Ginkgo Improves Some Glaucoma
Ginkgo biloba extract can partially restore visual field losses in people with normal tension glaucoma, according to a new study in Ophthalmology (2003;110:359–64).
Glaucoma is a disease of the eyes characterized by deterioration of the optic nerve that results in diminished field of vision and eventual blindness. It is a leading cause of blindness around the world. Factors that increase the risk of developing glaucoma include older age, African descent, nearsightedness, and family history of the disease. High intraocular pressure (pressure inside of the eye), which prevents normal function of the optic nerve, is a common feature of glaucoma. In normal tension glaucoma, however, the intraocular pressure is normal and the cause of optic nerve damage and visual field loss is unknown, although reduced blood flow to the optic nerve is believed to play a role. Eyedrops that lower intraocular pressure are typically used to treat cases of glaucoma in which the intraocular pressure is elevated, but these medications have no effect on progressive vision loss in normal tension glaucoma.
In the current study, 27 people with normal tension glaucoma and visual field losses were randomly assigned to one of two groups. One group received 40 mg of Ginkgo biloba extract three times per day for four weeks, followed by eight weeks with no treatment and finally four weeks of placebo. The other group received placebo for four weeks, followed by the same eight weeks with no treatment and ending with four weeks of Ginkgo biloba. Both groups experienced significant improvement (approximately 24%) in indices used to evaluate visual fields after treatment with Ginkgo biloba. There were no improvements for either group during placebo phases. Intraocular pressures remained normal throughout the trial, and no side effects from Ginkgo biloba were noted.
Ginkgo biloba extract has several properties that might have contributed to the beneficial effects observed in this trial. Its antioxidant activity might have protected the optic nerve from oxidative damage, and its ability to increase blood flow and oxygen utilization might have protected the optic nerve from damage due to lack of oxygen. In fact, a previous trial found that people with glaucoma experienced increased blood flow in the artery supplying blood to the optic nerve after treatment with Ginkgo biloba extract. Furthermore, its ability to increase blood flow to the brain might have improved eye sensitivity, resulting in improved visual function.
The leaves of the Ginkgo biloba tree have been used in traditional Chinese medicine for more than 5,000 years. Its traditional uses include the treatment of asthma and bronchitis, and in recent times it has been shown to act as an antioxidant, improve oxygen uptake and use by cells, and increase blood flow to the brain and extremities of the body. Results from clinical trials demonstrate that standardized leaf extracts of Ginkgo biloba reduce the symptoms of age-associated memory impairment and dementia, including early Alzheimer's disease. In addition, preliminary results suggest that it might be useful in preventing and treating cardiovascular disease.
Other studies have suggested that Ginkgo biloba extract may be beneficial for people with age-related macular degeneration, another major cause of visual loss and blindness.
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, Vermont, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
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