The ciliary body is the structure in the eye that releases a transparent liquid (called the aqueous humor) within the eye.
The ciliary body also contains the ciliary muscle, which changes the shape of the lens when your eyes focus on something. This process is called accommodation.
Evans M. Uveitis and other intraocular inflammations. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, Mo: Mosby Elsevier; 2008:chap 7.