Arteritic AION (Giant Cell Arteritis)

Arteritic anterior ischaemic optic neuropathy (A-AION): vasculitis of posterior ciliary artery → optic nerve infarction. Features: • Age ≥50, classically >65y. • Sudden painless monocular vision loss (severe). • Pale swollen optic disc on fundoscopy ('chalky white'). • ± altitudinal visual field defect. • ± RAPD. • GCA features: temporal headache, jaw claudication, scalp tenderness, polymyalgia, malaise, weight loss, fever. Risk of contralateral involvement up to 75% within days-weeks if untreated. Distinguish from non-arteritic AION (NA-AION): • Younger, vasculopathic. • Less severe vision loss. • Disc swelling more variable. • Crowded disc anatomy. • Steroid less effective.