Chat Highlights
The Role of Blood Flow
March 21, 2001

Norma Devine, Editor

On Wednesday, March 21, 2001, Dr. Jeff Henderer, a glaucoma specialist at Wills, and the glaucoma chat group discussed "The Role of Blood Flow." 

Moderator:  Welcome, Dr. Henderer.  Tonight the topic is "The Role of Blood Flow."  Doctor, do you think that having poor blood flow is part of having glaucoma?

Dr. Henderer:  Yes, in certain cases blood flow is probably very important. This may be especially true in normal-tension glaucoma (NTG).  Remember that the NTG study showed benefits from IOP reduction of 30%.  

P:   The big NTG study found that some NTG patients benefit from IOP being lowered by 30%.  The question is: Which NTG patients will benefit and which patients will not?    

P:  Dr. Jeff, how do you know if you have poor blood flow?

Dr. Henderer:  There is no way to tell unless you have low blood pressure.   Low blood pressure is almost certainly a risk factor for glaucoma.  And it is tough to measure blood flow to the nerve.  Alon Harris at Indiana University in Indianapolis is the expert in that area.  We are trying to get started on that research at Wills, too.   Some of Dr. Harris' work seems to indicate that estrogen is helpful.

P:  I've been taking estrogen for years, but look where I am now:  half  blind in one eye.  

P:  Actually, I hope estrogen is not the answer! (He says in his most manly voice.)

Dr. Henderer:  Estrogen is only part of the answer. We haven't identified the other factors.

Moderator:  What does the estrogen do, if you know?

Dr. Henderer:  I'm not entirely sure of  the mechanism, but estrogen probably acts through a pathway similar to that involved in protection against heart attacks.

P:  I live in Cincinnati,  just 90 minutes from Indianapolis.  I may contact Dr. Harris to see if I may join the study.

P:  Is it relevant to discuss the relationship of blood flow to blood pressure, both low and high?

Dr. Henderer:  High blood pressure has been linked to high eye pressure. However, it has not been linked to glaucoma.  Low blood pressure is more of a problem as the eye does not get enough blood. That's the theory.

P:  What else should we do to try to increase blood flow to the optic nerve besides exercise, follow a low-fat diet, control weight, and take vitamin E and aspirin?   What about taking ginkgo biloba?

Dr. Henderer:  There is a school of thought that ginkgo biloba might help to increase  blood flow by decreasing blood viscosity (the stickiness of blood). This might be helpful, but if you're already taking aspirin, I wouldn't recommend it.

P:  Will you please explain the relationship between Timoptic and blood flow?

Dr. Henderer:  The evidence is inconclusive for the class of medicines, the beta-blockers.  Timolol probably doesn't help blood flow, but Betoptic S might be neuroprotective due to the postulated activity of the calcium channel blocker. 

P:  Is there a test that measures blood viscosity?

Dr. Henderer:  Sorry, I don't know of one off-hand. I suppose there is.  I'm just not sure. 

P:  I have a good ophthalmologist, but he has never taken my blood pressure or asked about it.    Is this something he should be aware of, or that I should make him aware of even though blood pressure medications are listed on my chart?  

Dr. Henderer:  Yes, I would make him aware of it.

P:  I note a generally less positive approach to life since I learned that I had glaucoma and started using eye drops.  The warning on the eye drops  suggests that they may be depressants.  Do you have any thoughts on that?  

Dr. Henderer:  Yes, depression is one of the side effects. If you have symptoms of depression, tell your doctor.  

P:  Did you say that calcium channel blockers are neuroprotective?  

Dr. Henderer:  Calcium channel blockers MAY be protective. There are mixed data on that subject.  Most researchers have abandoned the studies because calcium channel blockers may cause hypotension (low blood pressure). 

P:  Can Timoptic reduce blood pressure in some patients at night and lower blood flow to the optic nerve enough to do harm?

Dr. Henderer:  Dr. Hayreh in Iowa published a paper about that subject.  That was his postulated mechanism.  It has not been confirmed by others, that I know of.   You can find information about Dr. Hayreh's study in the December 1999 issue of the American Journal of  Ophthalmology.

P:  I don't want to be a pain about this, but if  blood flow is so important, what treatments should we be considering?

Dr. Henderer:  You aren't being a pain about it.  People are basing careers on that question.  We just don't know right now.

P:  Thanks, doctor.  I hope their careers are successful in time to save my sight.

P:  What role does the permeability of the blood-aqueous barrier play, particularly in primary open-angle glaucoma?  

Dr. Henderer:  I don't know.  That is usually thought to be more of an issue in inflammation, which may or may not lead to high pressure.

P:  Do you recommend salt intake for low blood pressure at night for NTG patients?

Dr. Henderer:  That's a great question.  I don't know the answer. I don't think it has been studied.

P:  I often bend over from the waist to pull weeds in my garden.  Could that cause damage to my optic nerve by increasing the IOP?   

Dr. Henderer:  Probably not. But I would crouch down.

P:  Sometimes I get an uncomfortable feeling of great pressure in my eyes when bending over for a brief time.  Is that because of  glaucoma?    

Dr. Henderer:  That's probably not caused by glaucoma.  I would guess it is caused by fluid building up around the eye. 

On March 28, Dr. Wilson discussed "Testing in Glaucoma" in the Chat room. Click here for highlights of that meeting.

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