In the family of corrective contacts, bifocal lens is totally different. This is because bifocal lens has some characteristics that others do not have. Since the day when bifocal eyeglasses were invented by Benjamin Franklin, they have helped a lot of people. And now they have become much perfect though the mechanism is still the same.

People who have been diagnosed as presbyopia are in need of bifocal lens. For the uniqueness of presbyopia, there are still many problems in solving them. The patients either can see the objects near and far simultaneously, or can they move their eyes freely. As for these symptoms, people have designed bifocal lenses to tackle with them.

By and large, people can find two kinds of these lenses at the market, namely, alternating bifocal lenses and simultaneous bifocal lenses. When people look upward or downward, alternating bifocal lenses can help a lot, because pupils can notice the two power distance between distance and near powers. As their names indicate, simultaneous bifocal lenses can make sure that the two powers can be looked at the same time.

Though bifocal lenses are mainly for people suffering presbyopia, not all of the presbyopia suffers can wear these contact lenses. Each bifocal lens should fit the conditions of individual patients. Some repulsive effects may happen to people who can not wear bifocal lens. Some criteria must be met if presbyopic patients need to be prescribed bifocal lenses. They should have very good tear system, healthy cornea, and normal blink rates. If they fail to meet these requirements, bifocal lenses are not suitable for them.

Additionally, some items need to be noticed when storing and cleaning bifocal lens. In order not to be infected, hands should be clearly washed before handling these lenses. Moreover, bifocal lens should be cleaned regularly using proper solutions.

• Previous Entry: Sunglasses clip care
• Next Entry: Ready-made reading eyeglasses VS custom-made glasses