A 58-year-old woman from Mumbai with a 15-year history of uncontrolled hypertension presents with sudden vision loss in the right eye. Blood pressure is 186/118 mmHg. Fundoscopy of the right eye shows retinal whitening with a cherry-red spot at the macula, along with flame hemorrhages and cotton-wool spots. What is the most likely diagnosis?

Explanation

## Central Retinal Artery Occlusion (CRAO) in Hypertensive Retinopathy **Key Point:** The cherry-red spot at the macula is pathognomonic for central retinal artery occlusion (CRAO). It represents the contrast between the pale, ischemic retina and the underlying choroidal circulation visible through the fovea. ### Clinical Features of CRAO | Feature | Pathophysiology | |---------|------------------| | Sudden vision loss | Acute cessation of retinal blood flow | | Cherry-red spot | Foveal choroidal perfusion visible through ischemic retina | | Retinal whitening (edema) | Acute retinal ischemia and swelling | | Flame hemorrhages | Superficial retinal vessel rupture | | Cotton-wool spots | Nerve fiber layer infarction | | Afferent pupillary defect (APD) | Severe retinal ischemia | **High-Yield:** CRAO is an ophthalmologic emergency. In hypertensive patients, severe uncontrolled BP can precipitate CRAO through acute vasospasm and endothelial damage. The cherry-red spot is virtually diagnostic. **Clinical Pearl:** The cherry-red spot appears because: 1. The inner retina (supplied by central retinal artery) becomes pale and edematous from ischemia 2. The fovea is thin and allows visualization of the underlying choroid (supplied by ciliary arteries) 3. The choroid remains perfused, appearing red through the transparent fovea 4. This creates the characteristic "cherry-red spot on white retina" appearance **Mnemonic: CRAO Features** — **C**herry-red spot, **R**etinal whitening, **A**cute vision loss, **O**phthalmoplegia absent (unlike carotid artery disease). ### Hypertensive Retinopathy as a Risk Factor Severe hypertensive retinopathy (Grade III–IV) increases the risk of CRAO through: 1. Endothelial dysfunction and increased vascular permeability 2. Acute vasospasm from severe BP elevation 3. Platelet aggregation and thrombosis 4. Arterial wall damage and narrowing **Warning:** Do not confuse CRAO with branch retinal artery occlusion (BRAO). BRAO presents with sectoral vision loss and retinal whitening in a wedge-shaped distribution, NOT a cherry-red spot. CRAO causes global vision loss and the characteristic cherry-red spot. [cite:Khurana Ophthalmology Ch 8, Ch 10]