what is the difference between progressive and bifocal lenses?
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Progressive lenses lack lines and help you see at three distances. Bifocals have lines and allow for two prescriptions and two distances. Many types of bifocals and progressive lenses are available for different needs.
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Shipping is $4.95. (Bifocals are more along the lines of $35 and progressives $47 as starting price points.) However, there are a couple things to keep in mind if you're going to order from Zenni.
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What's the difference between a Single Lens and Double Lens? Single lenses are the classic most cost effective option, mainly used by ski racers. ... Double lenses are more durable, have more color variations, and have stronger anti-fog properties.
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People with astigmatism primarily choose eyeglasses to improve their vision. ... Generally, a single-vision lens is prescribed to provide clear vision at all distances. However, patients over age 40 who have presbyopia may need a bifocal or progressive addition lens.
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Bifocal contact lenses generally have two prescriptions (or 'powers') in the same lens. The two prescriptions are used to correct near vision and distance vision. ... Simultaneous vision lenses force your eyes to look through distance and near powers simultaneously.
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Most people have a much easier time adjusting to progressive lenses than they do to bifocal or trifocal lenses. However, bifocal lenses can be a good depending on your individual situation. For instance, if you've grown accustomed to bifocals, switching to progressives will take some getting used to.
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What is the difference between single-vision and bifocal lenses? Single-vision lenses have one prescription. Whereas bifocal lenses have a distinct line in the lens where the two prescriptions vary – the upper part is to correct distance vision and the lower part is to correct close vision.
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Multifocal contact lenses are designed with a gradual transition between a prescription for close reading on one end and a prescription for normal distance viewing on the other. They are very similar to progressive eyeglasses.
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Trifocal glasses have three distinct prescriptions on the lens, indicated by lines, to correct faraway, intermediate, and near vision. Progressive lenses blend the prescriptions so that there are no lines on the lens.
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Reading glasses have lenses to maximize resolution at a comfortable reading distance—-typically 14 inches—only. Bifocals have lenses that have two distinct areas with the bottom of the lens like a reading glass lens and the top designed to maximize resolution at a greater distance, typically infinity.
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Lenses are classified by the curvature of the two optical surfaces. A lens is biconvex (or double convex, or just convex) if both surfaces are convex. ... If one of the surfaces is flat, the lens is plano-convex or plano-concave depending on the curvature of the other surface.
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Varifocal lenses, also known as progressive lenses, are used when you have two prescriptions. ... Varifocal lenses contains multiple focal points although unlike bifocals, they do not have a segment or dividing lines within the lens.
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There are no hard and fast rules. But, in general, aspheric multifocal contact lenses tend to work best for mild to moderate presbyopia, and concentric or segmented multifocal contacts often are more successful for advanced presbyopia.
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Today, you can select from many bifocal and trifocal lens designs, depending on your age and visual needs. There are even special bifocals and trifocals designed for glasses for computer work and other tasks that take place at the intermediate range.
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What's more, trifocal lenses allow a person to switch effortlessly between all three distances – near (reading) distance, long distance and the in between distances. Vision is clear at all those points – something the previous multifocal IOLs couldn't achieve.
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Multifocal and Bifocal Contact Lenses for Presbyopia. Bifocal contact lenses are designed to provide clearer vision for those suffering from presbyopia. This condition, a result of the aging process, is also called long-sightedness.
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Standard progressive lenses are manufactured for standardized parameters like the distance between your eyes and how the glasses sit in your face. Premium progressive lenses can be manufactured individually for you. That can result in bigger sharper areas and a more relaxed vision.