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From the Retina Experts

The Benefits Of Medical Marijuana

February 14, 2012Share

Many people may not realize it, but Hawaii has allowed the medical use of marijuana within the state since June 14, 2000, when Governor Ben Cayetano signed Hawaii's medical marijuana bill into law. Since that time, 15 other states, including the District of Columbia, have legalized the use of marijuana for certain medical conditions.1

There are a couple of steps necessary in order to use marijuana legally in Hawaii. Patients first need a recommendation from a registered medical doctor. They are then registered themselves with the Department of Public Safety. This gives patients the legal right to grow seven plants in their home for their own use. Alternatively, patients may have a single caregiver grow plants for them.

However, Hawaii's law has no provisions for a person to legally obtain seedlings in order to grow plants. There are also no legal marijuana dispensaries in Hawaii. The result is that patients must turn to the black market for medicine. There is no way to be certain about the potency and purity of the marijuana obtained in that way.

What Medical Marijuana Can Do For Treating Glaucoma
There are real uses for medical marijuana, including the treatment of glaucoma, or elevated pressure inside the eye. There has already been a surprising amount of research in this field. Studies have shown that about 60% of people will respond to the inhaled effects of marijuana with a decrease in the pressure inside their eyes. The reduction in pressure over a three- to four-hour period is about 25%, on average.2 In the United States, due to federal restrictions, patients with glaucoma must usually smoke marijuana to receive its pressure-lowering effects. However, in some other countries—for example, Jamaica—-patients have access to a pharmaceutical medication called Canasol. Canasol, which was developed by Dr. Lockhart and Medi-Grace Pharmaceuticals, is a cannabis-based eyedrop created specifically for the treatment of glaucoma. Cannabis is the scientific name for marijuana, which is what it was called before it was prohibited in the 1930s.

When most people think of marijuana, they think of tetrahydrocannabinol, or THC, the psychoactive compound in cannabis that is responsible for the "high" that most recreational users desire. But the fact is that over 80 different cannabis compounds, known as cannabinoids, have been identified in cannabis and have been shown to have a variety of medical properties. There are compounds that may protect other parts of the eye, the retina in particular.

One of these cannabinoids, called cannabidiol, or CBD for short, is a very interesting compound. It does not cause the "high" associated with THC.1,3 This increases the potential use of CBD in treating disease. CBD is being studied in laboratories to learn how it works.4

The human retina, in the back of the eye, is subject to many types of vision-threatening damage. It appears that CBD can protect the retina from some of this damage. Like other tissues, the cells in the retina can be damaged by free radicals in the environment. This is called oxidative damage. There are a variety of antioxidant vitamins and supplements that may help stop free radicals, but there is no ideal treatment at the current time. CBD can function as an antioxidant to protect the retina.

Diabetes also damages the retina, causing what is called diabetic retinopathy. Diabetics are at extreme risk for losing their vision over time. In fact, diabetic retinopathy is a leading cause of blindness in the United States. Diabetic retinopathy is usually treated with laser therapy. CBD has the potential to prevent some of the damage that occurs with diabetic retinopathy because of its unique properties. In addition to working as an antioxidant, it can reduce the inflammation around blood vessels that causes much of the damage in diabetic retinopathy.5

Macular degeneration is another common type of significant visual loss in the United States, also caused by changes in the retina. CBD has also shown the ability to help prevent some of this damage.

Retinal specialists are extremely interested in any new medication that could help slow down these common vision-threatening conditions. CBD is already in use in other countries, approved for treating other medical conditions, such as pain due to multiple sclerosis and cancer.

The Need For More Research
Additional research in this field is desperately needed, which is nearly impossible given the current federal restrictions. One solution would be to institute state legislation that would legalize such research at the state level. This is the goal of two bills, SB113 and HB1624, which are currently making their way through Hawaii's 26th legislative session.

In the meantime, as medical marijuana patients enjoy their locally grown medicine in the safety of their own homes, with a backdrop of palm tree silhouettes against a Hawaiian tropical sunset, they can remember that their eyes are thanking them just the same.

2. Green, K., Marijuana Smoking vs. Cannabinoids for Glaucoma Therapy. Arch Ophthalmol. 1998;116:1433–1437
3. Liou, GI, Diabetic Retinopathy: Role of inflammation and potential therapies for anti-inflammation. World J Diabetes. 2011;1(1):12–18
4. Liou, GI, Auchampach JA, Hillard C.J., et al. Mediation of cannabidiol anti-inflammation in the retina by equilibrative nucleoside transporter and A2A adenosine receptor. Invest Ophthalmol Vis Sci. 2008;49:5526–5531


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