Treating Recalcitrant Glaucoma
Chat Highlights
April 10, 2002

Norma Devine, Editor

On Wednesday, April 10, 2002, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Treating Recalcitrant Glaucoma."

Moderator:  Welcome, Dr. Rick.  A patient is ready with the first question about the topic, "Treating Recalcitrant Glaucoma."

Dr. Rick Wilson:  Okay.  Let's start.

P:  Dr. Rick, how do you define recalcitrant glaucoma?

Dr. Rick Wilson:  Glaucoma that is resistant to the usual therapy.

P:  And what you do you mean by "the usual therapy?"  

Dr. Rick Wilson:  Eye drops, lasers, and the first surgery.  

P:  Do all eyes eventually become resistant to glaucoma eye drops?  

Dr. Rick Wilson:  Allergies gradually increase with time.  A person is usually not allergic to a medication right away.  In one study, epinephrine allergy gradually increased to the point that over a period of five years 50% of patients became allergic to it.  

P:  So if 50% of patients become allergic to the meds, doesn't everyone eventually become blind if they get glaucoma at age 45 and live till age 85?

Dr. Rick Wilson:  No.  That 50% figure was just with a drug that is no longer used much.  The newer medications are not that allergenic.  The prostaglandins seem to hold their effectiveness for many years.  The prostaglandins are Xalatan, Travatan, Lumigan, and Rescula.

P:  What was the drug with the 50% allergy rate?

Dr. Rick Wilson:  Epinephrine and probably Iopidine (apraclonidine).  

P:  Are allergies common with Xalatan?

Dr. Rick Wilson:  No.  Allergies in the usual sense from using Xalatan are quite rare.  Toxic effects like red eyes and corneal problems are more common.

P:  How is recalcitrant glaucoma treated if all else fails?

Dr. Rick Wilson:  If trabeculectomy with mitomycin-C fails, then usually an aqueous shunt is used.  If the shunt fails, then a laser or freezing procedure is used to kill the part of the eye that makes the fluid.  If the eye makes less fluid, then it is hoped that a balance between what is made and what can leave the eye can be achieved with medications. 

P:  What are the risks of using the anti-scarring drugs after several surgeries have built up a lot of scar tissue?  I know some doctors won't use them.

Dr. Rick Wilson:  I always use mitomycin-C for a second trabeculectomy or after several procedures.  

P:  So we can never give up.  There are usually options of one kind or another, right?

Dr. Rick Wilson:  Yes.  There is always another operation to lower IOP.  The risks and side-effects are greater with the more end-stage glaucoma surgeries, but there is always something else to do.

P:  How much of the recalcitrant glaucoma is due to uncontrolled IOP (intraocular pressure) and how much is due to normal-tension glaucoma?  

Dr. Rick Wilson:  The recalcitrant glaucomas are often those with very high IOPs of 50 mm Hg to 80 mm Hg.  It is dangerous just to lower the IOP quickly to normal in those eyes.  

P:  Why is it dangerous to lower IOP that is over 50 mm Hg? 

Dr. Rick Wilson:  The sudden change predisposes eyes with weak vessels in the middle layer of the eye, the choroid, to break and bleed, or leak serum between the layers of the eye, which is a dangerous problem.

P:  How many trabeculectomies can a patient have?  Three?

Dr. Rick Wilson:  Usually.  Occasionally, however, if the patient has a corneal graft (which usually does much better with a trabeculectomy), I have worked in a fourth. 

P:  What is the difference between a trabeculoplasty and a trabeculectomy?  

Dr. Rick Wilson:  A trabeculoplasty is a laser procedure that causes the trabecular meshwork to help remove more debris from the outflow track.  A trabeculectomy is the flap valve on the top of the eye that bypasses the blocked, natural drain.

P:  Do you consider a hypotonous eye after trabeculectomy as recalcitrant glaucoma? 

Dr. Rick Wilson:  No, I consider that to be overly submissive glaucoma. 

P:  What do you mean by "overly submissive" glaucoma? 

Dr. Rick Wilson:  I just meant that the glaucoma gave up too easily and the treatment overshot the mark.

P:  Do you consider a hypotonous eye after a trab as recalcitrant glaucoma?  

Dr. Rick Wilson:  Clearly, too low an IOP is a serious problem for vision, so I do not make light of it.

P:  Killing part of the eye sounds pretty drastic.  What is the success rate of that procedure?

Dr. Rick Wilson:  It's high.  The procedure can be repeated until the amount of fluid is brought down to a manageable level.  Unfortunately, the procedure is not an accurate one.   In our study, on average, five percent of patients undergoing each procedure developed IOPs that were too low. 

P:  How can cyclophotocoagulation be made more accurate?  Is there any way to see exactly where the fluid is being made in the ciliary processes?

Dr. Rick Wilson:  Not yet.  We have to learn some things yet.

P:  Would cyclophotocoagulation have a higher success rate if the ciliary processes could be visualized through a sector iridectomy?  I saw a paper by Dr. Moster about such a case.

Dr. Rick Wilson:  Not much.  The success rate wasn't much higher in a procedure where the ciliary processes are visualized with a fiber optic probe and lasered directly. 

