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  • Updated 09.25.2024
  • Released 04.26.1999
  • Expires For CME 09.25.2027

Ischemic optic neuropathy

Introduction

Overview

Ischemic to the optic nerve is the most common cause of sudden visual loss in patients over 50 years of age. The conventional form of this condition is called nonarteritic anterior ischemic optic neuropathy (NAION) because it is limited to the optic disc. Occurring typically in just one eye in the context of “standard vasculopathic” risk factors, particularly diabetes, hypertension, and hyperlipidemia. Its precise pathogenesis is unresolved.

A much less common nonarteritic form is limited to the retrobulbar segment of the optic nerve and is therefore called nonarteritic posterior ischemic optic neuropathy. It occurs most often in the perioperative period after cardiac or spine surgery, but also in the setting of arteriosclerosis, herpes zoster infection, connective tissue disorders, surgical manipulation of the intracranial optic nerve, and radiation therapy in the region of the optic nerves and optic chiasm.

Another variant of ischemic optic neuropathy occurs after systemic hypotension (“hypotensive or shock-induced”). It has an anterior variant that affects only the optic disc segment, a posterior variant that is limited to the retrobulbar optic nerve segment, and a variant that affects both segments. Ischemic optic neuropathy has been linked to a variety of medications like amiodarone and phosphodiesterase inhibitors, but a causal relationship has not been firmly established. The visual loss in these nonarteritic variants extends from mild to severe and is largely irreversible. Treatment is not effective.

Finally, there is the uncommon but most perilous variant called arteritic ischemic optic neuropathy (AION). Occurring most often in giant cell arteritis. Arteritic ischemic optic neuropathy almost always affects the optic disc but may also affect the orbital optic nerve segment, as well as its dura and surrounding orbital soft tissues. Because the optic disc is affected in over 90% of patients, a posterior arteritic variant is hardly acknowledged. Limited to patients over age 50, it causes severe and irreversible visual loss, often in both eyes. High-dose corticosteroid treatment probably prevents second-eye involvement.

Key points

• Ischemic optic neuropathy is named according to cause (nonarteritic or arteritic) and location (anterior with optic disc swelling or posterior with an initially normal-appearing optic disc).

• Nonarteritic anterior ischemic optic neuropathy is a common cause of vision loss in individuals over 50 years of age and does not have a proven treatment.

• Nonarteritic anterior ischemic optic neuropathy is associated with vasculopathic risk factors, some medications, obstructive sleep apnea, and crowded optic nerve heads.

• Nonarteritic posterior ischemic optic neuropathy is rare.

• Arteritic anterior or posterior ischemic optic neuropathy is typically caused by giant cell arteritis, which requires emergent treatment to prevent other ischemic events.

Historical note and terminology

In 1966 Miller and Smith described a syndrome of acute, monocular, painless visual loss, afferent pupillary defect, and optic disc edema, terming it ischemic optic neuropathy (68). The term ischemic optic neuropathy identified the noninflammatory nature of the disorder, which previously had been variously named “vascular pseudopapillitis,” “arteriosclerotic papillitis,” and “ischemic papillitis.” Hayreh subsequently added the keyword “anterior” to denote those cases of ischemic optic neuropathy that included optic disc edema in the acute phase (nonarteritic anterior ischemic optic neuropathy), differentiating them from the rarer posterior ischemic optic neuropathy, in which the optic disc appearance is initially normal (37). The term arteritic ischemic optic neuropathy describes ischemic optic neuropathy that occurs in vascular inflammation, typically giant cell arteritis.

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