Contact lenses are available for two different wear schedules: daily wear and extended wear. What distinguishes extended wear contact lenses is that they allow more oxygen to reach the eye's cornea. Soft contact lenses are made of plastic materials that incorporate water. Extended wear contact lenses are made of a material designed to last two to four weeks.
The water makes extended wear contacts soft and flexible while allowing oxygen to reach the cornea. Most extended wear lenses are FDA approved to be worn without removal for up to seven days. Many people are able to wear extended wear contacts continuously for many days with no apparent problem or complication. However, sleeping in contact lenses, while convenient, could substantially increase the risk for infection and other complications. The oxygen supply to the cornea drops overnight while wearing a contact lens.
A new generation of contact lenses is making 30-day contact lens wear safer. These continuous wear lenses are made from new super-permeable silicone hydrogel materials. The lenses provide much more oxygen to the eye than most conventional extended wear contact lenses, in some cases allowing six times more oxygen to pass through to the cornea than typical disposable lenses. The new lenses also repel bacteria much better than older materials.
Proper Care is Critical:
People who choose extended wear lenses can reduce their risk of infection by following an eye doctor's instructions for replacing and caring for the lenses. Studies show that a large percentage of infections and other complications are directly related to improper cleaning and disinfecting.
One option that works well for some wearers is to use extended wear lenses on a daily wear basis, with occasional overnight wear. This can be helpful if someone doesn't want to remove lenses to take a nap, or if they want to sleep in lenses only occasionally, such as on a weekend trip.
Another way to avoid a problem with extended wear lenses is to consult an eye doctor with early signs of irritated or red eyes or reduced vision.
Not everyone can get fitted properly with the new lenses. Some lenses are not yet made to correct astigmatism, an inability of the eye to focus sharply due to an abnormally shaped cornea. And they are not yet available as disposables, although industry experts expect they will be in the future.