If your glaucoma seems to be getting worse, even though you’re using your drops faithfully, keeping appointments, and doing all the “right” things, you’re not imagining it. Sometimes, glaucoma progresses because of something outside the eye.

One often-overlooked factor? Your blood pressure.

Experts at Massachusetts Eye and Ear, including glaucoma specialist Dr. Lucy Shen, emphasize that both high and low blood pressure can influence how well your optic nerve is nourished, and that this can affect glaucoma progression even when your eye pressure (IOP) looks stable. As Dr. Shen explains, “Blood pressure and glaucoma have a complicated relationship. Blood pressure does not always affect eye pressure, but it’s important to follow it regularly.”

Below is what their guidance means for you, and what you may want to discuss with your care team. *

How Glaucoma Works and Why Blood Flow Matters

Glaucoma damages the optic nerve, the cable that carries visual information from your eye to your brain. Elevated eye pressure is the most common culprit, but not the only one.

Your optic nerve depends on healthy, steady blood flow. When blood flow drops too low or pressure inside tiny vessels rises too high, the nerve becomes more vulnerable.

Mass Eye and Ear specialists note that even people with normal-tension glaucoma, whose eye pressure isn’t particularly high, can lose vision if the nerve isn’t getting enough oxygen and nutrients.

When Blood Pressure Is Too Low

Your optic nerve needs a minimum level of blood flow to stay healthy. If your blood pressure dips too low, especially at night, the nerve may not get what it needs.

Dr. Shen puts it simply: “If blood pressure is too low, blood flow to the optic nerve might decrease… and an optic nerve with existing glaucoma might then be more vulnerable to damage.”

You might be at risk for these nightly drops if you:

• Take blood pressure medication at night
• Run naturally low pressures
• Frequently feel light-headed or faint
• Have vascular conditions or circulation issues

If your glaucoma is progressing despite good IOP control, your doctor may recommend checking nighttime blood pressure, something not typically measured at regular appointments.

When Blood Pressure Is Too High

The link between hypertension and glaucoma isn’t as well-proven as the low-BP connection, but experts believe it could play a role. Constant high pressure can damage the tiny vessels that feed the optic nerve.

According to Dr. Shen: “High blood pressure may damage blood vessels that supply the optic nerves, keeping them from getting enough blood, nutrients, and oxygen.”

Some research backs this up. One eight-year study found that patients with high or highly fluctuating blood pressure experienced faster glaucoma progression.

What You Can Do Right Now

1. Ask your ophthalmologist whether blood pressure may be part of the picture

If progression continues despite treatment, bring it up. Your doctor may recommend:

• 24-hour blood pressure monitoring
• Adjusting your BP medications
• Collaborating with your primary care doctor or cardiologist

2. Check daytime AND nighttime readings

Daytime BP at or above 130/80 mmHg should be addressed. But nighttime pressure matters too.

Dr. Shen notes: “If the bottom number is below 50, that’s too low.” This could mean your medication timing or dose needs an adjustment.

3. Review lifestyle factors that influence BP

These habits can push blood pressure up or down:

• Smoking
• High salt intake
• Sedentary habits
• Alcohol use
• Sleep apnea
• Stress levels

Discussing these with your care team can help stabilize both your BP and your glaucoma.

4. Don’t change your medications without guidance

Stopping BP or glaucoma medications on your own can be dangerous. Always check with your providers first.

The Bottom Line for You

Blood pressure may not be the first thing you think of when you think about glaucoma, but it can absolutely influence how quickly the disease progresses. If your optic nerve isn’t getting steady blood flow, even “normal” eye pressure may still cause damage.

Monitoring your blood pressure, especially at night, and working with your healthcare team to optimize both BP and IOP management could help protect your vision long-term.

If you’ve noticed changes in your vision despite doing everything right, bring this up at your next appointment. Your care team may uncover something important.

* Harvard Health (May 1, 2025). “Don’t overlook blood pressure control when you have glaucoma.” health.harvard.edu

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