contact The concept of corrective lenses that sit directly on the eyeball was developed in the ninth century, but it was not until the late 20th century that manufacturing and grinding techniques for contact were perfected. Originally contact were made of glass, then later of hard plastic, and still later of flexible, highly oxygen-permeable soft plastic. Today, the majority of lenses worn are of two basic types: rigid gas permeable (so-called "hard" lenses) and lenses. best lenses are smaller and more durable, but require a longer period of adjustment for the wearer. Hard contact discount can correct some vision problems, like astigmatism, that the lenses cannot. The lenses are slightly larger than best lenses. They are more comfortable lenses and less expensive, but can be easily torn. The latest generations of contact are extended and disposable lenses. extended lenses are intended to be worn for several weeks at a time, while disposable discount lenses are thrown away every day or every few weeks, or in the newest versions, every day.

One, lenses he didn''t think they were available from any other source," "and two, he had heard they weren''t as highly controlled as those dispensed through doctors."Neither assertion is true. got on the Internet and found her lenses on several Web sites for $35.95 for a box of six pairs. (Her doctor was charging $50 a box.) says her doctor told her that lenses offered by places like may have failed manufacturers'' quality checks. Bausch contacts and other lensmakers discount say there''s no difference in quality between the lenses lenses sold through doctors and those sold directly to consumers. STATES CRACK DOWN. Attorneys general in 32 states have sued the American Optometric Association and two of the top contact-lens manufacturers (Vistakon, discount a division of contacts, and Bausch), alleging that the AOA tried to get manufacturers to agree to selllenses only through optometrists or other eye-care professionals. The attorneys general say they also have evidence that doctors agreed to lenses withhold prescriptions from people who sought to buy lenses from other sources, despite the fact that at least 22 states have laws requiring discount eye doctors to give out contact-lens prescriptions upon request.Although the AOA says patients should be able to buy their lenses anywhere, the organization has reservations about mail-order purchases. "The difficulty lenses when someone goes through mail order is that they don''t come back for regular checkups," says AOA president Dr. Harvey Hanlen.

Plastic frames are durable, can accommodate just about any lens prescription, and are available in a wide range of prices. They are also offered in a variety of plastics (including acrylic, epoxy, cellulose acetate, cellulose propionate, polyamide, and nylon) and in different colors, shapes, and levels of resistance to breakage. Epoxy frames are resilient and return to their original shape after being deformed, so they do not need to be adjusted as frequently as other types. Nylon frames are almost unbreakable. They revert to their original shape after extreme trauma and distortion; because of this property, though, they cannot be readjusted after they are manufactured.Fit The patient should have the distance between the eyes (PD) measured, so that the optical centers of discount the lenses lenses will be in front of the patient''s pupils. Bifocal heights also have to be measured with the chosen frame in place and adjusted on the patient. Again, this is so the lenses will be positioned correctly. If not positioned correctly, the patient may experience eyestrain or other problems. This can occur with over-the-counter reading glasses.