hypertensive retinopathy
Summary
Hypertensive retinopathy refers to retinal vascular damage caused by chronic or acute severe hypertension. Findings on fundoscopic exam include arteriolar narrowing, AV nicking, cotton-wool spots, flame-shaped hemorrhages, and in severe/malignant cases, papilledema. It is a key exam finding tested for both diagnosis and grading of hypertensive end-organ damage.
Detail
Hypertensive retinopathy results from chronic elevated blood pressure causing arteriolosclerosis and, in acute severe hypertension, breakdown of the blood-retinal barrier. Pathophysiology involves two phases: (1) vasoconstrictive/sclerotic phase - chronic HTN causes arteriolar narrowing (focal or generalized), AV nicking (arteriovenous crossing changes due to sclerotic arterioles compressing venules), and copper/silver wiring (arteriolar wall thickening); (2) exudative phase - seen with severe or malignant hypertension, causing disruption of the blood-retinal barrier leading to flame-shaped (superficial) hemorrhages, cotton-wool spots (microinfarcts of the nerve fiber layer due to ischemia), hard exudates (lipid deposition, sometimes forming a macular star), and papilledema (optic disc swelling) in malignant hypertension/hypertensive emergency indicating elevated intracranial pressure or severe ischemia.
The Keith-Wagener-Barker classification grades severity: - Grade I: mild arteriolar narrowing - Grade II: moderate narrowing + AV nicking - Grade III: grade II + hemorrhages, cotton-wool spots, exudates - Grade IV: grade III + papilledema (malignant hypertension)
Clinical significance: Hypertensive retinopathy is a marker of systemic vascular damage and correlates with damage in other organs (kidney, heart, brain). Grade III-IV changes, especially papilledema, indicate hypertensive emergency requiring immediate BP-lowering treatment. It's important to distinguish from diabetic retinopathy, which features microaneurysms and neovascularization, though both can coexist and cotton wool spots/hemorrhages may overlap. Fundoscopic exam is essential in the workup of hypertensive urgency/emergency and in longitudinal monitoring of chronic hypertensive patients.
Sources
- First Aid for the USMLE Step 1
- Vaughan & Asbury's General Ophthalmology
- UpToDate: Hypertensive retinopathy
- Harrison's Principles of Internal Medicine
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