Ginkgo biloba (1999, '03, '06, '15), Glaucoma & Intraocular Pressure
Learn more information about glaucoma treatment and information.
25% of Ginkgo biloba is comprised of antioxidant flavanoids. Because of their antioxidant, anti-inflammatory and nerve-protecting capacity they have been used in treatment for glaucoma, including normal-pressure glaucoma. Conventional treatments for normal tension glaucoma and open-angle glaucoma do not always prevent progression of the condition.
While there have been many small studies on the effect of flavanoids in general and Ginkgo in particular, the results have been conflicting, although many of them indicated positive benefits for patients with normal tension glaucoma.
This meta-analysis and review of the best of these small studies did find a statistically that flavanoids did help protect or improve the peripherial field vision in patients with glaucoma, particularly those with more several loss of visual field. The study found improved ocular blood flow, and apparent improved retinal nerve cell functioning.
Researchers: S. Patel, J.J. Mathan, et al,
Published: The effect of flavonoids on visual function in patients with glaucoma or ocular hypertension: a systematic review and meta-analysis, Graefes Archive for Clinical & Experimental Ophthalmology, November, 2015.
This study examined the effects of Ginkgo on intraocular pressure in young rabbits with (steroid-induced) glaucoma (ocular hypertension).
The rabbits received topical TobraDEX and/or 5 mcg of Ginkgo biloba extract 4x daily for 2 weeks, and their intraocular pressure was measured periodically.
The trabecular meshwork (TM), the network of fibers near the base of the cornea, was examined. Ginkgo biloba extract had reduced the accumulated material clogging the TM, but suppressed the intraocular pressure. In general better TM cell health resulted.
In addition, the researchers examined lab-cultured human TM cells and found that ginkgo markedly reduced degradation of meshwork cells and reduced production of DEX-induced myocilin that can clog the meshwork. Ginkgo biloba extract also controlled the expression of related proteins but not other stress-related genes. Furthermore, it reduced direct damage to the TM cells from steroids.
The researchers concluded that Ginkgo biloba extract suppressed the high intraocular pressure caused by the steroids and protected the meshwork cells against steroid damage.
Published: Jia LY, Sun L, Fan DS, et al. Effect of Topical Ginkgo biloba Extract on Steroid-Induced Changes in the Trabecular Meshwork and Intraocular Pressure. Arch Ophthalmol 2008;126(12):1700-1706.
A early clinical trial suggests that ginkgo biloba extract has possibilities.
The research looked at the effect of inkgo biloba extract on pre-existing visual field damage in normal tension glaucoma.
In normal tension glaucoma damage occurs to the optic nerve and visual field are present despite intraocular pressure measurements being 'normal'. The exact mechanisms behind the damage are unknown, but there are two primary factors:
- reduced blood flow to the optic nerve
- versus relatively high intraocular pressure
The researchers felt that because some patients with normal tension glaucoma can experience narrowing of the peripherial field despite conventional medical treatment, the value of other treatments is worthy of investigation. Since Ginkgo biloba has been shown to improve blood flow at a tissue level, it was an obvious candidate for selection in such investigations.
In a randomized, double-blind, placebo-controlled, crossover trial, 27 patients with bilateral visual field damage (less peripherial vision) resulting from normal tension glaucoma received Ginkgo biloba extract or a placebo. Visual field tests were performed at the beginning of the trial and at the end of each 4-week period.
The researchers measured any changes in the visual field and the development of any ocular or systemic complications. After Ginkgo biloba treatment, a significant improvement in visual field indices was recorded, but there were no significant changes found in intraocular pressure, blood pressure or heart rate.
No ocular or systemic side effects were noted in any patient during the trial. The authors concluded that Ginkgo biloba extract can improve pre-existing visual field damage in some individuals with normal tension glaucoma. However, they observed that the exact explanation is not currently understood.
Researchers: Quaranta L, Bettelli S, Uva MG et al.
Published: Effect of Ginkgo biloba extract on preexisting visual field damage in normal tension glaucoma. Ophthalmology February, 2003.
Researchers found a possible benefit from treatment with Ginkgo biloba for existing glaucoma patients. The benefit comes from Ginkgo's ability to improve blood flow in the eye. The trial was a crossover trial in which 11 patients received a series of different therapies in order to compare them. The treatments were:
- 40 mg daily Ginkgo biloba extract 2 days followed by a two week rest period,
- placebo for 2 days
Treatment with Ginkgo improved diastolic velocity in the main artery in the eye while placebo caused no change. Ginkgo did not change blood pressure, heart rate or intraocular pressure in this short trial.
Researchers: H.S. Chung, et al,
Published: Ginkgo biloba extract increases ocular blood flow velocity, Journal of Ocular Pharmacology and Therapeutics, June, 1999.