P:  After two trabs, do you usually suggest a shunt or a third trabeculectomy? 

Dr. Rick Wilson:  That depends upon how long it has been since the last trab, who did it, and whether mitomycin-C was used. 

P:  What can be done when shunts fail?  

Dr. Rick Wilson:  Shunts can be revised.  They are just plumbing.  The blockage can be at the end, in the front of the eye,  or at the other end of the tube.  In the eye, the blockage can be seen and removed.  At the other end, the usual problem is that the scar tissue around the plates that the tubes discharge onto becomes too thick and has to be excised. 

P:  Is shunt revision usually done before adding another shunt?  And in what circumstances would adding another shunt be better than revising the current one?

Dr. Rick Wilson:  For patients with very thin scleras, an IOP of even 12 mm Hg would be too low.  The sclera constricts like a rubber band and throws the next layer into folds. Young and near-sighted patients are more likely to have thin sclera.  Old patients have nearly fossilized sclera.  I have several with IOPs of 2 mm Hg to 3 mm Hg who read the 20/25 or 20/30 lines on the Snellen chart.

P:  When would you add another shunt, instead of revising an existing shunt?

Dr. Rick Wilson:  If there is only one plate, that is, one quadrant taken above, I would add another plate and tube.  If there were already two, I would revise the present shunt.

P:  Are there any glaucoma eye drops that should not be used after a shunt?

Dr. Rick Wilson:  Not necessarily. 

P:  I tried carbachol and it did weird things to my vision.  I thought it was because of the shunt.  Any ideas?

Dr. Rick Wilson:  Carbachol is an extremely strong miotic, causing the muscles in the eye to constrict greatly.  That in itself can cause changes in vision.

P:  Thank you so much for your help. I have a difficult situation and am trying to figure out what is going on and what to do. 

P:  What's the difference in the success of controlling normal-tension glaucoma and open-angle glaucoma?  Is it possible to successfully keep your vision with either of those types for 30 years without fear of blindness?

Dr. Rick Wilson:  Clearly, it is a little harder to get IOPs low enough for NTG, but with the anti-scarring meds we have, it is easily possible.  I reported a series of normal-tension glaucoma patients who attained an average IOP of 6.9 mm Hg.  It certainly is possible to keep vision with either type of glaucoma for life.

P:  Is a pressure of 16 mm Hg in both eyes low enough for controlling normal- tension glaucoma or should it be lower?

Dr. Rick Wilson:  That depends on many factors.  Most importantly, at what IOP were you getting worse?  The IOP should be lowered 30% to 40% from that level.  If the visual field loss is severe, then the IOP should be down around 12 mm Hg to 13 mm Hg.  Low blood pressure, migraine headaches, and severe family history are risk factors that would make me want to lower my target pressure.

P:  Can a trabeculectomy, a cornea graft and cataract removal be done at the same time?  Is it advisable? Are there any disadvantages to getting these procedures over with at one time or is the problem getting the two different specialists together at the same time to do the procedures?

Dr. Rick Wilson:  Yes, they can be done at the same time.  Yes, it is advisable. No, there should not be disadvantages to having these procedures done at the same time.   Some corneal specialists may worry about too much fluid getting out of the eye after the glaucoma procedure, so they may be reluctant.  They will need to find a glaucoma specialist they can trust to pull the cornea through and control the IOP.

P:  Earlier this year, when my IOP was 61 mm Hg, I was given manitol intravenously.  How much would that lower the IOP?

Dr. Rick Wilson:  That would depend upon the kind of glaucoma.  In glaucomas where it is most effective, it might lower the IOP anywhere from 20 to 35 mm Hg.  

P:  I recently read of a successful treatment of Parkinson's disease using the patient's own stem cells.  Is there anything similar on the horizon for glaucoma?

Dr. Rick Wilson:  Yes, but it may be 5 to 10 years away -- maybe less if Bush allows our scientists to work full tilt. 

P:  If stem cells can restore optic nerve tissue, how would that be done?

Dr. Rick Wilson:  The cells would probably be grown from bone marrow, fat, sperm cells, or cultured embryos, and then specialized to become immature nerve cells.  The cells could then be injected into the head of the nerve; into the vitreous if the cells could be shown to populate the nerve.  Researchers have found that injected stem cells in the animal model actually found the correct paths posteriorly -- a very pleasant surprise.

P:  Bush's policies can't stop stem-cell research everywhere in the world! 

Dr. Rick Wilson:  One of our best stem-cell researchers went to England, and one of England's just went to Singapore to get to better environments for research.

P:  I read about an infrared laser that emits quick pulses of light that physically shake and unclog the drainage canal.  Do you have any comment about this?

Dr. Rick Wilson:  I doubt that it really works like that, but we will see.  Got to leave on time tonight.  Sorry.  Good night.

Moderator:  Good night, Dr. Rick.  Thank you.

End of highlights for April 10, 2002.

On April 17, Dr. Schmidt discussed "Glaucoma and Medications" in the Chat room. Click here for highlights of that meeting.

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