A cataract is a painless, cloudy area in the lens of the eye that blocks the passage of light to the retina.

The retina is the nerve layer at the back of the eye. The nerve cells in the retina detect light entering the eye and send nerve signals to the brain about what the eye sees. Because cataracts block this light, they can cause vision problems.

Aging and exposure to sunlight can cause cataracts. Changes in your eyes are often a normal part of aging. But the changes do not always lead to cataracts. Cataracts can also happen after an eye injury, as a result of eye disease, after you use certain medicines, or as a result of health problems such as diabetes. Sometimes children are born with cataracts.

Cataracts can affect your vision.

• You may have cloudy, fuzzy, or foggy vision.
• You may see glare from lamps or the sun. You may have trouble driving at night because of glare from car headlights.
• You may need frequent changes to your eyeglasses prescription.
• You may get double vision in one eye.
• Your near vision may improve for a short time if you get a cataract. This temporary improvement is called second sight.

The vision loss from a cataract often happens slowly and may never become severe. Sometimes cataracts do not cause vision problems.

There is no proven way to prevent cataracts. But there are some things you can do that may help slow cataract growth.

• Do not smoke.
• Wear a hat or sunglasses when you are in the sun.
• Avoid sunlamps and tanning booths.
• Eat healthy foods
• Limit alcohol drinks.
• Keep diabetes under control.

If you do get cataracts, there are a number of things you can do that may help you manage your vision problems, including:

• The use of eyeglasses, contacts, or other vision aids.
• Keeping your eyeglasses or contact lens prescription up to date.
• Making sure you have plenty of lighting in your home.

Surgery can remove cataracts. For most adults, surgery is only needed when vision loss caused by a cataract affects their quality of life. Whether you need cataract surgery depends on how much of a problem the cataract causes for daily activities like driving and reading. Surgery is almost always by your choice (elective) and can be scheduled when it is convenient. For people who decide to have surgery, the surgery usually works very well.

Some people have to have surgery. Children are sometimes born with cataracts that need to be removed. Other people may get cataracts after an eye injury or as a result of eye disease or other health problems. Cataracts from these causes may also need to be removed.