$A$ person uses spectacles of power $+2D$. He is suffering from

$A$ person's near point is $50 \, cm$ and his far point is $3 \, m$. The power of the lenses he requires for $(i)$ reading and $(ii)$ seeing distant stars are:

When the human eye is focused on an object,the ciliary muscles are least strained when the object is at:

$A$ person has a near point of $50 \, cm$ and a far point of $3 \, m$. What power of lens is required to $(i)$ read and $(ii)$ see distant stars?

An imaginary line joining the optical centre of the eye lens and the yellow point is called as

Hypermetropia is a: