A relatively new concept are the extended wear lenses that are made from Silicon Hydrogel. This material gives the lenses an extremely high oxygen permeability, this in turn makes it possible to be able to sleep while wearing the lenses. These kinds of lenses are often a better alternative for those with dry eyes and those who stay for extended periods of time in dry environments. Extended wear lenses also grant the user a greater sense of freedom especially if you want to avoid the cleaning that accompanies the use of more traditional lenses. Consult a qualified eye care professional for instructions on how long you can wear these lenses. LensOn offers the most common extended wear lenses at really low prices.