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.
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.
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.
There are three main types of cataract.
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.
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.
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.
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:
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.
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.
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