Final answer:
The cornea creates the most refraction as light passes through it, providing about two-thirds of the eye's focusing power and bending light rays significantly at the air-cornea interface.
Step-by-step explanation:
The part of the eye that creates the most refraction as light passes through it is the cornea. Refractive indices are crucial for image formation using lenses, and the air-cornea interface is where the greatest change in the refractive index occurs, resulting in the most significant bending of the light rays. The cornea provides about two-thirds of the eye's focusing power due to the considerable change in the speed of light as it travels from air into the cornea. The lens provides the remaining focusing power necessary to produce a clear image on the retina. Together, the cornea and lens can be conceptualized as a single thin lens, creating an image much like one produced by a convex lens. Although images formed in the eye are inverted, the brain corrects this to make them appear upright.