The human eye works just like a camera. In the front of the eye there is the lens and cornea – together, they work just like the lens of a camera. In the back of the eye, the retina serves as the film of the camera. In between the lens and the retina is the vitreous cavity. The vitreous is a jelly-like substance that adheres to the retina. The vitreous is made up mostly of water. When light enters the eye, it is focused by the cornea and lens onto the retina. The retina sends this "light signal" to the brain (via the optic nerve). The brain then interprets this "light signal". This interpretation represents our vision.