A study was conducted to determine the efficacy of low water content, hyper-thin lenses for extended wear by myopic patients. Patients selected had from 1 to 7 D of simple myopia or myopia with up to 2 D of astigmatism. Patients were either first time wearers or previously successful soft lens wearers. All patients were fitted with Bausch & Lomb O3 or O4 series lenses and were evaluated for 6 months. Either heat or a chemical disinfection system was used. The study shows that Bausch & Lomb O Series lenses may be used successfully for up to 1 week of continuous wear. Visual acuity, patient comfort, lens life, and physiological tolerance compared favorably with those achieved when the currently available high water content lenses were used for extended wear.