Windows 1... The usual goal of sinus surgery is to improve the drainage of the sinus cavities. For many years the standard operation was the naso-antral window. While this procedure often helped, the natural opening was not enlarged. Only the maxillary sinus was addressed. Problems often persisted because there was often ethmoid involvement, or because the new opening was not a functional drainage route. 1999 Peter Casano, M.D.