How High Blood Pressure Can Affect Your Vision

High blood pressure usually does not present noticeable symptoms, and often the only way to know if you have it is to have consistent blood pressure tests. Hypertension can affect different parts of the body, including the eyes. Hypertensive retinopathy can lead to damage to the optic nerve and cause short- and long-term blindness.

What Is High Blood Pressure?

High blood pressure, or hypertension, is when the blood your heart is pumping exerts too much force against the walls of your arteries. Your body relies primarily on arteries to deliver blood (with oxygen and nutrients) to various organs.

When you have hypertension, these major vessels may become damaged at specific sites in your body. The organ where the vascular damage has occurred, such as the heart, brain or eyes, can malfunction, sometimes with severe outcomes for the patient.

You may not know you have hypertension unless you have a blood-pressure (BP) test. The condition does not have any noticeable early signs or symptoms.

But symptoms sometimes occur, especially in advanced cases. For example, people may experience:

• Morning headaches
• Vision problems
• Irregular heart rates
• Nose bleeding 
• Chest pain

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Hypertensive Retinopathy

The retina enables you to see by detecting light and then sending signals to the brain for interpretation. Hypertensive retinopathy occurs when the vessels supplying blood to this important tissue layer at the back of your eye are damaged.  

In the retina, these arteries are unique in that they can “automatically” control blood flow. They will normally constrict without problems to absorb an initial spike in blood pressure.

However, their “auto response” has a limit that gradually gets reached if your blood press continues to rise. Beyond a certain BP threshold, the muscle layer and the membrane lining the inside of your retinal blood vessels begin to succumb to the excess force being exerted.

Damage to the vessels (hypertensive retinopathy) occurs over time in these main phases:

• Phase 1: Initial spike in blood pressure causes narrowing of retinal blood vessels and restriction of blood flow.
• Phase 2: Narrowing of the arteries increases with high blood pressure as certain changes occur in the vessel wall. Wall layers thicken, enlarge and degenerate.
• Phase 3: Severe hypertensive retinopathy occurs, with serious damage to retinal blood vessels. The damaged arteries are leaking blood and there may be noticeable signs on the retina upon inspection using special instruments.
• Phase 4: Also called malignant hypertension, this phase may involve serious vision damage. Blood flow to the optic nerve is restricted among other detectable signs.  

Symptoms

When you have malignant hypertensive retinopathy, you may experience various outward symptoms, including:

• Eye pain
• Headaches
• Reduced vision 

Even when no early hypertensive retinopathy symptoms are showing, detailed eye exams may detect an occurrence of retinal damage. Among the detectable signs of the condition are:

• Fluid buildups in the eye (edema)
• Dot-blot and flame-like shapes that indicate bleeding in the retina
• Cotton-wool spots or fluffy white patches that indicate retinal ischemia (inadequate supply of blood to the retina)
• The existence of hard exudates (plaque-like material forms in the outer layers of the retina because of accumulation of fluid inside)
• The presence of Elschnig’s spots (yellow or red halos around black spots appear on the retina)

Diagnosis

There are several ways to test for hypertensive retinopathy in your eyes, all of which incorporate a blood pressure test. The primary eye exams for retinal damage include:

• Ophthalmologic exam 
• Fluorescein angiography (FA)

Ophthalmologic Exam 

During an ophthalmoscopic exam, or fundoscopy, your eye doctor (usually an ophthalmologist) will examine the back area of your eye for problems. The area under examination comprises the retina, retinal blood vessels and the optic disc.

Your doctor may place drops in your eye to dilate your pupil for a more accurate view of the target structures. Your doctor will then use an ophthalmoscope to point a beam of light onto the retina through the widened pupil.

With the instrument, the doctor can obtain images showing signs of structural abnormalities on any part of the fungus. The test can detect outcomes of hypertension damage on the retina, such as:

• Flamed-shaped or dot-blot retinal bleeding 
• Cotton wool spots
• Optic nerve damage, such as swelling of the optic disk

Fluorescein Angiography (FA)

Fluorescein angiography is a procedure for checking blood circulation through retinal blood vessels. It involves taking pictures of the back of your eye using a camera-like instrument.

Your doctor will then inject a special dye into a vein and take another set of pictures. Looking at these images, your doctor can easily assess movement of the dye (and blood) through the vessels supplying your retina.

This test can reveal several retinal issues due to hypertensive retinopathy, including:

• Poor circulation
• Blockage of vessels
• Leaking vessels

Hypertensive retinopathy has similar retinal symptoms to diabetic retinopathy and a few other conditions that cause retinal damage. For this reason, your physician will perform differential diagnosis, which entails examining the patient for any other suspected systemic disease.

Treatment

If you have hypertensive retinopathy, you can avoid vision loss by seeking treatment and adopting a healthier lifestyle. Left untreated, this condition can eventually result in optic neuropathy (nerve damage), which can cause short-term or permanent blindness. 

Blood pressure control is the only way to treat moderate or severe hypertensive retinopathy. Your doctor has to implement the treatment in a controlled manner since a sharp drop in your BP may cause irreversible damage to affected parts of the eye.

The ultimate treatment goal for most hypertensive patients is to lower blood pressure to a safe level in the next two to three months. Here are some of the BP drugs your doctor may prescribe for outpatient administration:

• Angiotensin-converting enzyme (ACE) inhibitors: These drugs can lower your blood pressure by keeping your blood vessels relaxed.
• Diuretics: Taking these blood pressure control pills helps decrease the amount of fluid circulating through your blood vessels.
• Calcium channel blockers: These drugs help keep your blood pressure low by blocking calcium from entering the cells of your blood vessels. Calcium promotes contraction of arteries, which can increase your blood pressure. 

Prevention

Keeping your blood pressure down consistently by maintaining a healthy lifestyle is the surest way to prevent hypertensive retinopathy. Practical suggestions for this include:

• Consume less salt (below 5g a day)
• Incorporate a fruit- and vegetable-heavy diet daily
• Mind your physical fitness (stay active and work out more regularly)
• Avoid or reduce alcohol consumption
• Avoid or limit consumption of unhealthy fats, including saturated fats and trans fats

References

1. Hypertensive Retinopathy. (December 2021). American Academy of Ophthalmology.

2. Hypertension. (August 2021). World Health Organization.

3. Hypertensive Retinopathy. (July 2021). StatPearls.

4. Ophthalmoscopy in the 21st Century. (January 2018). American Journal of Neurology.