Assessing the Science Base. Washington, DC: National Academy Press, pp. 203-204.

Read chapter Marijuana and Glaucoma: Some people suffer from chronic, debilitating disorders for which no conventional treatment brings relief. Can mariju…

What Are The Uses of Medical Marijuana?

Medical practitioners are finding more and more practical uses of medical marijuana. This has been a subject of debate among the general public and people in the medical field for years now. Some argue this is just an excuse for people to get high, but research and clinical studies show otherwise.

What Are The Health Benefits of Medical Marijuana

Cannabis and Pain: Testimonial

Dr. Dotson is a private practitioner who did Lasik and cataract surgery for years in Tennessee. However, a couple of years ago it proved to be financially unsustainable for him, and due to the changes in reimbursement and oppressive regulatory atmosphere, he was forced out of practice.

He then relocated to the northwest. Dr. Dotson and his friend then traveled to India, and much to his amazement, he saw cannabis growing wild there. The plant practically grew as high as 10 feet in ditches for miles on end. His friend, who had bad shoulders and chronic pain said that she would try eating some of the leaves and see what it would do for her pain. So they stopped, and she tried some. Almost immediately, her pain went away. It was the first time in a decade that she had been pain-free because she had avoided taking any opiates.

When they returned to the northwest, they began looking into cannabis as a medical tool. It was a real light bulb experience for him.

Uses of Medical Marijuana in Various Forms

There are several ways to ingest marijuana other than smoking it. As for Dr. Dotson, he encourages his patients to take it using a vaporizer since it’s considerably healthier. However, most people use it in its most edible form via oil or butter. Culinary science has made other forms of edible marijuana very practical, such as medicated crackers, popcorn, cookies, gummy bears, lollipops, chocolate bars, chews, ice cream and nut mixes, to name a few. With the right recipe and ingredients, you can hardly taste the cannabis in it. Don’t want to eat it? Another form of consuming cannabis is in tinctures.

Under whatever circumstances or uses of medical marijuana, history shows that cannabis has been used as a form of medicine and spiritual applications for 7,000 to 8,000 years. Probably just like any other plant that has been discovered to have medicinal properties. In fact, anointing oils have been cited in the Bible where cross-examination of the original language used may have been referring to cannabis.

Benefits of Medical Marijuana

One of the primary advantages patients may get from the uses of medical marijuana is relief from pain. People who served in the armed forces and are going through Post Traumatic Stress Disorder or PTSD can greatly benefit from this.

Cancer patients who suffer from symptoms such as pain and nausea after radiation and chemotherapy may be relieved from their suffering by ingesting medical marijuana.

Other examples where cannabis can be of great help to patients suffering from Lou Gehrig’s disease, other immune dysfunctions, amyotrophic lateral sclerosis, multiple sclerosis, ALS, migraines, and chronic headaches.

Uses of Medical Marijuana and Glaucoma

Another great use for medical marijuana is for the treatment of Glaucoma. Glaucoma, also known as intraocular pressure, is a disease where the optic nerve of the eye can be damaged over time causing partial or complete blindness. Such diseases can be identified and arrested by undergoing regular eye exams.

Studies have shown that THC, which is the active ingredient in cannabis, does help lower IOP in the eye for a certain period of time. Dr. Dotson performed various studies, where one study showed intraocular pressure dropping up to 40 percent using cannabis as a form of medicine.

With a precise and methodical approach for uses of medical marijuana, studies have shown that it really helps drop blood pressure in an orthostatic hypotension sense. For example, if you stand up quickly after lying down, your blood pressure drops momentarily but then naturally goes back to normal. However, it does not apply to everybody. Another benefit from medical marijuana is how it increases heart rate and ocular blood flow.

What About the Negative Media from People who Had Bad Experiences?

Colorado Medical Chief Says Cannabis Legalization Has Caused No “Significant Issues” – News https://t.co/bxaFMtY4SH

Marijuana has been given a bad light due to its street use. People who smoke it often don’t know what exactly is in it. Street gangs have been known to lace it with extenders, chemicals and other contaminants, even heroin.

The abuse of marijuana use may have derailed people from the plant’s medicinal properties. However, the use of marijuana could be considered a miracle drug since it has been known as a natural ailment ease for so many diseases.

Listen to Dr. Dotson on the uses of medical marijuana as he talks about his findings to healing glaucoma:

The web has so many resources to support any of the facts mentioned above. Feel free to browse and find answers to any questions you may have. If you’re suffering from Glaucoma, it would be best to consult a medical professional or someone who knows the effects for the uses of marijuana better. There’s no harm in trying if it may indeed help you in the end.

What do you think about the uses of medical marijuana? Let us know in the comments section below.

The uses of medical marijuana may come as a shocker for many these days. But this article will show you just how it can help you.