Near sightedness Myopia


 
 
Concept Explanation
 

Near Sightedness Myopia

Near-sightedness (Myopia): Near-sightedness is a defect of vision due to which a person is not able to see distant objects clearly. This defect is also called short-sightedness or myopia. It arises mainly due to two reasons.

  • In certain people, the eyeball becomes elongated, i.e, longer than the normal eye. As a result, the distance of the retina from the crystalline lens increases. Parallel rays of light from far away objects get focused at a point before the retina.
  •  In some cases, the curvatures of the cornea or the lens are such that the image forms short of the retina.
  • In both cases, far away objects cannot be seen clearly, although nearby objects can. Clearly, the far point of a myopic person is much closer than infinity.

    Sample Questions
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    Question : 1

    In a certain eye defect, image is formed in front of retina. The focal length of the lens used to correct the defect is ______________

    Right Option : B
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    Question : 2

    The lens used in spectacles for the correction of short-sightedness is a _______________________.

    Right Option : A
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    Explanation
    Question : 3

     Nearsightedness is also known as _____________________.

    Right Option : D
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