The ciliary body is a modified part of this layer (tunic) of the eyeball. the ciliary body is a modified part of this layer (tunic) of the eyeball. fibrous layer (sclera) vascular layer (uvea) sensory layer (retina)

vascular layer

Explanation:

The wall of the eyeball is made up of three layers which are a fibrous tunic, vascular tunic, and retina, also known as an inner tunic. The middle layer of the eyeball is the vascular tunic or uvea which in turn is composed of three parts: choroid, ciliary body, and iris.

Choroid becomes the ciliary body in the anterior portion of the vascular tunic. The ciliary body is a dark brown structure and contains melanin-producing melanocytes. Other structural components of the ciliary body are ciliary processes and ciliary muscle. The ciliary processes arise as protrusions or folds on the internal surface of the ciliary body.

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.