Researchers have found that people who wear silicone hydrogel (SH) contact lenses are likely to suffer corneal staining (mild abrasions of the eye), but that these situations rarely turn into more serious corneal infiltrative events. Corneal infiltrates are marked by eye discomfort, feeling like there is something in your eye, light sensitivity, and conjunctival hyperemia.
Factors likely to cause these more serious corneal infiltrates include smoking and the presence of bacteria on the lens. Smoking is a factor in the development of many other eye diseases as well – including everything from dark circles under your eyes to macular degeneration.
Silicone hydrogel lenses are purported to allow more oxygen to the eye and are designed for long term use (up to 3o days in some cases). SH lenses on the market include: Ciba Focus Night & Day, Acuvue Oasys, and Bausch and Lomb’s PureVision lenses.
Source: Medscape