What is Accommodation is maximum in: and explain in detail?
Ans. (a) ChildrenRef: A.K. Khurana 6th ed. 145-49; Khurana's 4th Ed./ 39- 41ACCOMODATION* Mechanism by which we can focus the diverging rays coming from a near object on the retina in an attempt to see clearly is called accommodation.* During this there occurs increase in the power of crystalline lens due to increase in the curvature of its surface.Mechanism of Accommodation* When the eye is at rest (unaccomodated), the ciliary ring is large and keeps the zonules tense.* Because of zonular tension the lens is kept compressed (flat) by the capsule.* Ciliary muscles and zonules have inverse relation in function.* Ciliary ring is shortened due to contraction of the ciliary muscle which releases zonular tension on the lens capsule. This allows the elastic capsule to act unrestrained to deform the lens substance. The lens then alters its shape to become more convex (conoidal).* The lens assumes conoidal shape due to configuration of the anterior lens capsule which is thinner at the centre and thicker at the periphery* Note: The crystalline protein of lens and contraction of ciliary muscle is finest in child as compared to adult and elderly. Hence children have maximum accommodation.