Explain the defects in human eye.

Explain the defects in human eye.
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1 Answer

Answer :

I. Short-sightedness (Myopia)

In short-sightedness a person can see near objects clearly but distant object appear blurred.

Reason

When the eye lens becomes much thicker or eyeball becomes too long, the image of distant object is formed in front of the retina rather at retina. This defect is also called Myopia.

Correction of the Defect

This defect is removed by using concave lens of suitable

image

focal length (f). The concave lens diverges the light rays before they enter the eye. Hence the rays again meet at the retina.

II. Long-sightedness (Hyperopia)

In long-sightedness a person can see distant objects clearly but near object appear blurred.

Reason

When the eye lens becomes thin or eyeball becomes too short, the image of near object is formed beyond the retina rather at retina. This defect is also called

Hyperopia.

Correction of the Defect

image

This defect is removed by using convex lens of suitable focal length (f). The convex lens converge the light rays before they enter the eye. They are further bent by the eye lens to meet at the retina.

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