The human eye is the organ, which gives us the sense of sight, allowing us to learn more about the surrounding world, than we do with any of the other four senses.  We use our eyes in almost every activity we perform, whether reading, working, watching television, writing a letter, driving a car, and in countless other ways.  Probably most people would agree that sight is the most precious of the five senses, and many people fear blindness more than any other disability.