Aniseikonia is a difference in image size caused by what?

• A. The refractive status of the two eyes.
• B. Unequal pupil sizes.
• C. The presence of cataracts.
• D. The curvature difference of a cornea.

Answer: (A)

Aniseikonia happens when the two eyes form images that are different in size, most often because the eyes have different refractive powers (anisometropia). When each eye requires a different lens correction, the magnification each eye experiences with its correction isn’t the same, so one image appears larger or smaller than the other. Unequal pupil sizes don’t change image size, cataracts affect clarity rather than size, and while corneal curvature differences can create refractive differences, the core issue behind image size disparity is the unequal refractive status between the eyes.