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(Lenses made from occular polycarbonate, the same type of plastic used for the space shuttle windshield, are about 50 times stronger science than other lens materials.) Also, people at risk of receiving electric shock should avoid metal frames.People employed contact in certain lens occupations occular and science and contact and lens and occular and science and contact may be prohibited from wearing contact, or may be required to wear safety eyewear over the contact. Some occupations, such as construction lens or auto repair, may require safety lenses and safety occular frames. Physicians and employers should be consulted for recommendations. science Description Eyes are examined by optometrists (O.D.) contact or by ophthalmologists (M.D. or D.O.--doctor of osteopathy). Prescriptions, lens if necessary, are then given to occular and science patients contact for glasses. The glasses are generally made by an optician. lens A separate lenses-fitting exam is necessary if the patient occular and science wants contact, because an lenses prescription contact is not the same as a lenses lens prescription. Rimless frames are the least noticeable occular type, and science they are lightweight because the nosepiece and temples are attached directly to the lenses, eliminating the weight of the rims. They tend to not be as sturdy as frames with rims, so they are not a good choice for people who frequently remove their glasses and put them on again. They are also not very suitable for lenses that correct a high degree of farsightedness, because contact such lenses are thin at the edges.Metal frames are less lens noticeable than plastic, and they are lightweight. They are available in solid occular and science gold, gold-filled, anodized aluminum, nickel, silver, stainless steel, and now titanium and titanium alloy. Until the late 1980s, when titanium-nickel alloy contact and titanium frames were introduced, metal frames were, in general, more fragile than plastic frames. The titanium frames, however, are very strong and lightweight. An alloy of titanium lens and nickel, called Flexon, is occular not only strong and lightweight, science and contact but returns to its original shape after being lens and occular twisted or dented. It is not perfect for everyone, though, because science some people contact are sensitive to its lens nickel. Flexon frames are also relatively expensive.
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