How the Eye Works

Seven parts following light from the front of the eye to the brain. It opens on the outside — the white, the coloured iris and the hole in the middle that is not a part at all but a gap — and on the tear system that keeps the surface clear, because an eye that dries out stops working within minutes. Then inside, where the lens focuses and the retina converts light into nerve signals, with a zoom into the retina itself to see the layers doing it. The fourth part follows a focused image to a sharp picture, the fifth the six muscles that aim both eyes at the same point so you see one world instead of two, and the last the pathway from eye to brain — where half the signal crosses to the other side.

52 min to complete

Beginner level

7 Parts

CodePLU Goal

Upgrading Human Mental Models

Learn how to think in Workflows

Look at an eye in the mirror and name every part staring back — the black opening, the coloured ring, the white, and the lids and lashes that guard them

Beginner 7 min Part 1

What Are the Parts of the Eye You Can See?

Before you look inside the eye, learn the parts you can already see in a mirror. Label the pupil, iris, sclera, eyelid, eyelashes and the tear-duct corner, and learn what each visible part does to let in light and protect the eye — in an interactive playground.

Tears are not just for crying — your eyes are being washed and drained every second. Follow a tear from the gland that makes it, across the eye, and down the pipe into your nose

Beginner 7 min Part 2

Where Do Your Tears Come From and Go?

Your eyes make and drain tears all day to stay clean and wet. Label the tear gland, the eye, the tear ducts, the tear sac and the duct to the nose, and follow a tear from where it is made to where it drains — in an interactive playground.

Open the eyeball and follow a ray of light on its way to becoming sight — through the clear window and the focusing lens, onto the screen at the back, and down the cable to your brain

Beginner 8 min Part 3

How Does Your Eye Turn Light Into a Picture?

Your eye works like a living camera. Cut it open and label the cornea, lens, iris, retina, optic nerve and sclera, and follow light as it is focused onto a screen at the back of the eye and sent to the brain — in an interactive playground.

This is the view a doctor sees down an ophthalmoscope — the living screen at the back of your eye, with the one spot where you see sharpest and the one spot where you are completely blind

Beginner 8 min Part 4

What Does the Back of Your Eye Look Like?

The retina is the screen at the back of your eye — but it is not the same all over. Label the retina, optic disc, macula, fovea and blood vessels on the real view a doctor sees, and learn where your sight is sharpest, where your blind spot is, and how the retina is fed — in an interactive playground.

Follow the light rays as they fan into your eye and are bent to meet at a single point — and see what 'being in focus' actually means, landing exactly on the back of the eye

Beginner 7 min Part 5

How Does Your Eye Bring the World Into Focus?

Being 'in focus' means the light from what you look at is bent to meet at one sharp point on the retina. Label the cornea, lens, light rays, focus point and retina, and see how the eye focuses light like a camera — in an interactive playground.

Your eyes dart, flick and follow all day without you thinking — meet the little strap muscles inside the socket that aim each eyeball exactly where you want to look

Beginner 7 min Part 6

What Muscles Move Your Eyes?

Every glance is a set of muscles at work. Look inside the eye socket and label the eyeball, the muscles that roll it up and down, the point where they anchor, and the bony socket that holds them — and learn how these little straps aim your gaze, in an interactive playground.

Your eyes only catch the light — you actually see with your brain. Follow the wiring from both eyes, through the crossover where the two views are sorted, to the back of the brain

Beginner 8 min Part 7

How Do Signals Travel From Your Eyes to Your Brain?

Seeing happens in the brain, not the eye. Label the eye, optic nerve, optic chiasm, optic radiation and visual cortex, and follow the signals from both eyes — through the crossover where they swap sides — all the way to the back of the brain, in an interactive playground.