they can be worn 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 spiral to get used to than rigid lenses, but red 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 contact more of a risk of infection with extended-wear lenses than with lenses daily-wear lenses. extended-wear disposable lenses are lenses worn continually for up to six days and then discarded, with no need for cleaning.

they can be worn 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 spiral to get used to than rigid lenses, but red 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 contact more of a risk of infection with extended-wear lenses than with lenses daily-wear lenses. extended-wear disposable lenses are lenses worn continually for up to six days and then discarded, with no need for cleaning.

plastic frames are durable, can accommodate just about any lens prescription, and sfx are available in a wide range of prices. theatrical 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 crazy 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 the lenses will be in front of the patient''s pupils. bifocal spiral heights also have to be measured with the chosen frame in place and adjusted on the red patient. again, this contact is so the lenses will be positioned correctly. if not positioned correctly, the patient may experience eyestrain or other problems. lenses this can sfx occur theatrical with over-the-counter crazy and spiral reading glasses.