Definition: A ring of tissue that encircles the lens. The ciliary body contains smooth muscle fibers that help control the shape of the lens. It controls accommodation by altering the shape of the lens. When the muscle fibers contract, the lens becomes more convex and can bring objects into focus. The ciliary body also secretes aqueous humor, the clear fluid that fills the front part of the eye.
With age, the ciliary body and lens gradually lose flexibility, causing difficulty reading. This condition is known as presbyopia.
