Also known as Varifocal lenses, or progressive glasses, Varifocals has the features of a pair of bi-focal lenses without the issues related to the line along the middle. Bifocals are employed by people who has problem seeing long-distance, but are finding it hard to read print or newspaper. People sometimes realize this grouping of difficulties as they age, because the lens gets looser, thus whereas they may have experienced extreme myopia as a young adult , they currently want to appear a lot closely at the book or computer screen. Varifocal glasses provide the wearer the opportunity to do both at once and even avoid the thickness of bifocals.
Bifocals got their bad fame in 70s and 80s, because they were seen as unattractive and awkward . Lens grinders had to mix two different sorts of lens, one enlarging the distance , and another enlarging the near space. This means that they often resorted to using thick glass, together with a heavy frame to support the two lenses. They may even cause problems with sight because of the line which joined one lens to the other not being completely ground away. Wearing these glasses for a long time would become wearing, and several people chose to leave them off because of the effort required to wear them. Because bifocals have been so unpopular with several wearers, they are being less frequently prescribed by opticians, who will usually request two pairs of glasses for the myopia and hyper myopia.
Varifocal glasses are an alternative to the bifocal that uses a much thinner lens to attain a similar results. Rather than being two different lenses, the glass is gradually ground to the desired consistencies, with the top portion of the lens being for long viewing, with the lower half getting used for close reading. Combining the lenses like this means that the lens maker can use a much thinner piece of glass, and then employ a lighter frame to support the glasses. In addition , there is no fine line down the middle.
Those who work in computers, particularly in IT and computer displays, usually find that bifocal lenses are totally inappropriate for their needs . Instead, they select Varifocal glasses that will be worn for long stretches at a time, and don't require the user to change the frames, move the glasses, or do anything which requires effort or risks eye strain. Without the line down the middle , they could clearly see the screen in front of them, a important part of their job .