Final answer:
The ciliary body, containing the ciliary muscle, is a crucial structure in the eye for focusing on objects at varying distances through the process of accommodation.
Step-by-step explanation:
The ciliary body is a smooth muscle structure within the eye. It is part of the vascular tunic that also includes the highly vascular choroid tissue and the iris. The ciliary body is important for vision because it contains the ciliary muscle, which is responsible for changing the shape of the eye's lens. This action, facilitated by zonule fibers, is essential for focusing on objects at different distances, a process known as accommodation. The ciliary body's function can be compared to sphincters, such as the orbicularis muscles, which control openings in the body by contracting and relaxing.