Ginkgo biloba extract can partially restore visual field losses in people with normal tension glaucoma, according to a new study. In glaucoma, deterioration of the optic nerve results in a diminished field of vision that can eventually lead to blindness. High pressure inside of the eye, which prevents normal function of the optic nerve, is a common feature of glaucoma. However, in normal tension glaucoma, the inner eye pressure is normal and the cause of optic nerve damage and visual field loss is unknown, though assumed to be related to reduced blood flow to the optic nerve.
The study involved 27 people with normal tension glaucoma and visual field losses who were randomly assigned to receive either 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 the placebo first, then eight weeks with no treatment, and finally four weeks of ginkgo. The researchers found that both groups had significant improvement (about 24%) in visual field after taking ginkgo. There were no improvements for either group during the placebo phases. No side effects from ginkgo were noted.
The researchers say that ginkgo’s antioxidant activity may have protected the optic nerve from oxidative (free radical) damage. The herb is also known to increase blood flow and oxygen utilization, which may have also protected the optic nerve from damage. Furthermore, its ability to increase blood flow to the brain might have improved eye sensitivity, resulting in improved visual function.