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Eye glasses and contact lenseses and contact are devices that correct refractive errors in vision. lenses lenses are mounted in frames worn on the face, sitting mostly on cibavision the ears and cibavision nose, so that the lenses are positioned in front of the eyes. contact appear to be worn in direct contact with the cornea, but they actually float on a layer of tears that separates them from the cornea.PurposeThe purpose of lenseses and contact is to correct or improve the vision of people with nearsightedness cibavision (myopia), farsightedness (hyperopia), presbyopia, and astigmatism.Precautions cibavision People allergic to certain plastics should not wear contact or lenses frames or lenses manufactured from that type of plastic. People allergic to nickel should not wear Flexon frames. People at risk of being in accidents that might shatter glass lenses should wear plastic lenses, preferably polycarbonate. Originally, hard contact were made of a material called PMMA. Although still available, the more common types of contact are listed 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 cibavision important because the cornea has no blood supply and cibavision 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) 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. ©2003 www.contacts-soft-colored.com. All rights reserved. |