How the Eye Works

Think of your eye as a camera capturing the world around you. When you look at something, light reflects off of that object and enters your eye, first through the clear protective surface called the cornea,   Cornea: The clear, curved surface at the front of the eye through which light enters the eye. Along with the sclera, the cornea provides external protection for the eye.   then through the pupil,   Pupil: The black, circular area in the center of the iris that regulates the amount of light entering the eye by constricting and dilating.  or hole in your iris,   Iris: The membrane in front of the eye's lens that manipulates the size of the pupil, thus regulating the amount of light that enters the eye.  that expands and retracts to control the amount of light entering, much like a camera's aperture.

How The Eye Works

Like a camera’s lens, your eye’s crystalline lens, which sits behind the iris, must be clear to allow this light to pass and focus onto the retina,   Retina: The transmitter located at the back of your eye that sends the images to your brain.   the thin layer of tissue at the back of your eye that contains millions of tiny light-sensing nerve cells. Called cones and rods, these cells provide sharp vision in bright light and detect colors and details, provide peripheral, or side, vision, and allow our eyes to detect motion and see in dim light.1 But the small muscles that help shape the lens2 must also be able to thicken the lens3 for nearby vision or thin, or relax, it for faraway vision.4

When the retina converts these light rays into electrical impulses, they travel to the brain through the optic nerve and, once there, manifest into images.1

Fortunately, there are several things you can do on a regular basis to help keep your eyes healthy. Find out about preventing vision problems here.

Next: Prevent Vision Problems


  1. American Optometric Association. How your eyes work. Accessed October 16, 2010.
  2. American Optometric Association. Activity Sheet 3: Focus on Seeing. Accessed October 16, 2010.
  3. Emory University Eye Center. Ophthalmology Terms: ciliary muscle. Accessed October 16, 2010.
  4. Oracle ThinkQuest Education Foundation. Disorders of the Eye. Accessed October 16, 2010.