Ischemic optic neuropathies (ION), sometimes referred to as “optic disk infarction,” result in the sudden loss of vision of an eye.
They result from the dysfunction of neurons of the optic nerve due to oxygen deprivation caused by insufficient blood supply (ischemia).
The vast majority (90%) of ION cases are non-arteritic (NA), that is, they are not related to inflammation of the vessel wall. NAION affects 2.3 to 10.3 people per 100,000 people per year, making it the most common cause of acute optic neuropathy in patients over 50 years of age.
NAION presents as a painless loss of vision, often when awakening, that occurs over hours to days. Most patients lose the lower half of their visual field (an inferior altitudinal loss), though superior altitudinal loss is also common. The pathophysiology of NAION is unknown, but it is related to poor circulation in the optic nerve head. NAION is often associated with diabetes mellitus, elevated intraocular pressure, high cholesterol, a drop in blood pressure, and sleep apnea. The second eye is affected for 15 to 24% of patients within 5 years of first eye involvement.
To date, there is no treatment for NAION.