Myopia or "Nearsightedness"
en.wikipedia.org/wiki/MyopiaMyopia or Near Sightedness is a common refractive error of the eye, in which those having the condition have the symptom of blurred vision in the distance while closer objects are clearer. The myopic eyeball may be longer than a normal eyeball (see diagram to right) or the refractive surfaces or curvature of the cornea might be the reason the light from a distant object is focused in front of the photoreceptive retina in the back of the eye, rather than directly on the retina as in a normal eye.
In either case the rays of light in a myopic eye are focused in front of the retina (upper diagram to left). Concave eyeglass lenses or contact lenses diverge rays of light and redirect them to focus directly on the retina (lower illustration to left). Refractive surgery (such as LASIK) also redirect the rays of light to the retina, but in myopic LASIK this is accomplished by flattening the cornea. Another form of refractive surgery involves implanting a concave lens in the eye, usually behind the iris. This is the method preferred in high degrees of myopia. A weblink and flash animation in All About Vision illustrates the condition and the reference in Wikipedia at http://en.wikipedia.org/wiki/Myopia describes potential causes and classifications of myopia in more detail.