[JOAN CARTAN-HANSEN]AN EYE IS ABOUT THE SIZE AND SHAPE OF A PING PONG BALL.

ITS TOUGH OUTER LAYER IS CALLED THE SCLERA, THAT’S THE WHITE PART OF YOUR EYE.

ON THE FRONT OF YOUR EYE IS THE CORNEA. WHEN YOU LOOK AT SOMETHING, LIGHT BOUNCES OFF THE IMAGE AND TRAVELS THOUGH THE CORNEA AND THEN THROUGH THE ROUND BLACK HOLE IN THE CENTER OF YOUR EYE, OR THE PUPIL.

A MUSCLE CALLED THE IRIS OR THE COLORED PART OF YOUR EYE, OPENS AND CLOSES THE PUPIL. WHEN IT’S DARK THE PUPIL OPENS UP TO ALLOW IN MORE LIGHT. WHEN IT’S BRIGHT THE PUPIL CLOSES UP.

BEHIND THE PUPIL IS THE LENS. LIGHT TRAVELS THOUGH THE LENS IN A CLEAR JELLY-LIKE SUBSTANCE CALLED THE VITREOUS HUMOR AND FOCUSES THE IMAGE OF WHAT YOU’RE LOOKING AT ON THE BACK OF THE EYE, OR THE RETINA.

THE RETINA HAS MILLIONS OF LIGHT-SENSITIVE NERVE CELLS CALLED RODS AND CONES. RODS PICK UP BLACK AND WHITE AND SHADES OF GRAY. THEY HELP YOU SEE IN LOW LIGHT. CONES PICK UP COLORS AND BRIGHT LIGHTS.

ALL THE DIFFERENT PARTS OF YOUR EYES WORK TOGETHER TO HELP YOU SEE EVERYTHING AROUND YOU.

DID YOU KNOW WHEN YOU LOOK AT SOMETHING THE IMAGE COMES INTO YOUR EYE UPSIDE-DOWN AND BACKWARDS?

THE IMAGE GOES THROUGH THE OPTIC NERVE BEHIND THE RETINA TO YOUR BRAIN, AND THEN YOUR BRAIN TURNS IT RIGHT-SIDE UP.

MUSCLES ATTACHED TO YOUR EYEBALL MOVE IT AROUND SO YOU CAN SEE IN DIFFERENT DIRECTIONS.AND OTHER PARTS OF YOUR FACE ARE THERE TO PROTECT YOUR VISION.

YOUR EYEBROWS STOP SWEAT FROM DRIPPING INTO YOUR EYES.

YOUR EYELASHES STOP THINGS FROM BRUSHING AGAINST THE CORNEA.

AND EYELIDS ARE LIKE WINDSHIELD WIPERS. EVERY TIME YOU BLINK, TEARS SWEEP ACROSS THE SURFACE OF YOUR EYES TO KEEP THEM MOIST AND CLEAN. YOU BLINK ABOUT 30 TIMES A MINUTE AND YOU DON’T EVEN THINK ABOUT IT.

MOST OF US TAKE OUR EYES FOR GRANTED, BUT SOME PEOPLE HAVE TROUBLE SEEING.

THE LENS OR THE CORNEA MAY BE TOO CURVED OR TOO FLAT. OR THEIR EYES MAY BE TOO LONG OR TOO SHORT FROM FRONT TO BACK. WHEN THAT HAPPENS, PART OF THE IMAGE MAY BE OUT OF FOCUS OR BLURRY.

IF YOU CAN SEE THINGS CLOSE-UP, BUT NOT FAR AWAY YOU’RE NEARSIGHTED.

IF YOU CAN SEE THINGS FAR AWAY BUT NOT CLOSE IN, YOU ARE FARSIGHTED.

PEOPLE CAN WEAR GLASSES OR CONTACTS, OR IN SOME CASES HAVE SURGERY ON THEIR EYES TO CORRECT THEIR VISION.

AND SOME PEOPLE ARE COLORBLIND. THAT MEANS HE OR SHE CAN’T SEE ONE OR MORE COLORS, IT JUST LOOKS GRAY.

BOYS ARE MORE LIKELY TO BE COLORBLIND THAN GIRLS.

YOUR SIGHT IS YOUR MOST IMPORTANT SENSE. PROTECT YOUR VISION AND SEE HOW FAR YOU CAN GO.

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