# Hypertensive and Arteriosclerotic Retinopathy

## Introduction

Systemic hypertension affects approximately 1.3 billion adults worldwide and is a major cause of retinal vascular disease. Hypertensive retinopathy reflects the acute and chronic effects of elevated blood pressure on the retinal vasculature, while arteriosclerotic retinopathy represents the chronic structural changes of long-standing hypertension and aging. The retinal examination provides a unique, non-invasive window into the systemic vasculature and cardiovascular risk.

## Pathophysiology

### Normal Retinal Vascular Autoregulation

Retinal arterioles maintain constant blood flow over a range of perfusion pressures through **autoregulation**. Mechanisms: myogenic response (smooth muscle contraction) and metabolic regulation. Autoregulation fails when blood pressure exceeds the compensatory range.

### Acute Hypertensive Changes

**Vasospasm**: initial arteriolar constriction to protect the capillary bed from high pressure. **Breakthrough**: when autoregulation fails, plasma and blood leak into the retina. Results in: flame-shaped hemorrhages, cotton-wool spots, retinal edema, hard exudates. In severe acute hypertension: **optic disc edema** (malignant hypertension)

### Chronic Hypertensive/Arteriosclerotic Changes

**Intimal thickening** and **hyaline degeneration** of arteriolar walls. Progressive narrowing of the arteriolar lumen. Changes in the light reflex: **copper-wiring** (moderate) and **silver-wiring** (severe) Arteriovenous (AV) crossing changes: shared adventitial sheath causes venous compression.

## Clinical Features

### Arteriolar Changes

**Generalized arteriolar narrowing**: reduced arteriole-to-venule ratio (normal A:V ratio is 2:3) **Focal arteriolar narrowing**: localized constriction indicating focal vasospasm or sclerosis. **Copper-wiring**: thickened arteriolar wall reflects more light; yellowish-red reflex. **Silver-wiring**: severely sclerotic arteriole with minimal blood column visibility; silver-white reflex.

### Arteriovenous Crossing Changes (Gunn and Salus Signs)

**AV nicking (Gunn sign)**: apparent interruption of the venous blood column at AV crossings due to shared adventitial compression. **Venous banking and tapering**: dilated venous segment distal to crossing, tapered proximal segment. **Salus sign**: deflection of the venous course at the AV crossing. **Bonnet sign**: S-shaped venous segment at the crossing. AV crossing changes are a risk factor for branch retinal vein occlusion.

### Retinal Signs of Acute Hypertension

**Flame-shaped hemorrhages**: in the nerve fiber layer; follow the NFL architecture. **Cotton-wool spots**: microinfarctions of the retinal nerve fiber layer (swollen axons) **Hard exudates**: lipid and protein deposition in the outer plexiform layer; may form a **macular star** pattern. **Retinal edema**: diffuse or focal thickening. **Optic disc edema**: hallmark of **malignant (accelerated) hypertension**; constitutes a medical emergency.

![Fundus photograph showing malignant hypertensive retinopathy with disc edema, flame hemorrhages, cotton-wool spots, and macular star](images/hypertensive-retinopathy-malignant.jpg)

## Classification Systems

### Keith-Wagener-Barker Classification (Historical)

**Grade I**: mild arteriolar narrowing; barely detectable. **Grade II**: more marked narrowing; focal constriction; AV crossing changes (AV nicking) **Grade III**: Grade II changes plus hemorrhages, cotton-wool spots, and hard exudates. **Grade IV**: Grade III changes plus **optic disc edema** (papilledema) = malignant hypertension.

### Modified Mitchell-Wong Classification (Modern)

**None**: no detectable signs. **Mild**: generalized arteriolar narrowing, focal narrowing, AV nicking, arteriolar wall opacity. **Moderate**: hemorrhages (blot, dot, flame), cotton-wool spots, hard exudates, microaneurysms. **Severe (Malignant)**: moderate signs plus optic disc swelling. Simplifies grading; better correlation with systemic cardiovascular risk.

## Malignant Hypertension

### Definition

Severely elevated blood pressure (typically diastolic > 120 mmHg) with end-organ damage. Retinal findings: disc edema with hemorrhages, cotton-wool spots, and exudates (Grade IV) Medical emergency with risk of hypertensive encephalopathy, renal failure, cardiac failure, stroke.

### Ophthalmic Management

**Urgent referral** to internal medicine or emergency department for blood pressure control. Retinopathy improves with blood pressure normalization. Avoid overly rapid blood pressure reduction (risk of watershed infarction, especially optic nerve) Serial fundus photography to document resolution.

