No, single vision glasses are also available for people who have strong prescription. Bifocals are eyeglasses with two distinct optical powers. Bifocals are most commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism.
Those people who get both nearsightedness and farsightedness will need bifocal glasses in which the upper portion is for distance vision and the llower half is for reading.People who get old have the big chance to get bifocal glasses.
People who have strong prescription don't necessarily need bifocals,they just need the single vision glasses.bifocal glasses are used for people who need two different strengths of lenses,especially for those who have presbyopia and myopia at the same time.