What is the total refractive power of the eye?

What is the total refractive power of the eye?

• A. +60 D
• B. +43 D
• C. -60 D
• D. 0 D

Answer: (A)

The eye’s ability to converge light comes from two main refracting components whose powers add up. The cornea provides about +40 to +43 diopters, and the crystalline lens adds roughly +17 to +20 diopters. When you combine them, you get about +60 diopters total, which corresponds to a focal length of roughly 1/0.60 m ≈ 16.7 mm. This means parallel rays from a distant object are brought to focus on the retina in an emmetropic eye. That’s why the total refractive power is about +60 D. The other options correspond to only one component or the wrong sign, and 0 D would imply no focusing power at all.

The eye’s ability to converge light comes from two main refracting components whose powers add up. The cornea provides about +40 to +43 diopters, and the crystalline lens adds roughly +17 to +20 diopters. When you combine them, you get about +60 diopters total, which corresponds to a focal length of roughly 1/0.60 m ≈ 16.7 mm. This means parallel rays from a distant object are brought to focus on the retina in an emmetropic eye. That’s why the total refractive power is about +60 D. The other options correspond to only one component or the wrong sign, and 0 D would imply no focusing power at all.