1. Few old people, suffer both myopia and hypermetropia.
2. In bifocal lens upper part is concave lens to correct myopia and lower part is convex lens to correct hypermetropia.
3. The concave lens is useful for distant vision and convex lens for near vision.
4. Hence old people use bifocal glasses.
2. In bifocal lens upper part is concave lens to correct myopia and lower part is convex lens to correct hypermetropia.
3. The concave lens is useful for distant vision and convex lens for near vision.
4. Hence old people use bifocal glasses.
