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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 freshlookcolorscontactlenses 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. Planned-replacement lenses are daily wear lenses that are replaced on a regular schedule, which is usually every two weeks, monthly, or quarterly. They must also be cleaned. Soft contact come in a variety of materials. There are also different freshlookcolorscontactlenses 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 freshlookcolorscontactlenses and freshlookcolorscontactlenses 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 solutions that are used to clean or lubricate the lenses. freshlookcolorscontactlenses For that reason, patients should not randomly switch products unless they speak with their doctor. contact The concept of corrective lenses freshlookcolorscontactlenses that sit directly on the eyeball was developed freshlookcolorscontactlenses in the ninth century, but it was not until the late 20th century that manufacturing and grinding techniques for contact were perfected. Originally contact were made of glass, then later of hard plastic, and still later of flexible, highly oxygen-permeable soft plastic. Today, the majority of lenses worn are of two basic types: rigid gas permeable (so-called "hard" lenses) and lenses. best lenses are smaller and more durable, but require a longer period of adjustment for the wearer. Hard contact can correct some vision problems, like astigmatism, that the lenses cannot. The lenses are freshlookcolorscontactlenses slightly larger than best lenses. freshlookcolorscontactlenses They are more comfortable and less expensive, but can be easily torn. The latest generations of contact are extended and disposable lenses. extended lenses are intended to be worn for several freshlookcolorscontactlenses weeks at a time, while disposable lenses are thrown away every day or every few weeks, or in the newest versions, every day. ©2003 www.contacts-soft-colored.com. All rights reserved. |