A cloudy lens inside your eye is called a cataract. About a third of people over 65 have age-related cataracts. The condition is rare in young people but babies can be born with them or you can develop cataracts in childhood.

What causes cataracts and who can get them?

The lens inside your eye is made of proteins that are transparent like the ‘white’ of a raw egg. If the proteins inside your lens are damaged it makes them turn cloudy and eventually white (imagine the change in the clear jelly of an egg going white when you cook it). The lens inside your eye needs to be clear for you to see properly.

The most common cause of cataracts is old age. The proteins in the lenses of old people gradually go cloudy. This happens faster if they smoke or frequently expose their eyes to strong sunshine without sunglasses. Once a cataract has developed the proteins will never be clear again (just like a cooked egg will never look like a raw one again).

A virus infection can cause cataracts in babies. This is more likely to occur in countries where rubella is common, or if the mother has not been vaccinated against viral illness when she was a child. In Britain, cataracts caused by rubella are rare.

In the UK, children born with cataracts often come from a family where other members have the condition. The proteins in their lenses are different and might contain cloudy proteins. You inherit lens proteins in the same way that you inherit the colour of your hair or skin from your parents.

Metabolic conditions

In very rare circumstances a young person might have a medical disorder where the lens becomes cloudy. This is when the eye doesn’t receive the correct chemicals from the body to stay healthy. These disorders are called ‘metabolic disorders’. An example of a metabolic disorder that can cause cataracts at a young age is diabetes.

Injury

You might also get a cataract if your eye has a serious injury. A cataract can be caused if a sharp object cuts into the inside of the eye. For example, a small fast object, such as a squash ball, can cause major injury if eye protection isn’t worn.

What are the signs and symptoms of cataracts?

Cataracts can make your vision:

• Blurred – both far away and close up. Eyesight is still blurry when glasses are worn.
• Dazzled by light – the cloudy proteins in the lens scatter light, which dazzle you when light is shone into your eye.

How are cataracts diagnosed and treated?

A cataract is diagnosed by a health professional (usually a doctor). They shine a light into the eye to look for a reflection from the inside of the healthy eye called the ‘red reflex’. You see your own red reflex if a photograph is taken with a flash. This is known as ‘red eye’.

Cataracts in adults are common and are treated by a routine surgical operation, which is carried out under local anaesthetic and only takes about 20 minutes. The cataract is broken up with a delicate instrument inside the eye and sucked out. An artificial lens is then placed into the eye. After the operation you will need to use eye drops that contain steroids to reduce inflammation and take antibiotics to avoid an infection.

It is important to treat cataracts in small babies very quickly to correct their sight. Otherwise the vision part of the brain might not develop properly.

The operation in a small baby or child is more complicated and is always carried out under a full general anaesthetic. It isn’t always possible to safely put an artificial lens inside the eye.

Young people need to wear glasses after a cataract operation even if they have an artificial lens implanted.

Sometimes cataracts don’t interfere with your sight and therefore won’t need to be removed. If the condition doesn’t run in your family and if you haven’t got problems with vision, it is unlikely you will be checked regularly for cataracts when you are young.

Looking forward

A healthy balanced diet with plenty of fruit and vegetables can help damaged cells repair themselves, which will help to protect you against developing cataracts in later life.

Protect your eyes from the sun by wearing sunglasses with UVA and UVB protection. Also make sure you wear eye protection when playing sports, such as squash, where the ball is small enough to hit the eye (rather than the bones around your eye).

Smoking can make you more prone to cataracts.

Further help and Information

Visit the RNIB (Royal National Institute for the Blind) website to find out more about eye conditions

Last reviewed by Great Ormond Street Hospital: 27 October 2007

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