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NIH MedlinePlus the Magazine, Trusted Health Information from the National Institutes of Health


Leading Causes of Blindness

A photograph of two boys blurred to represent eyesight with Cataracts.

Photo National Eye Institute


Cataracts are a clouding of the lenses in your eyes. They affect vision and are very common in older people. More than 22 million Americans have cataracts. They are the leading cause of blindness in the world. By age 80, more than half of all people in the United States either will have a cataract or have had cataract surgery.

Common symptoms are:

  • Blurry vision
  • Colors that seem faded
  • Glare
  • Not being able to see well at night
  • Double vision
  • Frequent prescription changes in your eye wear

Treatment with new glasses, brighter lighting, anti-glare sunglasses, or magnifying lenses can help at first. Surgery is also an option. It involves removing the cloudy lens and replacing it with an artificial lens. Wearing sunglasses and a hat with a brim to block ultraviolet sunlight may help to delay cataracts.

A photograph of two boys darkened around the edges to represent eyesight with Glaucoma

Photo National Eye Institute


Glaucoma damages the eye’s optic nerve and is a leading cause of blindness. It usually happens when the fluid pressure inside the eyes slowly rises, damaging the optic nerve. Often there are no symptoms at first, but a comprehensive eye exam can detect it. About 2.2 million Americans have glaucoma.

Glaucoma is a leading cause of blindness among African Americans and Hispanics. African Americans experience glaucoma at a rate three times that of whites. They suffer blindness four times more frequently. Between the ages of 45 and 64, glaucoma is 15 times more likely to cause blindness in African Americans than in whites.

People at risk should get eye exams at least every two years, especially:

  • African Americans over age 40
  • People over age 60, especially Hispanics
  • People with a family history of glaucoma

Treatment usually includes prescription eye drops and/or surgery. There is no “cure” for glaucoma. Early diagnosis and treatment can control glaucoma before vision loss or blindness occurs. New research is focusing not only on lowering pressure inside the eye, but also exploring medications to protect and preserve the optic nerve from the damage that causes vision loss. There has been progress in understanding the genetics of glaucoma in the last few years, including the discovery of genes found to be associated with many forms of glaucoma.

A photograph of two boys blurred to represent eyesight with Age-Related Macular Degeneration.

Age-Related Macular Degeneration.
Photo National Eye Institute

Macular degeneration

Macular degeneration, often called age-related macular degeneration (AMD), is a leading cause of vision loss in Americans 60 and older. It is a disease that destroys the sharp, central vision needed to see objects clearly. This affects the ability to read, drive, watch television, and do routine daily tasks.

AMD affects the macula, the part of the eye that allows you to see fine detail. It does not hurt, but causes cells in the macula to die. In some cases, AMD advances so slowly that people notice little change in vision. In others, the disease progresses faster and may lead to vision loss in both eyes. There are two kinds of AMD—wet and dry. Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula. Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye.

Treatment: Although there is no cure for AMD at this time, regular eye exams can detect the disease so treatment can be most effective. Findings from the NEI-supported Age-Related Eye Disease Study (AREDS) show that a specific combination of vitamins and minerals can help slow the progression of advanced AMD.

The NEI recently concluded the first year of a two-year clinical trial to compare the relative safety and effectiveness of two drugs currently used to treat wet AMD. The two drugs, which are injected into the eye, are Lucentis (ranibizumab) and Avastin (bevacizumab). Results indicate that the two drugs are equally effective in treating AMD.

Diabetic Retinopathy

Diabetic retinopathy is caused by diabetes. It affects the retina, the light-sensitive tissue at the back of the eye, and causes the most blindness in U.S. adults. It affects the vision of more than half of the 25.8 million people diagnosed with diabetes age 18 or older.

People with diabetes should have a complete eye exam through dilated pupils at least once a year.

Treatment: Diabetic retinopathy is treated with surgery or laser surgery. With timely treatment; adequate control of blood sugar, blood pressure, and cholesterol levels; and regular follow up, 90 percent of all cases of blindness from diabetes can be prevented.

Comprehensive Dilated Eye Exams

A comprehensive dilated eye exam is a painless procedure in which an eye care professional examines your eyes to look for common vision problems and eye diseases, many of which have no early warning signs. Regular comprehensive eye exams can help you protect your sight and make sure that you are seeing your best.

What does a comprehensive dilated eye exam include?

A comprehensive eye examination includes dilation, tonometry, visual field test, and visual acuity test.

Dilation: Drops are placed in your eyes to dilate, or widen, the pupils. Your eye care professional uses a special magnifying lens to examine your retina to look for signs of damage and other eye problems, such as diabetic retinopathy or age-related macular degeneration. A dilated eye exam also allows your doctor to check for damage to the optic nerve that occurs when a person has glaucoma. After the examination, your close-up vision may remain blurred for several hours.

Tonometry: This test helps to detect glaucoma by measuring eye pressure. Your eye care professional may direct a quick puff of air onto the eye, or gently apply a pressure-sensitive tip near or against the eye. Numbing drops may be applied to your eye for this test. Elevated pressure is a possible sign of glaucoma.

Visual field test: This test measures your side (peripheral) vision. It helps your eye care professional find out if you have lost side vision, a sign of glaucoma.

Visual acuity test: This eye chart test measures how well you see at various distances.


Winter 2012 Issue: Volume 6 Number 4 Page 12-13