Computed tomography-based evaluation of optic canal orientation and its relationship to the internal carotid artery: implications for skull base surgery.

BACKGROUND: The optic canal represents a critical surgical landmark during endoscopic endonasal and transcranial skull base procedures. Variations in canal orientation and its relationship with the internal carotid artery (ICA) may directly influence surgical safety. METHODS: Cranial computed tomography angiography (CTA) datasets of 100 adults (50 males and 50 females) were retrospectively evaluated. Bilateral optic canal transverse diameters, canal length, distance from the midline, angular orientation, and optic canal-ICA distance were measured using multiplanar reconstructed images. RESULTS: Significant side-related differences were observed in optic canal position relative to the midline (right: 11.25 ± 2.62 mm, left: 10.08 ± 2.92 mm; p < 0.001) and angular orientation (right: 53.88 ± 9.50°, left: 62.26 ± 11.58°; p < 0.001). No significant side differences were identified for canal diameter, length, or optic canal-ICA distance. The mean optic canal-ICA distance was approximately 2.2 mm, indicating a narrow surgical safety margin. Sex-related differences were limited to selected morphometric parameters. CONCLUSIONS: Optic canal morphology is characterized by substantial variability in spatial orientation and side-related asymmetry. In addition to linear dimensions, canal trajectory and its relationship to the ICA represent critical determinants of the surgical corridor. Preoperative CTA evaluation may contribute to safer and more individualized planning of skull base procedures.