Increased pressure in the eyes, also called intraocular pressure (IOP), is related to the obstructed or impaired flow of fluid within the eye. Left untreated, this elevated pressure can damage the optic nerve and lead to glaucoma, a leading cause of visual impairment and blindness.
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Early detection and treatment is essential, as this eye damage can be halted — but not reversed. Current management options include drugs and surgery, yet there is increasing interest in the role of diet and nutrition supplements in the prevention or treatment of these eye disorders.
Oxidative stress, created from an imbalance of too many free radicals in the body — a product of normal metabolism or pollutants — and not enough protective antioxidants, is known to play a role in the development of IOP and glaucoma.
Consequently, the antioxidants in foods, particularly those found in fruits and vegetables, are believed to reduce the risk of, or halt the progression of these disorders. However, the benefits of supplementation have yet to been proven.
One study investigated the effect of a multi-antioxidant supplement on primary open angle glaucoma, the most common type of this eye disorder. Participants were given a supplement containing lutein and zeaxanthin, plant chemicals known for eye health benefits, along with vitamins A, B, C and E, and the minerals zinc, copper, manganese and selenium.
In addition to these antioxidant nutrients, some participants were also given omega-3 fatty acids. After 2 years, no benefits were noted.
Several vitamins with antioxidant properties may reduce the risk of IOP and glaucoma. A study of African-American women linked 3 daily servings of fruit or fruit juice to a 79 percent lower risk of glaucoma — compared to women eating less than 1 serving daily.
Another study of mostly Caucasian women demonstrated about half the glaucoma rates with regular — but not even daily — inclusion of carrots, peaches and dark, leafy greens such as kale and collard greens. However, a study reviewing the effects of vitamin supplementation on glaucoma risk failed to show a benefit from vitamins A and E, and only found a weak benefit from supplemental vitamin C.
To date, there is inadequate evidence to warrant recommending vitamins to prevent or treat IOP or glaucoma, according to a research review published in the March 2018 issue of "Nutrients." However, emphasizing foods high in vitamins A and C, such as yellow, orange and green fruits and vegetables, appears to reduce glaucoma risk.
Many other supplements have been studied for their impact on managing — or treating — IOP and glaucoma. Examples include ginkgo biloba, an antioxidant which has been shown to improve blood flow in the eyes, as well as saffron, black currants, and a bilberry and pine bark blend.
Current data on these supplements is sparse, and does not support their use in the treatment of IOP or glaucoma. While increasing dietary intake of foods rich in these antioxidants may reduce the risk of glaucoma, caution is advised with supplementation, since high doses of certain antioxidants — notably vitamins A and E — have been associated with an increased risk of health problems, including cancer. Also, some high doses of supplements can interact with prescription medications.
Although anyone can suffer from glaucoma, some people are at higher risk, including anyone over the age of 40, people of African descent, and people with diabetes. Glaucoma can cause severe vision loss, but there are steps you can take to protect your eyes. Regular eye exams that include the measurement of eye pressure are essential for early detection and treatment.
If diagnosed with IOP or glaucoma, your eye doctor will outline a treatment plan, which will include a healthy diet that emphasizes colorful, antioxidant-rich fruits and vegetables. If you want to try the use of nutrition supplements as an adjunct to your treatment plan, talk with your doctor.
Reviewed by Kay Peck, MPH RD