How to read your eyeglasses prescription

Considering a particular eyesight disorder, a different rx lens can be prescribed. As a rule opticians distinguish 4 types of prescription lenses: single vision, bifocal, trifocal and progressive.

Single Vision lenses have only one viewing area throughout the lens. This corrected are

a can be for far distance, near distance or reading.

Bifocal Lenses have two distinct viewing areas within the same lens; the distance area and the near area. The distance area in bifocal is designed like a single vision lens, while the near area contains the distance prescription and the additional amount of ADD power nee

ded to see at a reading distance. If you would like to learn more about lined bifoca

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Trifocal lens is an extension of the bi-focals, which provide

vision correction only for distance and close up near viewing, leaving the int

ermediate area between distance and reading uncorrected. Tri-focals provide another segment on the lens above the reading viewing area to correct the intermediate viewing area between far and near.

Progressive lenses correct vision for two or three different distances without the

visible segment lines seen in bifocal or trifocal lenses. Instead they have a graduated section in which the power of the lens progresses smoothly from one prescription to the other, allowing the wearer to see clearly at all distances. Transition Zone is the area of progressive sunglasses lenses where the distance vision curve gradually changes into the near-vision curve.