Basic Facts

The lens of the eye is clear structure in the inner eye. Normally, light passes through it easily. A cataract is a cloudy lens located behind your iris (the colored part of your eye).

Cataracts can develop with age and cause blurry or dull vision. It can seem like a person is looking through a foggy window. These problems are often worse at night. Cataracts often grow slowly.

Stronger lighting and changes to eyeglasses can help when cataracts are small. People may need surgery if their cataracts grow too large and affect their daily activities.

The Most Common Types of Cataracts

Some kinds of cataracts are named depending on their location:

  • Nuclear Cataracts appear in the center of the lens. They may cause double vision or even multiple copies of an image.
  • Cortical Cataracts affect the edges of the lens. They cause problems with glare.
  • Posterior Subcapsular Cataracts occur on the back of the lens. They reduce your ability to read, even in bright light. This type of cataract may cause glare or halos around lights at night.

Other kinds of cataracts are grouped according to their causes:

  • Secondary cataracts sometimes form because of a chronic illness such as diabetes, after surgery for other eye problems, or from long-term steroid use.
  • Traumatic cataracts result from an eye injury.
  • Congenital cataracts appear in newborn babies or in childhood. They may be caused by a genetic mutation or as a result of an illness in the mother during pregnancy.
  • Radiation cataracts may occur after severe exposure to ionizing radiation.

Risks of Cataracts

Aging is the most common cause of cataracts. Also, many conditions and habits make cataracts more likely to develop. 

  • Diabetes
  • Alcohol use
  • Too much exposure to sunlight
  • Smoking
  • Inadequate vitamin intake
  • Long-term steroid use


Last Updated May 2023

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