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Cataracts symptoms, causes and diagnosis

A cataract is a clouding of the lens of the eye that makes a person's vision seem misty or blurred.

Cataracts are more common as people get older with more than half of over-65s in the UK having some degree of cataracts.

What causes cataracts?

The eye works much like a camera. Light rays enter through the front of the eye, passing through the cornea, the pupil and the aqueous humour (the 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 Eyes

The cataract is a lens that has become clouded. Cataracts occur when there is a build-up of protein in the lens that makes it cloudy. This prevents light from passing through a normally clear lens, causing some loss of vision. No one knows what causes the build-up of protein responsible for clouding the lens.

Types of cataracts include:

  • Age-related cataracts. As the name suggests, this type of cataract develops as a result of ageing.
  • Congenital cataracts. Babies are sometimes born with cataracts as a result of an infection they had before they were born, or that may develop early in childhood.
  • Secondary cataracts. These may develop as a result of other diseases, like diabetes or long-term exposure to toxic substances, certain medications (such as corticosteroids or diuretics), ultraviolet light and radiation.
  • Traumatic cataracts. These can form after injury to the eye.

Other factors that can increase a person's risk of developing cataracts include cigarette smoke, air pollution and excess alcohol consumption.

What are the symptoms of cataracts?

Cataracts often form slowly and cause few symptoms. When symptoms are present, they can include:

  • Vision that is cloudy, blurry, foggy or filmy
  • Sudden short sightedness
  • Changes in the way you see colour, especially yellow
  • Problems driving at night because oncoming headlights are distracting
  • Problems with glare
  • Double vision
  • Sudden temporary improvement in close-up vision

How are cataracts diagnosed?

A series of tests can be performed by your optometrist. An eye examination will be performed to test how well you can see. Make sure you take your glasses or wear your contact lenses to the appointment. Your optometrist may also dilate your pupil in order to examine the condition of the lens and other parts of the eye.

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