Anatomical study of the possibilities of endoscopic transnasal and endoscopic transorbital medial orbitotomy and decompression of the optic nerve

The study objective is to examine the anatomical characteristics of transnasal endoscopic and transorbital endoscopic approaches to perform medial orbitotomy and decompression of the optic nerve. Materials and methods. The study was based on the results of anatomical approaches on cadavers. The comparison was carried out according to the following anatomical-surgical parameters: 1) the area of interest in mm2 ; 2) the area of orbitotomy in mm2 ; 3) the area of the optic nerve decompression in mm2 ; 4) the length of periorbital incision in mm; 5) the depth of the wound in mm; 6) the horizontal angle of attack in degrees; 7) the vertical angle of attack in degrees. The measurements were carried out using the Russian optical navigation system “Neuroplan”. Results. It has been established that the area of orbitotomy is noticeably larger, and the depth of the operative wound is smaller with the transorbital approach. It was also revealed that there are no noticeable differences in the area of the optic nerve decompression between the transnasal endoscopic and transorbital endoscopic approaches. In addition, there is a tendency for large angles of attack in both horizontal and vertical planes with transorbital access, which is probably due to the smaller depth of the wound and the possibility of lateral traction of the eyeball. It was determined that as with transnasal, as with transorbital approaches, the length of the periorbital incision did not differ significantly. Conclusion. The study demonstrates the equivalent possibilities of both transnasal and transorbital endoscopic approaches in the implementation of the medial orbitotomy and decompression of the optic nerve in patients with endocrine ophthalmopathy. Some advantages, in particular, a large area of orbitotomy, as well as the preservation of the paranasal structures, make it possible to speak out in favor of choosing transorbital endoscopic approaches to the medial wall of the orbit and the optic nerve when performing surgical decompression in this group of patients. Further collection of clinical material is needed for final results.