Which part of the eye changes shape to help focus light onto the retina?

• A. Iris
• B. Retina
• C. Pupil
• D. Lens

Answer: (D)

Focusing at different distances relies on the lens changing shape. The lens is flexible and sits behind the iris. When you look at something close, the ciliary muscles contract, making the lens rounder and more curved, which increases its refractive power so light converges on the retina. For distant objects, the ciliary muscles relax, the lens becomes flatter, and light is focused correctly. The retina is the light-sensitive layer where the image forms, while the iris and pupil regulate how much light enters but don’t adjust focus. Therefore, the part that changes shape to help focus light onto the retina is the lens.