Otto Wichterle, a Czech chemist, synthesizes in 1960 poly(2-hydroxyethyl methacrylate) — HEMA — the first synthetic hydrogel biocompatible with living tissue, and demonstrates that it can be made into soft contact lenses using a centrifugal spinning device built from a Merkur toy construction kit in his Prague apartment. He publishes the method in Nature in 1960. The patent was registered by the Czechoslovak Academy of Sciences, which assigned it to National Patent Development Corporation (US), which in turn licensed it to Bausch & Lomb. Bausch & Lomb marketed soft contact lenses globally from 1971 without Wichterle's name appearing on any product. Today HEMA and its derivatives are the basis for more than 140 million soft contact lens users worldwide.