A lens is transparent material or a piece of glass that forms optical images. The images are formed from either convergent or divergent light that has been transmitted. The lens in the eye is called the crystalline lens, and it allows light to focus on the retina. You can find more information here: http://encyclopedia2.thefreedictionary.com/Lens+of+the+eye
. http://www.stlukeseye.com/anatomy/Lens.asp
