Both low and high blood pressure may increase the risk of eye disease, such as glaucoma.* Traditional risk factors for glaucoma include elevated eye pressure, family history, age, and ethnicity. In people with glaucoma who already have high intraocular pressure (IOP), abnormal blood pressure can exacerbate one’s IOP. For those who don’t have high IOP, uncontrolled blood pressure could lead to eye pressure issues.

High blood pressure can impact those with glaucoma because it may raise eye pressure. Moderate to low blood pressure, however, can also cause problems. This is because the optic nerve must receive adequate blood flow to function properly, and low blood pressure may prevent this from happening effectively.

High blood pressure

The research is not conclusive on whether blood pressure causes glaucoma, but it is known that high blood pressure, or hypertension, increases eye pressure, which could progress the disease. This is because high blood pressure increases the production of aqueous humor (AH), or fluid, in the eye and affects the eye drainage system.

Fortunately, the level that eye pressure increases is minimal. It is thought that blood pressure needs to increase by 10 mmHg for eye pressure to raise 0.26 mmHg. In addition to an increase in eye pressure and the possible risk of glaucoma, high blood pressure can lead to damage to the retina—resulting in hypertensive retinopathy, or damage to the retina and circulation to it.

Therefore, getting blood pressure under control and at normal levels is crucial, especially for those diagnosed with or at risk of glaucoma.

Low blood pressure

More data shows that hypotension, or low blood pressure, is a risk factor for developing glaucoma. In particular, ocular perfusion pressure (the difference between blood pressure and eye pressure) puts people more at risk of eye disease, like glaucoma. 

Ocular perfusion pressure not only occurs in those with naturally low blood pressure but also in anyone who is overtreated (typically with medication) for hypertension or high blood pressure.

Blood and eye pressure levels change throughout the day. For example, blood pressure can naturally dip at night, which can increase eye pressure overnight, leading to optic nerve damage.

Talking to your doctor about blood pressure

If you have glaucoma, it’s important to have your blood pressure checked regularly. If you already have hypertension or hypotension, you should discuss the connection between blood and eye pressure at your next doctor’s appointment to see if any precautionary steps should be taken.

Other things to discuss with your doctor include:

• If you’re using a topical beta blocker (eye drops), a commonly used glaucoma medication, in combination with systemic beta blockers (taken orally) used to treat high blood pressure, this can sometimes lead to lower-than-desired blood pressure and decreased heart rate. It’s important to talk about this potential interaction with your doctor.
• Some people with glaucoma also have chronic kidney disease (CKD). If you’re undergoing dialysis treatment, you may experience a fluctuation and dip in your blood pressure, which could lead to low ocular perfusion pressure. Therefore, it’s important to discuss with your doctor whether your dialysis protocol should be modified to ensure reduced risk to your optic nerve.

Overall, it is best to try to maintain your blood pressure at a normal level. Blood pressure levels that are too low or too high should be rare or infrequent events. Ongoing research continues to look at the relationship between blood pressure and glaucoma so that doctors can better help their glaucoma patients.

Additional information on this topic can be found in the article, “Blood Pressure and Glaucoma,” by the BrightFocus Foundation. 

*Louis, C. (2019, June 3). Does Blood Pressure Affect Glaucoma? Glaucoma Research Foundation. https://www.glaucoma.org/glaucoma/does-blood-pressure-affect-glaucoma.php

Any sources from outside of Prevent Blindness do not imply an endorsement from Prevent Blindness. The contents of the material used are the responsibility of the authoring organization, Responsum Health.