Tint, however, does not block-out UV rays, so a UV coating is needed. Polaroid lenses that block out much of disco the reflected light also allow better vision in sunny weather and are helpful for people who enjoy boating. Photosensitive (photochromatic) lenses that darken in the presence of bright light are handy for people who don''t want to carry an extra set of glasses. Photochromatic lenses are available in glass and plastic.Frames Frames can be made from metal or plastic, and they can be rimless. disco There is an almost unlimited variety of shapes, colors, and sizes. The type and degree of refractive correction in the lens determine to some extent the type of frame most suitable. Some disco lenses are too thick to fit in metal rims, and some large-correction prescriptions are best suited to frames with small-area lenses.

They can be worn disco and disco 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 do not correct all vision 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 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 disco 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.

NEARSIGHTED? NEED READING GLASSES? New developments in lens technology ensure a solution to almost every vision problem. Talk to your eye doctor about what''s available (costs vary).Rigid gas-permeables Recommended for those with high degrees of corneal astigmatism, RGPs are firm plastic lenses with microscopic slits that allow more oxygen to reach the disco eye. RGPs have a greater resistance to bacteria because they don''t contain water. Improved extended-wear materials also disco guarantee greater durability, sharper vision, comfort and cheaper maintenance costs. Allow yourself a week or two to get used to these slightly stiff lenses.Bifocals These contact correct presbyopia, a kind of farsightedness that usually occurs around age 40. There are two types: