How eyes work
The eye functions on a similar principle to an old fashioned camera. Your iris or coloured portion of your eye acts as the shutter regulating the amount of light. The cornea or clear dome covering your iris, combined with your lens behind the iris are the lenses that focus the light onto your retina at the back of your eye. This simulates the film of a camera sending images to the brain.
The shape of your eye determines how well your vision can focus. Light rays enter the eye through the clear cornea, then through the pupil and the lens.
In a normal eye the light rays are focused onto the retina, a light-sensitive tissue lining the back of the eye. Signals from the retina are sent through the optic nerve to the brain, where they are interpreted as the images we see.