Which of the following is NOT a risk factor for central retinal venous occlusion?

• A. Anemia
• B. Hypertension
• C. Diabetes
• D. Hypercoagulable state

Answer: (A)

Central retinal vein occlusion occurs when the central retinal vein becomes blocked by a thrombus, typically in a setting of vascular risk factors that promote arterial changes or a hypercoagulable state. Hypertension and diabetes contribute to arterial wall damage and atherothrombotic changes, which can compress the retinal vein or promote local thrombosis. Hypercoagulable states provide a systemic tendency for clot formation, increasing the likelihood of a retinal venous thrombosis. Anemia, however, does not predispose to this venous occlusion; it does not drive the same vascular or thrombotic mechanisms. In fact, anemia lowers blood viscosity and is not a recognized risk factor for CRVO, whereas the others are well-established contributors.