<P> 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, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a sharp real image of the object of interest to be formed on the retina . This adjustment of the lens is known as accommodation (see also below). Accommodation is similar to the focusing of a photographic camera via movement of its lenses . The lens is more flat on its anterior side than on its posterior side . </P> <P> The lens is also known as the aquula (Latin, a little stream, dim. of aqua, water) or crystalline lens . In humans, the refractive power of the lens in its natural environment is approximately 18 dioptres, roughly one - third of the eye's total power . </P> <P> The lens is part of the anterior segment of the human eye . In front of the lens is the iris, which regulates the amount of light entering into the eye . The lens is suspended in place by the suspensory ligament of the lens, a ring of fibrous tissue that attaches to the lens at its equator and connects it to the ciliary body . Posterior to the lens is the vitreous body, which, along with the aqueous humor on the anterior surface, bathes the lens . The lens has an ellipsoid, biconvex shape . The anterior surface is less curved than the posterior . In the adult, the lens is typically circa 10 mm in diameter and has an axial length of about 4 mm, though it is important to note that the size and shape can change due to accommodation and because the lens continues to grow throughout a person's lifetime . </P> <P> The lens has three main parts: the lens capsule, the lens epithelium, and the lens fibers . The lens capsule forms the outermost layer of the lens and the lens fibers form the bulk of the interior of the lens . The cells of the lens epithelium, located between the lens capsule and the outermost layer of lens fibers, are found only on the anterior side of the lens . The lens itself lacks nerves, blood vessels, or connective tissue . </P>

The structure of the eye that continues to grow throughout life is the