The most common condition related to aging is cataract. More than quarter of all Indians aged 65 and older have a cataract. A cataract is a clouding of the eye's natural lens. When the lens becomes cloudy, the light is blocked and scattered, and therefore the image that appears is blurred. As a cataract develops, it becomes harder for a person to see. The lens is that part of the eye which helps to focus light on the retina. The retina is the eye's sensitive layer that sends visual signals to the brain. To produce a sharp image, the lens must remain clear.