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.