Introduction: The orbit is a compact conical space containing a variety of complex neurovascular structures with intricate relationships to the intracranial compartment. Throughout the years, a multitude of surgical techniques have emerged to access the orbit, ranging from traditional orbitotomies and cranio-orbitotomies, to contemporary endoscopic transorbital (ETOAs) and endoscopic endonasal approaches (EEAs). In this study, our goal is to provide a didactic description of both microsurgical and endoscopic approaches to the orbit. These descriptions are presented in a step-by-step manner, anchored in anatomical foundations, and tailored for trainees in skull base surgery. Furthermore, clinical cases and indications are also presented.
Methods: Six formalin-fixed latex-injected cadaveric head specimens were dissected. In each specimen the following approaches were modularly performed: ETOAs, including preseptal lower eyelid approach, lateral cantotomy, precaruncular approach, and superior eyelid crease approach; EEAs, including EEA to the medial and inferior of the orbit and endoscopic endonasal optic canal decompression; Caldwell-Luc approach; orbitotomies and cranio-orbitotomies, including lateral cantotomy orbitotomy, supraorbital approach, fronto-orbital approach, and orbito-zygomatic approach. A 0-degree, 30-degree, and 45-degree endoscope (4 mm, 18 cm, Hopkins II, Karl Storz, Tuttlingen, Germany), attached to a high-definition camera were utilized for dissection. After each step was completed, the specimens were 3D photo-documented.
Results: Endoscopic transorbital approaches provide a direct subperiosteal corridor along the orbital walls. Each approach is guided by distinct anatomical landmarks that are progressively identified, including the ethmoidal arteries, optic foramen, superior and inferior orbital fissures, and the meningo-orbital fold. By selectively drilling the orbital walls, it becomes possible to create openings towards the three cranial fossae and major extracranial regions. Endoscopic endonasal approaches grant accessible entry to the medial aspects of the orbital wall, apex, optic canal, and floor, offering advantages such as improved aesthetics and reduced external scarring, minimal displacement of orbital structures or extraocular muscle disinsertion, and enhanced visibility. The Caldwell-Luc approach harnesses the natural workable space of the maxillary sinus to access the orbit floor, utilizing the inferior and lateral rectus muscles for orientation in relation to the optic nerve. In contrast, orbitotomies and cranio-orbitotomies provide a direct and comprehensive view of the surgical field, facilitating precise manipulation and resection of orbital lesions. These approaches benefit from their well-established nature and clearly defined anatomical landmarks, empowering surgeons to navigate intricate neurovascular structures with heightened confidence. Moreover, the adaptability of these methods allows for tailored adjustments to address diverse pathologies, ultimately fostering optimal surgical outcomes.
Conclusion: Considering the steep learning curve involved, this study aims to provide a succinct and instructive elucidation of the intricate surgical anatomy and fundamental procedural steps of the approaches to and through the orbit, along with their variants and applicable scenarios. The objective is to enhance the comprehension and learning journey for trainees specializing in skull base surgery.
