How can the human eye accommodate for viewing very close and very distant objects?

Natural: The lens of the eye is connected to a muscle behind the iris is called the ciliary body. When the ciliary body contracts, the fibers connecting the lens called the zonules relax, & the lens fattens. When the ciliary body relaxes the fibers tighten & the lens flattens. This change in shape causes a change in the way light is bent through the lens and this changes the focusing for distance & near.