Myopia is due to

For a normal eye,the cornea of the eye provides a converging power of $40\, D$ and the least converging power of the eye lens behind the cornea is $20\, D$. Using this information,the distance between the retina and the cornea-eye lens can be estimated to be ......... $cm$.

When objects at different distances are seen by the eye,which of the following remains constant?

If you are using eyeglasses of power $2 D$,what is your near point (in $cm$)?

Myopia can be corrected with the help of a/an ...

$A$ far-sighted man who has lost his spectacles reads a book by looking through a small hole $(3-4 \,mm)$ in a sheet of paper. The reason is: