Chat Highlights
Your Blood Pressure and Glaucoma
September 26, 2001

Norma Devine, Editor

On Wednesday, September 26, 2001, Dr. Elliot Werner, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Your Blood Pressure and Glaucoma." 

Dr. Elliot Werner:  Hello, everybody.  Who has a question about blood pressure and glaucoma?  

P:  I have read that Alphagan can lower blood pressure and also raise it.  Is that correct?

Dr. Elliot Werner:  Alphagan is derived from a drug called clonidine, which is used to treat high blood pressure.  Alphagan can drop the blood pressure, but that is an unusual side effect.

P:  Does high or low blood pressure affect intraocular pressure (IOP)?  

Dr. Elliot Werner:  Very high blood pressure can raise the IOP, but the effects are more indirect, mainly on the circulation of the eye.

P:  Can Timoptic lower blood pressure?

Dr. Elliot Werner:  Yes, beta blockers like timolol can drop the blood pressure profoundly, and even cause fainting from low blood pressure and slow heart rate.  Beta blockers should be avoided in people with chronically low blood pressure.  

P:  How much does punctal occlusion mitigate the blood-pressure lowering effect of Timoptic?

Dr. Elliot Werner:  Occluding the puncta helps somewhat, but timolol can still be absorbed directly through the conjunctiva.  

P:  How does high blood pressure affect circulation?  

Dr. Elliot Werner:  High blood pressure is associated with small vessel disease in the body generally, and can cause decreased circulation in the optic nerve and retina.

P:  Then why would beta blockers be given to a glaucoma patient with a blood pressure of 90/40?  I have to be careful not to stand up too fast.

P:  Wow!  That's low.  

Dr. Elliot Werner:  I'm no

t sure, but if you can be treated with something else, it might be a good idea.

P:  I have been treated.  I don't use any glaucoma medications now.  My IOPs are 10 mm Hg in both eyes.  But I have retinal folds, macular puckers and low vision.   

Dr. Elliot Werner:  I'm sorry.  I don't know all of your clinical situation.

P:  I've had four trabs, one repair, and three to four blood injections, all to no avail. 

Dr. Elliot Werner:  Chronic low blood pressure is associated with poor perfusion of the optic nerve and has been shown to be associated with progression of glaucoma visual field damage.

P:  What is a good, safe drug to lower blood pressure in a glaucoma patient? 

Dr. Elliot Werner:  That depends on the patient and the patient's general health status.  Treatment needs to be individualized.

P:  How do calcium channel blockers fare, assuming no other problems?

Dr. Elliot Werner:  Calcium channel blockers combined with beta blockers can cause profound drops in blood pressure, which can be dangerous in glaucoma.

P:  Is any particular cause of elevated BP (e.g., adrenergic, renin-angiotensin) correlated more with high IOP than other causes?  

Dr. Elliot Werner:  High blood pressure caused by steroids, either from disease or given as treatment, is associated with increased IOP.  To my knowledge, the others are not.

P:  Yet we use some of the same meds to lower both BP and IOP.

P:  I took steroid drops for six months after a trabeculectomy.  Could this be the cause of my current high blood pressure?

Dr. Elliot Werner:  Steroid drops do not deliver enough steroid to the bloodstream to affect blood pressure.  

P:  What would be a "profound" drop in blood pressure?  

Dr. Elliot Werner:  Probably 30% below baseline.

P:  Why would the combination of a calcium channel blocker and a beta blocker be dangerous for a glaucoma patient to use? 

Dr. Elliot Werner:  Because the drugs can interact to lower blood pressure and perfusion of the optic nerve.  Blood pressure is like intraocular pressure in the sense that the body works best in the normal range.  Too low or too high blood pressure causes problems.  

P:  So it sounds like a patient needs to be really careful about blood pressure medications if he or she is on beta blockers and perhaps also Alphagan. 

Dr. Elliot Werner:   Interactions of blood pressure medications and glaucoma medications can be a real problem.  Communication between most eye docs and primary care docs needs to be improved.  

P:  When you say calcium channel blockers combined with beta blockers, do you mean beta blocker eye drops?

Dr. Elliot Werner:  Yes, problems from the interactions have been observed. 

P:  You're so right about poor communication between eye docs and PCP's (primary care physician).  My PCP does not seem to think blood pressure medications affect my glaucoma. 

P:  One glaucoma specialist recommended saying, "Doctor, I know that I need my blood pressure lowered, but I hope it can be done in a way that isn't going to make my glaucoma worse." 

P:  When I told my doctor I had glaucoma, she actually backed away from me -- like it was contagious!

P:  It appears that a pharmacist has more information about drug interactions than a doctor, at least in Canada.  

P:  I get more information at Wal-Mart. 

P:  Why isn't my blood pressure taken when I see an ophthalmologist?  

Dr. Elliot Werner:  Most ophthalmologists do not routinely take blood pressure, but maybe we should.  

P:  I take Avapro, Cardiazem, and Cosopt.  So far, everything is pretty good.  Does that sound like a likely combination to you?

Dr. Elliot Werner:  That's a common combination and may cause no problem.  It just needs to be carefully monitored and your PCP needs to know about your eye drops.

P:  You know, I'm not sure I told him I'm on the drops.  Thanks, Doctor.  Things kind of came on quickly, so I will mention it to him next visit.

Dr. Elliot Werner:  Many patients do not seem to think of their eye drops as medications, and do not tell their PCPs that they are using them. 

P:  What is the relationship between high blood pressure and high intraocular pressure?  

Dr. Elliot Werner:  It is not well understood.  It probably has to do with the blood volume in the eye, but it may be hormonal.

P:  Is there anything other than increasing my salt intake to raise my blood pressure?  

Dr. Elliot Werner:  It is very difficult to raise chronic low blood pressure. 

P:  My husband's doctor told him to eat salt, too, to try to increase his low blood pressure.

P:  Are blood pressure problems more common in glaucoma patients? 

Dr. Elliot Werner:  I am not aware of any data that blood pressure problems are more common in glaucoma patients.  Both conditions are very common and therefore often coexist.

P:  Does having too much iron in your blood have any effect on blood pressure and glaucoma?  

Dr. Elliot Werner:  Anemia reduces the oxygen carrying of the blood and can affect the function of the eye and other structures.

P:  What do you consider too-high blood pressure for a glaucoma patient?  

Dr. Elliot Werner:  That's a tough question to answer, but hypertension is a very dangerous disease and should be treated to normalize the blood pressure.  Three U.S. presidents, Theodore Roosevelt, Woodrow Wilson and Franklin Roosevelt, all died from complications of high blood pressure.  

P:  Is there a non-invasive way to measure episcleral venous pressure, which would in part determine the outflow resistance of the eye to aqueous humor?

P:  What on earth does that mean? 

Dr. Elliot Werner:  There are devices to measure episcleral venous pressure.  They are available at most academic eye centers, but it is not done much as it doesn't usually yield much useful information.  There are some glaucomas caused by elevated episcleral venous pressure, but they are uncommon.

P:  Doesn't the episcleral venous pressure determine the lowest IOP that could theoretically be achieved without a trabeculectomy?

Dr. Elliot Werner:  Yes, but it is not usually an issue in most glaucoma patients.  Time for me to leave.  Thank you all.  I'll be back on Halloween and the last Wednesday of each month.    

End of highlights for September 26, 2001.

On October 3, Dr. Wilson discussed "Exercise and Glaucoma" in the Chat room. Click here for highlights of that meeting.

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