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lensesesOver contacts and bargain 140 million contacts people in the United States wear lenseses. People whose eyes have refractive errors do not see clearly without glasses, because the light bargain emitted from the objects they are observing does not come into focus on their retinas. For people who are farsighted, images come into focus behind the retina; for people who contacts are nearsighted, images come into focus in front of the retina. Lenses work by changing the direction of light so that images come into focus on the retina. The greater the index of refraction bargain of the lens material and the greater the difference in contacts the curvature between the two surfaces of the lens, the greater the change in direction of light that passes through it, and the greater the correction.Lenses can be unifocal, with one correction for all distances, or they can be correct for more than one distance (multifocal). One type of multifocal, the bifocal, has an area of the lens (usually at the bottom) that corrects for nearby objects (about 14 in from the eyes); the remainder of the lens corrects for distant objects (about 20 ft from the eyes). One, bargain he didn''t think they were available from any other source," contacts "and two, he had heard they weren''t as highly controlled as those dispensed through doctors."Neither assertion is true. got on the bargain Internet and found her lenses on several Web sites for $35.95 for a box of six pairs. (Her doctor was charging $50 a box.) says her doctor told her that lenses offered by places like may have failed manufacturers'' quality checks. Bausch contacts and other lensmakers say there''s no difference in quality between the lenses sold through doctors and those sold directly contacts to consumers. STATES CRACK DOWN. Attorneys general in 32 bargain states have sued the American Optometric Association and two of the top contact-lens manufacturers (Vistakon, a contacts division of contacts, and Bausch), alleging that the AOA tried to bargain get manufacturers to agree to selllenses only through optometrists or other eye-care professionals. The attorneys general say they also have evidence that doctors agreed to withhold prescriptions from people who sought to buy lenses from other sources, despite the fact that at least 22 states have laws requiring eye doctors to give out contact-lens prescriptions upon request.Although the AOA says patients should be able to buy their lenses anywhere, the organization has reservations about mail-order contacts purchases. "The difficulty when someone goes through mail order is that they don''t come back for regular checkups," says AOA president Dr. Harvey Hanlen. Originally, hard contact were made of a material called PMMA. Although still available, the more common types of contact are bargain listed contacts below:Rigid gas-permeable (RGP) daily-wear lenses are made of plastic that does not absorb water but allows oxygen to get from the atmosphere to the cornea. (This is important because the cornea has no blood supply and needs to get its oxygen from the atmosphere through the film of tears that moves beneath the lens.) They must be removed and cleaned each night. Rigid gas-permeable (RGP) bargain extended-wear lenses are made from plastic that also does not absorb water but is more permeable to oxygen than the plastic used for daily-wear lenses.
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