extended lenses in durasoft particular freshlook and toric pose a much greater risk than daily wear lenses. Though extended-wear lenses are extremely thin and allow some oxygen--necessary for healthy eyes--to reach the cornea, they are contacts worn continuously, including at night while the eyelid is closed. Bacteria can easily grow durasoft more easily under these conditions. freshlook Twenty-one in 1,000 extended lens wearers develop infections as opposed to 4 in 1,000 daily soft lens wearers. To reduce this risk, eye care professionals now recommend toric removing extended lenses at night. In addition, newer contacts versions of extended durasoft lenses being developed may offer increased oxygen exchange and pose less risk. Disposable lenses may also help to prevent infection, since the wearer is guaranteed a clean pair of lenses every few weeks or every day.

They are flatter and lighter than conventional lenses.There freshlook are many lenses and lens-coating options for individual needs, including toric and contacts coatings that block the ultraviolet (UV) light or UV and blue light which have been durasoft found to be harmful to the eyes. freshlook 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 block out 99-100% of both UV-A and UV-B rays. There are anti-scratch toric and contacts coatings that increase the durasoft surface hardness of lenses (an important 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 freshlook be particularly helpful to people who use computers or who drive at night. Mirror coatings that prevent other people from seeing the wearer''s eyes are also available. There is a whole spectrum of tints, from toric light tints to darker tints, contacts used durasoft in sunglasses.

Glass freshlook was the first material to be used for lenses lenses, and was toric used for several contacts hundred years before plastic was introduced. The crown glass used for lenses lenses durasoft has an index of refraction of 1.52.Optical-quality freshlook acrylic was introduced toric for lenses use in the early 1940s, but because contacts it was easily scratched, brittle, and discolored rapidly, it did not supplant glass as the material of choice. Furthermore, it had a relatively low index of refraction, durasoft so it wasn''t suitable for people with freshlook large refractive errors. A plastic called CR-39, introduced toric and contacts in the 1960s, was more suitable. Today, lenses wearers durasoft can also choose between polycarbonate, freshlook and toric which is the most impact-resistant contacts material available for eyewear, and polyurethane, which has exceptional optical qualities and an index of refraction of up to 1.66, much higher than the conventional plastics used for lenses, and even higher than glass. Patients with high prescriptions should ask about high index material options for their lenses. Aspheric lenses are also useful for high prescriptions.