Poorly controlled hypertension results in target-organ damage. In the eye, it results in choroidopathy, retinopathy and optic neuropathy. This article will focus on hypertensive retinopathy, a relatively common presentation.

The major risk factors for hypertensive retinopathy are the severity and duration of hypertension, and to a lesser extent people of African descent.

Hypertension is defined by NICE as¹:

The prevalence of hypertension is expected to rise by 29% by 2025².

In response to elevated blood pressure, the retinal circulation undergoes various pathophysiological changes. Hypertensive retinopathy incorporates two disease processes – acute elevation of blood pressure triggers vasospasm to auto-regulate perfusion resulting in acute hypertensive retinopathy whereas chronically elevated systemic blood pressure sequentially causes vasoconstrictive, sclerotic and exudative histologic changes in the ocular vessels.

History

When taking a history, remember to ask about:

• Hypertensive history (severity, duration, compliance with medications)
• Symptoms of hypertension: headaches, eye pain, reduced VA, focal neurological deficits, chest pain, dyspnoea, palpitations
• Complications of hypertension: stroke, TIA, coronary/peripheral vascular disease, HF

Investigations

Hypertensive retinopathy is usually asymptomatic. Investigations include fundoscopy and fluorescein angiography.

Lesions seen on fundoscopy:

• Flame shaped haemorrhage; caused by necrotic vessels that bleed into superficial retina / nerve fibre layer
• Dot blot haemorrhage; caused by necrotic vessels that bleed into inner retina
• Cotton wool spots; caused by fibrinous necrosis and luminal narrowing leading to ischaemia of nerve fibres, decreased axoplasmic flow and nerve oedema
• Hard exudates; caused by accumulation of lipid around areas of haemorrhage due to breakdown of blood-retinal barrier. These can form a macular star around the macula
• Papilloedema; due to leakage/ischaemia of arterioles supplying optic disc
• AV nipping:
  • Salus’s sign: deflection of retinal vein as it crosses the arteriole
  • Gunn’s sign: tapering of retinal vein on either side of AV crossing
  • Bonnet’s sign: banking of retinal vein distal to AV crossing
• Arterial narrowing; decrease in AV ratio to 1:3 (normal is 2:3)
• Silver wiring; due to arteriolar light reflex
• Optic disc swelling can appear in hypertensive optic neuropathy

On fluorescein angiography, changes including leakage, microaneurysms, capillary non-perfusion and choroidopathy can be seen.

Photo taken from EyeWiki³ and edited

Classification is based on lesions seen in fundoscopy:

Management

Although there’s no specific ophthalmological interventions for hypertensive retinopathy, management instead revolves around good control of blood pressure to halt progress of disease. Lifestyle advice should be recommended for all (low salt diet, reduce caffeine intake, reduce alcohol intake, stop smoking, exercise and weight reduction).

For stage 1 hypertension, treat if 80 years or younger with evidence of target organ damage, diabetes, or 10-year cardiovascular risk of >10% (using QRISK2 score)⁴.

For stage 2 hypertension, start treatment immediately. If younger than 55 years or has type 2 diabetes, start on an ACE-inhibitor or angiotensin 2 receptor blocker. If 55 years and older or of Afro-Caribbean ethnicity, start on a calcium channel blocker⁴.

If younger than 40 years, exclude secondary causes of hypertension.

For those with malignant hypertension (>180/120) and retinal haemorrhage or papilloedema, or life-threatening symptoms (acute confusion, chest pain, heart failure, AKI), refer urgently for same-day specialist assessment. In hospital, they should be on strict bed rest with regular monitoring of blood pressure. Blood pressure should not be reduced too rapidly (>25% per day) due to risks of cerebral infarction. The aim is to reduce blood pressure to 110mmHg diastolic over 24 hours, using either nifedipine (with or without loop diuretic), labetalol or beta-blockers depending on concomitant factors⁵.

Prognosis

Although visual loss is rare, it can occur secondary to optic atrophy or prolonged papilloedema or exudative retinal detachment. Other complications to bear in mind include retinal vein or artery occlusion.

References

1. National Institute for Health and Care Excellence CKS. (2023). Hypertension, what is it? https://cks.nice.org.uk/topics/hypertension/background-information/definition/
2. Mittal BV, Singh AK. Hypertension in the Developing World: Challenges and Opportunities. American Journal of Kidney Diseases. 2010;55(3):590-8.
3. Bhagat N, Mehta J et al. Hypertensive Retinopathy. EyeWiki. American Academy of Ophthalmology. 2023.
4. National Institue for Health and Care Excellence. (2019). Hypertension in adults: diagnosis and management. Guidance NG136.
5. GP notebook. Hypertension (malignant). 2018. https://gpnotebook.com/en-GB/pages/uncategorised/hypertension-(malignant)

Written by Dr. Sandra Halim (IMT2 London) & reviewed by Dr. Shruti Chandra (ST3 ACF London)