Risk and safety of contact lenses

The contact lens industry has grown steadily during the last forty years; it will continue to expand because the public demands correction of refractive errors without the need to wear glasses. The popularity of contact lenses rests largely on their cosmetic and optical advantages as well as their usefulness in sports and professional activities. Hard plastic polymethylmethacrylate (PMMA) contact lenses were for decades the industry standard. They were inserted and removed each day, and lens care was simple. Hard lenses, however, were often irritating and uncomfortable. Soft contact lenses, made from hydroxyethylmethacrylate (HEMA), were introduced around 1970. In 1980 extended wear soft contact lenses were approved by the U.S. Food and Drug Administration for continuous (day and night) use over periods of 30 days. More recently, new rigid gas-permeable lenses have been approved for extended wear, and disposable soft extended wear lenses are currently also available. Because of their relative convenience, many users prefer extended wear soft lenses to soft (and hard) lenses requiring daily removal.