Which structure is primarily responsible for accommodation by changing its curvature to focus light?

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

Answer: (B)

Accommodation is the process of adjusting focal length to focus on objects at different distances. The lens is responsible for this because it is flexible and can change its curvature. When you shift your gaze from far to near, the ciliary muscle contracts, loosening the zonular fibers and allowing the lens to become more spherical. This increased curvature raises the lens’s optical power, shortening the focal length so light is focused onto the retina. For distant vision, the ciliary muscle relaxes, the lens is pulled flatter, its curvature decreases, and the focal length lengthens to bring distant objects into focus.

The cornea provides most of the eye’s initial light bending, but its curvature is fixed and does not participate in accommodation. The iris controls pupil size, not focusing. The retina is where the image lands after focusing, not the structure that changes shape to adjust focus.