How does the eye adjust for near and far vision?

How does the eye adjust for near and far vision?

• A. The pupil dilates or constricts
• B. The ciliary muscles change the shape of the lens
• C. The retina becomes more sensitive
• D. The cornea thickens or thins

Answer: (B)

The adjustment of the eye for near and far vision primarily involves the ciliary muscles, which are circular muscles located around the lens. When focusing on nearby objects, the ciliary muscles contract, allowing the lens to become thicker and more curved. This increased curvature helps to refract light more strongly so that close objects can be brought into focus on the retina. Conversely, when looking at distant objects, the ciliary muscles relax, causing the lens to become thinner and flatter. This decreases the refractive power of the lens, enabling the eye to focus on objects that are further away. While the other options pertain to different functions of the eye, the alteration in lens shape specifically driven by the ciliary muscles is the critical mechanism for adjusting focus between near and far distances. The dilation or constriction of the pupil primarily affects the amount of light entering the eye rather than focus, sensitivity of the retina is more related to changes in light conditions, and the cornea's curvature remains relatively constant during normal viewing adjustments.

The adjustment of the eye for near and far vision primarily involves the ciliary muscles, which are circular muscles located around the lens. When focusing on nearby objects, the ciliary muscles contract, allowing the lens to become thicker and more curved. This increased curvature helps to refract light more strongly so that close objects can be brought into focus on the retina.

Conversely, when looking at distant objects, the ciliary muscles relax, causing the lens to become thinner and flatter. This decreases the refractive power of the lens, enabling the eye to focus on objects that are further away.

While the other options pertain to different functions of the eye, the alteration in lens shape specifically driven by the ciliary muscles is the critical mechanism for adjusting focus between near and far distances. The dilation or constriction of the pupil primarily affects the amount of light entering the eye rather than focus, sensitivity of the retina is more related to changes in light conditions, and the cornea's curvature remains relatively constant during normal viewing adjustments.