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A hypermetropic eye is able to see distant objects distinctly but near objects appear blurred. The point within which the object cannot be seen distinctly is called the near point.

Causes of Hypermetropia

Hypermetropia can be due to :

(i) Contraction of the length of the eye ball; when the eye ball contracts, the distance between the eye lens and the retina decreases, this results in the image being formed behind the retina. So it is blurred.

(ii) The focal length of eye lens becomes too large.

Correction of Hypermetropia

In this case, the cilliary muscles of the eye become weak and are not able to decrease its focal length by suitable thickening the eye lens. So the eye lens will have large focal length, which will converge the rays behind the retina. To focus these rays at the retina, the rays must be converged suitable. This is done by using a convex lens of suitable focal length.

Some of the important features of hypermetropia are given below :

(i) Hypermetropia is another name for long sightedness.

(ii) In case of hypermetropia, eye is not able to see the nearby objects clearly, though it can clearly see the distant objects.

(iii) Hypermetropia arises either due to contraction of the length of the eye ball or the focal length of the eye lens becoming too large.

(iv) Hypermetropia can be corrected by making the eye lens more convergent (or using a convex lens of suitable focal length.