Ischemic optic neuropathy

Ischemic optic neuropathy is the most common cause of the very uncommon postoperative visual loss.

Often bilateral.

Elevated ICP transmits pressure to retina → blood flow stasis, as well as mechanical trauma to optic chiasm from enlarging third ventricle (latter more commonly thought to be responsible for bitemporal hemianopia, but could, if unchecked, progress to complete visual loss). Also, if hypotension and anemia were present, consider the possibility of ischemic optic neuropathy, which may be anterior, or posterior (the latter of which carries a poorer prognosis).

If hypotension and anemia were present, consider the possibility of ischemic optic neuropathy,

Usually associated with significant blood loss (median: 2 L), and/or prolonged operative time ( ≥ 6 hrs ).

All cases had anesthetic time > 5 hrs or blood loss > 1 L. Blood loss can cause hypotension (may cause release of endogenous vasoconstrictors in addition to reduced blood flow due to low hemodynamic pressure) and increased platelet aggregation. It is not due to direct pressure on the globe in most cases, and can occur at any age and even in otherwise healthy patients. No association with age, HTN,atherosclerosis, smoking or DM.

Anterior ischemic optic neuropathy.

Posterior ischemic optic neuropathy (carries a poorer prognosis).