Bifocal lenses contain two optical corrections with a distinct dividing line between the two parts. The most common use of bifocals is for people who have become presbyopic and need a different prescription for close work. The upper part of the lens corrects distance vision and the lower half is for near vision. Trifocals are also available that have three sections and incorporate a correction for intermediate vision. Bifocals and trifocals come in a range of designs but nowadays varifocal lenses are much more likely to be prescribed.
