Hypertensive retinopathy: Retinal vascular damage caused by hypertension

What is hypertensive retinopathy?

Hypertensive retinopathy is when high blood pressure (hypertension) damages the blood vessels on the inside of the eye (retina and choroid). Hypertensive retinopathy is generally diagnosed during an eye exam and usually does not affect vision unless it has progressed to an advanced stage. 

Even in an early stage, however, hypertensive retinopathy is associated with serious health conditions such as stroke, kidney damage and heart disease.

A diagnosis of hypertensive retinopathy allows the eye doctor to refer to a primary care doctor or cardiologist for additional testing and blood pressure management. Advanced stages of hypertensive retinopathy require immediate treatment, often in an emergency room.

Causes

Hypertensive retinopathy is caused by high blood pressure. Blood pressure is measured using two numbers: 

• The first number is called systolic blood pressure and measures the pressure in your arteries when your heart beats. 

• The second number is called diastolic blood pressure and measures the pressure in the arteries between heart beats.

It is often written as a fraction of systolic/diastolic. For example, a blood pressure of less than 120/80 mm Hg is considered within the normal range.

Blood pressure is considered elevated when the systolic pressure is over 120 mm Hg with a normal diastolic under 80 mm Hg. Grade 1 hypertension is when the systolic is over 130 or the diastolic is over 80, and it is grade 2 hypertension when the systolic is over 140 or the diastolic is over 90.

According to this criteria, 46% of adults in the United States have hypertension. In about 85% of cases, the exact cause of high blood pressure is not known. This is called essential hypertension.

In the rest of cases, elevated blood pressure is a direct cause of another disease. This is called secondary hypertension. 

READ MORE: Valsalva retinopathy

Risk Factors

While an exact cause is unknown, several risk factors for essential hypertension have been identified:

• Genetics – Hypertension is 2.4 times more likely when both parents have hypertension. It is thought that 30% to 50% of the risk of hypertension is genetic.

• Lifestyle – Physical inactivity, obesity, tobacco use and excessive alcohol use have all been shown to increase the risk of high blood pressure.

• Diet – A diet that is too high in sodium and too low in potassium can put one at risk for hypertension.

• Age – The rate of hypertension is 7.5% among adults aged 18 to 39. This rate increases to 33.2% among those aged 40 to 59, and to 63.1% among those aged 60 and over.

• Pregnancy – Hypertension affects 5% to 10% of pregnancies and can be a sign of preeclampsia, a serious and potentially life-threatening condition. 

Risk factors for secondary hypertension include:

• Kidney disease

• Hormone imbalance

• Vascular disorders

• Autoimmune diseases

• Sleep apnea

• Use of certain medications

Hypertensive crisis, also called malignant hypertension, is a type of secondary hypertension that comes on very quickly. It occurs when blood pressure exceeding 180/120 causes damage to the kidneys, which in turn causes the blood pressure to go up. This type of hypertension is the most likely to cause damage to the eyes.

Symptoms

Hypertensive retinopathy generally does not cause symptoms. However, a hypertensive crisis can present with:

• Blurred vision

• Anxiety

• Headache

• Chest pain

• Nausea and vomiting

• Confusion

• Not responding to a stimulus (unresponsiveness)

• Seizures

Blurred vision in a hypertensive crisis can be from swelling of different structures in the back of the eye.

READ MORE: Sudden blurry vision in one eye: What does it mean?

Diagnosis

Hypertensive retinopathy is detected by looking into the eye. To get the best view, the eye doctor will likely dilate the pupils. If there are changes in the eye that look like hypertensive retinopathy, the eye doctor may order additional tests or refer to a retina specialist. 

Progression

Hypertensive retinopathy progresses through five different stages:

In the vasoconstrictive stage, the small arteries (called arterioles) in the retina become narrow when compared to the small veins (called venules). The size-ratio between arterioles and venules is usually 2 to 3 but may become 1 to 2 in hypertensive patients. In older patients, the narrowing of the blood vessels may be irregular, making the blood vessels appear irregular as well. 

The sclerotic stage is when the arterioles harden. Moderate hardening causes the blood vessels to look more yellow (called copper-wiring) and severe hardening makes the blood vessels appear silver (called silver-wiring). When a hardened arteriole compresses a venule, this is called arteriovenous (AV) crossing changes.

