A 52-year-old man presents with sudden painless loss of vision in the left eye. On examination, he has a cherry-red spot at the macula with retinal whitening in the distribution of the central retinal artery. Fundoscopy shows no optic disc swelling. What is the most appropriate immediate next step in management?

Explanation

## Central Retinal Artery Occlusion (CRAO): Emergency Management ### Clinical Presentation & Pathophysiology The cherry-red spot with surrounding retinal whitening is pathognomonic for CRAO. The whitening represents retinal ischemia and edema in the distribution of the central retinal artery. The cherry-red appearance occurs because the fovea—supplied by the underlying choroidal circulation—remains perfused while the inner retina becomes pale and opaque. **Key Point:** CRAO is an ophthalmologic emergency with a critical window for intervention. Vision loss is typically sudden, painless, and profound (light perception or counting fingers at best). ### Why Immediate Referral & Thrombolysis/Thrombectomy? **High-Yield:** The retina can tolerate only 90–120 minutes of complete ischemia before irreversible damage occurs. Reperfusion therapy (intra-arterial thrombolysis or mechanical thrombectomy) must be initiated within 24 hours of symptom onset, ideally much sooner. **Clinical Pearl:** Unlike acute stroke, CRAO does not have a strict 4.5-hour window for IV thrombolysis (which carries high risk of vitreous hemorrhage). Intra-arterial approaches are preferred and can be considered up to 24 hours in select cases. ### Management Algorithm ```mermaid flowchart TD A[Sudden painless vision loss + cherry-red spot]:::outcome --> B{Time since onset?}:::decision B -->|< 24 hours| C[Urgent ophthalmology referral]:::action C --> D{Thrombolysis/thrombectomy candidate?}:::decision D -->|Yes| E[Intra-arterial intervention]:::action D -->|No| F[Ocular massage, AC chamber paracentesis, carbogen inhalation]:::action B -->|> 24 hours| G[Supportive care + investigate etiology]:::action E --> H[Reperfusion achieved]:::outcome F --> I[Minimize further ischemia]:::outcome ``` **Key Point:** Immediate measures while awaiting intervention include ocular massage, anterior chamber paracentesis (to lower IOP and improve perfusion pressure), and carbogen (95% O₂ + 5% CO₂) inhalation to improve retinal oxygenation. ### Why Other Options Are Incorrect - **Topical timolol alone:** Addresses glaucoma management, not acute ischemia. No role in CRAO. - **Oral aspirin + observation:** Too slow; irreversible damage occurs within hours. Antiplatelet therapy is adjunctive, not primary. - **B-scan ultrasonography:** Diagnostic imaging for retinal detachment or posterior segment pathology, not indicated for CRAO diagnosis (clinical diagnosis is sufficient). **Warning:** Delay in referral or failure to recognize the emergency nature of CRAO results in permanent vision loss. This is one of the few true ophthalmologic emergencies.