Myopia is a refractive defect of the eye in which images focus in front of the retina.
This may be caused by a defect of the lens/cornea or when the shape of the eye is longer then usual. Those with myopia are often described as nearsighted or short-sighted in that they typically can see nearby objects clearly but distant objects appear blurred because the lens cannot flatten enough.
The opposite of myopia is hyperopia or "farsightedness".
Myopia is the most common eyesight problem in the world. About one quarter of the adult population in the United States has myopia. In places like Japan, Singapore and Taiwan, as many as 44% of the adult population is myopic.