What is a cataract?

A cataract is a clouding of the normally clear lens of the eye. This clouding can weaken vision. The amount and pattern of cloudiness in the lens can vary.

What causes a cataract?

The eye functions much like a camera. Light rays enter through the front of the eye, passing through the cornea, the pupil, and the aqueous humor (transparent fluid in the front of the eye) onto the lens. The lens then bends light rays to focus objects onto the retina in the back of the eye. From there, the retina, the optic nerve, and the brain process the images and form vision.

Cataracts occur when there is a buildup of protein in the lens. The protein makes the lens cloudy and prevents light from passing through, which causes some loss of vision.

Cataracts can also be caused by:

  • Genetic (inherited) disorders.
  • Medical problems such as diabetes.
  • Certain medications.
  • Injury to the eye.

Other factors that increase the risk of developing cataracts include cigarette smoke, air pollution, and heavy alcohol use.

What are the symptoms of a cataract?

Cataract is a normal aging change of the eye. Cataracts often form slowly and cause few symptoms. When symptoms are present, they can include:

  • Vision that is cloudy, blurry, foggy, or filmy.
  • Glare or light sensitivity (especially when driving at night with oncoming headlights).
  • Prescription changes in glasses (sudden nearsightedness).
  • Double vision in one eye.
  • Need for brighter light to read.
  • Poor night vision.
  • Changes in the way you see color, especially yellow.

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