Progressive lenses are a type of multifocal lens that have seamless magnification from the top to the bottom of the lens, allowing you to see clearly at all distances with just one pair of glasses. They contain multiple prescriptions, or "powers," that enable you to do tasks that require close-up vision, intermediate vision, and distance vision without swapping frames or taking glasses off. Progressive lenses are an update on bifocal and trifocal lenses, which have telltale lines in the lenses, and they are sometimes called "no-line bifocals" or "no-line trifocals". They are more specialized than other lenses and more expensive because of the extra time that goes into creating a lens with multiple prescriptions and no lines. Progressive lenses can cause peripheral distortion when moving your eyes from side to side, and during the learning period, you may feel off-balance or even nauseated from looking through the wrong section of the lens. However, they are a great option for people who need help seeing near, far, and in-between, and they can be considered a better pair of progressive lenses than single or bifocal lenses.