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Key points

  • A cataract is a gradual clouding of the lens of your eye causing blurred or misty vision. It can affect one or both eyes.
  • You’re more likely to get cataracts as you get older.
  • If you think you may have cataracts, you should have your eyes tested by an optometrist.
  • Cataracts are treated with surgery to replace the cloudy lens of your eye with a new, artificial lens.

An image of a woman taking a photograph

A cataract is a clouding of the lens of your eye that can make your vision blurred or misty. It can affect one or both of your eyes.

About cataracts

Cataracts generally develop over a long period of time, causing your eyesight to gradually get worse.

You're more likely to get cataracts as you get older. In the UK, about a third of people aged over 65 have cataracts in one or both eyes.

You can have a cataract in one or both of your eyes; however, it won’t spread from one eye to the other.

Your eye

The lens is near the front of your eye, just behind your iris – the coloured part of your eye. Your lens is normally clear and helps you to see things in focus. It directs light rays on to the back of your eyeball (retina), to form an image, which is then sent to your brain. Your lens can change its shape to allow you to see things near and far away. If your lens becomes cloudy from a cataract, your vision will become blurred.

Illustration showing the structure of the eye

Types of cataract

There are three main types of cataract.

  • Nuclear cataracts. These may make it difficult for you to recognise the intensity of colours. If you have nuclear cataracts, your reading vision won’t normally change.
  • Cortical cataracts. These can cause you problems with glare if you drive. You may also have difficulty reading and find sunlight uncomfortable during the winter because of the sun being lower on the horizon and shining into your eyes.
  • Subcapsular cataracts. These can make your vision poor during the daytime, making it difficult for you to drive. You may also have difficulty reading.

Symptoms of cataracts

Your symptoms will depend on where your cataract is on your lens, its size and if you have a cataract in one or both eyes. The most common symptoms are listed below.

  • Cloudy or blurry vision.
  • Frequent changes to the prescription of your glasses or contact lenses.
  • You may get more glare or see halos from lights or the sun. It may make driving at night difficult because of the glare caused by oncoming vehicle headlights.
  • Colours may seem washed out or faded.

These symptoms may be caused by problems other than cataracts. If you have any of these symptoms, see your optometrist (a registered health professional who examines eyes, tests sight and dispenses glasses and contact lenses) for advice.

Complications of cataracts

If left untreated, cataracts may eventually lead to blindness. However, cataracts are normally diagnosed and treated well before they severely affect your vision. Left untreated, your lens may become so cloudy that it will be like trying to see through fog.

Causes of cataracts

Cataracts are caused by changes in the structure of the lens of your eye. This is usually as a result of getting older.

There are other factors that may increase your risk of getting cataracts. These include:

  • diabetes
  • an injury to the eye
  • other eye problems, such as uveitis
  • exposure to ultraviolet (UV) light from sunlight
  • long-term use of steroid medicines
  • smoking
  • drinking too much alcohol
  • a family history of cataracts

Diagnosis of cataracts

If you think you have symptoms of cataracts, you should have your eyes tested by an optometrist. He or she will look into your eyes using a special instrument called an ophthalmoscope. Your optometrist will refer you to an ophthalmologist (a doctor specialising in eye health) if he or she suspects you have cataracts.

Eye tests using standard charts will help identify worsening eyesight. It's quite common to be diagnosed with a cataract during a routine eye test without having any symptoms as changes in the lens tend to occur gradually over many years.

Treatment of cataracts


Wearing glasses and using brighter lighting may improve your vision to begin with, but your cataracts will probably get worse over time, so this will only be a temporary solution.


So far, no medicine has been found to slow down the development of cataracts, and there isn't a medicine or eye drop that can clear a clouded lens.


Replacing your cloudy lens with a new, artificial lens is the only way to improve your vision. The most common operation for this is called phacoemulsification. This usually takes about 30 minutes. The cloudy lens is destroyed with sound waves and taken out, and a lens made of a clear, artificial material, such as plastic or silicone, is put in. This is usually done under local anaesthesia or with anaesthetic drops. The anaesthetic completely blocks the feeling from your eye area and you will stay awake during the operation.

If you have a cataract in both eyes, the surgery to remove each one will be done at different times – usually four to eight weeks apart.


Produced by Dylan Merkett, Bupa Health Information Team, September 2012.

For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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