Painless vision loss with altitudinal defect and disc edema in a patient on anticoagulation
A 68-year-old woman with hypertension and atrial fibrillation on warfarin (INR 2.8) presents with sudden painless loss of the superior visual field in the left eye noted on waking. Acuity is 20/40 left and 20/25 right. There is a left relative afferent pupillary defect. Fundoscopy shows a swollen, hyperemic left optic disc with peripapillary flame hemorrhages and a small cup. The right disc is crowded with a small cup-to-disc ratio. She denies jaw claudication, scalp tenderness, or fever. ESR is 28 mm/h and CRP is 4 mg/L. She has a history of obstructive sleep apnea and uses a CPAP.
1. What is the most likely diagnosis, and how do you reconcile the normal inflammatory markers with the need to exclude giant cell arteritis?
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Most likely diagnosis: nonarteritic anterior ischemic optic neuropathy (NAION) in a crowded disc ('disc at risk'), given sudden painless altitudinal field loss, sectoral disc edema, small cup, and absence of systemic symptoms.
Reconciling normal ESR/CRP:
- Normal markers lower but do not eliminate the probability of GCA, especially in a patient over 50 with disc edema. However, the classic picture (altitudinal defect, crowded disc, no systemic symptoms, normal markers) strongly favors NAION.
- The judgement call: do not anchor on normal labs. If there is any concern (e.g., pallid disc edema, systemic symptoms, elevated markers, or atypical features), pursue temporal artery biopsy and consider empiric corticosteroids while awaiting results, because untreated GCA risks bilateral blindness.
- In this case, with a hyperemic (not pallid) disc, altitudinal defect, and no symptoms, observation with urgent follow-up is reasonable, but document the reasoning and give return precautions for visual loss in the fellow eye.
2. What is your management of the anticoagulation and sleep apnea, and what is the prognosis for the fellow eye?
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Anticoagulation:
- Do not stop warfarin solely for NAION; the risk of thromboembolism from atrial fibrillation generally outweighs any theoretical risk. Coordinate with the patient's internist/cardiology to ensure the INR is in therapeutic range and review whether antiplatelet therapy is appropriate.
- Address modifiable vascular risk factors: blood pressure, lipids, glucose, smoking.
Sleep apnea:
- OSA is associated with NAION; reinforce CPAP adherence and refer for sleep medicine optimization if poorly controlled.
Prognosis:
- The affected eye has a risk of further visual loss but often stabilizes; no proven treatment reverses NAION. The fellow eye is at substantial risk (roughly 15-20% over 5 years) because it also has a crowded disc.
- Counsel on the importance of seeking urgent care for any new visual symptoms and on controlling vascular risk factors.
Judgement point: avoid unproven 'treatments' (e.g., high-dose steroids for NAION) and focus on risk-factor modification and fellow-eye vigilance.