Question

how is the eye lens held in its position

Answer 1

Lens of the eyes are held in its position with the help of ciliary muscles. To change the focal length of the lens, the movement of muscles help in doing so. (Extra info.)

Answer 2

A lens is a transparent object designed to bend light in order to form an image. Lenses are found in cameras, microscopes, telescopes, eyeglasses, and also in the eyes of humans and other animals. A lens causes the light rays that hit it to bend, and the direction the rays bend depends on the shape of the lens.