When the eye focuses on a nearby object, the ciliary muscles - TopicsExpress

When the eye focuses on a nearby object, the ciliary muscles contract, pulling the choroid toward the lens, which reduces the tension on the ligaments. As the ligaments slacken, the elastic lens becomes thick and round. This change allows the diverging light rays from a close object to be bent and focused. The light rays from the object actually cross as they pass through the eyeball, resulting in an upside-down image striking the retina. (The brain interprets this inverted image so that we perceive it as right-side up.)