The lens is located in the eye. By changing its shape, the lens changes the focal distance of the eye, enabling the images of objects of varying distances to form on the retina. It also works together with the cornea to refract light. The lens is of ellipsoid, biconvex shape, about 10mm in diameter and 4mm in axial length in adults, although its shape and size varies as it changes its focus. The lens consists of the lens capsule, the lens epithelium and the lens fibers. The lens capsule is the smooth, transparent outermost layer of the lens while the lens fibers are long, thin, transparent cells that form the bulk of the lens. The lens epithelium lies between these two and is responsible for the stable functioning of the lens. It also creates lens fibers for the lifelong growth of the lens. Common diseases of the lens include cataract, which causes opacity in the lens. Other common ailments are presbyopia, ectopia lensis, aphakia and nuclear sclerosis.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Lens