Crosslinked hyaluronic acid or salts thereof prepared by crosslinking hyaluronic acid or salts thereof with a polyfunctional epoxy compound wherein a crosslinking index or number is 5 or more per 1000 repeating disaccharides composed of glucronic acid in hyaluronic acid and N-acetylglucosamine, and having...http://www.google.es/patents/US4716224?utm_source=gb-gplus-sharePatente US4716224 - Crosslinked hyaluronic acid and its use
