 Wearing lenses designed for daily wear overnight has an increased risk for corneal infections, corneal ulcers and corneal neovascularization—this latter condition, once it sets in, cannot be reversed and will eventually spoil vision acuity through diminishing corneal transparency.The most common complication of extended wear is giant papillary conjunctivitis (GPC), sometimes associated with a poorly fitting contact lens.Contact lenses are often categorized by their replacement schedule.