Affixes

This ending appears in a few medical terms relating to the ability of the eye to form images: hypermetropia (Greek huper, over, above) is long-sightedness; anisometropia (Greek anisos, unequal) refers to an inequality in the refractive power of the two eyes; ametropia (Greek a‑, not, without) is faulty refraction of light rays by the eye, as in astigmatism or myopia; emmetropia (see en‑²) is the normal refractive condition of the eye, in which the rays of light are accurately focused on the retina. Associated adjectives are formed in ‑metropic (emmetropic, hypermetropic).