Nearsightedness (myopia) is a very common condition that affects nearly 30 percent of the U.S. population. Some evidence supports the theory that nearsightedness is hereditary. There is also growing evidence that nearsightedness may be caused by the stress of too much close vision work.
It normally first occurs in school age children. Since the eye continues to grow during childhood, nearsightedness generally develops before age 20. An individual that has myopia has trouble seeing clearly at a distance, while close objects are seen clearly.

Nearsightedness is a condition in which the eye becomes too long from front to back, causing images to focus in front of the retina instead of directly on it. Because of this error, objects at a distance become blurry and difficult to focus on. Nearsightedness is measured in negative diopters. The farther the number is away from zero, the more extreme the nearsightedness.

Nearsightedness, farsightedness, and astigmatism can all be successfully treated today with LASIK up to certain approved parameters, depending upon the laser and the skill of the surgeon performing the procedure. For example, people who wear glasses only for reading are not good candidates. In addition to the visual and medical requirements, laser refractive surgery can be done on a patient with up to 14 diopters of myopia, or nearsightedness, and with up to 5 diopters of astigmatism. The best candidates tend to be people who are dissatisfied with their contact lenses or glasses and are motivated to make a change for occupational or lifestyle reasons.