Among uncorrected ametropes, which category yields the largest retinal image size?

Among uncorrected ametropes, which category yields the largest retinal image size?

• A. Uncorrected axial myope
• B. Uncorrected axial hyperope
• C. Uncorrected refractive myope
• D. Uncorrected refractive hyperope

Answer: (A)

Retinal image size for a given viewing angle is largely set by how far the retina sits from the eye’s lens. A longer eyeball means the retina is farther away, which increases magnification and makes the image on the retina larger. Uncorrected axial myopia has the longest eyeball, so the lens-to-retina distance is greatest. This extra distance magnifies the retinal image more than in the other forms of ametropia, so the retinal image tends to be the largest. Uncorrected hyperopia has a shorter eyeball, reducing this magnification, and uncorrected refractive errors mainly change where the image focuses rather than the retina’s distance from the lens, so they don’t produce as large a retinal image as axial myopia.

Retinal image size for a given viewing angle is largely set by how far the retina sits from the eye’s lens. A longer eyeball means the retina is farther away, which increases magnification and makes the image on the retina larger.

Uncorrected axial myopia has the longest eyeball, so the lens-to-retina distance is greatest. This extra distance magnifies the retinal image more than in the other forms of ametropia, so the retinal image tends to be the largest. Uncorrected hyperopia has a shorter eyeball, reducing this magnification, and uncorrected refractive errors mainly change where the image focuses rather than the retina’s distance from the lens, so they don’t produce as large a retinal image as axial myopia.