To navigate the world, we rely upon our sight more than any other sense. So it’s unfortunate that more than 3 million American adults suffer from eye diseases such as cataracts, glaucoma, macular degeneration and retinopathy. A recent survey found that the prevalence of chronic eye diseases in American adults increased more than 20 percent between 2002 and 2008—an upsurge driven in large part by an increase in diabetes, as well as the aging of the general population.
4 Common Eye Diseases
Some age-related eyesight changes happen universally, and therefore aren’t considered diseases. For instance, the loss of elasticity in the eye’s lens makes it difficult to focus on near objects. (We compensate with reading glasses.) Common eye changes may also reduce night vision.
But four of the main causes of reduced or lost eyesight are these common eye diseases.
■ Cataracts: opacities in the lens scatter incoming light, leading to decreased visual acuity and glare
■ Glaucoma: abnormally high pressure within the eye eventually leads to blindness
■ Macular degeneration: deterioration in an area of the retina (light-sensing tissue) creates loss of vision in the center of the visual field—the part we use to read and recognize faces
■ Diabetic retinopathy and hypertensive retinopathy: widespread disease in the retina caused by diabetes and high blood pressure, respectively
These eye conditions usually occur later in life, after years of wear and tear. While genetics play a role—especially in macular degeneration—lifestyle factors can help preserve the health of our eyes. With wise habits and the right foods and supplements, we can prevent or slow the progression of these diseases.
Our eyesight is affected by many of the same factors that affect overall health. To protect your eye health and ward off many eye diseases, follow these general health tips.
■ Wear sunglasses outside during the day. Ultraviolet light damages several structures in the eye. UV light penetrates clouds, so wear sunglasses on overcast days, as well.
■ Avoid tobacco smoke. Smoking is the leading cause of preventable death, and it damages the eye by generating free radicals and escalating the risk of arterial disease.
■ Protect the health of your heart and arteries. High levels of triglycerides (blood fats), cholesterol and blood pressure increase the risk of conditions such as cataracts, hypertensive retinopathy and macular degeneration.
■ Manage blood sugar. High blood sugar contributes to cataracts and damages small arteries, including the delicate blood vessels in the retina, which leads to diabetic retinopathy.
■ Keep your weight in a healthy zone. Being overweight can increase inflammation and elevate risk of high blood pressure, arterial disease and diabetes—all harmful to eye health.
Lifestyle solutions to these last three factors overlap: Regular physical activity and a varied, colorful plant-based diet both help stave off cardiovascular disease, diabetes and being overweight. Plant fiber slows absorption of cholesterol and sugar. And plants are full of antioxidant and anti-inflammatory chemicals. Studies show that the Mediterranean diet—centered around vegetables, fruits, whole grains, nuts, olive oil and fish—protects against cataracts and glaucoma in diabetics, a population at high risk for eye disease. Another study showed that eating at least three servings a day of antioxidant-rich vegetables reduced cataract risk.
Foods for Eye Health
While nearly all fruits and vegetables offer antioxidant value, certain foods are especially beneficial for the eyes.
Carotenoids are a class of antioxidants that seem to be particularly beneficial. Lutein and zeaxanthin—two important carotenoids—accumulate in the macula (the specialized central area of the retina), and their yellow color allows them to filter out damaging blue and ultraviolet light. Higher dietary intake of carotenoid-rich vegetables seems to protect against macular degeneration and cataracts. Kale is especially rich in lutein and zeaxanthin. Other good sources include other green leafy vegetables (spinach, beet and turnip greens, collards, mustard, Swiss chard and romaine lettuce), winter squash, okra, broccoli, Brussels sprouts, green peas, pumpkins and carrots.
Flavonoids, in particular anthocyanins, are another important group of plant chemicals beneficial to eye health. These potent antioxidants and blood-vessel strengtheners are responsible for the blue, purple and ruby pigments in berries. Top sources include bilberries, blackberries, blueberries, huckleberries, pomegranate, cherries, elderberries, cranberries and eggplant.
Eating fish twice a week also benefits eye health, as the retina requires the omega-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic (DHA) contained in oily fish. Studies show that people who consume more fish have a 38 percent reduction in macular degeneration. Some excellent fish options that are high in omega-3s—yet responsibly fished and low in toxic mercury—include Alaskan wild salmon, arctic char (farmed or wild-caught), Atlantic mackerel, Pacific sardines, Alaskan or British Columbian sablefish (or black cod) and oysters (farmed). To learn more about sustainable fishing practices and healthy fish, visit the Monterey Bay Aquarium’s Seafood Watch site.
