Don't overlook blood pressure control when you have glaucoma

Your glaucoma seems to be getting worse, and you're not sure why. You're doing everything your doctor has recommended to fight the vision-robbing disease, but it continues marching forward. As you worry about reasons for the progression and how to stop it, consider your blood pressure: doctors increasingly suspect that high or low blood pressure might be a stealthy yet powerful contributor.

What is glaucoma?

Glaucoma is an umbrella term for a group of eye diseases that progressively damage the optic nerves (which carry information about vision from the eyes to the brain).

The nerve damage typically develops when pressure is too high inside the eye, often due to a backup of fluid due to diseased or blocked drains in the eye. Examples of glaucoma include open-angle glaucoma, which occurs gradually, and closed-angle glaucoma, which often comes on quickly.

Optic nerve damage can also occur with normal eye pressure (normal-tension glaucoma), a result of fragile optic nerves, pressure in the brain, or abnormal blood flow to the optic nerve.

Low blood pressure and glaucoma

Your eyes get oxygen and other important nutrients from blood. If blood pressure is too low, blood flow to the optic nerves might decrease. As a result, your optic nerves might not get enough nourishment and might suffer damage. "An optic nerve with existing glaucoma might then be more vulnerable to damage from high pressure inside the eye," says Dr. Lucy Shen, an ophthalmologist who specializes in glaucoma at Harvard-affiliated Massachusetts Eye and Ear. She notes that the link between low blood pressure and glaucoma is a widely accepted idea that has been confirmed (but not proved conclusively) in numerous studies among various groups of people.

High blood pressure and glaucoma

The link between glaucoma and high blood pressure is also a theory, but it's not as well established as the connection with low blood pressure.

"It could be that high blood pressure — the same condition that leads to heart disease and stroke — is damaging blood vessels that supply the optic nerves, keeping the nerves from getting enough blood, nutrients, and oxygen," Dr. Shen says. "It could also be that fluid in the eye is unable to drain well because pressure is too high in the small veins that carry fluid away."

Some evidence suggests that high blood pressure leads to faster glaucoma progression. For example, an observational study of about a thousand people with confirmed or suspected open-angle glaucoma, who were followed for about eight years, found that having blood pressure that was high or that fluctuated a lot over time seemed to speed up vision loss from glaucoma. The findings were published in the January 2025 issue of JAMA Ophthalmology.

What you can do

If your glaucoma is getting worse despite treatment, ask your ophthalmologist if it could be due to your blood pressure. If your blood pressure is high during the day — at or above 130/80 millimeters of mercury (mm Hg) — Dr. Shen says you'll need to work with your primary care physician or cardiologist to get it under control. That could mean starting a blood pressure medication, adjusting an existing prescription, or looking for other causes of high blood pressure, such as

• smoking
• a coexisting health condition (such as sleep apnea)
• a sedentary lifestyle
• an unhealthy diet
• high alcohol intake.

Controlling high blood pressure doesn't guarantee that the glaucoma will stabilize or that it will lower your eye pressure, but it will benefit your health in many ways.

If your blood pressure is normal during the day, Dr. Shen suggests measuring it at night, when blood pressure normally dips slightly. "If the bottom number of the measurement is below 50, that's too low," Dr. Shen says. "Maybe your blood pressure medication is working a bit too well. You might need to take it in the morning or take a different drug."

That fix might be more involved if you are not taking blood pressure drugs and your blood pressure is too low at night. For example, if that's the case and your eye pressure is normal, Dr. Shen says you might need to lower your eye pressure further, perhaps with surgery. (Even normal eye pressure can damage an optic nerve that isn't getting enough blood.) "Blood pressure and glaucoma have a complicated relationship," Dr. Shen says. "Blood pressure does not always affect eye pressure, but it's important to follow it regularly."

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