Sudden Vision Loss in a Patient with Giant Cell Arteritis
A 74-year-old woman presents with sudden painless loss of vision in the left eye for 6 hours. She reports jaw claudication, scalp tenderness, and a recent episode of transient visual loss in the same eye. Visual acuity is no light perception in the left eye and 6/6 in the right. Fundoscopy shows a pale, swollen left optic disc with a normal right disc. ESR is 78 mm/h and CRP is elevated. She has no known systemic disease.
1. What is the most likely diagnosis, and what is the pathophysiological basis of the visual loss?
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Diagnosis: Giant cell arteritis (GCA) with arteritic anterior ischemic optic neuropathy (A-AION).
Pathophysiology:
- GCA is a granulomatous vasculitis affecting medium and large arteries, particularly the cranial branches of the external carotid artery (temporal, ophthalmic, posterior ciliary arteries).
- Inflammation leads to intimal hyperplasia and luminal thrombosis, causing ischemia of the optic nerve head supplied by the short posterior ciliary arteries.
- The result is ischemic damage to the optic nerve, producing a pale, swollen disc and profound visual loss.
Supporting features: Age >70, jaw claudication, scalp tenderness, elevated ESR/CRP, and preceding amaurosis fugax are classic. The fellow eye is at high risk of involvement within days to weeks.
2. Outline your immediate management, including the role of temporal artery biopsy and steroid therapy, and explain why treatment should not wait for biopsy results.
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Immediate management:
- High-dose systemic corticosteroids - IV methylprednisolone 1 g/day for 3 days, then oral prednisolone 1 mg/kg/day. This is the cornerstone of treatment and should be started immediately.
- Temporal artery biopsy - to confirm the diagnosis, but treatment must not be delayed. Biopsy remains positive for up to 2 weeks after starting steroids.
- Aspirin (low dose) may reduce the risk of further ischemic events.
- Monitor the fellow eye closely; steroid therapy reduces the risk of bilateral blindness.
Why not wait for biopsy: Visual loss in the fellow eye can occur within hours to days, and steroids are the only intervention that reduces this risk. The diagnosis is clinical, supported by ESR/CRP; biopsy confirms but does not change the urgent need for treatment.
Follow-up: Gradual steroid taper guided by symptoms and inflammatory markers; monitor for steroid complications.