The present invention relates to a sterile aqueous ophthalmic solution comprising N—(N-acetylcysteinyl-)chitosan or a pharmaceutically acceptable salt thereof in a carrier solution, wherein the N—(N-acetylcysteinyl-)chitosan has a content of free thiol groups in an amount of from 80 μmol/g polymer to 280 μmol/g polymer, for use in the treatment of corneal wounds.