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Question
Describe the mechanism of focusing the image of a distant object in your eye when you raise your head after reading a book.
Solution 1
While reading a book, the lens is more convex or rounded due to contraction of ciliary muscles because the book is usually read from a short distance. When we raise our head and look at a distant object, the ciliary muscles relax to build the tension on the suspensory ligament so that they can stretch the lens. This change in the curvature of the lens makes us focus on distant object.
Solution 2
The lens is adjusted through accommodation to focus on a distant object while reading. This is a full description:
- Near Vision (Reading a Book):
- Reading causes ciliary muscle contractions in the eyes.
- When the ciliary muscles contract, the suspensory ligaments that support the lens slacken.
- This enables the lens to become more convex or rounded.
- Transition to Distant Vision (Raising Your Head):
- Your ciliary muscles relax when you elevate your head to focus on a distant object.
- Suspensory ligaments pull and flatten the lens.
- The ciliary muscles relax, and the suspensory ligaments strain on the lens.
- Accommodation Power of the Eye:
- Accommodation refers to the process of adjusting focus by modifying the lens shape.
- The eye's accommodation power relies heavily on the ciliary muscles.
- The eye's capacity to concentrate clearly at diverse distances is vital for adapting to various visual tasks.
The ciliary muscles alter the lens shape dynamically, making it convex for near vision and flat for distant vision. The eye's ability to focus clearly at varied distances is due to the process of accommodation.
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