Question

Focal length of the eye lens changes with the help of

• A. Pupil
• B. Aqueous humour
• C. Ciliary muscle
• D. Optical nerve

Answer 1

The Correct Option is C

To solve the problem, we need to identify which part of the eye helps change the focal length of the eye lens.

1. Understanding the Eye's Focal Length Adjustment:
The ability of the eye lens to change its focal length, allowing it to focus on objects at different distances, is a crucial feature of vision. This adjustment is necessary for focusing on both nearby and distant objects.

2. Role of the Ciliary Muscle:
The ciliary muscles control the curvature of the eye lens, thus adjusting its focal length. When the ciliary muscles contract or relax, they change the shape of the lens, allowing the eye to focus on objects at different distances.

3. Verifying Other Options:
- The pupil controls the amount of light entering the eye, but it does not affect the focal length.
- Aqueous humour is the fluid in the anterior chamber of the eye, and it does not directly control the focal length.
- The optical nerve transmits visual information to the brain but does not control the lens' focal length.

Final Answer:
The focal length of the eye lens changes with the help of the $ \mathbf{Ciliary \, Muscle} $.