like a skin that forms over the eye or lens. This is not true. A cataract is a gradual change in the structure of the lens in an eye, which makes it gradually more and more cloudy. Who gets cataracts and how common are they? There are different types of cataracts: Age-related cataract (senile cataract) This is by far the most common type and affects older people. It becomes more common with increasing age. In the UK about 1 in 3 people over the age of 65 has a cataract. Men and women are equally affected. Often both eyes are affected, but one eye may be worse than the other. Typically, an age-related cataract forms gradually over many years. Many people with an early cataract do not realise they have it. This is because the cloudiness caused by an early cataract is not too bad and the vision is only mildly affected. In some people, the cataract does not become too severe. However, in many cases, vision becomes gradually worse over the years. Congenital cataracts (present at birth) These are uncommon but important to diagnose early. This is because vision and seeing have to be learnt very early in infancy. A cataract that is present at birth stops the eye from learning to see and can cause blindness which may persist even if the cataract is removed later in life. A congenital cataract must be removed as early as possible after birth. This is why doctors examine the eyes of