Our eyes contain a transparent structure just behind our pupils called the lens. The lens mainly functions as the major refracting structure (concentrating the light rays onto your retina) of the eye. Clouding of this lens causes blurring of vision, which is called cataract. It is a very common occurrence and more than 90% people over the age of 70 years have cataract in one or both eyes. Rarely it can also occur in childhood. When an infant is born with it, it is called congenital cataract. Cataract is the leading cause of blindness in the developed world.