The main goal of sinus surgery is to help the sinuses drain better. For many years, the standard operation was a procedure called a naso-antral window, which made a new opening into the cheek sinus. It often helped, but it did not enlarge the natural opening, and it only treated the cheek sinus. Problems often kept coming back because the ethmoid sinuses were also involved, or because the new opening did not actually drain the way the body expects.