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Nearsightedness (myopia)
is usually caused either by an abnormally long eye
length or by an excessively steep curvature of the
cornea or crystalline lens resulting in light rays
coming into focus in front of the retina. This results
in distant objects appearing blurry, while objects near
to the viewer can be seen in focus. |
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Farsightedness (hyperopia)
is frequently caused by an abnormally short eye shape or
by an excessively flat cornea or crystalline lens
thereby bringing distant objects into focus behind the
retina. The result of farsightedness is that objects
near to the viewer appear blurry, while objects in the
distance are seen more clearly. |
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Astigmatism occurs
when the cornea and/or lens are not mostly spherical in
shape. Most commonly the cornea is curved differently
in one area than in another area – often shaped more
like a football than a basketball. The result of
astigmatism is that objects are not focused into a
single image and vision is distorted or blurry. It may
occur by itself or together with myopia or hyperopia.
Most people have at least a small degree of astigmatism. |
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