Figure 1: Extended maximal middle meatal antrostomy grade 4 (postlacrimal approach, [293]): Resection of the bone (green) medially, dorsally, and laterally of the nasolacrimal duct in order to mobilize it and to improve the insight into the maxillary sinus. Resection of the bone in case of prelacrimal access (yellow). a) axial CT scan, b) coronal CT scan.