Posterior ischemic optic neuropathy
Posterior ischemic optic neuropathy (PION): may follow surgery (surgical PION). 1).
Usually in the setting of shock, rarely following spine surgery in the prone position
Risk factors
● surgery in the prone position (can cause periorbital edema, and rarely, direct pressure on the orbit)
● lack of tight glycemic control
● use of Trendelenburg position.
● Hemodilution or overuse of crystalloid vs. colloid (blood) fluid replacement
● prolonged hypotension
● cellular hypoxia
● decreased renal perfusion
● male gender: odds ratio (OR) = 2.53
● obesity: by clinical assessment or BMI ≥ 30 OR = 2.83
● use of Wilson's frame: OR = 4.30
● length of anesthesia: OR = 1.39 per hour
● EBL: OR = 1.34 per liter
● use of colloid as a percentage of nonblood replacement: less certain (small difference). OR = 0.67 per 5% colloid 2).