The ciliary body is the anterior portion of the choroid to which the lens is attached via the suspensory ligaments (or zonules). On the posterior surface of the ciliary body are the ciliary processes that secrete aqueous humor.

The ciliary epithelium rests on the leaf-like projections of the ciliary processes in the posterior chamber, covering the core with stroma and blood vessels. It consists of two layers of columnar cells, which appear structurally and functionally distinct. The outer layer of the epithelium is pigmented, but the inner layer, which lies near the aqueous humor, is not. In mammalian eyes, non-pigmented ciliary epithelial cells (NPCEpiC) are largely responsible for the influx of aqueous humor. NPCEpiCs generate an osmotic gradient by transferring solutes, which then leads to movement of water from the stroma into the posterior chamber. Other studies have implicated NPCEpiC in the synthesis of macromolecules required for phototransduction and in the development of rare adenomas in the ciliary body.