“…The overall incidence has been reported as 0.06-0.11%. 3,7 The etiology of such ION remains poorly understood but the predominant proposed mechanism is critical reduction in blood supply or oxygen carrying capacity to the optic nerve secondary to prolonged hypotension [1][2][3][4][5][6]8,9 , anemia from intraoperative blood loss [1][2][3][4][5][6]8,9 , hypoxia 1,8 and excessive fluid replacement perioperatively. 2,5,8,9 Based on our recent experience: we wish to propose an additional mechanism in which the venous system is involved.…”