Zeitschrift für klinische und experimentelle Ophthalmologie
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Nonarteritic Anterior Ischemic Optic Neuropathy: An Update on Demographics, Clinical Presentation, Pathophysiology, Animal Models, Prognosis, and Treatment

Rudrani Banik

Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common acute ischemic optic neuropathy. The condition typically affects middle-aged and elderly individuals, though it may occur in younger age groups. Recent evidence suggests that its prevalence is higher than previously estimated. The clinical presentation of NAION is very classic and includes acute loss of visual afferent function (acuity, field and/or color) with the funduscopic appearance of an edematous optic nerve. The unaffected fellow eye usually has a small, crowded appearance described as a ‘disc at risk’. The pathophysiology of NAION is believed to be multi-factorial with the common pathway being circulatory insufficiency of the small caliber vessels supplying the optic nerve head. However, the exact location and mechanism of ischemia are still under debate. Prognosis of NAION is guarded; up to 50% of patients may have acuity of 20/200 or less with significant visual field loss, though approximately 40% will have improvement in their acuity. There are currently two animal models employed in investigating the histopathologic, molecular, and electrophysiologic changes seen in NAION. Treatment of the condition is quite controversial. Numerous medical and surgical interventions have been tried without clear evidence of benefit. The Ischemic Optic Neuropathy Decompression Trial demonstrated no benefit of optic nerve sheath fenestration in acute NAION. The role of oral corticosteroids is unclear, as is the use of aspirin in the prevention of the condition in the fellow eye. Several other promising agents are currently under investigation for the treatment of acute NAION.