Major eye diseases

WASHINGTON – The leading causes of vision impairment and blindness in the United States are diabetic retinopathy, age-related macular degeneration, cataract, and glaucoma.

Diabetic retinopathy is a common complication of diabetes. Retinal blood vessels can break down, leak, or become blocked, affecting and impairing vision over time.

Nearly half of all people with diabetes will develop some degree of diabetic retinopathy during their lifetime, and risk increases with age and duration of diabetes.

People with diabetes are encouraged to seek annual dilated eye exams. Currently, laser surgery and a procedure called a vitrectomy are highly effective in treating diabetic retinopathy.

Age-related macular degeneration is a condition that primarily affects the part of the retina responsible for sharp central vision. There are two forms of AMD – dry AMD and wet AMD.

Because AMD often damages central vision, it is the most common cause of legal blindness and vision impairment in older Americans.

While there is no generally accepted treatment for dry AMD, laser therapies to destroy leaking blood vessels can help reduce the risk of advancing vision loss in many cases of wet AMD.

Research sponsored by the National Eye Institute has recently shown that a combination of zinc, vitamins C and E, and beta-carotene may also reduce the risk of advanced AMD by 25 percent.

Cataract is a clouding of the eye’s naturally clear lens. Most cataracts appear with advancing age. Scientists are unsure what causes cataract.

The most important factor is increasing age, but there are additional factors, including smoking, diabetes, and excessive exposure to sunlight.

Cataract is the leading cause of blindness in the world, and affects nearly 20.5 million Americans 40 and older. By age 80, more than half of all Americans develop cataract.

Cataract is sometimes considered a conquered disease because surgical treatment that can eliminate vision loss due to the disease is widely available.

Glaucoma is a disease that causes gradual damage to the optic nerve, that carries visual information from the eye to the brain. The loss of vision is not experienced until a significant amount of nerve damage has occurred.

For this reason, as many as half of all people with glaucoma are unaware of their disease. About 2.2 million Americans 40 and older have been diagnosed with glaucoma, and another 2 million do not know they have it.

Most cases of glaucoma can be controlled and vision loss slowed or halted by timely diagnosis and treatment. However, any vision lost to glaucoma cannot be restored.