Hypertensive Retinopathy

How high blood pressure damages the retina

The retina's small arteries can be seen directly through the pupil, making the eye the only place doctors can view blood vessels without a scan. When blood pressure is high:

1. Vasoconstriction: arteries narrow to protect the tissue from high pressure.
2. Sclerosis: over years, artery walls thicken and harden. Where a hardened artery crosses a vein, it compresses it (AV nicking), which can lead to retinal vein occlusion.
3. Exudation: very high or prolonged pressure breaks down the vessel barrier, causing bleeding, fluid and fatty deposits, and areas of reduced blood supply.
4. Optic disc swelling: in malignant hypertension, the optic nerve head swells.

Stages (Keith-Wagener-Barker and Wong-Mitchell)

The older Keith-Wagener-Barker system uses grades I to IV, which correspond roughly to these categories.

Symptoms

Most people have no symptoms until the disease is severe. Possible symptoms:

• blurred or reduced vision
• headaches, often with severely raised pressure
• double vision
• sudden vision loss from a retinal vein or artery occlusion

Malignant hypertension can also cause chest pain, breathlessness, confusion, seizures and reduced urine. See malignant hypertension.

Risk factors

• long-standing or poorly controlled hypertension
• very high blood pressure, especially rapid rises
• diabetes, which adds its own retinal damage (see diabetic retinopathy)
• smoking and high cholesterol
• kidney disease
• preeclampsia in pregnancy
• conditions that cause secondary hypertension, such as pheochromocytoma

Diagnosis

• dilated fundus examination with an ophthalmoscope or slit lamp
• retinal photographs to record and compare changes
• optical coherence tomography (OCT) to measure retinal and macular swelling
• fluorescein angiography in selected cases
• blood pressure measurements and tests for organ damage: kidney function, urine protein, ECG and echocardiogram

Doctors also consider other causes of similar findings, such as diabetes, blood disorders, radiation retinopathy and retinal vein occlusion from other causes.

Treatment

Blood pressure control

The central treatment is lowering blood pressure to target, usually under 130/80 mm Hg for most adults according to the ACC/AHA guideline, with:

• lifestyle changes: less salt, weight loss, regular exercise, limiting alcohol, stopping smoking
• medicines such as ACE inhibitors, ARBs, calcium channel blockers, thiazide diuretics and others

Mild and moderate retinal changes often stabilize, and hemorrhages and cotton wool spots usually fade over weeks to months once pressure is controlled. Arterial narrowing and AV nicking tend to persist.

Hypertensive emergency

When retinal hemorrhages or disc swelling occur with very high blood pressure, blood pressure is lowered in hospital in a controlled way, usually by no more than about 25% in the first hour, to avoid starving the brain, heart and eyes of blood.

Treating complications

• anti-VEGF injections or laser for macular edema from vein occlusion
• management of retinal artery occlusion as a stroke equivalent

Outlook

With good blood pressure control, most people keep good vision. Severe or malignant hypertensive retinopathy can leave permanent damage, particularly to the optic nerve or macula. Because retinal changes mirror damage elsewhere, hypertensive retinopathy is a signal to check the heart, kidneys and brain and to treat blood pressure seriously.

Frequently asked questions

What is hypertensive retinopathy?

It is damage to the blood vessels of the retina caused by high blood pressure. It ranges from narrowing and hardening of retinal arteries to bleeding, fluid leakage and swelling of the optic nerve in severe cases.

What are the symptoms of hypertensive retinopathy?

Most people have no symptoms in early stages, which is why regular eye exams are useful. Advanced disease can cause blurred or reduced vision, headaches and, if a blood vessel becomes blocked, sudden vision loss.

Can hypertensive retinopathy be reversed?

Partly. Hemorrhages, cotton wool spots and swelling usually improve within weeks to months after blood pressure is controlled. Long-standing artery narrowing and hardening tend to remain. Permanent vision loss can occur if the optic nerve or macula is badly damaged.

What are the stages of hypertensive retinopathy?

It is classified as mild (artery narrowing and AV nicking), moderate (hemorrhages, cotton wool spots and exudates) and malignant (moderate signs with optic disc swelling). The older Keith-Wagener-Barker system grades it from I to IV.

Is hypertensive retinopathy an emergency?

Mild and moderate forms are not emergencies but signal that blood pressure needs better control. Malignant hypertensive retinopathy, with optic disc swelling and very high blood pressure, is a medical emergency needing immediate treatment.