Medical use of cannabis for Glaucoma
By Dr. Girivar Singhal
This is the slowly progressive, insidious optic naturopathy, usually associated with chronic elevation of intraocular pressure. The pressure inside the eye is sufficiently elevated to cause optic nerve damage and result in visual field defects. Normal intraocular pressure (IOP) is 10-21mmHg. Some type of glaucoma can result in an IOP exceeding 70mmHg. Glaucoma is the second commonest cause of blindness worldwide and the third commonest cause of blind registration in UK.
Glaucoma is usually painless (except in angle closure glaucoma).Foveal acuity is spared until end- stage disease is reached. For these reasons, severe and irreversible damage can occur before either the patient or physician the diagnosis. Screening of patients for glaucoma by nothing cup-to-disc ratio on ophthalmoscopy and by measuring intraocular pressure is vital. Glaucoma is medically treated with topical adrenergic agonists, cholinergic agonists, beta blockers and prostaglandin analogues. Occasionally, systematic absorption of beta blocker from eye drop can be sufficient to cause side effects of bradycardia, hypotension, heart block, bronchospasm or depression. Tropical or oral carbonic anhydrase inhibitor is used to lower intraocular pressure by reducing aqueous production. Laser treatment of the trabecular meshwork in anterior chamber angle improves aqueous outflow from the eye.
The only way to control glaucoma and prevent vision loss is to lower your IOP levels. Studies conducted that marijuana can be helpful in treating glaucoma. Smoking marijuana lowered the IOP of people with glaucoma. As a result of this research, additional studies were conducted examining whether marijuana or its active ingredient, a compound known as THC, could be used to keep IOP lowered. This research was supported by the National Eye Institute, a division of the federal National Institutes of Health. The research found that when marijuana is smoked or when a form of its active ingredient is taken as a pill or by injection, it does lower IOP. However, it only lowers IOP for a short period of time—about three or four hours.
This short period of time is a major drawback for the use of marijuana as a glaucoma treatment. Because glaucoma needs to be treated 24 hours a day, you would need to smoke marijuana six to eight times a day around the clock to receive the benefit of a consistently lowered IOP. Because of marijuana’s mood-altering effect, smoking so much of it daily would leave you too impair As scientists learn more about glaucoma, they have also come to understand that IOP is not the only factor that damages the optic nerve. Recent studies characterize glaucoma as a neurologic disease similar to Parkinson’s or Alzheimer’s. And, there is increasing evidence that reduced flow of blood to the optic nerve may also cause damage in patients with glaucoma. Unfortunately, marijuana not only lowers IOP, but it lowers blood pressure throughout the body. As a result, it has the potential to lower the blood flow to the optic nerve, effectively canceling out the benefit of a lowered IOP. Scientists are still exploring whether the active ingredients in marijuana may yet offer a glaucoma treatment. However, such developments require much more research and are many years from becoming a reality. So, while marijuana can temporarily lower your IOP; it’s not recommended for treating glaucoma. Prescription, medication and surgical treatment have been tested and proven as effective treatments for the condition.
Dr. Girivar Singhal for The Marijuana Company
Before using Marijuana for medical purposes, consult with a physician.