Anterior Ischemic Optic Neuropathy (AION) – Etiology, Clinical features, Investigations, Treatment

• Anterior Ischemic Optic Neuropathy is a condition in which there is segmental or total infarction of the anterior part of the optic nerve

Etiology:

• AION occurs due to blockage of Short posterior ciliary arteries which supply the optic nerve
• The different types of AION are:
  • Idiopathic – most common – thought to be due to atherosclerotic changes in the vessels
  • Arteritic – associated with giant cell arteritis
  • Miscellaneous – associated with various conditions like
    • Severe anemia
    • Malignant hypertension
    • Papilledema
    • Migraine
    • Massive haemorrhage
    • Collagen vascular disorders

Clinical features:

• Sudden visual loss
  • involving the upper or lower (more common) half of the visual field – altitudinal hemianopia
• Fundus changes – disc
  • oedematous (segmental / diffuse)
  • pale or hyperemic

Investigations:

• ESR and C reactive protein may be elevated in the arteritic variety
• Definitive diagnosis of arteritic AION is by temporal artery biopsy

Treatment:

• High dose steroids (prednisolone 80mg daily) – taper it by 10mg every week
• Low dose steroids may have to be given for 3 months to 1 year