Eye conditions


Cataract clouds the lens of the eye, causing blurred vision and sensitivity to light. It’s common in older people.

What is a cataract?

Cataract is a common eye condition where the lens becomes cloudy over time.

The lens sits behind the iris – the coloured part of the eye. Its job is to focus light onto the retina at the back of the eye. The retina changes this light into nerve signals so the brain can process the image.

A cataract forms when protein in the lens is damaged and clumps together. This limits the light passing through the lens to the retina, causing low vision. It’s much like a dirty camera lens or foggy window.

Most cataracts occur in adulthood but they can develop in children. Some people are born with cataract.

Cataracts usually develop slowly and at a different rate in each eye.

How common is cataract?

Cataract becomes more common as we age. It affects around half of people over 50 years of age. Almost everyone will develop cataract by age 80.

Causes and risk factors

Most cataracts develop as part of the ageing process – although the exact cause is unknown.

Risk factors include:

  • age
  • family history of cataract

These also increase your risk of developing cataract at a younger age.

Long-term use of certain medications, eye trauma and some types of eye surgery can also increase your risk.

Signs and symptoms

In its early stages, cataract may not cause vision problems.

Signs of advanced cataract include:

  • blurred vision
  • sensitivity to light
  • reduced night vision
  • fading or ‘yellowing’ of colours
  • a feeling of looking through a curtain or veil
  • distortion or double vision in one eye.


Cataract can also change your eye’s focusing power. Frequent prescription changes for glasses can indicate a cataract.


An optometrist or ophthalmologist can diagnose cataract with an eye exam. It’s important to get your eyes checked at least every two years after age 50.

If you notice any changes to your vision, see your eye healthcare provider – don’t wait for your routine eye check.


New glasses, appropriate lighting or other visual aids may improve early symptoms of cataract.

Your eye healthcare provider may suggest removing the cataract if it affects your everyday activities.

Surgery is the only effective way to remove a cataract. It’s commonly done in hospital under a local anaesthetic. There are usually no stitches and vision can recover in a few days. A cataract will not redevelop after removal. Modern cataract surgery is very safe and highly effective. It can minimise the need for glasses.

A cataract does not have to be removed just because it is there. Your eye healthcare provider will advise if surgery could be a good option for you.

Can it be prevented?

Wearing sunglasses to protect your eyes from the sun may help prevent the early onset of cataract.