 In 1965, National Patent Development Corporation (NPDC) bought the American rights to produce the lenses and then sublicensed the rights to Bausch & Lomb, which started to manufacture them in the United States.The Czech scientists' work led to the launch of the first soft (hydrogel) contact lenses in some countries in the 1960s and the first approval of the Soflens material by the US Food and Drug Administration (FDA) in 1971.These soft lenses were soon prescribed more often than rigid ones, due to the immediate and much greater comfort (rigid lenses require a period of adaptation before full comfort is achieved).