Chat Highlights
Normal Tension Glaucoma
March 22, 2000

Norma Devine, Editor

On Wednesday, March 22, 2000, Dr. Rick Wilson, a glaucoma specialist at Wills, and the Glaucoma Chat Group discussed "Normal Tension Glaucoma." Here are some highlights from the evening.

Moderator:  Dr. Wilson, the topic is Normal Tension Glaucoma (NTG).

P:  How does the typical progression of NTG differ from progression in other types of glaucoma?

Dr. Wilson:  If a patient has advanced glaucoma as a result of IOPs of 30 mmHg for five years, then the nerve is "softened up" enough to sustain damage at IOPs of 12 to 18. That patient would have Primary Open Angle Glaucoma with low tension progression.

P:  Is Xalatan supposed to stop or slow the progression of glaucoma?

Dr. Wilson:  Xalatan is supposed to control IOP and prevent further damage.

P:  Dr. Rick,  I've never had a pressure over 20.

Dr. Wilson:   A typical NTG patient, like my Dad, would never have had an IOP above 22. When I discovered his glaucoma, his IOP was 18 mmHg.

P:   So what happened to him? What did you do?

Dr. Wilson: I placed him on medication, which held him for 10 years. Then a laser held him another five years. He is about to have a cataract and glaucoma procedure in one eye. Unfortunately, he also has macular degeneration. That's a bad combination: one disease that takes the side vision and one that takes the central vision.

P:  Is Xalatan used for NTG? I've been on it for three months and my pressure actually went UP in one eye.

P:  Does Xalatan work for everyone?

P:  Xalatan did not work for me. I have open-angle glaucoma.

P:  Unfortunately, sometimes the drops do not work..

P:  Could these drops worsen the condition in any way? By that I mean, if the eye gets adjusted to lower and lower pressure, could even a slight increase damage it?

Dr. Wilson:  Good question. We think not. Did you have a one-eyed therapeutic trial? That is, did you have medication added to one eye to see if the IOP dropped in relation to the control eye, without additional meds.

P:  Yes. When I went back, they thought it was working fine, so they put me on Xalatan drops in both eyes.

Dr. Wilson:  Sometimes it is hard to figure out.

P:  Dr. I have borderline high blood pressure.  What does that mean in terms of NTG?

Dr. Wilson:  Hypertension is actually protective of glaucoma damage early on, until you get the changes of chronic hypertension on the blood vessels. Then hypertension, especially when treated, is a risk factor.

P:  I have high blood pressure, too. Dr.Wilson, more in layman terms, please, what are the changes in blood vessels?

Dr. Wilson: The changes with hypertension are hardening of the vessels, with decreased responsiveness to changes in blood flow, i.e., a decreased ability to adjust the flow of blood to the eye, depending upon circumstances.

P:  A poll of patients showed that many of us younger patients have NTG. I thought NTG was something much older patients get.

Dr. Wilson: Most of the younger NTG patients are 40- to 50-year-old women, with low systemic blood pressure.

P:  NTG is supposed to affect mostly older people. Do you see quite a few younger people with NTG, too?

Dr. Wilson: Not very many.

P:  In the younger women, where is the loss?

Dr. Wilson:  Usually just off the central vision.

P:  The drops stop working after a while. Would it work better if they were used in a round robin fashion? I guess like crop rotation.

Dr. Wilson:  Some drops, like Iopidine, lose effectiveness. Others, like Timolol are said not to. Xalatan and Propine actually are more effective with time.

P:  What about Reynaud's Syndrome?

Dr. Wilson:  Reynaud's Syndrome is a disease in which vessels go into spasm for some pathologic reason, decreasing blood flow to the organ in question. If that organ is the eye, then Low Tension Glaucoma can result.

P:  You say Xalatan can be more effective with time. How long?

Dr. Wilson: Three months.

P: That is after three months.

Dr. Wilson: The effectiveness of Xalatan seems to increase gradually for about three months.

P:  And then remains stable for a long time without losing effectiveness?

Dr. Wilson:  Yes.

P:  Does Alphagan help make the nerves stronger?

Dr. Wilson: It's uncertain, but rather doubtful, other than the effect of lowering IOP. The company is suggesting that to doctors, based on crushing rat optic nerves and watching which fibers survive. That doesn't sound like glaucoma to me, but there may be some carryover (effect).

P:   Have any studies been done with biofeedback to lower iops?

Dr. Wilson:  Relaxation and decreased blood pressure will lower IOP, as will exercise.

P:  Can you tell me why it is okay to use antihistamines after a trabeculectomy?

Dr. Wilson:  Antihistamines are only dangerous to those who have narrow angles that have not been treated.

P:  How do you decide how low the pressure should be for NTG?

Dr. Wilson:  One usually drops the IOP by 30 to 40% from the levels that had been causing glaucoma damage.

P:  I have open-angle glaucoma. Why are steroids a no-no?

Dr. Wilson:  Steroids can cause your IOP to go up.

P:  Why are steroids not recommended for open angle? My doctor just put me on them for my allergies and I told him I had glaucoma.

Dr. Wilson:  Steroids usually make your IOP go up if you have glaucoma and take them for any length of time. If you have allergies, Pantanol would be a better choice than steroids, as a rule.

P: Dr. Wilson, what is the percentage rate for successful trabs on NTG patients?

Dr. Wilson: The rate should still be high, in the 80 % range, I would guess.

P: I am getting a second opinion soon about my normal-tension glaucoma. I feel guilty about that--as if I don't trust my doctor.

P:  Always get a second opinion.

P: I second that.

P:  You are the one who needs to feel comfortable.

P:  Get a second opinion. Do not worry about "hurting your doctor's feelings" or anything like that. You have to consider YOU are dealing with YOUR sight.

P: I told my doctor I was getting a second opinion. No problem with her at all.

P:  If the doctor doesn't like it, that's not the doctor for you.

Dr. Wilson: Patients often get second opinions. I 'm happy when my patients get a second opinion. It should reassure them they are doing all they can.

P:  Thank you everyone. That helped tons!

P:  When having a laser PI (Peripheral Iridotomy) done, what is the average number of times to zap someone?

Dr. Wilson:  One to six.

P: I was zapped 25 times on Tuesday, and found out it had closed up overnight.

Dr. Wilson:  Do you have a thick, brown iris?

P:  The doctor said something about hitting it 70 times due to a dark iris. Does this seem right?

Dr. Wilson:  One worries if too much energy is put into the eye. It can cause inflammation. It's hard to be more specific without seeing you in person to see what's going on.

P:  I was zapped many times. Not all of us are average.

P: How do you differentiate between side effects from drugs and from allergies?

Dr. Wilson:  Allergies usually cause itching and redness.

P: Is any promising research being done to help us NTG patients?

Dr. Wilson:  Yes, lots. Our understanding is moving ahead steadily, if not terribly rapidly.

P:  What percentage of people in the world get glaucoma? Is it 10 percent?

Dr. Wilson:  One to ten percent, depending upon the population.

Dr. Wilson:  I have to leave. Keep in touch. Good luck and good night.

End of highlights for March 22nd chat.

On March 29th, Dr. Katz discussed Pigmentary Glaucoma in the Chat room. Click here for highlights of that meeting.

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