The Mayo Clinic stated in its Aug. 25, 2006 article "Marijuana as Medicine: Consider the Pros and Cons," published on its website:
"In the early 1970s, scientists discovered that smoking marijuana reduced pressure in the eyes. Exactly how the cannabinoids in marijuana produce this effect isn't known. Scientists have discovered CB1 receptors in the eyes, which may provide clues for future research on how marijuana affects glaucoma.
Your doctor can prescribe other medications to treat glaucoma, but these can lose their effectiveness over time. Researchers are working to develop medications containing cannabinoids that can be put directly on the eyes — to avoid the mind-altering side effects and other health consequences of smoking the plant."
Time magazine stated in a Nov. 4, 2002 cover story "Is Pot Good For You?":
"Marijuana does reduce pressure on the eye-ball, about 25%, but the drug isn't always practical as a glaucoma treatment. Many who have the disease are elderly and can't tolerate pot's tendency to raise heart rates."
GW Pharmaceuticals stated on its website (accessed Jan. 2004):
"The ability of cannabis and THC to lower intra-ocular pressure in glaucoma was serendipitously discovered in the late 1970's by a variety of patients and researchers. Several patients in the US Compassionate Use Investigational New Drug Program maintained their vision while employing large amounts of daily cannabis in situations where standard drug therapy failed....
An emerging concept is that glaucoma represents a progressive vascular retinopathy that requires a neuroprotectant to preserve vision. Some of the resulting optic nerve damage accrues due to NMDA hyperexcitability, an effect that THC and CBD may counter as neuroprotective antioxidants.
Thus, glaucoma is an area where cannabis and cannabinoids may offer particular advantages over available single ingredient ocular anti-hypertensive agents. Delivery methods remain an exacting challenge."
The Glaucoma Research Foundation stated in a website article "Medical Marijuana" (accessed May 8, 2007):
"Advocates of medicinal marijuana cite evidence that hemp products can lower intraocular pressure (IOP) in people with glaucoma. However, these products are less effective than safer and more available medicines. Most research regarding marijuana use took place before some current medications with fewer side effects were available.
The high dose of marijuana necessary to produce a clinically relevant effect on IOP in the short term requires constant inhalation, as much as every three hours.
The number of significant side effects generated by long-term oral use of marijuana or long-term inhalation of marijuana smoke make marijuana a poor choice in the treatment of glaucoma, a chronic disease requiring proven and effective treatment."
The American Medical Association (AMA) House of Delegates stated in the 1997 Report of the Council on Scientific Affairs:
"Neither smoked marijuana nor THC is a viable approach in the treatment of glaucoma, but research on their mechanism of action may be important in developing new agents that act in an additive or synergistic manner with currently available therapies."
The American Academy of Ophthalmology's (AAO) Committee on Drugs stated in its 1992 Information Statement "The Use of Marijuana in the Treatment of Glaucoma":
"There was no scientifically verifiable evidence that the use of marijuana is safe and effective in the treatment of glaucoma.
The Academy could not support proposed legislation to transfer marijuana from Schedule I to Schedule II of the Controlled Substances Act in order to permit its use in treating glaucoma."
The Institute of Medicine's Mar. 1999 report "Marijuana and Medicine: Assessing the Science Base" stated on page 177:
"High intraocular pressure (IOP) is a known risk factor for glaucoma and can, indeed, be reduced by cannabinoids and marijuana. However, the effect is too short lived and requires too high doses, and there are too many side effects to recommend lifelong use in the treatment of glaucoma. The potential harmful effects of chronic marijuana smoking outweigh its modest benefits in the treatment of glaucoma."
