Generally, most users of prescription glasses use single-vision glasses, primarily due to the fact that they suffer from a single vision disorder. When a person is suffering from one of myopia, hyperopia and presbyopia, single vision glasses can take care of it. But a presence of more than one vision disorder will entail the need of more than one focal point on the lenses. This calls for bifocal, trifocals or progressive lenses. These glasses take time to adjust too, but once a person gets used to it, can offer a much better vision than they expect.
Bifocal glasses are the simplest form of varifocal glasses, though they are not strictly varifocals. Bifocal glasses have the lenses separated in two halves. The upper part of the lens is used to view objects at a distance while the lower part is for nearer vision. However, due to the presence of the line, the transition between the two parts can be sudden and it takes time to get used to it. Many users complain about a headache while using the bifocal glasses for the first time.
The transition should be smooth and gradual and that is the reason why no-line bifocals and trifocals have become popular. The absence of lines dividing the lenses into different parts reduces the chances of image-jump. The trifocals are almost similar to bifocals except they have an intermediate power in the middle of the lenses which is used for viewing objects at an intermediate distance. Computer users find this part of the lenses particularly important.
The most innovative of these kinds of multi-focal glasses is the varifocal glasses. Also known as progressive glasses they comprise of lenses which have gradual increase of power. The power is least at the top and it keeps increasing as we keep moving downwards. The notable absence of lines helps in a smooth transition among the different parts of the lenses.
The easiest, cheapest and the most satisfying way to purchase multi – focal glasses is to browse the collection available at online stores which deal with prescription glasses. These online stores have more exhaustive collection than retail stores and the web – model of doing business help them to charge prices which is far less than their retail counterparts.
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