The near-point of a person suffering from hypermetropia is at 50 cm from his eye. What is the nature and power of the lens needed to correct this defect? (Assume that the near-point of the normal eye is 25 cm).

Convex lens is needed to rectify the defect.

Its calculation for the power of the lens is given by

The defected eye can see the nearby object kept at 25 cm clearly if the image is formed at its own near point i.e. 50 cm.

Object distance, u = –25 cm

Image distance, v = –50 cm