What is meant by the near point of the eye?

$A$ person is able to see objects clearly only when these are lying at distances between $50\, cm$ and $300\, cm$ from his eye.
$(a)$ What kind of defect of vision is he suffering from?
$(b)$ What kind of lenses will be required to increase his range of vision from $25\, cm$ to infinity? Explain.

$A$ person cannot see distinctly objects kept beyond $2\, m$. This defect can be corrected by using a lens of power:

The change in focal length of an eye lens is caused by the action of the

$A$ person needs a lens of power $-5.5$ dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power $+1.5$ dioptre. What is the focal length (in $cm$) of the lens required for correcting distant vision?

Why does it take some time to see objects in a cinema hall when we just enter the hall from bright sunlight? Explain in brief.