Evaluation of functional, structural, and electrophysiological optic nerve changes following extradural anterior clinoidectomy in patients without preoperative optic canal compression

Extradural anterior clinoidectomy is increasingly used to improve exposure and proximal vascular control in aneurysm surgery, but its isolated effect on an otherwise uncompromised optic nerve remains unclear. To evaluate the functional, structural, and electrophysiological impact of EAC with optic canal unroofing in patients without preoperative optic nerve compression or optic canal pathology. We conducted this single-center study included 16 adults who underwent no-drill extradural anterior clinoidectomy (EAC) during microsurgical clipping of ruptured aneurysms (January 2023-December 2024). Patients with visual or optic pathway pathology were excluded. Postoperative assessment (6-12 months) included visual acuity, automated perimetry (visual field index, VFI), OCT-derived retinal nerve fiber layer (RNFL) thickness, and visual evoked potentials (P100 latency). Eyes were compared using paired tests, with repeated-measures ANOVA for quadrant-based ΔRNFL. Visual acuity was preserved in all patients. Global RNFL thickness was similar in ipsilateral and contralateral eyes (95.8 ± 12.7 vs. 99.2 ± 18.6 μm; p = 0.230). Quadrant ΔRNFL varied by quadrant, but no pairwise differences remained after correction, with a trend toward greater thinning in the superior quadrant. VFI was similar (p = 0.7); one patient had inferior nasal quadrantanopia and two had mild blind-spot enlargement. P100 latency was comparable (114.8 ± 9.7 ms vs. 113.8 ± 8.9 ms; p = 0.223). No major EAC-related neurovascular complications were observed. Extradural anterior clinoidectomy was not associated with statistically significant optic nerve impairment, although visual field changes occurred in 3/16 patients (18.75%) with a trend toward superior RNFL thinning.