What causes them?
Cataracts most commonly develop as people get older - called age-related cataracts. Smoking and exposure to UV radiation make them more likely to develop.
Congenital cataracts are present from birth and are usually the result of exposure to infection, radiation or drugs before birth, or caused by a genetic problem. Left untreated, congenital cataracts can result in permanent visual loss.
Other causes of cataracts include illnesses such as diabetes, certain drug treatments, long-standing inflammation and eye injury.
Who's affected?Cataracts can develop at any age, with age-related cataracts becoming more likely as people get older. Men and women are affected equally, and in the UK it's estimated about one in three people over 65 has a cataract. Usually, one eye is more affected than the other.
What are the symptoms?The symptoms of age-related cataracts develop gradually, getting worse over many years. Blurred and cloudy vision is common.
It may be difficult to see in dim light and bright lights may appear more glaring. Colours may appear different and there may be a yellow tinge to vision.
What's the treatment?
Not smoking and protecting the eyes from UV radiation by wearing sunglasses, when appropriate, may help reduce the risk of developing age-related cataracts.
Good management of conditions such as diabetes reduces the risk of cataracts developing.
Regular eye tests can help to detect problems early.
Early cataracts that aren't affecting sight don't need treating. Once a cataract starts to affect vision patients are usually recommended to have it treated.
The most effective treatment is then to remove the affected lens surgically and replace it with an artificial one.
