The lens is a transparent biconvex structure located behind the iris. It has slightly more curved posterior surface with radii of curvature of 10mm (anterior) and 6mm (posterior). The lens thickens with age from 3mm at birth to 6mm in older age. It focuses light onto the retina and its elasticity allows it to change shape for accommodation via the ciliary body. The lens is composed of transparent cells and fibers arranged in concentric layers surrounded by an elastic capsule.