A cataract is a clouding of the lens inside the eye which leads to a decrease in vision. It is the most common cause of reversible blindness and most cataracts are a result of the aging process. Cataracts occur when there is a buildup of protein in the lens that makes it cloudy. This prevents light from passing clearly through the lens, causing some loss of vision. The only treatment for cataract is a surgical removal of the opaque lens. Nowadays, it is a very safe and effective procedure done under drops of anesthesia, resulting in improvement of vision from the first day.