Question

(A) The elderly people, may have both near sightedness and far sightedness. Write the possible solutions, can be proposed for correction of their eye defect.

(B) How does the eye control the amount of light entering into it?

Accepted Answer

(A) Bifocal lenses with concave upper part and convex lower part. (B) Iris regulates pupil size.. (A) **Correction for Presbyopia (combined myopia & hypermetropia):** - Corrected using **bifocal lenses**. - The upper portion consists of a **concave lens** to facilitate distant vision. - The lower portion consists of a **convex lens** to facilitate near vision. (B) **Control of Light Entry:** - The **iris** acts as a muscular diaphragm controlling the size of the **pupil**. - In bright light, iris contracts the pupil to let less light in. - In dim light, iris expands the pupil to allow more light in.

Vision Defects and Eye Control

Explanation

Practise this under board exam conditions