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Cataracts

What is a cataract?

A cataract is a clouding of the lens in the eye that affects vision. Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.

A cataract can occur in either or both eyes. It cannot spread from one eye to the other.

What is the lens?

The lens is a clear part of the eye that helps to focus light, or an image, on the retina. The retina is the light-sensitive tissue at the back of the eye.

In a normal eye, light passes through the transparent lens to the retina. Once it reaches the retina, light is changed into nerve signals that are sent to the brain.

The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a cataract, the image you see will be blurred.

Are there other types of cataract?

Yes. Although most cataracts are related to aging, there are other types of cataracts:

  • Secondary cataract. Cataracts can form after surgery for other eye problems, such as glaucoma. Cataracts also can develop in people who have other health problems, such as diabetes. Cataracts are sometimes linked to steroid use.


  • Traumatic cataract. Cataracts can develop after an eye injury, sometimes years later.


  • Congenital cataract. Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may be so small that they do not affect vision. If they do, the lenses may need to be removed.


  • Radiation cataract. Cataracts can develop after exposure to some types of radiation.


Eyeball Illustration - Cataracts


Next: What are the causes and risk factors for cataracts? »

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Cataracts

What problems are caused by smoking?

By smoking, you can cause health problems not only for yourself but also for those around you.

Hurting Yourself

Smoking is an addiction. Tobacco contains nicotine, a drug that is addictive. The nicotine, therefore, makes it very difficult (although not impossible) to quit. In fact, since the U.S. Surgeon General's 1964 report on the dangers of smoking, millions of Americans have quit. Still, approximately 440,000 deaths occur in the U.S. each year from smoking-related illnesses; this represents almost 1 out of every 5 deaths. The reason for these deaths is that smoking greatly increases the risk of getting lung cancer, heart attack, chronic lung disease, stroke, and many other cancers. Moreover, smoking is perhaps the most preventable cause of breathing (respiratory) diseases within the USA.

Hurting Others

Smoking harms not just the smoker, but also family mem...

Read the Smoking (How to Quit Smoking) article »











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