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Conditions InDepth: Cataracts

A cataract is a clouding of the eye's lens that causes decreased vision. The lens of the eye focuses light rays onto the retina (the light-sensitive tissue at the back of the eye) where an image is recorded. This allows us to see things clearly. The lens of the eye comprises mostly water and protein. The protein is arranged in a way that keeps the lens clear and lets light pass through it. A cataract develops when some of the protein clumps together and starts to cloud an area of the lens. A cataract won't spread from one eye to the other, although many people develop cataracts in both eyes.

Normal Anatomy of the Eye
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As the cataract matures and gets cloudier, it may become difficult to read and do other normal tasks. Some people with “ripe” cataracts describe their vision as “trying to see through a waterfall.” Many people are not aware that their vision is blurry as cataracts usually progress slowly. That is just one reason why regular comprehensive eye examinations are important.

Cataract
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Copyright © Nucleus Medical Media, Inc.

The exact cause of this clouding is not known. However, a number of factors are known to contribute to the formation of cataracts, including, but not limited to:

  • Aging—Proteins in the lens change as part of the normal aging process. Aging is the most common contributing cause of cataracts.
  • Smoking
  • Excessive alcohol intake
  • Medical conditions, such as diabetes or galactosemia
  • Certain infections
  • Eye disease, or injury or burns of the eye
  • Exposure to radiation, toxins, or certain medications
  • Taking steroid medications for a long period of time
  • Excessive exposure to sunlight
  • Birth defect
What are the risk factors for cataracts?What are the symptoms of cataracts?How are cataracts diagnosed?What are the treatments for cataracts?Are there screening tests for cataracts?How can I reduce my risk of developing cataracts?What questions should I ask my healthcare provider?What is it like to live with cataracts?Where can I get more information about cataracts?

Revision Information

  • Cataract. American Optometric Association website. Available at: https://www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/cataract?sso=y. Accessed May 10, 2017.

  • Cataracts in adults. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T116240/Cataracts-in-adults. Updated November 28, 2016. Accessed May 10, 2017.

  • Cataracts. Patient website. Available at: https://patient.info/health/cataracts-2. Updated November 20, 2015. Accessed May 10, 2017.

  • Facts about cataract. National Eye Institute (NEI) website. Available at: https://nei.nih.gov/health/cataract/cataract%5Ffacts. Updated September 2015. Accessed May 10, 2017.

  • What are cataracts? American Academy of Ophthalmology website. Available at: https://www.aao.org/eye-health/diseases/what-are-cataracts. Updated November 15, 2016. Accessed May 10, 2017.

  • What is a cataract? NIH Senior Health website. Available at: https://nihseniorhealth.gov/cataract/whatisacataract/01.html. Accessed May 10, 2017.

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