How the Eye Works

The Anatomical Structure

It's a simple sphere, about 1" in diameter, yet its power is awesome. It discerns colors and shapes. In bright or dim light. From near or far. It helps you read books, and situations, and people. It is a vital link to the world around you. 

  • Cornea - a clear window that transmits and focuses light into the eye

  • Iris - the colored disc that helps regulate the amount of light entering the eye

  • Pupil - the dark center of the iris that changes size to accommodate available light

  • Lens - the transparent structure that focuses light rays onto the retina

  • Retina - nerve layer that reads light rays and sends images through the optic nerve to the brain

  • Macula - the small area of the retina that uses special light-sensitive cells to clarify fine details

  • Optical Nerve - the nerve that connects the eye to the brain

  • Vitreous Gel - the clear, jelly-like substance that fills the middle of the eye

The Inner Workings

Light reflected off an object passes through the cornea. Muscles around the eye contract or relax to adjust the shape of the lens, focusing the light rays. The rays then reach the retina, where over 100 million light-sensitive cells read them and transmit the image through the optic nerve to the brain.


Photo above courtesy of National Eye Institute, National Institutes of Health.
NPR.0085.USA.18