What is a cataract?

Cataract is the word used to describe an area of increasing cloudiness in the lens of the eye — the lens of the eye is located behind the iris (the coloured part of the eye). A cataract may begin as a white spot at the edge of the lens or as a haze at the centre of the lens and gradually worsens until the vision is badly blurred. One eye is usually more seriously affected than the other. Cataracts do not usually cause complete blindness, although a person with cataracts may be declared legally blind, depending on the amount of vision loss.

What causes cataracts?

There is no known cause, but they are so common among elderly people that they could be regarded as a natural part of the ageing process — the majority of people over 65 will experience some degree of cataract. However, they can also affect people who have diabetes or who have suffered an eye injury, been exposed to prolonged sunlight, radiation or toxic substances, or who have a family history of cataracts. In rare cases, children can be born with congenital cataracts. This can be caused by an infection, especially the rubella virus, early in the pregnancy or as a result of the effects of drugs taken during pregnancy or by a genetic disorder such as Down’s syndrome.

What are the symptoms of cataracts?

Cataracts are painless but cause the following visual symptoms:

How are cataracts diagnosed?

Cataracts develop slowly and are painless, so you may not suspect that you have a problem until your vision begins to deteriorate. Tell your doctor of your suspicions and ask for a thorough examination of your eyes.

How are cataracts treated?

Cataracts cannot be treated by tablets or eye drops, although if cataracts are not interfering with your work or lifestyle, your doctor may suggest changing the prescription for your glasses. If the cataracts are seriously affecting your vision, your doctor will recommend that they are removed surgically, usually by phacoemulsification or extracapsular surgery. In phacoemulsification a small hole is made into the eye, the lens is broken up and removed through this hole and your lens is replaced by a plastic lens. Stitches are not usually necessary. In extracapsular surgery a larger opening is made in the eye, the lens is removed and replaced by a plastic lens. Stitches are used to close the opening. Surgery is usually performed under local anaesthetic. Following surgery you may be prescribed a tablet to reduce the pressure inside the eye shortly after the operation and a course of eye drops (a mixture of antibiotics to prevent infection and steroids to reduce inflammation).

What is the outlook?

Cataract removal is one of the most common and successful surgical procedures performed and you should regain your vision quite quickly. Your doctor will probably advise against swimming, heavy lifting or vigorous exercise for the first couple of months following surgery and prescribe a new pair of reading glasses.

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