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

(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.

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 ?
Participating children were assigned to one of three treatment groups: 41 wore single-vision lenses, 48 wore bifocals and 46 wore bifocals with prism, which helps the eyes work together.
Table 1 A review of myopia control data from 2011 (26) Method Cochrane review conclusion (2011) Spectacles Under-correction versus full * Limited evidence favouring correction full-correction compared with under-correction Progressive addition lenses * Clinically insignificant benefit of versus single vision using PALs * Dioptric refractive error changes are not supported by changes in axial length and corneal curvature Bifocals versus single vision * Limited and inconsistent evidence Contact lenses Bifocal versus single vision * Although a study has shown soft bifocal contact lenses to help reduce myopia progression, the study was described in the Cochrane review as being at 'high risk of bias' Rigid gas permeable lenses * Conflicting evidence.
Franklin split bifocals offer another alternative solution, where the bifocal consists of two separate lenses which are cut in two and glazed together (see Figure 4).
The Mustang has a titanium frame and the lenses come in bronze or grey and are available for prescriptions, including bifocals. The Mustang has CR-39 lenses that are available in six-layer non-polarized or eight-layer polarized coating options.
Mplus provided significantly worse UNVA than high-add refractive-diffractive bifocal IOLs (WMD: 0.07, 95% CI: 0.04 to 0.09, P < 0.00001), although the difference was not very clinically significant.
Their insight that the SC 'bifocals' directly translate into faster and more accurate eye movements towards the upper visual field could help in strategic placement of essential feedback requiring rapid orienting.
THE SCOPEAID FROM CLEMIT WAS CREATED FOR SHOOTERS WHO WEAR bifocals. Its intended purpose is to bring the reticle of a riflescope into sharp focus.
Now, rather than being randomly placed, the bifocal is custom-placed for your specific needs.
Their bifocal LASIK procedure, which can often completely eliminate the need for glasses after laser vision correction, has become one of the most popular surgeries among middle-aged patients in the past fifteen years since it was adopted by this laser center.
To prepare for a data breach now and understand what to do should a crisis occur is truly the definition of a bifocal view of cyber risk--and the source of security today and in the future.
You can opt for bifocal and multi-focal versions but that will ratchet up the price.
Gateway Safety's Conqueror MAG is stylish bifocal eye protection that meets the needs of workers who work with small print or perform intricate tasks involving small details.