bifocal


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Related to bifocal: bifocal glasses

bifocal

 [bi´fo-kal]
of a lens, having two areas with different refractive powers.
bifocal glasses eyeglasses in which each lens is made up of two segments of different refractive powers, or strength. Generally, the upper part of the lens is used for ordinary or distant vision, and the smaller, lower section for near vision, for close work such as reading or sewing. Bifocal eyeglasses may be prescribed for presbyopia, which often occurs with aging.

bi·fo·cal

(bī-fō'kăl),
Having two foci.

bifocal

/bi·fo·cal/ (bi-fo´-) (bi´fo-k'l)
1. having two foci.
2. containing one part for near vision and another part for distant vision, as in a bifocal lens.

bifocal

(bī-fō′kəl, bī′fō′-)
adj.
1. Having two focal lengths.
2. Having one section that corrects for distant vision and another that corrects for near vision, as an eyeglass lens.
3. Having two distinct goals or objects of attention: a bifocal approach to the problem.
pl.n. bifocals (bī′fō′kəlz, bī-fō′-)
Eyeglasses with bifocal lenses.

bi·fo′cal·ism n.

bifocal

[bīfō′kəl]
Etymology: L, bis + focus, hearth
1 pertaining to the characteristic of having two foci.
2 (of a lens) having two areas of different focal lengths.

bi·fo·cal

(bī-fō'kăl)
Having two foci.

bifocal

Having two different foci. In bifocal spectacles each lens has a lower segment of greater power for convenience in reading.
References in periodicals archive ?
For some situations I like having the bifocal in both the upper right and lower left, while at other times in daily life it can be a bit distracting.
While improving the poor eyesight of many since then, Franklin's bifocals also provide a lesson in the kind of vision that businesses must possess to be successful.
My bifocals and I are making our way through this brave new invisible-line world where what you see depends on how you hold your eyes.
We found that before bifocal wear, Downs syndrome children have a focusing problem not because they cannot focus but because they do not focus.
Pyramex's V2 safety glasses have bifocal magnification for reading shop notes and plans while still offering safety protection for the tool end of things.
Northwest) explores how young people with a heritage society in Haiti and a host society in the province of Quebec negotiate their way through the various complexities of their bifocal social arrangement, and how their choices have consequences for their own emerging identity.
These include bifocal (for close and distance seeing) or multifocal (for close, intermediate and distance viewing) contact lenses.
If these two countries are going to bridge their differences, it will require not just bilateral talks, but a bifocal view of history as well.
Consumers in the baby boom age demographic are extremely resistant to anything that looks like a bifocal.
For centuries, Christian theology has used bifocal categories, such as "Christians and non-Christians," or "faithful and unbelieving.
The second is the slightly bifocal character of the collection as a whole, which seems undecided whether its subject is the English Revolution or the English (or British) Civil Wars--the slippage can be a little jarring as one moves between different contributions and different parts of the collection.
Adults aged 63 to 90 years who wear bifocal or progressive lenses while walking outside are twice as likely to fall than those who wear single-focus lenses, according to a study published in The Johns Hopkins Medical Letter (February 2003).