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a few years ago, a collaborative effort by ciba vision, novartis in switzerland, contact and the cooperative research centre lens for eye research and technology in australia developed a new polymer called lotrafilcon a. it contains a modest 24 percent water yet allows six times as much oxygen to pass through as the best of the hema hydrogels do. lotrafilcon a consists of interspersed micrometer-size bits of two different plastics. one material, a hydrogel, lets water and ions reach the eye surface; the other, called fluorosiloxane, channels oxygen. the combination is as transparent as a conventional contact lens. the ability of a disposables material to convey oxygen relative to its thickness is called transmissibility. lenses should have a transmissibility of at least 90 barrers for oxygen, according to researchers at the university of california, berkeley and indiana university in bloomington.

a few years ago, a collaborative effort by ciba vision, novartis in switzerland, contact and the cooperative research centre lens for eye research and technology in australia developed a new polymer called lotrafilcon a. it contains a modest 24 percent water yet allows six times as much oxygen to pass through as the best of the hema hydrogels do. lotrafilcon a consists of interspersed micrometer-size bits of two different plastics. one material, a hydrogel, lets water and ions reach the eye surface; the other, called fluorosiloxane, channels oxygen. the combination is as transparent as a conventional contact lens. the ability of a disposables material to convey oxygen relative to its thickness is called transmissibility. lenses should have a transmissibility of at least 90 barrers for oxygen, according to researchers at the university of california, berkeley and indiana university in bloomington.

optometrists encourage contact many patients to use daily disposable lenses, which are thrown away after each wearing. automated lens manufacturing has lowered the cost of lenses enough to make this practice feasible. most longer-lasting lenses are made by clamping together plastic molds for the front and back surfaces of the lens. a thin layer disposables of liquid polymer is squeezed into the remaining space and either cured with uv light or baked to turn it solid. then, all the excess molecules are washed away and contact water is added.for its daily disposable lenses, ciba vision uses a material called nelfilcon a, a polyvinylalcohol. the material allows the manufacturing process to be fully automated. the lenses emerge with the water already incorporated. because it takes only a few minutes to manufacture each lens, the process is efficient and a pair costs only about $1.

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