Vision impairment during cardiac surgery and extracorporeal circulation: current understanding and the need for further investigation.

The aim of this article was to provide a comprehensive review of current knowledge regarding ocular hemodynamic alterations affecting the retinal neuroglial cells and optic nerve head (ONH) function during cardiac surgery. Literature indicates that visual loss after heart surgery is a rare but devastating complication provoked by two main causes of optic ischaemia and infarction during on-pump cardiac procedures: microembolism and/or hypoperfusion. Retinal ischaemia and ischaemic optic neuropathy are two possible major consequences of extracorporeal circulation in cardiac surgery. The hemodynamic modifications within the vascular beds of retina and ONH during cardiovascular operations have been incompletely studied. Consequently, it is of great interest to investigate the hemodynamic changes during cardiopulmonary bypass within the choroidal, retinal and optic nerve microcirculations as well as other potential causes of vaso-occlusion. Maintaining stable hemodynamic parameters during cardiovascular surgery seems to be the key to prevent visual impairment.