A, The medial orbital incision on the left side is shown in the inset. The approach exposes the medial orbital wall, ethmoid air cells, and sphenoid sinus back to the level of the optic canal. The periorbita has been elevated from the frontal process of the maxillary bone and adjacent frontal bone forming the medial part of the orbital rim to expose the medial canthal ligament, which, if divided, should be reapproximated at the end of the procedure to maintain canthal balance. B, The medial palpebral ligament has been divided and the edges of the divided ligament have been preserved for re-approximation at the end of the procedure. The lacrimal sac has been retracted laterally. The exposure extends backward along the lacrimal and ethmoid bones to the level where the anterior ethmoidal artery enters the anterior ethmoidal canal. The lacrimal groove, in which the lacrimal sac sits, is formed anteriorly by the maxilla and posteriorly by the lacrimal bone. C, The exposure has been extended backward along the ethmoid, lacrimal, and frontal bones, past the level where the anterior and posterior ethmoidal arteries enter the anterior and posterior ethmoidal canal to the orbital apex and anterior end of the optic canal. The medial ethmoid air cells and adjacent part of the sphenoid sinus can be removed to expose the optic nerve in the optic canal. This approach is sometimes used to decompress the optic canal. D, The exposure includes not only the medial orbital wall, but also the adjacent part of the floor. Two small maxillary osteotomies have been completed. The medial one includes the part of the maxilla forming the anterior wall of the nasal cavity. The lateral osteotomy exposes the anterior part of the maxillary sinus. The medial palpebral ligament has been divided to expose the medial wall of the orbit. E, Removing the medial osteotomy fragment exposes the nasal cavity and the nasal septum and inferior and middle conchae. Removing the lateral osteotomy fragment exposes the maxillary sinus, medial part of the orbital floor, and the nasolacrimal duct, which courses along the medial maxillary wall and opens below the inferior concha into the inferior meatus. F, The nasolacrimal duct and lacrimal sac have been retracted laterally and the exposure extended along the medial orbital wall to the area posterior to where the anterior ethmoidal artery was divided. The posterior part of the osseous nasolacrimal canal has been exposed. (Images courtesy of AL Rhoton, Jr.)