SUNDAY, July 25, 2004 (HealthDayNews) -- Vision loss is one of the health conditions Americans fear most. One survey ranked it third, after cancer and heart disease.

More than ever, there's good reason for concern. Americans are living longer, and as people age their risk of contracting eye diseases such as age-related macular degeneration, cataracts, glaucoma and diabetic retinopathy tends to increase.

And with type 2 diabetes on the rise, more folks -- young and old -- are at risk of developing eye disease. Diabetic retinopathy alone accounts for up to 24,000 new cases of blindness each year, according to Prevent Blindness America (PBA), a national eye health and safety organization.

One in three children born in 2000 will develop diabetes in their lifetime, according to the U.S. Centers for Disease Control and Prevention. The coming wave of diabetic children worries eye health professionals.

"As a society, if we don't get a handle on that, that's going to be the next big surge of vision loss," cautioned Dr. Lylas G. Mogk, an ophthalmologist and spokeswoman for the American Academy of Ophthalmology.

Loss of vision is devastating, no matter what the cause. Some 1.1 million Americans are legally blind, 3 million have low vision, and 200,000 have severe visual impairment, according to Healthy People 2010, the U.S. Department of Health and Human Services' (HHS) disease prevention initiative.

Yet, every year many people suffer from blindness or impaired vision that could have been prevented or stalled with appropriate diagnosis and treatment.

Federal data suggest an estimated 80 million Americans have a potentially blinding eye disease. By 2030, the number of blind and visually impaired people in the United States will double if nothing is done.

Diabetic retinopathy affects 4.1 million Americans aged 40 and older, but that number is expected to swell to 7.2 million by 2020.

The condition affects the small blood vessels that nourish the retina, the light-sensitive tissue that lines the back of the eye. In its early stages, it can lead to blurred vision, although some people may have no symptoms at all. Left untreated, the disease can cause blindness.

"It's a crisis," warns PBA spokeswoman Betsy van Die. Of the 18.2 million Americans with diabetes, 5.2 million don't even know they have it, she said.

Another 41 million Americans have "pre-diabetes," which means they have elevated blood sugar levels that put them at risk of diabetes, HHS warned earlier this year.

With 40 percent to 45 percent of diabetics at some stage of diabetic retinopathy, the National Eye Institute urges everyone with diabetes to have a complete dilated eye exam at least once a year.

The most prevalent eye problem in America is cataract, affecting 20.5 million people aged 40 and older. It's also one of the most treatable, eye health professionals say.

A cataract is a clouding of the lens of the eye, which can lead to blurred vision, glare, poor night vision and other sight problems. Most often, it is related to the aging of the eye, with more than half of Americans having cataracts by age 80, van Die said.

But surgical replacement of the lens makes it possible for most cataract sufferers to regain their vision. Thanks to advances in technology, cataract surgery is 95 percent successful in the United States, according to PBA.

Glaucoma, another common eye disease known as the silent thief of sight, can't be cured. But it can be controlled if detected and treated before major vision loss occurs.

Some 2.2 million adults aged 40 and older have glaucoma, which is caused by rising fluid pressure in the eyes. People can have the disease without symptoms, but as it progresses it can cause damage to the optic nerve, diminishing the field of vision and ultimately leading to blindness.

Anyone can get glaucoma, but it is five times more common in blacks than whites, according to the National Eye Institute.

"Glaucoma is the reason that everybody starting at 40 should have an eye exam every two to three years," Mogk said. "If you catch it early, you can treat it early."

Perhaps more worrisome is a disease known as age-related macular degeneration, which gradually destroys detailed central vision. The macula is a spot in the center of the retina that allows the eye to see objects clearly and perform tasks that require straight-ahead vision, such as reading, driving and sewing.

"Among adults, what they more and more are thinking about -- and for good reason -- is macular degeneration," said Mogk, noting the disease is exceedingly common and there's no effective treatment.

Prevent Blindness America says it affects 1.8 million people aged 40 and older, but another 7.3 million are at risk of vision loss due to the disease.

There are two types of macular degeneration -- wet and dry -- of which the most common form is dry. Studies suggest the macula becomes diseased, leading to gradual deterioration of that area's light-sensing cells.

Scientists don't know exactly what causes it, but one theory suggests that exposure to environmental toxins can damage the macula, explained Mogk.

Research suggests nutritional supplements may help. One study sponsored by the National Eye Institute found that people at high risk of developing advanced macular degeneration who took supplements that contained Vitamins C and E, beta carotene, zinc and copper reduced the risk of continued progression by 25 percent.

A National Institutes of Health-sponsored study found people who ate the highest amounts of lutein, a plant-based antioxidant found in dark green, leafy vegetables such as spinach and kale, reduced risk for macular degeneration by 43 percent compared with those who consumed the lowest amounts.

Lutein, a yellow pigment, is also found in high concentrations in the macular. The belief is that it helps neutralize damage caused by the sun's harmful rays and other environmental toxins, experts say.

In general, to prevent eye disease, experts recommend people eat a healthy diet, quit smoking and wear sunglasses that protect against the sun's harmful rays.

Above all, eye health professionals urge everyone, beginning at age 40, to have a dilated eye exam every two years. People with specific risk factors, of course, may need to be examined earlier and more often.

More information

Visit the National Eye Institute to assess your risk for eye disease.

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