Sudden Vision Loss With a Normal Fundus in a Patient on Anticoagulation
A 68-year-old woman with atrial fibrillation on apixaban and hypertension presents with painless sudden loss of vision in the left eye that she noticed on waking 2 days ago. Visual acuity is 20/200 OS and 20/20 OD. She reports no flashes, floaters, or eye pain. Pupils: there is a left relative afferent pupillary defect. Color plates are reduced OS. Anterior segment and IOP are normal. Dilated fundus exam of the left eye shows a mildly swollen, hyperemic optic disc with a blurred margin and a few peripapillary hemorrhages; the right disc appears normal. Macula and periphery are unremarkable. Blood pressure is 168/94 mmHg; she is afebrile. ESR and CRP are pending.
1. Build a differential for a unilateral swollen disc with vision loss and an RAPD, and explain which features argue for and against arteritic versus non-arteritic ischemic optic neuropathy.
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Differential for unilateral disc swelling + vision loss + RAPD:
- Non-arteritic anterior ischemic optic neuropathy (NAION)
- Arteritic AION (giant cell arteritis)
- Optic neuritis (usually younger, painful with eye movement, less disc swelling)
- Infiltrative/compressive optic neuropathy (tumor, sarcoid, metastasis)
- Central retinal vein occlusion (usually more hemorrhage, no RAPD unless severe)
- Papilledema (but that is bilateral)
- Diabetic papillopathy (usually bilateral, minimal vision loss)
Features favoring arteritic (GCA):
- Age >65, female, sudden severe vision loss to 20/200.
- Systemic vascular risk and hypertension; ask about jaw claudication, scalp tenderness, headache, polymyalgia, weight loss, fever.
- Disc swelling with pallor and a few hemorrhages can occur in both, so this is not decisive.
Features favoring non-arteritic:
- No systemic symptoms reported; afebrile; unilateral; classic disc appearance.
- However, absence of symptoms does not exclude GCA - a substantial minority have no systemic complaints.
The RAPD plus disc swelling plus sudden painless loss is the classic ischemic optic neuropathy picture. The critical judgment is that you cannot safely rule out GCA clinically, and the cost of missing it is bilateral blindness. So manage as GCA until proven otherwise.
2. State your immediate management, including what you would do before laboratory results return, and how you would interpret a normal ESR/CRP.
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Immediate management (do not wait for labs):
- Start high-dose systemic corticosteroids immediately - e.g., oral prednisone 1 mg/kg/day (or IV methylprednisolone 250 mg-1 g/day if vision in the fellow eye is threatened or there is concern for bilateral involvement). The fellow eye is at risk, and steroid is the only intervention shown to reduce second-eye involvement.
- Order urgent ESR and CRP (and CBC, platelets) - but treat first.
- Arrange temporal artery biopsy within ~1-2 weeks; steroids do not need to be delayed for biopsy and biopsy remains informative for up to ~2 weeks on treatment.
- Urgent referral to rheumatology for GCA management and long-term steroid-sparing therapy (e.g., tocilizumab).
- Do not use aspirin as a substitute; continue her anticoagulation per cardiology, and monitor for steroid-related hyperglycemia and hypertension.
Interpreting normal ESR/CRP: A normal ESR and CRP do not exclude GCA - a meaningful minority (especially with shorter symptom duration or on anticoagulation) have normal inflammatory markers. If clinical suspicion is high, proceed with biopsy and continue steroids; do not withdraw treatment based on normal labs. Conversely, if biopsy is negative but suspicion remains high, treat clinically. The decision hinges on probability and the asymmetry of harm: missing GCA risks irreversible bilateral blindness, while a course of steroids is reversible.