Bifocal glasses have lenses which are split into two parts, accommodating two different prescriptions in one lens. The upper portion of the lens is for distance vision. The lower portion of the lens has a different prescription, usually for near vision.
Why are bifocal glasses worth getting?
Bifocal glasses are worth getting if you have two different prescriptions because they can accommodate both in one lens so that you can easily switch between the two.
For example, wearers can use the distance portion of the lens the majority of the time, then quickly switch by looking through the bottom part of their lens for near-sighted activities, like looking at their phone or a computer screen.
This is more convenient than having to switch between two different glasses constantly.