Which of the following best describes the interocular ametropia when one eye is hyperopic and the other is myopic?

• A. Anisometropia
• B. Antimetropia
• C. Aniseikonia
• D. Astigmatism

Answer: (B)

Antimetropia is when the two eyes have refractive errors in opposite directions—one eye is hyperopic and the other myopic. This is a specific form of anisometropia, which simply means a difference in refractive power between the eyes; antimetropia highlights that the signs are opposite. Anisometropia on its own covers any difference in spherical power, which could be in the same direction or not, but antimetropia specifies the opposite directions. Aniseikonia is about differences in image size between the eyes, which can occur with anisometropia but isn’t about the direction of ametropia. Astigmatism refers to non-spherical refractive error and isn’t describing interocular differences in sign.