myopia

Defect of the eye in which a person can see clearly only those objects that are close up. It is caused either by the eyeball being too long or by the cornea and lens system of the eye being too powerful, both of which cause the images of distant objects to be formed in front of the retina instead of on it. Nearby objects are sharply perceived. Myopia can be corrected by suitable glasses or contact lenses.

Research carried out by a team at the University of Pennsylvania Medical Center in Philadelphia in 1999 found that the risk of myopia may be increased for infants and toddlers who sleep with a night light. Researchers found that children who had slept in a dark room were far less likely to have developed myopia.