Question

What changes take place in the shape of eye-lens :
(a) when the eye is focused on a near object ?
(b) when the eye is focused on a distant object ?

Answer 1

(a) When the eye focuses on a near object, the eye must accommodate to be able to see the object clearly. The ciliary muscle contracts. As a result, both lens surfaces become more curved and thicker(more convex) and the eye thus focuses on the nearby object.

(b) When the eye focuses on a distant object, The light rays that enter the eye are parallel. The ciliary muscles will relax which causes the lens to be flatten and thinner(less convex) and the eye thus focuses on the distant object.