Sudden Painless Vision Loss in a Patient with Cardiovascular Risk
A 68-year-old man with a history of hypertension and paroxysmal atrial fibrillation presents with sudden, painless loss of vision in the left eye upon waking. He reports a 'curtain' descending over his vision. Visual acuity is 20/200 OS and 20/20 OD. Pupillary examination shows a relative afferent pupillary defect in the left eye. Funduscopy reveals a pale, opaque retina with a cherry-red spot at the macula. He is not currently on anticoagulation. Blood pressure is 178/94 mmHg. He reports no headache, jaw claudication, or scalp tenderness. ESR is 12 mm/hr. You suspect a central retinal artery occlusion (CRAO).
1. What is the most likely mechanism of the CRAO in this patient, and what immediate workup and management should be initiated?
Read the worked answer
The most likely mechanism is thromboembolism from the heart due to atrial fibrillation, given the sudden onset and absence of giant cell arteritis symptoms (normal ESR). Immediate workup includes ECG, echocardiography, and carotid Doppler to identify the embolic source. Management: There is no proven effective treatment for CRAO, but attempts to dislodge the embolus may include ocular massage, anterior chamber paracentesis, or inhaled carbogen. However, the priority is to reduce future vascular events: start anticoagulation for atrial fibrillation (after neurology/cardiology consultation) and optimize blood pressure. The patient should be referred urgently to a stroke unit because CRAO is a marker of increased stroke risk.
2. How would you differentiate this from giant cell arteritis (GCA), and what would be your next step if GCA were suspected?
Read the worked answer
GCA typically presents with age >50, headache, jaw claudication, scalp tenderness, and elevated ESR/CRP. This patient lacks these symptoms and has a normal ESR, making GCA unlikely. If GCA were suspected, immediate high-dose systemic corticosteroids (e.g., IV methylprednisolone 1g/day for 3 days) should be started without waiting for biopsy to prevent vision loss in the fellow eye. Temporal artery biopsy should be performed within 2 weeks. In this case, the normal ESR and absence of symptoms make GCA unlikely, so corticosteroid therapy is not indicated.