Ischemic Optic Neuropathy (ION)
ION is divided into anterior and posterior types. Anterior ischemic optic neuropathy is characterized by Optic disc swelling, while posterior ischemic optic neuropathy is characterized by normal-appearing Optic discs.
Anterior Ischemic Optic Neuropathy (AION): Direct pressure on the globe in the prone position can cause anterior ischemic damage, commonly with surgeries that include using a horseshoe headrest that compresses the eyes. Preventive measures, such as switching to Mayfield pins or T-pillows, can reduce the incidence of anterior ischemic optic neuropathy.
Posterior Ischemic Optic Neuropathy (PION): This is the most concerning type during spine surgeries. It results from ischemia to the posterior optic nerve due to venous congestion during the prone position and prolonged surgery.
Central Retinal Artery Occlusion (CRAO)
This is most seen in patients undergoing cardiac surgery with cardiopulmonary bypass, where embolic events occlude the central retinal artery. Central retinal artery occlusion results in complete blindness in the affected eye or, in some cases, hemianopsia.
Occipital Lobe Stroke
Strokes affecting the occipital lobes can cause central blindness. Although it is rare in spine surgery, it can occur in cardiac or vascular surgeries due to emboli or vascular compromise.
