Ciliary muscle is the eye's smooth muscle, surrounding the crystalline lens. Through the tiny suspensory ligaments, the ciliary muscle is attached to the crystalline lens.
Ciliary muscle can help the eye to focus. When the ciliary muscle is constricted, the crystalline lens becomes protruding , allowing the eye to focus on near objects. When the ciliary muscle is relaxed, the crystalline lens becomes flattened, allowing the eye to focus on distant objects.
Ciliary muscle also controls the eye's fluid, allowing the eye to drain out aqueous humour. If the eye can not drain out aqueous humour, intraocular pressure will be elevated, causing eye problems such as glaucoma.