Nutrients for the Eye

The eye is the lens of a complex visual system that requires various nutrients to function properly. Diseases of the eye, such as macular degeneration, glaucoma, cataracts and infections, can result from inadequate nutrition, although genetic and environmental factors can affect their development and progression also. Certain vitamins, carotenoids and herbs not only promote visual acuity, but they are strong antioxidants and protect the eye against free-radical damage and premature degeneration.

Vitamin A

Vitamin A is useful to the eye in a number of ways. A form of vitamin A called retinol is required for the production of rhodopsin. Rhodopsin is a highly light-sensitive pigment covering the retina, which is the tissue lining the inner surface of the eye. Rhodopsin is required for night vision and is sensitive enough to distinguish about 500 shades of grey, according to "The Human Eye: Structure and Function." Without adequate intake of retinol, night blindness develops.

Vitamin A is also needed to produce and maintain the moist membranes covering the interior of the eyelid and exterior of the eyeball. The membranes not only act as a physical barrier to pathogens and debris, but they also serve to lubricate the eye during the thousands of blinks it performs daily. Without adequate vitamin A or beta-carotene, its chemical precursor, dry eye develops, which can scar the cornea and lead to blindness.

Lutein and Zeaxanthin

The central part of the retina is called the macula, which is responsible for visual acuity. The macula is colored yellow because of the presence of two carotenoids, lutein and zeaxanthin. Lutein and zeaxanthin absorb blue light and protect the retinal photoreceptor cells from damage. Lutein and zeaxanthin are also powerful antioxidants and can prevent free-radical damage in the macula. The more lutein and zeaxanthin the macula contains, the better the protection against light damage. A 2004 Veterans Hospital study published in "Optometry" found that visual acuity significantly improved with lutein supplements in patients with macular degeneration.

Vitamin E

Vitamin E is another strong antioxidant that is used for preventing and treating eye diseases. Vitamin E not only destroys free radicals, but it promotes blood vessel integrity and reduces platelet cell aggregation, which can otherwise restrict blood flow. A 1999 Spanish study published in "Mechanisms of Aging and Development" found that serum vitamin E levels negatively correlate with severity of age-related macular degeneration. In other words, those who had the lowest serum levels of vitamin E had the most severe forms of macular disease.

Bilberry

Bilberry has a long history of use for various eye conditions, such as reducing eye fatigue and improving night-time visual acuity. Bilberry is a good source of vitamins A and C, and is rich in flavonoid anthocyanosides, which are antioxidants with an affinity for the eye and vascular tissues. Specifically, anthocyanosides reduce inflammation and strengthen the small blood vessels surrounding the eye. A 2001 study published in "Alternative Medicine Review" found that a combination of bilberry and vitamin E delayed the progression of cataracts in patients with age-related cataracts. Bilberry has also been used in the treatment of glaucoma, macular degeneration and progressive myopia.