Question

What is presbyopia? Write two causes of this defect. Name the type of lens which can be used to correct presbyopia.

Answer 1

Presbyopia is that defect of vision due to which an old person cannot see the nearby objects clearly due to loss of power of accommodation of the eye.
Causes: Gradual weakening of the cilliary muscles and diminishing flexibility of the eye lens. It can be corrected by using convex lenses.