Eyeglasses widely employed by massive people are mainly single focal, mainly because these wearers only suffer from myopia, hyperopia and other ordinary vision errors. However, some unfortunate people may get more than one eye problem at the same time. In particular, when people are over forty, they are vulnerable to presbyopia and other eye problems, with both distant and nearby vision symptoms. For this, many multi-focal glasses can be employed, like bifocal glasses, trifocal glasses, and progressive glasses and so on. However, some of these multi-foal glasses are not ideal as people can ever think, like bifocals and trifocals, due to their vision lines. Therefore, no-line eyeglasses are usually deemed as better options, for they have more than two focal, but varifocals, and are usually called varifocal glasses.
Strictly speaking, bifocals and trifocals can not be called varifocal eye glasses, in which no-line bifocals and no line trifocals are included. Therefore, from a broader perspective, varifocal eye wear can be fallen into the following groups, namely, no line bifocals, no line trifocals, progressive glasses. Here is some detailed information about this eye wear.
No line bifocal glasses are upgraded from ordinary bifocals, mainly because many wearers are tormented by the vision lines in the lenses. Bifocals are combined by two different lenses, each of them are responsible for nearby vision and distant vision respectively. However, the transition between the two lenses is too radical and wearers will always suffer a lot when they change their visions. Or in some cases, wearers have to suffer from headache and dizziness. Therefore, the transition between the two vision areas should be natural and smooth, so as to ensure wearers have more vision comfort. And the emergence of no line bifocals has really benefited these sufferers. No such radical vision transition can be found between the two, for the transition areas are designed in varifocal.
No line trifocals are other important varifocal glasses in the industry. They are also upgraded from ordinary trifocal glasses. Similar to no line bifocals, these no line eye wear can ensure wearers have natural vision transition. And the only difference is- they have more lenses than no line bifocal glasses.
Progressive eyeglasses are some of the most popular viarifocal eye wear. They are composed of various focal, at least 20 focal and can make all vision transition in a progressive way- this is why they are called progressive. These eye wear are so perfect in vision transition that many wearers always think no eyeglasses are on their faces.
In addition, almost all these varifoal eyeglasses are used be designed in larger sizes. But now, they can also be designed in ordinary sizes, due to the employment of special materials.
In a word, varifocal glasses are the best options for people with both nearby and far vision problems. And all wearers are suggested to select according to their personal situations.