Question

Which defect of eye is corrected by bifocal lens ? What are the positions of convex and concave lens in bifocal lens and why ?

Answer 1

This defect is presbyopia . this is the defect in which man is unable to see nearer object as well as distant object .and for the correction of it ,bifocam lens is used in spectacles in which upper part is concave lens to see distant object and lower part is convex lens to see nearer object