Cataracts

Cataract is clouding of the natural lens of the eye. The most important factor in cataract formation is increasing age, but there are additional factors, including smoking, diabetes, and excessive exposure to ultra violet light. Cataracts can also be present at birth or be caused by injury to the eye.

More than 20 million Americans over the age of 40 have cataracts, and it is the most frequent cause of preventable blindness in the world.

While a comprehensive eye examination by an eye care practitioner can determine for certain if you have a cataract forming, there are a number of signs and symptoms which may indicate a cataract:

  •  Blurred or hazy vision where colors may seem yellowed
  • A tendency to become more nearsighted
  • A gradual loss of color vision
  • The feeling of having a film over the eyes
  • An increased sensitivity to glare, especially at night
Normal visionThe same scene as viewed by a person with cataract

Are there other types of cataract?

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

  1. 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.
  2. Traumatic cataract. Cataracts can develop after an eye injury, sometimes years later.
  3. 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.
  4. Radiation cataract. Cataracts can develop after exposure to some types of radiation.

What causes cataracts?

The lens lies behind the iris and the pupil. It works much like a camera lens. It focuses light onto the retina at the back of the eye, where an image is recorded. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away. The lens is made of mostly water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it.

But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the cataract may grow larger and cloud more of the lens, making it harder to see.

Researchers suspect that there are several causes of cataract, such as smoking and diabetes. Or, it may be that the protein in the lens just changes from the wear and tear it takes over the years.