### Choroidal Changes in Acute Hypertension

**Elschnig spots**: focal infarcts of the choriocapillaris with overlying RPE necrosis. **Siegrist streaks**: linear hyperpigmented lesions along choroidal arteries. **Exudative retinal detachment**: from choroidal ischemia and RPE barrier disruption. These changes indicate severe, acute hypertensive crisis (hypertensive choroidopathy)

![Fundus photograph comparing mild arteriosclerotic retinopathy (left) with AV crossing changes and moderate hypertensive retinopathy (right)](images/arteriosclerotic-retinopathy-comparison.jpg)

## Arteriosclerotic Retinopathy vs. Hypertensive Retinopathy

| Feature | Arteriosclerotic | Hypertensive |
|---------|-----------------|--------------|
| Time course | Chronic, progressive | Acute or chronic |
| Arteriolar changes | Copper/silver wiring, AV nicking | Narrowing, vasospasm |
| Hemorrhages | Uncommon | Common (flame-shaped) |
| Cotton-wool spots | Absent | Present in moderate-severe |
| Disc edema | Absent | Present in malignant phase |
| Reversibility | Irreversible structural changes | Partially reversible with BP control |

## Differential Diagnosis

**Diabetic retinopathy**: microaneurysms prominent; may coexist with hypertensive retinopathy. **Retinal vein occlusion**: unilateral; venous dilation, tortuous vessels. **Anemia/leukemia**: bilateral hemorrhages; Roth spots. **Papilledema from intracranial hypertension**: bilateral disc edema; absent hemorrhages/exudates initially. **Radiation retinopathy**: history of radiation; similar appearance to diabetic retinopathy. **Ocular ischemic syndrome**: dilated but non-tortuous veins; low IOP; asymmetric.

## Systemic Implications

### Retinal Findings as Cardiovascular Biomarkers

Retinal arteriolar narrowing independently predicts **stroke risk** (3-fold increase) AV nicking correlates with coronary artery disease. Retinal changes can precede clinical cardiovascular events. AI-based retinal vessel analysis is emerging as a cardiovascular screening tool.

### Associated Conditions

Hypertensive nephropathy (concurrent end-organ damage) Left ventricular hypertrophy. Cerebrovascular disease. Pre-eclampsia and eclampsia (hypertensive choroidopathy, serous retinal detachment)

## Pre-Eclampsia and Eclampsia

Hypertensive retinopathy develops in 40-100% of pre-eclamptic patients. **Serous retinal detachments** from choroidal ischemia (bilateral; usually resolve postpartum) Cortical blindness from posterior reversible encephalopathy syndrome (PRES) **Purtscher-like retinopathy**: rare, associated with complement activation. Definitive treatment: delivery of the fetus; retinal changes typically resolve.

![OCT scan showing subretinal fluid associated with hypertensive choroidopathy in pre-eclampsia](images/preeclampsia-serous-detachment.jpg)

## Management

### Systemic

Coordinate with internist/cardiologist for blood pressure control. Target BP per current guidelines (typically < 130/80 mmHg for most adults) Address modifiable risk factors: sodium restriction, weight loss, exercise, smoking cessation.

### Ophthalmic

Serial fundus photography to document response to treatment. Grade I-II changes: annual ophthalmic screening. Grade III-IV changes: urgent blood pressure management; close follow-up until resolution. Monitor for complications: BRVO from AV nicking, macular edema, ischemic optic neuropathy. OCT for macular edema assessment.

## Key Clinical Pearls

The retina provides a unique non-invasive view of the systemic vasculature; hypertensive retinopathy independently predicts cardiovascular events. Disc edema in the setting of hypertensive retinopathy (Grade IV/malignant) constitutes a medical emergency requiring immediate blood pressure control. Arteriosclerotic changes (copper/silver wiring, AV nicking) are irreversible structural changes, while acute hypertensive signs (hemorrhages, cotton-wool spots) may resolve with blood pressure control. In pre-eclampsia, serous retinal detachments from hypertensive choroidopathy typically resolve after delivery.

## References

1. Wong TY, Mitchell P. Hypertensive retinopathy. *N Engl J Med*. 2004;351(22):2310-2317.
2. Keith NM, Wagener HP, Barker NW. Some different types of essential hypertension: their course and prognosis. *Am J Med Sci*. 1939;197(3):332-343.
3. Wong TY, Klein R, Couper DJ, et al. Retinal microvascular abnormalities and incident stroke: the Atherosclerosis Risk in Communities Study. *Lancet*. 2001;358(9288):1134-1140.
4. Dung DH, Khuong DL. Hypertensive choroidopathy and retinopathy. *Curr Opin Ophthalmol*. 2022;33(6):487-493.