Natural Approaches to Eye Disorders

Conditions including cataract, conjunctivitis, macular degeneration and night blindness affect millions of consumers, but nutritional support can help.

One of the most common eye disorders is cataract, a term that refers to any cloudiness or opacity of the normally transparent crystalline lens. A cataract may or may not cause vision loss, depending on the size of the opacity, its density and its location. Severe cataracts are a major cause of treatable blindness throughout the world.

Conjunctivitis is an inflammation of the conjunctiva, the transparent mucous membrane lining the inside of the eyelids and the white of the eyeball. Normally the white, or sclera, is clearly visible through the conjunctiva, but when the conjunctiva is inflamed, its normally invisible blood vessels become engorged, making the eye appear red. Conjunctivitis may be caused by many types of infectious agents, such as viruses or bacteria, as well as by toxic, chemical and allergenic irritants. 

Macular degeneration, also called “age-related macular degeneration” (AMD), is the most common cause of blindness and vision impairment among the elderly in the United States. AMD damages the macula, a small part of the eye’s light-sensitive retina (the layer of tissue that sends signals for vision to the brain). Because the macula is responsible for seeing sharp details directly in the center of the field of vision, damage caused by AMD may interfere with fine detailed vision and a person's ability to see straight ahead.

Finally, nutrition may help in addressing impairment of the vision normally possible in dim light, known as night blindness or nyctalopia. It may be an early sign of vitamin A deficiency because that vitamin plays a major role in the cells of the eye sensitive to dim light. Night blindness is also a manifestation of various eye disorders such as glaucoma and optic nerve disease. It is often the earliest symptom of retinitis pigmentosa, a chronic and progressive inflammation of the retina.

Valuable Vitamins

Research conducted in healthy children demonstrated levels of vitamin A decline during conjunctivitis infections.¹ Furthermore, in a form of conjunctivitis characterized by a lack of tears, vitamin A deficiency was found to be one of the causal factors.² Perhaps the best reason for supplementing with vitamin A, however, is that it is necessary for the health of the mucous membranes that line the eyelid.³

There is a significant amount of research that validates the use of vitamin C for cataract prevention. In the Nurses Health Study, the risk of cataract was 45-percent lower among women who used vitamin C supplements for 10 or more years.⁴ In a smaller study, the use of vitamin C supplements for 10 or more years was associated with a 77-percent lower prevalence of early cataracts and an 83-percent lower prevalence of moderate cataracts compared with women who did not use vitamin C supplements.⁵ European researchers noted “antioxidant diet supplementation [including vitamin C] seems to be useful in prevention of age related cataract.”⁶

Vitamin E is also effective for the prevention of cataracts. In the Vitamin E and Cataract Prevention Study, it was concluded that prior vitamin E supplementation seemed to protect participants from developing early cortical cataracts.⁷ Another study found regular users of vitamin E supplements and persons with higher plasma levels of vitamin E had half the risk of developing cataracts.⁸

Vitamin B2 plays a key role in eye health, and a deficiency of this nutrient can lead to inflamed eyelids and sensitivity to light.⁹ Higher intake of vitamin B2 reduced the odds of developing more severe cataracts by 40 to 50 percent in one study.¹⁰ Chinese researchers further reported the prevalence of cataract was significantly lower in persons receiving vitamin B2 (and niacin) compared with persons not receiving these vitamins.¹¹ And in the Lens Opacities Case Control Study, dietary intake of vitamin B2 was found to be protective against cataract.¹²

Mineral Support

Sunlight triggers oxidative damage in the eye, which in turn can cause macular degeneration.¹³ Consequently, it’s not surprising to learn that animals given antioxidants, which protect against oxidative damage, have a lower risk of macular degeneration.¹⁴ Furthermore, people with high blood levels of antioxidants have a lower risk.¹⁵ Perhaps most significant is that those with the highest levels of the antioxidants selenium, vitamin C and vitamin E may have a 70-percent lower risk of developing macular degeneration.¹⁶ Selenium also works with a very important enzyme in the lens of the eye that protects against oxidative damage.

Zinc is well-known for its function in immunity and wound-healing. Congenital zinc deficiency may be associated with cataract formation and other disorders of the eye.¹⁷ A deficiency of zinc can cause night blindness.¹⁸ Research conducted in healthy children demonstrated zinc levels declined during conjunctivitis infections.¹⁹ Furthermore, a supplement of zinc with antihistamines, taken only on demand, had very good or excellent results in more than three-quarters of subjects with seasonal (allergic) conjunctivitis.²⁰

Two important enzymes needed for vision require zinc. Researchers have observed that zinc’s role in retinal metabolism may make it a beneficial supplement to fight macular degeneration.²¹ Research using 80 mg/d of zinc or placebo for two years found zinc prevented vision loss by 42 percent in people with “dry” macular degeneration;²² other research did not show a benefit with “wet” macular degeneration.²³

Specialty Compounds

Research has shown anthocyanosides—the active bioflavonoid compounds in bilberry—speed regeneration of rhodopsin, the purple pigment used by the rods in the eye for night vision.²⁴ Bilberry has been shown as a possible first line of defense for those with poor night vision.²⁵ Bilberry’s anthocyanosides act as an antioxidant, making it a potential preventive against AMD.²⁶ Bilberry has been shown to strengthen capillaries and reduce hemorrhaging in the retina.²⁷

From the botanical realm is Ginkgo biloba, which studies have shown may be useful in treating visual activity impairments and damage to the visual field. Specifically, ginkgo was found to provide a significant improvement in long distance visual acuity in AMD.²⁸

Carotenoids are also valuable for eye health—particularly lutein and zeaxanthin. These carotenoids are found in high concentrations in the macula, where they protect the retina from damage caused by sunlight.²⁹ Harvard researchers reported people eating the most lutein and zeaxanthin (a total of 5.8 mg/d) have a 57-percent decreased risk of AMD, compared with people eating the least.³⁰ Lutein and zeaxanthin are often found together in dietary supplements, and lutein can be converted in the eye to one of the zeaxanthin structural isomers.³¹

The amino acid taurine is found in high concentrations in the retina and has been used clinically in the treatment of a wide variety of eye conditions, including AMD.³² Taurine-containing eye drops have had beneficial results for patients with macular degeneration.³³

Gene Bruno is the Dean of Academics and is on the faculty of Huntington College of Health Sciences (HCHS). HCHS is an accredited distance learning institution offering undergraduate and graduate degrees, as well as a diploma program in nutrition. HCHS.edu, (800) 290-4226.

References

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