What glasses do myopic people need, and which farsighted people?

Myopia is due to the fact that the rays after refraction form such an angle that the focus is not on the retina of the eye, as in normal vision, but closer to the lens of the eye. To correct this disadvantage, it is necessary to use a lens that has a negative optical power.
With farsightedness, the rays after refraction form an angle at which the focus goes beyond the retina of the eye. In this case, the person needs to use lenses with positive optical power in order to focus on the retina.