The best way to understand how the eye works is to compare it to a camera. Like the eye, a camera creates images by allowing specific amounts of light to pass through a hole that creates a visual impression on film.

Beginning with the cornea, which serves as the camera lens, light enters the eye and is focused. Next, light passes through the pupil where the iris works as an aperture to adjust the amount of light allowed to enter. Light then enters the lens where the remaining focus is achieved. The shape of the lens can adjust (either thinner or thicker) by tensing or relaxing the muscles of the eye.

The final destination of this focused light is the retina, which functions as film. It converts the light into a signal using rods and cones. These signals travel to the brain where, in essence, the film is developed into an image - enabling the miracle of sight.