It is where the lens of the eye becomes cloudy, so it is difficult to see through.
You may find:
• things look cloudy or blurred
• bright lights dazzle
• you may see double in the affected eye.
The lens is inside the eye directly behind the coloured part, which is called the iris. Little muscles are attached to the lens. These move, and by slightly altering its shape they help you focus on what you want to see.
The most common cause is ageing, but occasionally they happen because of injury, or as a complication of other conditions.
• slight blurring of vision
• spectacles always seem to need cleaning
• seeing slightly double
• change of colour vision, becoming more yellow
• difficulty with glare and bright lights.
In the early stages of cataract, spectacles may help you see clearly enough.
When your vision has become so poor that it seriously affects everyday life - such as driving, watching TV, or reading - then your optometrist will refer you to an eye specialist, called an ophthalmologist, in the hospital. The ophthalmologist will assess your eyes and help you decide about an operation.
It is often carried out under local anaesthetic, and usually as a day-case procedure (no overnight stay).
The cloudy lens inside your eye is removed and replaced with a new, clear lens made of special plastic.
Afterwards, your vision is usually much better, unless there are other reasons for your poor sight besides the cataract.