Question

17. What are ,,bifocal lenses?Under what condition(s) are these required by a person?​

Answer 1

Bifocal glasses are necessary for people who have presbyopia (a condition caused by aging of the eyes) in addition to myopia, hyperopia (also called hypermetropia) and/or astigmatism. In other words, you need bifocal glasses if you suffer simultaneously from short-sightedness as well as long-sightedness, a common consequence of aging. Presbyopia is not the same condition as hyperopia, although people who have either one are unable to clearly observe objects at a short distance from their eyes.