The major complications with extended wear lenses are due to hypoxia and lens deposits. Certain patients tend to deposit proteins and lipids on the lens surface with daily wear and at a greater frequency during prolonged wear. A build-up of these deposits can be associated with decreased vision, conjunctival irritation, and giant papillary conjunctivitis. Frequent lens cleaning and the frequent use of concomitant topical artificial tears will hopefully reduce the incidence of lens deposits and their complications. Superficial circumlimbal vascularization occurs in a large percentage of patients who have worn lenses for weeks at a time. Corneal edema, ocular irritation, and decreased vision are also the hallmarks of a decreased oxygen supply to the cornea. A thin-loose-fitting lens will increase the percentage of patients who are able to successfully use extended wear lenses by increasing the amount of oxygen available to the cornea. Cessation or reduction in duration of lens wear will decrease the frequency and severity of this complication. Conjunctival and corneal infections are real risks; lens loss, breakage, deformation, or discoloration also occur during extended wear.