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45. Your Eyes
Light goes through the pupil, the dark hole
the center of your eye. The light becomes
image on the retina, which converts these images
nerve impulses. The brain reads these impulses and “
” you what you are seeing. The image that
retina receives is upside down, but the brain
it to right-side up.
In an experiment years
, a brave researcher wore special lenses that turned
upside down. After stumbling around for awhile, he
used to the lenses because his brain corrected
images. To conclude his experiment, he stopped wearing
lenses. After awhile, his brain returned his vision
normal.
People with vision problems are usually near-sighted
far-sighted. Near-sighted people see clearly only objects that
near; far-sighted people see clearly only objects that
far away. Both groups of people need corrective
(glasses or contacts).
People whose near and far
is good have “20/20” vision. People with poor
might have 20/40 vision (or worse). That is,
person with good vision can see an object
40 feet away as clearly as a person
poor vision can see the object from 20
away. No matter how good your vision is
you are young, you will need reading glasses
you get old.
Your pupils get bigger as
light source gets dimmer, but your pupils also
bigger if you see something (like a delicious
) that interests you. “Your eyes are bigger than
stomach” is an expression parents use when a
fills his plate with more food than he
eat.
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