Central Retinal artery occlusion is known to be associated with:
**Core Concept**
Central Retinal Artery Occlusion (CRAO) is a medical emergency characterized by sudden, unilateral vision loss due to obstruction of the central retinal artery. This condition is often associated with systemic vascular diseases, including atherosclerosis, hypertension, and vasculitis.
**Why the Correct Answer is Right**
CRAO occurs when a thrombus or embolus blocks the central retinal artery, leading to ischemia of the inner retinal layers. The most common cause of CRAO is an embolus originating from the heart, particularly from the left atrium or left ventricle. The embolus may be composed of a blood clot, air, or other foreign material. In some cases, CRAO may be caused by a thrombus in the central retinal artery itself, often as a result of atherosclerosis or hypertension.
**Why Each Wrong Option is Incorrect**
* **Option A:** While diabetes mellitus can cause retinal vascular disease, it is not the most common association with CRAO.
* **Option B:** Hypertension is a risk factor for CRAO, but it is not the most direct association.
* **Option C:** Vasculitis may cause retinal vasculitis, but it is not the most common association with CRAO.
**Clinical Pearl / High-Yield Fact**
CRAO is a medical emergency that requires prompt diagnosis and treatment to preserve vision. The "afferent pupillary defect" (APD) is a key clinical finding in CRAO, where the pupil constricts in response to light when the affected eye is occluded, but constricts normally when the unaffected eye is occluded.
**Correct Answer: A. Embolus from the heart. Embolus from the heart.**