Bifocals – What Are They? -

Details for Bifocals – What Are They?

ID:	2171
Author:	Suzanne Hughes
Title:	Bifocals – What Are They?
Article:	We have all heard about bifocal lenses. These lenses are divided into two areas each of which has different optical powers. You have to wear glasses with bifocal powers if you have presbyopia, and an additional problem of myopia, hypermetropia and, in some cases, astigmatism. Until recently, there were few choices for people who suffered from nearsightedness or farsightedness. One had to go in for thickish lenses with a visible line down the middle. There was no wide range of frames either. Most were thick, large and far from attractive. A lot of people faced adjustment problems with bifocals. Some complained of feeling giddy while climbing up or down stairs. The adjustment process was difficult for some. One had to wear a pair of glasses if they needed bifocals. Contacts came in a while later, but not bifocal ones. But the scenario has changed. You have a huge range of options if you wear contact lenses rather than eyeglasses. The great thing is that bifocal contact lenses have come into the market. These come in a lot of styles and finishes- rigid, soft or gas permeable. You might want to know who bifocal contacts are for. They are designed for people with presbyopia, that is, difficulty focusing on objects near you. Most victims are over forty years of age. How do these lenses work? Half of the lens lets you see what is near, and the other half is for distant objects. Some lenses will work for both near and distant vision problems. These sit on your pupil and are called simultaneous design. Slowly, your eyes will get accustomed to interpreting the circle power choices and tell you how far an object really is. Most common lenses are concentric design lenses. The inner lens will take care of distant vision or the other way round. Other lenses are available too. For instance, translating design contacts have the distant correction located above the nearness correction center. The lenses are separated by a line. The lens won’t shift positions in your eye even when you blink, as the bottom is perfectly flat. In Asferic design lenses, the near correction is at the center. The distance correction is all around this central zone.If you have a problem with this design, let your doctor know. He can tell you of a reversed design. Some lenses are mono vision. You have nearness correction in one eye and distance correction in the other. The doctor can tell you which is your dominant eye and the distance vision lens should be worn in this one. Simultaneous vision lenses are such that you can focus on near and far objects at the same time. The corrections for distance and near correction lie in concentric circles. Light from both near and far objects reach your eyes at the same time so you can focus on both together. Researchers today are working to find out how the limited field of vision can be reduced in bifocals. New materials are being designed, as is new technology. This way, the optical power of the lens can be adjusted to suit every person’s needs. There is a new type of switchable lens that come with a liquid crystal layer fitted between two glass substrates. Electricity is used to change the refractive index of the lens, thereby varying the optical power. About the author of this article: suzanne hughes is an eyewear style consultant specializing in reading glasses online . for more information about eyeglasses, vision, or great styles such as scojo reading glasses , visit her online boutique.
Category:	Health: Medical-Business
Date:	March 06, 2009 04:03:01 AM

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