As people age, they may find that their eyes are not adjusting to distances as they used to. When people inch closer to forty, the lens of the eyes begin to lose flexibility. It becomes difficult to focus on close objects. This condition is called presbyopia. It can be managed to a large extent with the use of bifocals.
Bifocal (also can be called Multifocal) eyeglass lenses contain two or more lens powers to help you see objects at all distances after you lose the ability to naturally change the focus of your eyes due to age.

The lower half of a bifocal lens contains the near segment for reading and other close-up tasks. The rest of the lens is usually a distance correction, but sometimes has no correction at all in it, if you have good distance vision.

When people inch closer to forty, they may find that their eyes are not adjusting to distances as they used to, the lens of the eyes begin to lose flexibility. It becomes difficult to focus on close objects. This condition is called presbyopia. It can be managed to a large extent with the use of bifocals.