Question

When you look at an object very close to your eyes, the:

• A. Ciliary muscles of your eye contract and the eye lens becomes thick.
• B. Ciliary muscles of your eye get relaxed and the eye lens becomes thick.
• C. Ciliary muscles of your eye contract and the eye lens becomes thin.
• D. Ciliary muscles of your eye get relaxed and the eye lens becomes thin.

Hint:

Accommodation:

• \textbf{Near object:} Ciliary muscles contract \(\Rightarrow\) Lens thick \(\Rightarrow\) Focal length decreases
• \textbf{Distant object:} Ciliary muscles relax \(\Rightarrow\) Lens thin \(\Rightarrow\) Focal length increases

This ability decreases with age (presbyopia).

Answer 1

The Correct Option is A

To understand the behavior of the eyes when looking at an object very close to them, we need to delve into the anatomy and function of the eye, specifically the role of the ciliary muscles and the eye lens.

When you look at something close, the following changes occur in your eye:

• The ciliary muscles contract: This action is necessary to change the shape of the eye lens.
• As the ciliary muscles contract, the tension on the suspensory ligaments is reduced, allowing the lens to become more convex or thicker.

This process is called accommodation. Accommodation is the eye's way of changing the optical power of the lens to ensure that the object is focused on the retina, providing a clear image.

The reasoning for elimination of other options:

• Ciliary muscles get relaxed and eye lens becomes thick: If the ciliary muscles were to relax, the lens would become thinner, not thicker.
• Ciliary muscles contract and eye lens becomes thin: The contraction of the ciliary muscles actually leads to the lens becoming thick, not thin.
• Ciliary muscles get relaxed and eye lens becomes thin: When the ciliary muscles relax, the lens does become thin, but this happens for distant vision, not close vision.

Therefore, the correct answer is that when looking at an object close to the eyes: Ciliary muscles of your eye contract and the eye lens becomes thick.