Optimizing Visualization and Localization During Endoscopic Orbital Surgery

Surgical Technique

The endoscopic transnasal approach to the orbit usually starts with complete sphenoethmoidectomy and wide opening of the maxillary ostium to oversee the orbital floor. Then the papyraceus lamina is identified and resected, and the periobit is opened to gain access to the intraorbital space. To facilitate identification of the lamina, the periorbit, or the tumor at a later stage, a simple trick is to exert gentle pressure to the eyeball to push and medialize the orbital wall or content. An alternative to that approach was proposed by Shah et al. to avoid moving one hand of the surgeon out of the field or require an assistant to push the globe. With this technique a blunt instrument is used to apply pressure to the expected location of the papyraceus lamina. If the lamina has been adequately exposed, the whole lamina will be seen moving. If residual ethmoid lamellae are attached, no movement or partial movement can be seen. Theses first steps can easily be accomplished with 0-degree endoscopes. When intraorbital pathology is addressed, angulated scopes (e.g., 30-degree or 45-degree) may help to increase visualization of the surgical field because the optical angle becomes wider the more lateral one dissects. Sometimes a partial septectomy or a septal window is helpful to approach the orbit from both nasal cavities and through both nostrils, especially in a four-handed technique. With the advent of three-dimensional (3D) endoscopy, spatial orientation may be enhanced, especially when targeting the orbital apex and skull base. In particular, the approach to the intraconal space harbors two major sources of difficulties for visualization and localization of pathology: the protruding orbital fat and the extraocular muscles. Contrary to orbital decompression, when protrusion of orbital fat and decrease of intraorbital pressure is desired, here it hampers the view and working space if intraorbital lesions, predominantly tumors, are addressed. Because of the mass effect of the tumor, intraorbital pressure is elevated, promoting the protrusion of fat after incision of the periorbit. However, it is advised not to remove the fat to maintain normal eyeball movement and ocular muscle function and to avoid enophthalmos postoperatively. Therefore incision through the periorbit should be limited before the ethmoidectomy has been completed to avoid obstruction of the surgical field. The fat should be dissected bluntly with standard instruments such as elevators or dissectors until the tumor capsule is identified. It is also helpful to use cottonoids or cotton-tipped applicators to gently dissect the connective tissue and spread the fat out of the way. Here, tactile feedback is very important, and advanced endoscopic techniques such as 3D endoscopy may not be as helpful as in fixed structures such as the skull base, because the fat is constantly manipulated and changes its orientation in space. Moreover, the endoscope lens could be obstructed more easily when closer to the fat and intraorbital space, which would additionally be of disadvantage for the 3D effect. In general—as in all endoscopic approaches—a clear field and endoscope lens is of utmost importance. Classically antifog solutions of different preparations and patties or small beakers are used to keep the lens clean. Automated self-cleaning devices for the scopes are beneficial to avoid frequent egress of the endoscope for extra nasal cleaning. Here the endoscope is put into an extra shaft that is linked to an irrigation device and pump and can be flushed on demand by operating a foot petal. The only disadvantage may be that the endoscope’s working diameter is increased owing to the extra shaft, which could hamper movement of instruments in narrow spaces and corridors (e.g.. if the nostrils are tight).