| Light passes through the cornea and is refracted. The iris can increase or decrease the pupillary diameter to determine the amount of light that enters the eye. The light is further refracted by the crystalline lens, which can be adjusted in shape by the smooth muscle of the ciliary body that tugs on the suspensory ligaments. The aqueous humor in the anterior chamber and the posterior chamber has minimal impact upon refraction of light. Ideally, the light is focused precisely upon the retina. |