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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 important because the cornea has no blood supply and needs to get its oxygen from the atmosphere through the film of ocularsciencebiomedics38&55contactlenses tears ocularsciencebiomedics38&55contactlenses 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. Planned-replacement lenses are daily wear lenses that ocularsciencebiomedics38&55contactlenses are replaced on a regular ocularsciencebiomedics38&55contactlenses schedule, which is usually every two weeks, monthly, or quarterly. They ocularsciencebiomedics38&55contactlenses must also be cleaned. Soft contact come in a variety of materials. There are also different kinds of RGP and soft multifocal contact available. Monovision, where one lenses corrects for distance vision while the other corrects for near vision, may be an option for presbyopic patients. Monovision, however, may affect depth perception and may not be appropriate for everyone. contact also come in a variety of tints. corrective are available that can change dark-colored eyes a different color. Even though such lenses have no prescription, they must still be fitted and checked to make sure that an eye infection does not occur. People should NEVER wear someone else''s contact. This can lead to infection or damage to the eye. Aftercarelenses wearers must be examined periodically by their eye doctors to make sure that the lenses fit properly and that there is no infection. Both infection and lenses that do not fit properly can damage the cornea. Patients can be allergic to certain ocularsciencebiomedics38&55contactlenses solutions that are used to clean or lubricate the lenses. ocularsciencebiomedics38&55contactlenses For that reason, patients should not randomly switch products unless they speak with their doctor. 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 the ears and nose, so that the lenses ocularsciencebiomedics38&55contactlenses are positioned in front of the eyes. contact appear to be worn in direct contact with the cornea, but they actually float ocularsciencebiomedics38&55contactlenses 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 (myopia), farsightedness (hyperopia), presbyopia, and astigmatism.Precautions 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.
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