Ginkgo Biloba Extract in Glaucoma Treatment
"Ginkgo Biloba Extract (GBE)" has become the subject of study and investigation for its possible use in the treatment of glaucoma. GBE is a freely-available herbal supplement, long known for its positive effect on the functions of the brain, most noticeably in the areas of memory enhancement, mental alertness and the reduction of mental fatigue.
GBE also has many other actions on biological function, such as the improvement of circulation and preventing "vasospasm", a sudden decrease in the internal diameter of blood vessels; it also seems to inhibit the disintegration and elimination of cells called "apoptosis".
Extracts of GBE are made from the leaves of the gingko tree, not the seeds, as the seeds contain other compounds that may be harmful.
Glaucoma includes several forms of eye disease that causes damage to the structures within the eye by the pressure of the fluid within the globe. The particular form of glaucoma that gingko biloba extract is used to treat is called low-tension glaucoma, when the eye sustains damage even though the internal pressure is within the normal range.
Usually, "intraocular pressure (IOP)" in glaucoma is elevated, and does damage to the retinal nerve fiber layer and the head of the optic nerve, causing vision loss. This type of glaucoma is called "primary open-angle glaucoma (POAG)" and is the most common type, causing loss of vision without symptoms, at least in the early stages. In this disease, medications are prescribed to lower IOP into the normal range, where the eye does not sustain damage.
POAG does its damage by both direct pressure on the tissues of the retina and optic nerve, and by restricting circulation within the eye. If the IOP is too high, the normal blood pressure is unable to overcome it and circulation of nutrients to the retina through the blood vessels is compromised. Conventional treatment using medications to reduce IOP does not help people with low-tension glaucoma, as IOP is already low.
It is not known why some eyes are damaged even by relatively low IOP, but GBE is thought to increase blood flow to the eye. Only calcium blockers are currently available for such treatment, but these have not been widely accepted. Improved circulation with gingko extract apparently works to prevent damage from even low-tension glaucoma, and is also thought to have beneficial effects on circulation elsewhere, such as the brain in dementias or the feet in diabetes, as well as preserve vision from both diabetic retinopathy and age-related macular degeneration, two other causes of major vision loss. Gingko biloba also has anti-oxidant activity that may be beneficial to prevent damage to the optic nerve. Also, elevated blood flow to the brain may increase sensitivity of the eyes, resulting in improved visual function; some studies indicate that this may be the mechanism by which GBE may be helpful in macular degeneration.
Interactions Make Caution Necessary
Gingko biloba extract shows promise when used in a sensible way, for treatment of the brain in memory loss caused by dementia, as well as to prevent damage to the inner eye from the pressure within, needed to maintain the spherical shape of the globe. However, there are some serious interactions with other medications that are possible, so consult your primary care physician, your eyecare practitioner and other physicians such as an endocrinologist if you are diabetic. You may ask your pharmacist about drug interactions as well if you are considering adding it to your usual supplements of vitamins and minerals.
Many times, we think of herbal supplements as being harmless, especially if we perceive them as “natural” additives to the diet, but many natural supplements cause major drug interactions and side effects of their own. In Canada and the US, there is less oversight of supplements, as to their quality and their dosage than there is with pharmaceutical medications, so the danger of interaction is perhaps higher.
As an example, ginkgo extracts interact in a major way with the pain reliever and non-steroidal anti-inflammatory drug ibuprofen, which slows blood clotting; taking gingko with ibuprofen can cause increased bleeding and bruising. Gingko interacts with other anti-coagulants as well, such as warfarin (Coumadin) that is used to prevent blood clotting in victims of stroke and heart disease.
Gingko Biloba is a very useful herb and has been used as such for literally thousands of years; it may very well be quite useful as an adjunct to other treatments for glaucoma, especially in difficult-to-treat forms of it that manifest without the usual increase in IOP seen otherwise. Choose a high-quality brand of supplement, with pharmaceutical-grade extract with exact dosage information.
And, as always, keep this and other medications and supplements out of the reach of children.