they are flatter and lighter than conventional lenses.there are many lenses and lens-coating options for individual needs, including coatings that block 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 nonprescription, should be labeled with an indication that they cat block out 99-100% of both uv-a and uv-b rays. there are anti-scratch coatings that increase sfx the surface hardness of lenses (an important theatrical feature when using plastic lenses) and anti-reflective (ar) coatings that eliminate almost all glare and allow other people to see the 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 green from seeing the wearer''s eyes are also available. there is a whole spectrum of tints, from light tints to darker tints, used in sunglasses.

they are flatter and lighter than conventional lenses.there are many lenses and lens-coating options for individual needs, including coatings that block 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 nonprescription, should be labeled with an indication that they cat block out 99-100% of both uv-a and uv-b rays. there are anti-scratch coatings that increase sfx the surface hardness of lenses (an important theatrical feature when using plastic lenses) and anti-reflective (ar) coatings that eliminate almost all glare and allow other people to see the 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 green from seeing the wearer''s eyes are also available. there is a whole spectrum of tints, from light tints to darker tints, used in sunglasses.

rimless frames are the least noticeable type, and 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 cat 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 such lenses are thin at the edges.metal frames are less noticeable than plastic, and they are lightweight. they are sfx available in solid gold, gold-filled, anodized aluminum, nickel, silver, stainless steel, and now titanium and titanium alloy. until the late 1980s, when titanium-nickel alloy and titanium frames were theatrical introduced, metal frames were, in general, more fragile than plastic frames. the titanium frames, however, are very strong and lightweight. an alloy of titanium and nickel, called flexon, is not only strong and lightweight, but returns to its original shape after being twisted or dented. it is not perfect for everyone, though, because some people are sensitive to its nickel. flexon frames are also relatively expensive.