Ciliary muscles are present as a smooth muscle ring in the middle layer of the eye. It suspends the ciliary body present between the sclera and ligaments that suspend the lens in the eye.
The curvature of the eye lens can be modified by the ciliary muscles, thereby helping in focusing the nearby objects.
Voluntary muscles (e.g. skeletal muscles) can be controlled consciously. The somatic nervous system plays an important role in regulating these muscles.
Ciliary muscles are not voluntary since they cannot be consciously controlled. They are regulated by the autonomic nervous system.