Which defect of vision can be rectified:

(a) by using a concave lens ?

(b) by using a convex lens?

Name one of the common defects of vision and the type of lens used to remove it.

Name the defect of vision in a person;

(a) whose near point is more than 25 cm away.

(b) whose far point is less than infinity

What type of lens is used to correct

(a) hypermetropia

(b) myopia?

What is the other name for

(a) myopia

(b) hypermetropia?