Night Vision (Impaired)

The ability to see in poor light depends on the presence of a substance in the eye called rhodopsin, or visual purple. It is destroyed by bright light but rapidly regenerates in the dark. However, for some people, the adaptation to darkness or the recovery from glare takes an unusually long time. There is no medical treatment for this condition.

Principal Proposed Treatments for Night Vision (Impaired):

The herb bilberry is widely used as a treatment for impaired night vision. However, current scientific evidence suggests that it does not work.

Bilberry: Widely Used in Europe for Impaired Night Vision

The herb bilberry, a close relative of the American blueberry, is the most commonly mentioned natural treatment for impaired night vision. This use dates back to World War II, when pilots in Britains Royal Air Force reported that a good dose of bilberry jam just before a mission improved their night vision, often dramatically. After the war, medical researchers investigated the constituents of bilberry and subsequently recommended it for a variety of eye disorders. However, the scientific evidence that it works is more negative than positive, with the most recent studies finding no benefit.

A double-blind crossover trial of 15 individuals found no short- or long-term improvements in night vision attributable to bilberry. Similarly negative results were seen in a double-blind placebo-controlled crossover trial of 18 subjects and another of 16 subjects.

In contrast, two much earlier placebo-controlled studies of bilberry found that the herb improved vision in semidarkness, shortened time necessary to adapt to darkness, and speeded recovery from glare. However, the effect was not found to persist with continued use. A later double-blind placebo-controlled study on 40 healthy subjects found that a single dose of bilberry extract improved visual response for 2 hours. Other small studies have also found benefits, but since they did not use a placebo group, they are not valid as evidence.

The effects of bilberry are believed to be due to a group of chemicals called anthocyanosides. These naturally occurring antioxidants appear to have numerous important effects on the eye.

For more information, including dosage and safety issues, see the full bilberry article.

Other Proposed Treatments for Night Vision (Impaired):

Evidence from a small double-blind placebo-controlled study suggests that anthocyanosides (see Bilberry discussion above) from black currant might have some benefit for night vision.

OPCs have also been recommended for improving night vision, although the evidence that they help is highly preliminary.

There is no question that deficiencies of vitamin A and zinc can also negatively affect night vision. For more information, including dosage and safety issues, see the full articles on vitamin A and zinc.