The lens in our eye has a special designed feature called accommodation. That is, the lens changes shape, curvature, or focal length to bring images into focus. When we look at a far distant object the lens becomes thinner. For nearby objects the lens thickens and becomes rounder for clear vision. The flexibility is possible because t
he lens is somewhat jellylike. Ciliary muscles around the edge of the lens control its shape. These muscles can become fatigued, and they recover when eyes are closed.
Technical application:
optical lens technology