What is the definition or description of: nearsightedness?

Nearsightedness: A nearsighted, or myopic, person is unable to see things clearly unless they are relatively close to the eyes, owing to the focusing of rays of light by the eye at a point in front of the retina. This may occur because the eye is too long from front to back or because the cornea is too steep. Distant objects appear blurry to a nearsighted person.