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They are flatter and lighter than conventional lenses.There are many lenses ocular and lens-coating options for science individual needs, including coatings that block the ultraviolet (UV) light or UV and blue light which contact have been found to be harmful to the eyes. Such coatings are not needed on polycarbonate lenses, which already have UV protection. UV coatings are particularly important on sunglasses and lens ski goggles. Sunglasses, when ocular nonprescription, should be labeled with an indication that they block out 99-100% of both UV-A and science UV-B rays. There are anti-scratch coatings that increase the surface hardness of lenses (an important feature when using plastic lenses) and anti-reflective (AR) contact coatings that eliminate almost all glare and allow other people to see the eyes of the wearer. AR coatings may be particularly lens helpful to people who use computers or who drive at night. Mirror coatings that prevent ocular other people from seeing the wearer''s eyes are also available. There is a whole spectrum of tints, from light tints to darker tints, science used in sunglasses. Originally, hard contact contact were made of a material called PMMA. Although lens still available, the more common types of contact are listed below:Rigid gas-permeable (RGP) daily-wear ocular lenses are made of plastic that does not absorb water but allows oxygen science and contact 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 lens.) ocular They must be removed and cleaned science each night. Rigid gas-permeable (RGP) extended-wear lenses are made from plastic that also does contact 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 kinds of RGP and soft multifocal lens contact available. Monovision, ocular where one lenses corrects for distance vision while the other corrects for near vision, may be an option for presbyopic patients. Monovision, however, science and contact 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 lens 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 ocular fit properly can damage the cornea. Patients can be allergic to certain solutions that are used to clean or lubricate the lenses. For that science reason, patients contact should not randomly switch products unless they speak with their doctor lens.
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