Your vision becomes blurred or dim because light cannot pass through the clouded lens to the back of the eye. The lens is a transparent body behind the iris, the coloured part of the eye. The lens bends light rays so that they give a clear image to the back of the eye - the retina. As the lens is elastic, it will change shape, getting fatter for close objects and thinner for distant objects. The diagram below shows the main parts of the eye.
Cataracts can form at any age, but most often develop as people get older.
In younger people they can result from an injury, certain drugs, long-standing inflammation or illnesses such as diabetes. You may notice that some things seem blurred round the edges, or that your glasses seem dirty or scratched. Seeing double The cloudiness in the lens may occur in more than one place, so that the light rays which reach the retina are split, causing a double image. Poor vision in bright light You may find that bright light or very sunny days make it more difficult to see. As the cataract develops its centre becomes more and more yellow, giving everything you see a yellowish tinge.