A cataract is a misting of the lens of the eye. It prevents light entering the eye properly and causes dimness of vision which can gradually worsen. Normally, sight can be restored by removing the damaged lens and replacing it with an artificial lens. Research is investigating ways of inhibiting the development of cataracts.

Cataracts are cloudy patches in the lens that can make vision blurred or misty. They are a very common eye condition.

Cataracts can develop in one or both eyes, and one eye can often be more affected than the other.

The lens is the transparent structure positioned at the front of the eye. It is normally clear and allows light to pass through to the back of the eye. However, if parts of the lens become cloudy (opaque), light is unable to pass through the cloudy patches.

Over time, the cloudy patches become bigger, and more of them develop. As less light is able to pass through the lens, the person’s vision is likely to become blurry or cloudy. The cloudier the lens becomes, the more the person’s sight will be affected.

Read more about the symptoms of cataracts.

When to see your optician

If you have problems with your vision, make an appointment to see your optician (also known as an optometrist). An optician can examine your eyes and test your sight.

It's advisable for you to have your eyes tested every two years as cataracts are sometimes diagnosed during a regular eye test, even if you have had no symptoms.

Read more information about how cataracts are diagnosed.

Who is affected

Cataracts are the main cause of impaired vision worldwide, particularly in developing countries. They affect men and women equally.

Cataracts are more common in older people. Cataracts that affect older people are known as age-related cataracts. In the UK, more than half of people who are over 65 have some cataract development in one or both eyes.

In rare cases, babies have cataracts when they are born, or children develop them at a young age. Read more about childhood cataracts.

Who's at risk

As well as your age, there are several things that may increase your risk of developing a cataract, including:

  • a history of cataracts in your family
  • smoking
  • lifestyle factors, such as poor diet
  • overexposing your eyes to sunlight
  • taking steroid medicines (medicines that contain powerful chemicals called hormones) for a long time
  • certain health conditions, such as diabetes

Read more information about the causes of cataracts and how to reduce the risk of cataracts.

Treating age-related cataracts

If cataracts are mild, stronger glasses and brighter reading lights may enable people to live with the condition. If left untreated, cataracts can cause blindness. However, this is very rare in developed countries.

Once cataracts start interfering with daily activities such as cooking or getting dressed, surgery is usually recommended. It's estimated that around 10 million cataract operations are performed around the world each year.

Read more about how cataracts are treated.

Are there any risks?

Cataract operations are generally very successful, with a low risk of serious complications. The most common risk is developing a condition called posterior capsule opacification (PCO), which causes cloudy vision to return.

If this happens, you may need to have laser eye surgery to correct it. Speak to your opthalmologist before cataract surgery to discuss any risks.

Read more about complications of age-related cataracts.

The information on this page is reproduced by kind permission of NHS Choices.