Key Facts

The retina is the only place in the body where arterioles can be directly visualised, making fundoscopy invaluable for assessing hypertensive end-organ damage.

Epidemiology

• Retinal changes present in ~10% of people with hypertension
• Severe retinopathy (grade III-IV) is uncommon with current BP management
• Malignant hypertension: incidence ~1-2 per 100,000/year

Aetiology

• Chronic hypertension: gradual arteriolar changes (sclerosis, narrowing, AV nipping)
• Acute/severe hypertension (malignant/accelerated): acute retinal damage (haemorrhages, exudates, papilloedema)

Pathophysiology

• Chronic: hyaline arteriosclerosis → thickened walls → reduced lumen → silver/copper wiring → AV nipping (arteriole compresses venule at crossing points)
• Acute: autoregulatory failure → fibrinoid necrosis → flame haemorrhages, cotton wool spots (nerve fibre layer infarcts), hard exudates (lipid leakage from damaged capillaries), papilloedema (optic disc swelling from severe hypertension)

Grading (Keith-Wagener-Barker)

• Grade I: mild arteriolar narrowing (subtle; increased light reflex — "copper wiring")
• Grade II: moderate arteriolar narrowing + AV nipping/nicking (arteriole indents venule at crossings)
• Grade III: flame haemorrhages, cotton wool spots, hard exudates, macular star
• Grade IV: all of grade III + papilloedema (disc swelling)

Symptoms

• Grades I-II: usually asymptomatic
• Grade III: may have visual symptoms (blurring)
• Grade IV: headache, visual disturbance, symptoms of malignant hypertension (nausea, confusion, chest pain)

Red Flags

• Grade III-IV: malignant hypertension — medical emergency
• Papilloedema: indicates end-organ damage; requires urgent BP reduction
• Branch/central retinal vein occlusion (complication of chronic hypertensive retinopathy)

Bedside

• Blood pressure (essential; repeated measurements)
• Fundoscopy (dilated): grade retinopathy
• Visual acuity
• Urinalysis (proteinuria — renal end-organ damage)

Bloods

• U&Es (renal function)
• FBC (anaemia exacerbates retinopathy)
• HbA1c (exclude diabetes)
• Lipid profile

Imaging

• OCT: macular oedema, disc swelling quantification
• FFA: if diagnostic uncertainty
• Renal USS: if secondary hypertension suspected
• ECG/echocardiography: LVH assessment

Special Tests

• 24-hour ambulatory BP monitoring
• Secondary hypertension screen if young or refractory

Non-pharmacological

• Lifestyle: salt reduction (<6g/day), weight loss, exercise, alcohol moderation, smoking cessation

Pharmacological

• Treat the underlying hypertension (NICE NG136):
  • Step 1: ACE inhibitor (ramipril 1.25-10mg OD) or ARB; CCB (amlodipine 5-10mg OD) if >55 or African-Caribbean
  • Step 2: ACEi/ARB + CCB
  • Step 3: ACEi/ARB + CCB + thiazide-like diuretic (indapamide 2.5mg OD)
  • Step 4: add spironolactone 25-50mg OD (if K+ ≤4.5)
• Malignant hypertension (grade IV): admit; IV antihypertensives (labetalol, sodium nitroprusside); reduce BP gradually (25% in first 24 hours; avoid precipitous drop)
• Target: <140/90 (or <130/80 if diabetes/CKD)

Surgical/Interventional

• Not applicable for retinopathy itself
• Retinal changes improve with BP control

Referral Criteria

• Grade III-IV: emergency medical admission for BP management
• Grade I-II: optimise BP in primary care
• Visual symptoms: ophthalmology referral
• Suspected secondary hypertension: specialist referral

• Grade I-II: reversible arteriolar changes with BP control; does not directly threaten vision
• Grade III: haemorrhages and exudates usually resolve over weeks-months with BP treatment
• Grade IV: papilloedema resolves with BP control; untreated malignant hypertension has 90% 1-year mortality
• Complications: branch/central retinal vein occlusion (from AV nipping), macular oedema
• Good BP control prevents progression and reduces cardiovascular morbidity/mortality

Keith-Wagener-Barker Classification

Fundoscopic Signs of Hypertensive Retinopathy