When light enters the eye, it passes through the transparent layer of tissue at the front of the eye, (the cornea) and the lens focuses it on the light-sensitive layer of cells at the back of the eye (the retina).
Cataracts occur when changes in the lens of the eye (which is normally clear) cause it to become less transparent. The lens is a crystalline structure that sits just behind the pupil (the black circle in the centre of the eye).
Cataracts are usually age related. As you grow older, your lenses get dense and cloudy and eventually restrict light reaching the retina. This can affect vision, making it increasingly cloudy, blurry, or misty.
Although cataracts are often associated with age, in rare cases babies are born with cataracts and young children can also develop them (childhood cataracts). Cataracts may also develop due to trauma. Also diabetic people are more likely to develop cataracts.
Cataract surgery is a procedure to remove the opaque lens of the eye and replace it with an artificial lens. Cataract surgery is a very common and generally safe procedure. It takes about 15-20 minutes to perform the surgery.