Walter E Becker was an optometrist from Pittsburgh USA who patented silicone elastomer lenses in 1956. However the only US Patent found in this area is 3,228 741, 29 June 1962. Various stories circulate, one being that he had to cut the edges of the lenses with scissors, later using a trephine for this purpose. It is thought that Bill Policoff also worked on silicone elastomer lenses. Joseph Breger from Breger Muller-Welt acquired the patents from Becker and worked on these materials from 1959-1972 when the company was bought by Dow Corning. The advantages were huge oxygen transmission and flexibility. The great disadvantages were poor wettability and the tendency for the lenses to stick to the eye. Bausch & Lomb acquired Dow Corning in the late 1970s and managed to bring a lens to market for aphakia. Heinrich Wohlk also researched and developed a similar material in Germany.