Abnormality of the refraction of the eye, resulting in an inability to focus light precisely on the retina. Contrasted with "emmetropia".
Myopia (short- or near-sightedness), hyperopia or hypermetropia (long- or far-sightedness), and astigmatism are types of ametropia.
Mid 19th century; earliest use found in Medical Times and Gazette. From ancient Greek ἄμετρος without measure, without metre + -opia, after Dutch ametropie.