Hypermetropia or long-sightedness: It is a vision defect in which a person can see the distant objects clearly but cannot see the nearby objects clearly.
Cause of hypermetropia: This defect arises due to either of the following two reasons:
(i) The eyeball becomes too small along its axis so that the distance between the eyelens and the retina is reduced.
(ii) The focal length of the eyelens becomes too large resulting in the low converging power of the eyelens.
As a result of the above causes, the rays coming from an object placed at 25 cm (normal near point) from the eye meet at a point behind the retina, as shown in Fig.(a). So the object is not seen clearly.