What is the primary function of the ciliary muscle?

The primary function of the ciliary muscle is to adjust the shape of the crystalline lens. Located in the eye, this muscle plays a crucial role in the process of accommodation, which allows for clear vision at varying distances. When the ciliary muscle contracts, it reduces tension on the zonule fibers that hold the lens in place, causing the lens to become more rounded. This increased curvature is essential for focusing on nearby objects. Conversely, when the muscle relaxes, the tension on the fibers increases, flattening the lens for distance vision. This dynamic adjustment is integral to the eye's ability to focus effectively, thereby enhancing visual clarity across different ranges.