What will people do if they have some very serious eye problems, like astigmatism, presbyopia, myopia, etc, especially when they are over forty? They may choose to wear bifocal lenses without any hesitation. It seems that those lenses are very common and sufferers of the above mentioned problems have got used to them. However, unlike common lenses, bifocals have really very short history, but they have evolved radically since their first emergence.

According to the data from bifocal lenses Wiki, the bifocal lenses history is no more than two and a half centuries. It is said that bifocals do not come into being till the 18^th century. And there are still some controversies about who is the bifocal lenses inventor. However, the universally recognized inventor is Benjamin Franklin, a well-known US state man in the 18^th century.

It matters little who have invented the first bifocals, but it matters much what the first bifocals are looked like. According to some documents, the first bifocals are roughly manufactured and very heavy to wear and inconvenient to use. The reason is each lenses are directly overlapped by two full lenses. Therefore, there are almost four full lenses on each pair of them. And such condition does not change until the 20^th century.

The 20^th century has witnessed the rapid developments and changes in glasses industry. And bifocals have also gained great rapidity then. Some designers have noticed that conventional bifocals are roughly made and have caused lots of troubles to wearers. Based on all possible scientific data in the industry, designers have combined each lens by two cut lenses. This innovation has greatly enhanced the comfort of wearing. Now that those lenses are combined by two different lenses, there is a division line between them. And there comes bifocal progressive as a result. Here is a contrast- bifocal lenses Vs Progressive.

The first type is called lined lenses and has very evident division line in their middle part, whereas no such line can be found in the latter form. Wearers will endure radical vision change with bifocal lenses, but never with progressive. And many people begin love to wear progressive thereafter.

Bifocals are always in the process of evolution and people will benefit from it. For example, some bifocal lenses for spectacles are available if people want to replace them.

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