A cataract is clouding or opacity of the lens inside the eye. It is useful to learn about how the eye works in order to understand what a cataract is. Inside the eye, behind the coloured part (the iris) with a black hole in the middle (the pupil), is the lens. In a normal eye, this lens is clear. It helps focus light rays on to the back of the eye (the retina), which sends messages to the brain allowing us to see. When a cataract develops, the lens becomes cloudy  and prevents the light rays from passing through.

What symptoms do cataracts cause?
Cataracts usually form slowly over years causing a gradual blurring of vision, which eventually is not correctable with glasses.  In  some people the vision can deteriorate relatively quickly. Developing a cataract can also cause glare, difficulty with night-time driving and multiple images in one eye which can affect the quality of the vision.

When do I have my cataract treated?
In many cases, cataracts are harmless and may be left in your eye. It is usually safe not to have surgery if you feel that you do not have a problem with your vision or do not wish to have an operation. When the cataract progresses to the point that it is interfering with daily activities or lifestyle, even when using up-to-date glasses, then cataract surgery may be the next step. Modern surgery is highly successful for the majority of patients but, as with all surgery, there are risks.

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