The lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens is made up of unusual elongated cells that have no blood supply but obtain nutrients from the surrounding fluids, mainly the intraocular fluid that bathes the front of the lens. Waste products are removed through these fluids as well. The shape of the lens can be altered by the relaxation and contraction of the ciliary muscles surrounding it, thus enabling the eye to focus clearly on objects at widely varying distances. The ability of the lens to adjust from a distant to a near focus, called accommodation, gradually declines with age, often requiring correction.