Which term describes the difference in image size or shape between the two eyes?

• A. Aniseikonia
• B. Anisometropia
• C. Diplopia
• D. Asthenopia

Answer: (A)

Aniseikonia is the difference in the size or shape of the visual image as seen by each eye. This happens when the two eyes don’t form retinal images that are the same size, often due to unequal refractive power or optical magnification differences from lenses. While anisometropia means there is a difference in refractive error between the eyes, it can cause aniseikonia, but the term described specifically refers to the image size discrepancy itself. Diplopia is double vision, and asthenopia is eye strain.