Presbyopia is a common vision problem among both men and women in their 40s and older ages. Suffering this bothersome vision defect, people have difficulty in reading newspapers, printed materials and so on. In those early days, only reading glasses were available for presbyopic patients to get vision correction. These glasses can perform well during close reading activities. But for some people who need to wear glasses dealing with myopia, it becomes haphazard to use two sets of spectacles at the same time.
Thanks to the innovative American statesman Benjamin Franklin, bifocal glasses were invented to address the inconvenience aroused by two pairs of glasses. The great statesman had long been bothered by his two sets of glasses, one for distance vision and the other for presbyopia. He got quite tired of using and juggling two pairs continuously. A creative idea came to him that he designed a bifocal lens by combining two half parts from his reading lenses and distance lenses. This was the basic design of bifocal lenses and has never been changed even after decades of evolution.
Although bifocal lenses have undergone slight changes, the primary style invented by Franklin is still absent on the market. A Franklin-style bifocal lens has a distinct border line between its two parts. They are called Franklin lenses or Executive lenses. The basic design of modern bifocal lenses is the same as Franklin’s. Variations only involve changes in the shape of each part of a bifocal lens. For instance, a modern bifocal lens may have a round part at the lower side of the lens. In addition, the lower part for reading can be other shapes, such as semi circle, ribbon’s segment and so on.
Presbyopic patients do have many more options of bifocal glasses than before. While the fundamental design remains unchanged, people can choose a best variation that meets personal visual needs perfectly.
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