Standardized Endoscopic Optic Nerve Decompression: A Comprehensive Radiological and Anatomical Study

Introduction: Despite expanding indications for endoscopic optic nerve decompression (EOND), uniform guidelines are lacking, resulting in variability in nerve exposure and hindering comparisons of treatment effectiveness. Aim: This study aims to propose a standardized approach for planning and performing EOND based on radiological and anatomical studies. Materials and methods: EOND was performed on fifteen freshly frozen cadaver heads using non-standard oblique reconstruction planes from computed tomography (CT) studies to trace the optic canal's circumference. The final decompression point was positioned a few millimeters posterior to the cranial end of the canal, where the nerve is surrounded by bone on 180 degrees of its circumference. After the transnasal procedure, transcranial access was used to verify the adequacy of the decompression. Results: The mean distances from the decompression endpoint to the orbital apex, cranial optic canal (OC) end, and lateral optico-carotid recess were 8.2 mm ±1.0, 3.0 mm ±1.1, and 0.4 mm ±0.8, respectively. In all 30 procedures, adequate coverage of the decompression was confirmed via the transcranial approach. Conclusions: Using non-standard oblique CT reconstruction planes allows for precise, individualized planning for EOND, reducing the risk of overly short or excessive decompression. Therefore, this method may be used to standardize the extent of optic nerve decompression performed using the endoscopic technique.