What is a cataract?

A cataract develops when the lens in your eye, which is normally clear, becomes foggy.

For your eye to see, light passes through a clear lens. The lens is behind your iris (colored part of your eye). The lens focuses the light so that your brain and eye can work together to process information into a picture.

When a cataract clouds over the lens, your eye can’t focus light in the same way. This leads to blurry vision or other vision loss (trouble seeing). Your vision change depends on the cataract’s location and size.

Who gets cataracts?

Most people start getting cataracts around age 40. But you probably won’t notice symptoms until after age 60. Rarely, babies are born with cataracts due to a birth defect.

You’re more likely to develop cataracts if you:

  • Smoke cigarettes.
  • Live in an area with bad air pollution.
  • Use alcohol heavily.
  • Have a family history of cataracts.

How common are cataracts?

Cataracts are common among older people. More than 50% of people age 80 and older have had cataracts.

Can you get cataracts in both eyes?

You can get cataracts in both eyes. But one eye may be worse than the other or develop at a later time.

What causes a cataract?

The lens of your eye is mostly water and proteins. As proteins break down over time, they hang around in your eye. These lingering proteins can make your lens cloudy, so it’s hard to see clearly. This is a typical — though unpleasant — part of aging.

Some things can speed up the formation of cataracts, such as:

What are the symptoms of a cataract?

Cataracts are a common part of the eye’s aging process. Eventually, they can cause:

  • Vision that’s cloudy, blurry, foggy or filmy.
  • Sensitivity to bright sunlight, lamps or headlights.
  • Glare (seeing a halo around lights), especially when you drive at night with oncoming headlights.
  • Prescription changes in glasses, including sudden nearsightedness.
  • Double vision.
  • Need for brighter light to read.
  • Difficulty seeing at night (poor night vision).
  • Changes in the way you see color.

Are cataracts painful?

Cataracts don’t usually hurt. But they can cause discomfort by making your eyes more sensitive to light.

Last reviewed by a Cleveland Clinic medical professional on 04/27/2020.


  • American Academy of Ophthalmology. What Are Cataracts? Accessed 6/4/2020.
  • American Optometric Association. Cataract. Accessed 6/4/2020.
  • National Eye Institute. Cataracts. Accessed 6/4/2020.

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