SSC MTS EXAM

Detailed explanation-1: -ciliary muscles. Explanation for the correct option, These muscles are present in the human eyes. Their function is to adjust the shape and the focal length of the eye lens for objects at various positions.

Detailed explanation-2: -When the ciliary muscle is contracted, the lens becomes more spherical – and has increased focussing power – due to a lessening of tension on the zonular fibres (a). When the ciliary muscles relax, these fibres become taut – pulling the lens out into a flatter shape, which has less focussing power (b).

Detailed explanation-3: -(c) The relaxation or contraction of ciliary muscles changes the curvature of the eye lens. The change in curvature of the eye lens changes the focal length of the eyes. Hence, the change in focal length of an eye lens is caused by the action of ciliary muscles.