The substance present in the choroid is:

The far point of a myopic person is $80\, cm$ in front of the eye. What is the power of the lens required to enable him to see very distant objects clearly?

The near point of a person is $75 \, cm$. In order for him to be able to read a book at a distance of $30 \, cm$,what should be the power of the spectacle lenses?

The human eye has a lens which has a

$A$ person cannot see distinctly at a distance less than $1 \, m$. Calculate the power of the lens that he should use to read a book at a distance of $25 \, cm$.

The far point of a myopic eye is at $40 \, cm$. To correct this defect,the power of the lens required will be: (in $, D$)