A new look at ischemic optic neuropathy

The majority of cases of POVL are now recognized to be caused by ION. This entity has long been known to ophthalmologists as a rare spontaneous event in the adult population and appears to be on the rise. Perfusion to the retina and optic nerve is determined by mean arterial pressure and may be limited by IOP and venous pressure. Perfusion to the optic nerve could therefore be limited, resulting in ischemia by a variety of conditions: an inappropriately low systemic blood pressure, high pressure within the globe (IOP), and high venous pressure. Anemia may also contribute to ischemia secondary to inadequate oxygen carrying capacity of the blood despite adequate perfusion. But more importantly, some patients may have co-morbidities that will facilitate the onset of this event. Unfortunately, at this point, it is extremely difficult to recognize which patients are at risk.