Presbyopia is a type of far-sightedness.

$A$ person is able to see objects clearly only when these are lying at distances between $50 \text{ cm}$ and $300 \text{ cm}$ from his eye. Identify the kind of defects of vision he is suffering from. Give reason for your answer.

What happens to the lens and the ciliary muscles when you are looking at nearby objects?

State the function of the pupil and ciliary muscles.

What is the other name of near-sightedness?

The far point of a myopic person is $40 \, cm$. What type of lens should they wear to see distant objects clearly? Calculate the focal length and the power of the lens they should use.