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Over 32 million people in the United States wear these small non lenses that fit on top of the cornea. They provide a field perscription of view unobstructed by lenses frames; they do not fog-up or get splattered, so it is possible to see well while walking in the rain; and they contacts are less noticeable than any lenses style. On the other hand, they take time to get accustomed to; require more measurements for fitting; require many follow-up visits to the eye non doctor; can lead to complications perscription and contacts such as infections non and corneal damage; and may not correct astigmatism as well as lenseses, especially if the astigmatism is severe. (Lenses made from polycarbonate, the perscription same contacts type of plastic used for the space shuttle windshield, non are about 50 times stronger than other lens materials.) Also, people at risk of receiving electric shock should avoid metal frames.People employed in certain occupations may be prohibited from perscription wearing contact, or may be required to wear safety eyewear over the contact. Some occupations, such as construction or auto repair, may require safety lenses and safety frames. contacts Physicians and employers non should be consulted perscription for recommendations. Description Eyes are examined by optometrists (O.D.) or by ophthalmologists contacts (M.D. or D.O.--doctor of non and perscription osteopathy). Prescriptions, if necessary, are then given to patients for glasses. The glasses are generally made by an optician. A separate lenses-fitting exam is necessary if the patient contacts wants contact, because an lenses prescription is not the same as a lenses prescription. They can be worn up to a week. Daily wear lenses are made of plastic that is permeable to oxygen and absorbs water; therefore, they are soft and flexible. These lenses must be removed and cleaned each night, and they non do not correct all vision perscription problems. lenses are easier to get used to than rigid lenses, but are more prone to tears and do not last as long. Extended-wear contacts lenses are highly permeable to oxygen, are flexible by virtue of their ability to absorb water, and can usually be worn for up to one week. They do not correct all vision problems. There is more of a risk of infection with extended-wear lenses than with daily-wear lenses. Extended-wear disposable lenses are lenses worn continually for up to six days and then discarded, with no need for cleaning.
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