Any abnormality of the eye that causes less-than-perfect sight. In a nearsighted eye, the lens is fatter than normal, causing light from distant objects to be focused in front and not on the retina. A person with this complaint, called myopia, cannot see clearly for distances over a few yards, and needs glasses with diverging lenses. Farsightedness, also called hypermetropia, is caused by an eye lens thinner than normal that focuses light from distant objects behind the retina. The sufferer cannot see close objects clearly, and needs converging-lens glasses. There are other vision defects, such as color blindness and astigmatism.
Any abnormality of the eye that causes less-than-perfect sight. Common defects are nearsightedness or myopia; long-sightedness or hypermetropia; lack of accommodation or presbyopia; and astigmatism. Other eye defects include color blindness.