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Eye
Conditions
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The
human eye has been described as an optical marvel. It works
just like a camera. Light rays pass through the clear part
at the front (the cornea) and pass through the lens, which
focuses them onto the "screen" at the back of the eye called
the retina. There, billions of photoreceptors (light-sensitive
nerve cells) turn the image into electrical impulses that
are transmitted to the brain. But not everybody's eyes are
perfect. When the cornea, lens or eye is an abnormal shape,
light cannot focus accurately on the retina and the image
is blurred. |
The
most common sight defects are as follows:
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(Nearsightedness):
if you are myopic, light rays come to a focus before they
strike your retina. You are able to see close objects clearly
but everything in the distance becomes blurred.
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(Farsightedness):
hyperopic people can see distant objects clearly but have
difficulty focusing on closer ones, as the rays come to a
focus behind the retina.
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Astigmatism
is that condition wherein the refraction varies in different
meridians of the eye. It occurs when light entering the eye
is "split" into two separate parts instead of focusing on
one precise point on the retina. Astigmatism is commonly caused
by abnormalities in the curvature of the cornea. If you are
astigmatic, you will experience a distortion or blurring of
images at all distances, nearby as well as distant.
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