The ciliary muscle is a ring-shaped muscle located in the eye, specifically around the lens. It plays a crucial role in the process of accommodation, which allows the eye to focus on objects at varying distances. When the ciliary muscle contracts, it relaxes the tension on the lens, enabling it to become thicker and focus on nearby objects. Conversely, when the ciliary muscle relaxes, the lens becomes thinner, allowing the eye to focus on distant objects. This muscle is controlled by the autonomic nervous system and is essential for clear vision, making it an important component of the visual system, along with the lens and iris.