The choroid thickens behind the iris and forms the circular ciliary body. Ciliary muscles are present in the ciliary body. The lens is attached to the ciliary body by ligaments. The function of the ciliary body is to holds lens in place and to serve in accommodation.
When focusing on a distant object, the relaxed ciliary muscles make the lens is flat and the suspensory ligament is taut. When focusing on a near object, the contraction of the ciliary muscles of the ciliary body allows the lens to accommodate. The lens becomes rounded causing the suspensory ligament to relax. Thereby, the ciliary body regulates the shape of the lens for near and far vision.