Glaucoma, one of the leading causes of blindness in the world, is characterized by damage to the optic nerve, either from compression of the nerve from high intraocular pressure or decreased blood flow, or a combination of the two. Since the optic nerve carries visual signals to the brain, any disruption in its function impacts vision. Ginkgo biloba, a common herbal supplement used as an alternative treatment for a number of conditions, may benefit people with glaucoma, but more studies are needed. Ask your doctor before taking ginkgo to treat glaucoma.
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While both the leaves and seeds of ginkgo have been used for medicinal purposes, an extract of the leaf called ginkgo biloba extract, or GBE, has been the focus of recent studies. Ginkgo appears to increase blood flow by relaxing blood vessels, the University of Maryland Medical Center reports. Ginkgo also contains two chemicals, called flavonoids and terpenoids, that act as antioxidants. Antioxidants destroy free radicals, substances that damage cells and cause a number of disorders.
Positive Studies
Improving blood flow to the optic nerve might decrease damage to the nerve, particularly in normal-tension glaucoma. In some cases of glaucoma, high pressure inside the eye compresses the nerve, reducing blood flow. In other cases, the pressure is normal but blood flow is decreased. One study conducted by the Clinica Oculistica Università di Brescia in Italy and reported in the February 2003 issue of "Ophthalmology" studied 27 patients with normal tension glaucoma. Subjects took either 40 milligrams of GBE three times a day for four weeks or placebo. A washout period of eight weeks followed, and then the two groups switched treatments. After taking GBE, subjects recorded improvement in visual field tests.
Negative Studies
A study reported in the September 2009 "Journal of Glaucoma" by the University of Alabama at Birmingham reviewed data from the 2002 National Health Interview Survey. Researchers found that people who had glaucoma were 26 percent less likely to take GBE than people without glaucoma, but this was not considered statistically significant. When demographic information and medical characteristic were corrected for, no difference was found. Researchers did note that more study was necessary to establish the effectiveness of GBE in glaucoma.
Risks
Ginkgo may increase bleeding times, particularly when taken by people with bleeding disorders or those who already take blood-thinning medications. Ask your doctor before taking ginkgo if you take blood thinners or are at risk for bleeding, including bleeding in the eye.
References
- Galucoma Research Foundation: Update on Alternative Glaucoma Medications
- University of Michigan Kellogg Eye Center: Glaucoma
- University of Maryland Medical Center: Ginkgo Biloba
- "Journal of Glaucoma:" The Association Between Self-Reported Glaucoma and Ginkgo Biloba Use; R. Khoury et al; September 2009
- "Ophthalmology:" Effect of Ginkgo Biloba Extract on Preexisting Visual Field Damage in Normal Tension Glaucoma; L. Quaranta et al; February 2003
