Perioperative visual loss after nonocular surgeries.

PURPOSE: To review the current knowledge of persistent visual loss after nonocular surgeries under general anesthesia.
DESIGN: Perspective.
METHODS: Literature review.
RESULTS: The incidence of perioperative visual loss after nonocular surgeries ranges from 0.002% of all surgeries to as high as 0.2% of cardiac and spine surgeries. Any portion of the visual pathways may be involved, from the corneas to the occipital lobes, but the most common site of permanent injury is the optic nerves, and the most often presumed mechanism is ischemia. Anterior ischemic optic neuropathy (AION) is more prevalent among cardiac surgery patients and posterior ischemic optic neuropathy (PION) predominates among those who have had spine and neck procedures. Patients range from age five to 81 years and typically awake with severe bilateral visual loss. Multiple factors have been proposed as risk factors for perioperative ION, including long duration in the prone position, excessive blood loss, hypotension, anemia, hypoxia, excessive fluid replacement, use of vasoconstricting agents, elevated venous pressure, head positioning, and a patient-specific vascular susceptibility that may be anatomic or physiologic. However, the risk factors for any given patient or procedure may vary and are likely multifactorial.
CONCLUSIONS: If, when an ophthalmologist is consulted for a patient with perioperative visual loss, an obvious ocular cause is not apparent, urgent neuroimaging should be obtained to rule out intracranial pathology. Anterior and posterior ION should be considered and careful documentation is essential. Currently, the pathogenesis of perioperative ION remains unclear, and preventive and therapeutic measures remain elusive.