Hypertensive retinopathy occurs when the retina (a transparent layer of tissue at the back of the eye) is damaged due to high blood pressure (hypertension). Hypertension exists when the systolic and diastolic measurements read over 140/90 mmHg.
The small blood vessels located in the retina supply it with blood. High blood pressure damages these blood vessels. It causes their walls to swell leading to reduced blood supply to the retina. Some parts of the retina may get damaged giving rise to retinopathy. Blood may also leak into the retina resulting in gradual loss of vision. This may happen especially when these changes affect the central part of the retina called the macula. Retinal veins can become twisted and dilate with very high pressure. Also, the optic disk (the meeting point of the retina and the optic nerve) may swell. When this happens, it’s an emergency. Mild blood pressure should be attended to because it can lead to damage if left untreated for years.
Causes and Risk Factors
Untreated elevated blood pressure causes hypertensive retinopathy. The longer it stays high, the more severe the damage.
Individuals with malignant hypertension (severe hypertension of more than 200/130 mmHg) are most at risk. Also, hypertensive people with diabetes, high cholesterol, and those who smoke stand a higher chance.
It is rare for blood pressure readings to get very high abruptly . Nevertheless, if they do, hypertension can cause serious damage in the eye.
Signs & Symptoms
The signs of hypertensive retinopathy may include:
- Retinal hemorrhage
- Cotton wool spots
- Hard exudates (leaked fluids)
- Retinal edema (swelling or fluid accumulation)
- Papilledema (swelling of optic disk)
Symptoms may not present themselves in mild to moderate hypertensive retinopathy. However, the disease may be diagnosed during a routine visit.
Symptoms of severe hypertensive retinopathy may include:
- A headache
- Reduced visual acuity
- Pain in the eye
If an individual experiences sudden symptoms, that is a medical emergency.
The eye professional will first determine the presence of systemic hypertension. He/she will take a comprehensive history of the individual. The focus is on the history of hypertension and its complications.
The professional will then conduct a dilated fundoscopic examination. He/she will use an ophthalmoscope (an instrument that projects light to the back of the retina). This examination determines if the blood vessels have narrowed. It also checks if any fluid has leaked from the blood vessels. A grading scale of 0 to 4 will establish the degree of retinopathy:
- Grade 0 - Symptoms are absent
- Grade 1 - The narrowing of the artery is barely detectable
- Grades 2 to 3 - Some changes in the blood vessels are noted. There may be bleeding in the blood vessels. Other parts of the retina may swell. Cotton wool spots (spots on the retina) and exudates may be present.
- Grade 4 - The optic disk and macula will swell leading to decreased vision.
A further test may be required to examine the blood vessels
Treatment of hypertensive retinopathy is directed toward lowering high blood pressure.
Patients with malignant hypertensive retinopathy may be put on medication to lower pressure to below 140/90 mmHg. Drugs may be used from groups such as beta blockers, diuretics, calcium channel blockers, angiotensin receptor antagonists and angiotensin converting enzyme inhibitors.
Intravitreal injection of vascular endothelial growth factor (VEGF) drugs can treat serious cases of hypertensive retinopathy.
Surgery is extremely rare for hypertensive retinopathy. However, laser surgery can be done for visual threatening complications occasioned by retinal edema.
In most cases, controlling the blood pressure will heal the retina.
Follow-up depends on the degree of hypertension and resistance to medication. The eye doctor and primary care physician will work together for consistent follow-up.
If left untreated, hypertensive retinopathy increases the risk of heart failure, heart attack, stroke and kidney failure. Hypertension can also lead to the progression of diabetic retinopathy. Visual acuity may be reduced due to damage to the macula and optic nerve.
To prevent hypertensive retinopathy, systemic hypertension should be controlled. Changes in lifestyle can also help to manage the disease. For example, an individual can avoid salt, tobacco, alcohol and so on. He/she can also eat healthy foods and exercise regularly.
Hypertensive individuals should undergo routine blood pressure monitoring and treatment. These will prevent the development of hypertensive retinopathy.