The ability of the eye to see objects at all distances is called

$A$ person wears glasses of power $-2.5 \, D$. The defect of the eye and the far point of the person without the glasses are respectively

$A$ man suffering from short-sightedness (myopia) is unable to see objects distinctly at a distance greater than $2\,m$. The power of the lens required to correct this defect should be.......$D$

The near point and far point of a person are $40\,cm$ and $250\,cm$ respectively. Determine the power of the lens he/she should use while reading a book kept at a distance of $25\,cm$ from the eye $..........D$

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

Astigmatism (for a human eye) can be removed by using