Definition of Anisometropia

Eye Diseases and Conditions Slideshow

Anisometropia: The condition in which the two eyes have an unequal refractive power. One eye may be myopic (nearsighted) and the other hyperopic (farsighted).

Anisometropia is a serious concern in newborns and young children because it can lead to amblyopia (impaired vision in one eye). With a major degree of anisometropia, the brain cannot able to reconcile the difference in images coming from the two eyes. It develops a preference for the image coming from one eye and suppresses the image from the other eye and, in time, the brain loses the ability to "see" the image from that eye.

Anisometropia is made up of four parts: an-, -iso-, -metr-, and -opia. All four parts are from the Greek and their meaning (in parentheses) is simple. An- (not) + -iso- (equal) + -metr- (measure) + -opia (vision). Literally, the measure of vision is not equal. The refractive power of the two eyes is different. The opposite of anisotropia is isometropia. In isometropia, the refractive power is equal in both eyes.