VEP-informed standardisation of optic canal unroofing and anterior clinoidectomy for mechanical optic nerve protection in paraclinoid aneurysm clipping

Permanent blindness is a devastating complication of paraclinoid aneurysm clipping. Intraoperative visual evoked potential (VEP) monitoring can reveal functional stress, but visual protection also depends on operative technique. We aimed to describe the technical transition after an early blindness event and report intraoperative VEP findings and postoperative visual outcomes across 114 consecutive procedures. We retrospectively reviewed 114 clipping procedures in 113 patients with flash VEP monitoring from January 2011 to March 2016. All procedures were performed through a transsylvian approach with optic canal unroofing and intradural anterior clinoidectomy. After a sentinel blindness event during procedure 3, a decompression-oriented, VEP-informed optic nerve protection workflow was standardised from procedure 4 onwards, emphasising adequate unroofing before clipping, avoidance of optic nerve pressure, clip–optic nerve inspection, vascular verification, and VEP monitoring through closure. Permanent ipsilateral blindness occurred during the third procedure after progressive VEP decline despite filling of the ophthalmic and superior hypophyseal arteries. Among four procedures categorised as VEP disappearance, one had no clinically evident visual deficit with concomitant electroretinographic deterioration, two had postoperative visual field deficits, and one had blindness. No additional blindness occurred in 111 subsequent procedures after adoption of the revised workflow. These findings support the inclusion of adequate bony decompression as an important mechanical component of a multicomponent optic nerve protection strategy, rather than as an exposure manoeuvre alone. Although causality cannot be established in this historical series, the absence of further blindness after workflow standardisation provides clinically meaningful longitudinal support for this approach.