Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How it help?

When a person can see objects that are placed nearby but find difficulty in seeing objects at a distance is known as myopia. Whereas if a person can see objects that are placed at a distance and find difficulty in seeing objects that are nearby is known as hypermetropia.

If a person is suffering from myopia as well as hypermetropia then that person is advised to use bifocal lenses in which the upper part consists of concave lens while the lower part consists of convex lens. The upper lens corrects myopia while the lower part corrects hypermetropia.