CBSE Class 12-science Answered

When the eye is viewing an object at a far distance (such that parallel rays of light are entering the eye), the ciliary muscle within the ciliary body relaxes.  The ciliary processes pull on the suspensory ligaments (or zonules), which in turn pull on the lens capsule around its equator.  This causes the entire lens to flatten or to become less convex, enabling the lens to focus light from the far-away object.

Conversely, when the eye views an object at a near distance, an “accommodative demand” is created.  As a result, the ciliary muscle works or contracts, causing tension to be released on the suspensory ligaments and, subsequently, on the lens capsule.  This causes both (front and back) lens surfaces to become more convex and the eye to be able to focus at near.