What is high blood pressure and why should it be treated?
Blood pressure is recorded in two numbers (e.g. 120/80 mmHg). These represent the pressure of blood flow when the heart muscle contracts and relaxes.
The range of normal blood pressure for healthy adults is 90/60 to 120/80 mmHg.4 A reading above 140/90 mmHg is considered high, and when several high readings are recorded over time, a diagnosis of high blood pressure or hypertension can be made.
Most people with hypertension experience no symptoms at all, though some may experience sweating, blushing, anxiety and difficulty sleeping. Any readings above 180/120 mmHg indicates what’s known as a hypertensive crisis and requires immediate medical attention. Symptoms of this include headache, chest pain, and anxiety.5
It’s important to keep blood pressure within the normal limits because it is one of the main risk factors for heart disease.6 High blood pressure can also increase the risk of stroke, chronic kidney disease, and certain types of dementia.7 In fact, when untreated, it can have a big impact on the body — so regular blood pressure testing is advised.6
How does high blood pressure affect the eyes?
Untreated hypertension can lead to a range of eye diseases. One of the conditions it can cause, for example, is hypertensive retinopathy, where the tiny arteries that supply blood to the retina are damaged. If blood pressure is not controlled, this can lead to more serious eye damage, including bleeding, blurred vision, and complete loss of vision.11
High blood pressure may also lead to the build-up of fluid under the retina, which can cause choroidopathy, a condition that can lead to distortion of vision or impaired vision due to scarring in the eye.11
Hypertension may also block blood flow and cause damage to the optic nerve. This is known as optic neuropathy and can result in the death of nerve cells in the eye, leading to bleeding within the eye or vision loss.11
High blood pressure and glaucoma: is there a link?
One particular condition that has been linked to high blood pressure is glaucoma, in which fluid builds up in the front part of the eye. This excess fluid increases the pressure in the eye, which damages the optic nerve, leading to progressive loss of vision.
Blood pressure and glaucoma share a complex relationship. Very high blood pressure can lead to an increase in intraocular pressure (pressure inside the eye), which is one of the main causes of glaucoma.
Low blood pressure is also not desirable, as it can lead to insufficient blood supply to the optic nerve.12 This is an important consideration because over-treatment of hypertension with medications can lead to a situation where the blood pressure is too low and can cause damage to the eye. The key is to avoid extremes of blood pressure and to let your optometrist or ophthalmologist know if you’re taking any antihypertensive medications.
What to do to reduce the impact of high blood pressure on your eyes
If you have high blood pressure, your GP might recommend that you take antihypertensive medications to bring your blood pressure numbers down. There are also a number of lifestyle changes you can try that can lower your blood pressure and reduce the risk of health problems, including heart disease and eye complications. These may help you avoid, delay, or reduce the need for antihypertensive therapy:13
Maintain a healthy BMI (body mass index)
Get regular exercise, at least 30 minutes most days of the week
Eat a healthy diet with fruits, vegetables, whole grains, and low-fat dairy
Reduce salt intake (read food labels, don’t add extra salt, eat fewer processed foods)
Limit alcohol consumption to moderate amounts
Cut back on caffeine
Reduce mental stress
It can also be useful to monitor your blood pressure at home and see your doctor periodically for health checks. Ultimately, a proactive approach to blood pressure management can help prevent many of the eye complications of hypertension, such as glaucoma. If you think your blood pressure may be high, it’s important to seek advice from your GP.
If you’ve been having any problems with your eyesight, book an appointment at your local Specsavers.
For more information on glaucoma causes, you can find it in our dedicated glaucoma causes resource.
1. WHO. (no date). Raised blood pressure. [Online]. Available at: https://www.who.int/gho/ncd/risk_factors/blood_pressure_prevalence_text/en/ [Accessed 17 May 2019].
2. Blood Pressure UK. (no date). Blood pressure facts and figures. [Online]. Available at: http://www.bloodpressureuk.org/mediacentre/Factsandfigures [Accessed 17 May 2019].
3. Public Health England. (2017). Health matters: combating high blood pressure. [Online]. Available at: https://www.gov.uk/government/publications/health-matters-combating-high-blood-pressure/health-matters-combating-high-blood-pressure [Accessed 17 May 2019].
4. BHF. (no date). High blood pressure. [Online]. Available at: https://www.bhf.org.uk/informationsupport/risk-factors/high-blood-pressure [Accessed 17 May 2019].
5. Mayo Clinic (no date). Hypertensive crisis: What are the symptoms? [Online]. Available at: https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/expert-answers/hypertensive-crisis/faq-20058491 [Accessed 17 May 2019].
6. WHO. (no date). Fact sheet on cardiovascular diseases. [Online]. Available at: https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds) [Accessed 17 May 2019].
7. Mayo Clinic (no date). High blood pressure (hypertension) [Online]. Available at: https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/symptoms-causes/syc-20373410 [Accessed 17 May 2019].
8. Britannica (no date). Hypertension pathology. [Online]. Available at: https://www.britannica.com/science/hypertension [Accessed 17 May 2019].
9. CDC (no date). High blood pressure family history. [Online]. Available at: https://www.cdc.gov/bloodpressure/family_history.htm [Accessed 17 May 2019].
10. Mayo Clinic (no date). Secondary hypertension [Online]. Available at: https://www.mayoclinic.org/diseases-conditions/secondary-hypertension/symptoms-causes/syc-20350679 [Accessed 17 May 2019].
11. Mayo Clinic (no date). High blood pressure dangers: Hypertension’s effects on your body [Online]. Available at: https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/high-blood-pressure/art-20045868 [Accessed 17 May 2019].
12. He, Z., et al. (2011). The role of blood pressure in glaucoma. Clinical and Experimental Optometry, 94(133-149). [Online]. Available at: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1444-0938.2010.00564.x [Accessed 17 May 2019].
13. Mayo Clinic (no date). 10 ways to control high blood pressure without medication [Online]. Available at: https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/in-depth/high-blood-pressure/art-20046974 [Accessed 17 May 2019].