Which part of the eye focuses light onto the retina?

Which part of the eye focuses light onto the retina?

• A. Iris
• B. Lens
• C. Cornea
• D. Optic nerve

Answer: (B)

Focusing light onto the retina is the job of the lens. The lens sits behind the pupil and bends light so it converges to a sharp image on the retina at the back of the eye. It does this by changing its shape: when you look at something up close, the lens becomes thicker to increase its refractive power, and when you look at distant things, it becomes thinner. The cornea also bends light, giving most of the eye’s focusing power, but it can’t adjust for distance the way the lens can. The iris just controls how much light enters by changing the pupil size, and the optic nerve carries the visual signal to the brain.

Focusing light onto the retina is the job of the lens. The lens sits behind the pupil and bends light so it converges to a sharp image on the retina at the back of the eye. It does this by changing its shape: when you look at something up close, the lens becomes thicker to increase its refractive power, and when you look at distant things, it becomes thinner. The cornea also bends light, giving most of the eye’s focusing power, but it can’t adjust for distance the way the lens can. The iris just controls how much light enters by changing the pupil size, and the optic nerve carries the visual signal to the brain.