What are bifocal lenses?

A bifocal lens consists of both convex lens as well as concave lens. It is used by the person suffering from myopia, hypermetropia, and presbyopia (not able to see very distant objects). Convex lens is used to correct hypermetropia (not able to see nearby objects clearly) and concave lens to correct myopia (not able to see far away objects clearly).The figure below shows the bifocal lens.


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