Herbs for Eye Health
Herbs also may help preserve our vision. Anthocyanins, thought to affect light receptors in the eye, are found in black currant. In one study, an extract of black currant sped the ability to adapt to the dark and reduced eye fatigue. Bilberry is an anthocyanin-rich European native. Research shows bilberry extracts may help defend against cataracts and glaucoma, and improve diabetic and hypertensive retinopathy. Mirtogenol (a product combining standardized bilberry extract with pycnogenol, an extract of French maritime pine bark) was shown to improve blood flow and reduce pressure within the eye, suggesting it may help fight glaucoma. Pycnogenol alone may also slow the progression of retinopathy caused by diabetes or arterial disease.
Green tea also has great potential for eye health. In addition to its protective effects against diabetes and heart disease, green tea extract defends against damage to the lens (where cataracts form) and retina. Enjoy one to two cups of green tea a day.
Ginkgo improves blood flow to the retina. Preliminary research indicates that a concentrated ginkgo leaf extract improves vision in people with glaucoma.
Cannabis is a chemically complex plant. More than three decades ago, scientists showed that smoking its leaves decreased eye pressure in people with glaucoma. However, it also decreased blood flow to the optic nerve (the bundle of nerve fibers carrying sensory information to the brain for further processing).
Interested in reaping the medical benefits without incurring the intoxicating side effects, researchers have examined the use of cannabinoids (marijuana’s active ingredients) in reducing eye pressure. Products that deliver the cannabinoids via eye drops are in development.
Turmeric powder, a key ingredient in curry, gets its yellow color from curcumin, a powerful anti-inflammatory and antioxidant substance. Researchers are optimistic about curcumin’s ability to combat a number of nervous system disorders, including glaucoma and macular degeneration. Turmeric has so many additional potential health benefits—among them fighting cancer and the inflammation that can cause joint pain—that it’s worth your while to make liberal use of this culinary spice.
Supplements for Eye Health
While it’s normally more effective to obtain nutrients from foods, supplements that blend antioxidant vitamins and minerals may help prevent and manage age-related eye diseases. A large trial called the Age-Related Eye Disease Study found that six years of supplementation with vitamin C (500 mg) and vitamin E (400 IU), beta-carotene (15 mg) and zinc (80 mg) significantly reduced the odds for progression of macular degeneration. Studies of shorter duration did not produce such benefits.
B vitamins also protect the eye. Several studies support the use of vitamin B6, vitamin B12 and folic acid. Likewise, thiamine (B1), niacin (B3) and riboflavin (B2) protect against cataracts. Rather than supplement solely with these B vitamins, take a B supplement or a multivitamin and mineral blend formulated for eye health.
Higher dietary intake of antioxidants, zinc and omega-3 fatty acids may decrease risk of developing macular degeneration in those at high genetic risk. But the research is less clear for whether antioxidant supplementation prevents or slows the progression of cataracts. Some researchers note that, to prevent cataracts, antioxidant supplements need to be started before the age of 50.
For people at risk for eye diseases, fish oil supplements, which contain DHA and EPA, may have merit. DHA helps maintain the retina’s function with age. Fish oil also reduces symptoms of dry eye, which is especially common in women.
Stay tuned for results of the Age-Related Eye Disease Study 2, a large-scale trial investigating whether lutein and zeaxanthin, plus or minus omega-3 fatty acids (the type found in fish) can reduce the risk of developing advanced macular degeneration. Results of the study are likely to be announced in the summer of 2013.
See the Eye Doctor
To maintain eye health, it’s crucial to keep up with regular eye examinations—once a year for otherwise healthy adults, more often for those at risk for eye disease. An eye specialist will check your visual acuity, examine the eye’s surface and retina, and measure pressure within the eye. This last part is critical because glaucoma usually causes no symptoms until permanent damage has occurred. If identified early, prescription eye drops can halt progression. Other treatments help preserve vision in the face of other serious eye diseases. Always check with your doctor before making changes to your health regimen.
Linda B. White, M.D. writes about integrative medicine. She has two books coming out in 2013: Health Now: An Integrated Approach and 500 Time-Tested Home Remedies and the New Science Behind Them.