Which eye muscles adjust the lens shape for focusing on near or distant objects?

Which eye muscles adjust the lens shape for focusing on near or distant objects?

• A. Iris
• B. Lens muscles
• C. Cornea
• D. Pupil

Answer: (B)

Accommodation, the ability to focus on objects at different distances, is controlled by the ciliary muscles in the ciliary body. When you look at something up close, these muscles contract, releasing tension on the suspensory ligaments and allowing the lens to become more curved. A thicker, curved lens increases its refractive power, bringing near objects into focus. For distant objects, the ciliary muscles relax, the suspensory ligaments tighten, and the lens flattens, reducing its focusing power. The iris, cornea, and pupil have other roles—iris controls light entry by changing pupil size, the cornea provides most of the eye’s fixed refractive power, and the pupil is the opening whose size changes with light, not the lens shape.

Accommodation, the ability to focus on objects at different distances, is controlled by the ciliary muscles in the ciliary body. When you look at something up close, these muscles contract, releasing tension on the suspensory ligaments and allowing the lens to become more curved. A thicker, curved lens increases its refractive power, bringing near objects into focus. For distant objects, the ciliary muscles relax, the suspensory ligaments tighten, and the lens flattens, reducing its focusing power. The iris, cornea, and pupil have other roles—iris controls light entry by changing pupil size, the cornea provides most of the eye’s fixed refractive power, and the pupil is the opening whose size changes with light, not the lens shape.