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extended lenses in particular pose a much greater risk than daily wear lenses. Though extended-wear lenses are extremely thin and allow some oxygen--necessary for healthy eyes--to contacts reach the cornea, they are and worn continuously, including at night while the eyelid is closed. Bacteria can easily grow more easily under these conditions. Twenty-one in 1,000 extended lens wearers develop infections as opposed to 4 in 1,000 daily soft lens wearers. To reduce this risk, eye care professionals now online recommend removing extended lenses at night. In addition, newer versions contacts of extended and lenses online being developed may offer increased contacts and and and online oxygen exchange and pose less risk. Disposable lenses may also help to prevent infection, since the wearer is guaranteed a clean pair of lenses every few weeks or every day.

They are flatter and lighter than conventional contacts lenses.There are many lenses and lens-coating options for individual needs, including coatings that block and and online and contacts and and the ultraviolet (UV) light or UV and blue light which 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 ski goggles. Sunglasses, when online nonprescription, should be labeled with an indication that they block out 99-100% of both UV-A and UV-B rays. There are contacts anti-scratch coatings that increase the surface hardness of lenses (an important feature when using plastic lenses) and and anti-reflective (AR) coatings that eliminate almost all glare and allow other people to see online and contacts and and the online and contacts eyes of the wearer. AR coatings may be particularly helpful to people who use computers or who drive at night. Mirror coatings that prevent other people from seeing the wearer''s eyes are and also available. There is a whole spectrum of tints, from light tints to darker tints, online used in sunglasses.