What is the primary function of the lens?

What is the primary function of the lens?

• A. Accommodation = focusing light on the retina
• B. Producing aqueous humor
• C. Generating nerve impulses
• D. Nourishing the retina

Answer: (A)

The lens’ main job is to adjust focus so light is sharp on the retina, a process called accommodation. The cornea does most of the eye’s refractive power, but the lens fine-tunes that focus as objects move closer or farther away. When you look at something near, the ciliary muscle contracts, the zonular fibers relax, and the lens becomes thicker, increasing its optical power. For distant vision, the muscle relaxes, the lens becomes flatter, and the focus shifts back. The lens is avascular and does not produce aqueous humor—that comes from the ciliary body. It also doesn’t generate nerve impulses; those signals originate in the retina and along the optic pathway. Nourishing the retina comes from the choroid and retinal vessels rather than the lens.

The lens’ main job is to adjust focus so light is sharp on the retina, a process called accommodation. The cornea does most of the eye’s refractive power, but the lens fine-tunes that focus as objects move closer or farther away. When you look at something near, the ciliary muscle contracts, the zonular fibers relax, and the lens becomes thicker, increasing its optical power. For distant vision, the muscle relaxes, the lens becomes flatter, and the focus shifts back.

The lens is avascular and does not produce aqueous humor—that comes from the ciliary body. It also doesn’t generate nerve impulses; those signals originate in the retina and along the optic pathway. Nourishing the retina comes from the choroid and retinal vessels rather than the lens.