An old man cannot see objects closer than 1 m from the eye clearly. Name the defect of vision he is suffering from. How can it be corrected ? Draw ray diagram for the (i) defect of vision and also (ii) for its correction.

The question describes a scenario where an old man cannot see nearby objects clearly (his near point has receded to $1\text{ m}$ instead of the normal $25\text{ cm}$). This is a classic symptom of Hypermetropia (far-sightedness). Since the individual is elderly, this is specifically caused by Presbyopia, which is the age-related loss of accommodation power due to the weakening of ciliary muscles and hardening of the crystalline lens.

To correct this, a convex lens is placed in front of the eye. The convex lens converges the diverging rays coming from the normal near point $N'$ ($25\text{ cm}$) so that they appear to diverge from the virtual near point $N$ ($1\text{ m}$) of the defective eye. The eye lens then easily focuses these rays directly onto the retina, restoring clear near vision.