Our eyes have a clear and obvious design flaw—they often fail to focus properly. This is a far greater problem than the eye’s other quirks, such as its blind spot and its inability to see certain colors. So why should such an elegant, intricate organ have such a glaring hitch?
Although there’s no definitive answer, many experts now believe that the problem has something to do with modern life. In the distant past, our ancestors spent most of their time wandering the savanna and staring into the distance. In today’s world, we spend far more time on near work—close-up activities like reading, writing, and drawing. During childhood, these activities may gradually reorient the eye from its natural state of mild farsightedness to the far more common condition of adult nearsightedness. In fact, our vision may have worked far better in the era before the invention of corrective eyewear (which was developed relatively recently, in 13th-century Italy).
Although this is all somewhat speculative, it may eventually lead to a way to prevent eye trouble. For example, children might be able to perform far-vision exercises to counterbalance the overload of near work. But for now, there’s no solution other than glasses and contact lenses, and there’s no evidence to suggest that you can help your eyes by cutting down on modern activities in adulthood. So now that your vision is already screwy, it’s safe to keep reading, writing, watching television, and surfing the Web.
Source of Information : Oreilly - Your Body Missing Manual