eyeglasses,The bifocal reading glasses can be traced back to Ben Franklin. Ben Franklin was a busy guy. He was a writer, printer, statesman, politician, scientist and inventor. Now, according to the historical story, Mr. Franklin needed to wear two pairs of glasses, one for seeing distance and one for seeing close up.
glasses,Being the active and busy guy that he was, he soon grew weary of having to exchange glasses all the time in order to see. So, he decided to cut both pairs of his glasses (called spectacles back then) and joining the two halves together, each for one lens. Now, this was a primitive way of taking care of the problem and technology has come a long way with bifocal reading glasses since then, but it got the job done.
eye glasses,In the most basic sense, bifocal reading glasses are two lenses in one. The smaller portion of the lens near the bottom is reserved for close-up viewing, while the larger area of the glass is used to see in the distance.
The theory behind this is that a person will look down for close-up viewing such as reading a restaurant menu, but will look up when looking afar. Some bifocal reading glasses have a distinct line that can be seen, while other bifocal reading glasses have an invisible line that joins the two lenses together.
cheap eye glasses,The most obvious advantage of bifocal reading glasses is that it prevents you from having to constantly switch glasses back-and-forth between two different pairs of glasses. For example, you can be looking down and reading a book, but still glance up at the television across the room and still see it!
A disadvantage of bifocal reading glasses is that they may take some time to get used to. There may be some initial discomfort and coordination to deal with, but this is usually temporary;most people get used to them fairly quickly. Some bifocal reading glass users have complained of headaches, but again this is usually a short-term side effect. The key for many is learning how to use the two portions of the glasses correctly by looking through the correct part of the lens when performing either close-up work or looking out in the distance.