Eye Health:

How Your Eyes Work

General Information	Contacts
How Your Eyes Work	Common Vision Problems
Eye Exam/Vision Testing	Common Eye Conditions
Corrective Lenses	Protecting Your Eyes
Glasses	Frequently Asked Questions

Have you ever thought about what's inside your eyes? For the most part we take our eyes for granted but if you think about it, our eyes have many parts working together to create the images we see.

Let's follow light as it enters your eye to understand how the eye works.

• The cornea is the eye's clear surface and what light first hits. The cornea bends light and sends it through the pupil.
• The pupil is an opening that gets bigger or smaller. The colored part of your eye, the iris, controls the pupil's size.
• The lens focuses the light onto the back of the eye (retina).
• The retina contains special cells (photoreceptors) that change light into signals.
• The optic nerve receives signals from the retina and passes it to the brain. The brain uses these signals to create a picture of what we see.

Other cool facts about your eyes:

• Your eyes are filled with a jelly-like stuff called vitreous gel that gives your eyes their round shape.
• The pupil (opening in your eye) gets larger when it's dark to let in more light.
• Muscles inside your eye can move your eyeball in almost any direction. That way you don't have to move your head to see what's out of the corner of your eye.
• Iris (colored part of your eye) means "rainbow" in Greek. Even though the iris can be hazel, green, grey, blue, or brown, only one pigment is responsible for creating the iris' color - it's called melanin.

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Written and reviewed by the CYWH Staff at Children's Hospital Boston

Updated: 11/19/2010