May 11, 2014

What are the defects of eyes?

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    May 11, 2014

    There are many defects of eyes, some few defects are

    discussed here : -

    >> Myopia : - In this defect a person can see near objects

    clearly, but the far objects appear blurred to him. The

    image is made infront of the retina instead of image made on

    retina. It happens because of long eyeball. The far images

    can be made seen by wearing glasses with concave lenses. It

    is also called nearsightedness.

    >> Hypermetropia : - In this a person can see far objects

    easily, but can't see near objects clearly. in this the

    image is formed behind the retina. It happens because of

    short eyeball. Hypermetropia can be corrected by wearing

    glasses of convex lenses. It is also called farsightedness.

    >> Astigmatism : - In this light rays don't come to a point

    of retina, some rays falls behind the retina and some falls

    infront of the retina. It is because of non-uniform

    curvature of the cornea. In this if a person see a pattern

    of lines placed at different angles then lines going in one

    direction will appear sharp and the lines in other direction

    will appear blurred. It can be corrected by using glasses of

    spherical cylindrical lens.

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