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MusclesHow does the eye see?
Light comes in at the front of the eye, goes through a small hole in the middle of the colored part and reaches the back of the eye. There, a very thin layer turns the light into messages. Those messages travel to the brain, and the brain builds the picture you see.
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Questions people ask
Why does the pupil change size?
To control how much light enters the eye. In the dark, the iris opens the pupil to let more light in; in sunlight, it closes it to protect the retina. It happens by itself, in under a second.
Where does eye color come from?
From the amount of melanin in the iris, the same pigment as in skin and hair. Lots of melanin makes eyes brown; little makes them green or blue. Color is inherited from parents, but the gene combination is complex.
What is a cataract?
It is when the eye’s lens, which should be clear, turns cloudy and vision gets blurry. It is common with age and is treated with surgery that replaces the lens with an artificial one.
Why do we blink?
To spread tears, wipe away dust and keep the eye moist. We also blink quickly to protect the eye when something comes close. A person blinks 15 to 20 times a minute.
What is the eye’s blind spot?
It is the spot on the retina where the optic nerve leaves. There are no light-sensing cells there, so nothing is seen at that point. We don’t notice because the other eye and the brain fill in the picture.
Sources
This text was written using these references:
- How the Eyes Work · National Eye Institute (NIH)
This content has not been medically reviewed.