Sudden-onset monocular blindness following orbito-zygomatic craniotomy for a ruptured intracranial aneurysm

We report the first case of sudden-onset ipsilateral blindness following orbito-zygomatic craniotomy and clipping of a ruptured anterior communicating artery aneurysm. CT showed no new intracranial or intraorbital pathology. Visual evoked potentials testing, electroretinography and diffuse flash stimulation all indicated loss of right optic nerve function. Although the patient made an excellent neurological recovery, complete right-sided monocular blindness persisted at 6-month follow-up. We postulate that external pressure on the eyeball, resulting in posterior ischaemic optic neuropathy, was the primary cause of our patient's blindness. This has been hypothesised in the 3 previously published cases of blindness following pterional or frontal craniotomy for aneurysm repair. Intraoperatively, the surgeon must avoid unnecessary pressure on the eyeballs and handle the optic nerves with the utmost care. Incomplete understanding of the mechanisms of sudden visual loss postcraniotomy may result in under-reporting of this adverse event. Nevertheless, its seriousness warrants discussion during consent.