Myopia, << my OH pee uh, >> also called nearsightedness or shortsightedness, is a visual defect that causes blurred distance vision. Except in extreme cases, near vision remains clear. For the eye to form a clear image, the light rays reflected or given off by an object must come together on the retina, the light-sensitive tissue lining the back and sides of the eyeball. In most people with myopia, the eyeball is longer than normal from front to back. As a result, light rays from a distant object meet in front of the retina. When the rays do strike the retina, they form a blurred image.
People may inherit a tendency to develop myopia. But intense close-up visual activity may contribute to the development of the condition.
Loading the player...Nearsightedness and farsightedness
People with myopia wear concave glasses or contact lenses to clear up their distance vision. Concave lenses are thinner in the middle than at the edges. They bend light rays outward so that the rays meet on the retina.
Laser surgery, often called LASIK, can correct myopia. In this procedure, surgeons use a laser to reshape the cornea (clear tissue covering the eyeball) so that light rays passing through it meet on the retina. A similar technique, called conductive keratoplasty, uses high-frequency radio waves to change the shape of the cornea. Artificial lens implants can also eliminate myopia when the cornea cannot be reshaped through other surgical techniques.
See also Eye (Defects of the eye); LASIK surgery.
