Central Retinal Artery Occlusion Following Prone Transcranial Surgery for Craniosynostosis and Discussion of Risk Factors.

Vision loss is a known rare complication of prone positioning during surgery. Vision loss following prone surgery is most commonly attributed to direct pressure on the eye but can also be caused by central retinal artery occlusion (CRAO) in the absence of pressure on the eye. Central retinal artery occlusion has not been previously described following prone transcranial surgery for craniosynostosis. We present two cases of monocular CRAO following prone calvarial expansion. A multidisciplinary root cause analysis suggested that raised intracranial pressure and intraoperative tranexamic acid may have been risk factors for the development of CRAO in these cases as no conventional risk factors for CRAO following prone surgery were present. Because of this, we retrospectively reviewed all prone transcranial procedures performed at the Oxford Craniofacial Unit for the presence of raised intracranial pressure and intraoperative tranexamic acid use. A total of 662 prone procedures have been performed between 1994 and March, 2019. Tranexamic acid has been used routinely in all transcranial procedures since 2012 and in the last 311 consecutive prone cases. Fifty-one (7.7%) prone procedures were performed for raised intracranial pressure, and tranexamic acid was used in the 33 most recent of these. Since the implementation of standard intraoperative administration of tranexamic acid there have been 2 cases of CRAO following prone surgery. The overall incidence of CRAO was 0.3% but was 6% in the context of raised intracranial pressure and tranexamic acid use. Prone positioning raised intracranial pressure and tranexamic acid use together may represent a potent combination of risk factors for CRAO.