Myopia
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Hypermetropia
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Myopia is also known as near-sightedness .
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Hypermetropia is also known as far-sightedness.
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In myopia , a person is not able to see distant objects clearly.
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In hypermetropia , a person is not able to clearly see the nearby objects.
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In this defect , lens are not able to produce sharp image of the distant objects on the retina instead the image is formed in front of the retina .
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In this defect , image is formed behind the retina.
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The reduction in the focal length of the eye lens may be a possible cause.
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The increase in focal length of the eye lens may be a cause.
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Another cause can be the elongation of eye ball.
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It may also be caused due to flattening of the eyeball .
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Myopia can be corrected by using concave lens of suitable focal length.
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Hypermetropia may be corrected using convex lens of suitable focal length .
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