Many people develop problems with close vision during their 40s. This condition is called presbyopia. If you already wear glasses for distance vision, and are later on diagnosed with presbyopia, you won't have to carry a separate pair of reading glasses. Multifocal lenses, which correct problems with both near and far sight, allow you to see well at all distances with one pair of glasses.
Before mulifocals, bifocals were widely prescribed, but they have a significant disadvantage; even though they correct problems with both near and distant objects, everything in between is blurred. In an effort to create something more helpful, progressive lenses were developed, which provide wearers with and intermediate or transition region which lets you focus on the area between things like the newspaper and far objects like road signs. How does this work? Well, progressive lenses feature a gradual curvature, unlike a bifocal lens, which is sharply sectioned. Because of this, progressive lenses are also known as no-line lenses. This makes for not only better vision at all distances, but also nice, easy transitions in between.
But, you might take a bit of time to get used to no-line lenses. Despite the fact that the subtle transition of progressive lenses is more aesthetically pleasing, the lens's areas of focus are relatively small, because they all need to fit.
Bifocals are still used though; they are helpful for children and teens who have a hard time focusing when reading.
Multifocal lenses work best when they're made to work with your specific requirements. When you're ready to get yours, make sure it's with a professional you feel comfortable with.
Glasses that aren't properly customized to you can lead to eye strain, discomfort and nausea. Unfortunately, presbyopia is just a part of aging. But keep in mind that multifocal lenses can make all the difference.