Blood Pressure and Blurred Vision

Content provided by the Faculty of the Harvard Medical School

Blood Pressure and Blurred Vision

Question:

Can high blood pressure cause blurred vision?

Answer:

High blood pressure is often referred to as the "silent killer" because most people with high blood pressure don't have symptoms. They only know if their pressure is too high by getting it measured.

High blood pressure is very common, and blurred vision, which has many different causes, also is very common. In any person who has both, it is most likely that the blurred vision is not directly related to high blood pressure, especially if the blood pressure is just slightly above the normal range.

That said, very high blood pressure that goes untreated can lead to a situation called malignant hypertension. In this condition, the brain and the eyes can be affected.

With malignant hypertension, there can be swelling in any part of the brain. The back part of the brain, which has direct nervous connections with the eyes, is especially vulnerable when blood pressures stay extremely high. The swelling causes a noticeable change in vision. The good news is that vision improves when blood pressure is controlled.

When there is more diffuse brain swelling, the nerve that connects the brain to the eye (the optic nerve) also can swell. This will make vision worse. In addition, the small blood vessels that send oxygen and nutrients to the eye can go into spasm and leak, affecting vision.

Although not a direct cause, untreated high blood pressure greatly increases the risk of stroke. Several different types of strokes result in vision problems. Usually there are other symptoms, not just blurred vision.

Howard LeWine, M.D., is chief editor of Internet Publishing at Harvard Health Publications. He is recognized as an outstanding clinician and teacher and is a recipient of the Internal Medicine Teacher of the Year award at Brigham and Women's Hospital. Dr. LeWine continues to practice Internal Medicine; most recently he became a hospitalist after practicing primary care for over 20 years.

Last updated:	July 20, 2009