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How the Eyes Work
The human eye is almost as big as a Ping-Pong ball and weighs about one-quarter of an ounce.
Despite its small size, the eye is a complex machine that feeds data to the brain at lightning speed. Light enters the eye through the cornea and passes through the pupil to the lens. The lens focuses the rays onto the retina, but images on the retina are upside down, reversed, and two-dimensional.
