What bi focal lenses are?
Having one segment for near vision and one segment for far vision. Multifocals let you focus through different prescriptions at different distances through the same lens — hence the name. Bifocals (meaning a lens with two points of focus — usually one for distance and one for near) are the most commonly prescribed multifocal lenses. Bifocals are usually prescribed for those of us over the age of 40 who have lost their ability to focus on close work. They are a convenience, but are not necessary if your lifestyle needs can be met with single vision glasses.