The exudative stage occurs when the blood vessels start to leak, or stop functioning. Leaky blood vessels release plasma (called hard exudate) or blood into the retina. When blood is released into the superficial retina, the hemorrhages have a flame shape. When it is released into the deeper retina, the hemorrhages have a dot or blot appearance.

Blood vessels may also stop functioning, creating small areas of reduced blood flow. In these areas, the retina will swell up, causing a grayish discoloration that is called a “cotton-wool spot” or a soft exudate.

In the malignant stage, two tissues close to the retina — the optic nerve and the choroid — are also affected. The optic nerve becomes swollen, called papilledema. Fluid from the optic nerve may then settle in the center of the retina (the macula), creating hard exudates in a ring shape, called a macula star.

The choroid, in turn, can develop areas of blockage. This then creates areas of too much or too little pigmentation in the retina. Pigmented spots surrounded by a halo of less pigment are called Elschnig spots. Lines of pigment loss are called Siegrist streaks. Fluid from the choroid may also push against the retina and cause a serous retinal detachment.

READ MORE: Retinal detachment: Types and what to look for

Classifications

A doctor may also grade a patient’s level of hypertensive retinopathy using one of the following classification systems:

• Modified Scheie classification

• Scheie classification

• Keith-Wagener-Barker classification

Each system uses grades or stages to summarize the signs of hypertensive retinopathy as it develops. 

Complications

Persistent swelling of the macula and optic nerve can cause permanent damage to both these structures and result in vision loss.

Hypertensive retinopathy is linked to several other eye complications:

• Branch retinal artery occlusion causes complete loss of side-vision in the area of the blockage.

• Branch retinal vein occlusion causes partial loss of side-vision in the area of the blockage and can lead to swelling of the macula and growth of new blood vessels in the retina or the iris. This can lead to glaucoma.

• Retinal macroaneurysm is an outpouching of a retinal arteriole and can result in swelling of the retina or bleeding into the eye (vitreous hemorrhage).

• Retinal detachment caused by fluid from the choroid or from new blood vessels growing in the retina (neovascularization) can result in blindness if it progresses into the macula.

• Retinal neovascularization is when new blood vessels grow from existing retinal arterioles. These new blood vessels are fragile and can cause a vitreous hemorrhage. They can also pull on the retina and cause a detachment.

• Diabetic retinopathy is made worse by hypertension.

Untreated hypertension can lead to several serious systemic problems. One study found that if patients with grade 4 hypertensive retinopathy did not receive treatment for hypertension, they had a 50% chance of dying within two months and a 90% chance in one year.

SEE RELATED: Retinal Vein Occlusion

Other complications of untreated hypertension include:

• Heart disease, including angina pectoris, irregular heartbeat, heart attack and heart failure

• Kidney failure

• Brain stroke, especially the hemorrhagic type

READ MORE: Types of diabetic eye problems

Treatment

In the case of hypertensive retinopathy, the best treatment is prevention or treatment of hypertension. However, certain ocular complications can be treated medically or surgically.

For example:

• Retinal neovascularization can be treated with surgery or injections of medications into the eye.

• Vitreous hemorrhage can be treated with surgery.

• Treatment for retinal detachment is surgery.

• Glaucoma treatment options can include medication and surgery.

• Retinal macroaneurysm can be treated with surgery.

Prevention

Hypertensive retinopathy is prevented by reducing blood pressure. The World Health Organization recommends the following preventative measures:

Dietary changes

• Reduce salt intake to less than 5 grams daily

• Eliminate trans fats in the diet

• Eat more fruits and vegetables

• Reduce foods with saturated fats

Lifestyle changes

• Be physically active

• Reduce alcohol intake

• Avoid tobacco use

• Manage stress

Manage blood pressure

• Regularly check blood pressure

• Treat blood pressure 

• Manage other health conditions

When should I see a doctor?

If you’ve been diagnosed with high blood pressure, it is important to have regular comprehensive eye exams to monitor for any eye complications. Dietary and lifestyle changes and good blood pressure management are an essential part of protecting your long-term eye health.

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Page published on Monday, October 31, 2022

Page updated on Monday, October 31, 2022

Medically reviewed on Friday, October 14, 2022