Medicine versus Surgery
Chat Highlights
August 11, 2004

Norma Devine, Editor

On Wednesday, August 11, 2004, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Medicine versus Surgery."

Moderator:  The topic tonight is "Medication Versus Surgery." Sounds like a wrestling match.

Dr. Rick Wilson:  World-Wide Wrestling.

P:  Have there been any studies comparing the results of medication and surgery in glaucoma patients?   

Dr. Rick Wilson:  Yes, quite a few.  Until the Collaborative Initial Glaucoma Treatment study (CIGTS), surgery had always won in each study.  That was because surgery lowered IOP more than drops and removed compliance with therapy from the hands of patients.  

P:  What eyedrops were used in that study?

Dr. Rick Wilson:  CIGTS used prostaglandins and was able to lower IOP more with just the once-a-day drop, which increased patient compliance.  In that study, for the first time, medically treated patients did just as well as surgically treated patients and had slightly fewer complaints.

P:  Did that study change the way glaucoma is treated?

Dr. Rick Wilson:  In the U.S., we have always followed the course of full medical treatment and lasers before moving to surgery, so it meant no change in approach for us.  In England, I would think they have had to rethink the way they approach the treatment of the glaucoma patient.

Moderator:  Have there been any comprehensive studies on the efficacy of medication or surgery for the initial treatment of glaucoma in infants?

Dr. Rick Wilson:  In an infant, we usually try the less invasive surgery before drops.  The blood volume of an infant is small compared to that of an adult, but the eye volume is close to an adult's.  Since the volume of the eyedrops is the same for everyone, we worry about side effects in infants.

P:  Why can't I tell my doctor that I am sick and tired of taking all these drops?  I would rather take all the risks of having a trabeculectomy in my right eye, just to stop needing to use eyedrops the next 70 years of my young life.  I know surgery has risks, and may have to be repeated, but I am so tired of having to instill five eyedrops every day.  The surgery in my left eye has worked so well for the past 12 years.  Why can't I just have the pressure in my right eye controlled with a trab, too? I am frustrated! 

Dr. Rick Wilson:  I think you could tell your doctor that.  While he or she might not agree that the approach you have chosen is the best or safest, it is your eye and your choice.

P:  What about those of us who are not using the prostaglandin class of eyedrops?  Would we be better off with surgery?

Dr. Rick Wilson:  If you are well-controlled with your drop regimen, I would stick with the drops.  The one proviso is that without prostaglandins, IOPs ( intraocular pressures) tend to vary more, which may or may not be a problem.  (Two out of three studies suggest IOP variation throughout the day is a risk for progression of glaucoma.)  Medications like Trusopt, Azopt, and Alphagan need to be used three times a day, as the drug insert says, unless they are used with another medication that is not a prostaglandin.

P:  Can you help me understand the value of clinical experience when deciding among strategies for managing glaucoma? For example, there seem to be a considerable number of patients who undergo surgery, but either (a) achieve little or only short-lived reductions in IOP or (b) experience progression of damage despite seemingly effective surgery.  A small number of patients suffer severe complications from the surgery.  The effectiveness of laser procedures and drugs seems to vary with time for many patients. Outcomes presumably depend upon a number of factors specific to the groups of patients represented by clinical statistics, making the statistics more or less relevant to the individual.  How can a patient best make an educated choice between more or less aggressive treatments, and revisit that choice as time passes and conditions change?

Dr. Rick Wilson:  That's a huge and tough question.  Surgery has become better and better.  We can now achieve target IOPs (see last week's chat) in 80 to 90+ percent of first-time surgeries. There are some patients whose IOP ends up too low and their vision is blurred.  There are some patients who are not helped enough by surgery and also need medication.  But that happens less frequently these days.  Selecting an adequate target IOP is crucial; an inadequately lowered IOP is the usual reason for a glaucoma patient progressing (losing vision) after surgery.

P:  In pigmentary glaucoma, what do you consider to be the indications for a peripheral iridotomy (PI)?  Does a PI provide any benefit once the trabecular meshwork has already been overwhelmed by pigment?

Dr. Rick Wilson:  The patient must have a dense pigment stripe down the middle of the cornea (Krukenberg spindle), transillumination defects in the peripheral iris, lots of pigment on the trabecular meshwork, and an iris that bows toward the back of the eye from its insertion into the wall of the eye. The posterior bow throws the iris into contact with the zonules or ligaments that hold the lens in place in the eye. That contact rubs the posterior pigment granules from the back of the iris and causes the pigmentary dispersion and glaucoma.  An iridectomy relieves the posterior bowing.  I use an iridectomy when all the factors above are present.

P:  Two years ago, I was on the verge of surgery because of serious contraindications or adverse effects from all the medical options.  My intraocular pressures averaged in the mid-twenties, which were definitely too high for me.  More or less accidentally (I wanted to investigate using eyedrops that were preservative free), I discovered that custom-compounded, half-strength Xalatan provided me with more than enough IOP-lowering (now consistently in the mid-teens) and tolerable side effects,  relative to the standard dose.  Visual field tests  and HRT (Heidelberg Retinal Tomography) tests have been stable or even improved since two years ago.  Needless to say, I wonder how often patients move to surgery when they might have done quite well (or even better than quite well) on a custom-compounded drop.  Is my impression correct that very few patients either try the custom compounding, or are advised to try it?   Since the standard dose usually is market-driven (the biggest braggable effect within tolerable adverse effects), perhaps there are many other patients who could benefit from using custom-compounded eyedrops. 

Dr. Rick Wilson:  I agree.  Topical medication (drop) strength is at the top of the dose-response curve for the average population. Since not all glaucoma patients are average, some may require more strength, others less than average; some become allergic to all preservatives after months of usage, others can take anything forever.

P:  I have been on medications for 17 years.  I am now using four different kinds of eyedrops.  My intraocular pressures are 20 and 18 mm Hg.  Does long-term use of the drops adversely affect surgery?  

Dr. Rick Wilson:  Yes, both the preservatives and the medications themselves are irritating to the conjunctiva.  Since glaucoma surgery only works if the body does not scar off the glaucoma drainage wound or implant, the more irritated the eye, the more scarring occurs.  Luckily, stronger anti-scarring medications have become available, but they can lead to too low a pressure or too thin a bleb, one that is subject to late leaks and infection.

P:  I have had almost every adverse reaction printed on the surgery (trabeculectomy) consent form, and some not even mentioned.  I would gladly go back to using eyedrops.  Could dilating an eye three weeks after a lens implant cause the implant to shift or could needling the bleb four weeks after surgery cause a lens implant to shift position? 

Dr. Rick Wilson:  The adage in glaucoma is, as one eye goes, so goes the other.  Therefore, the patient who earlier said she had good results from a trabeculectomy in one eye has an excellent chance of the other eye doing well after a trabeculectomy.  As a general rule, unless there were unusual complications with surgery in your first eye, you should be not be leery of surgery in your second eye.  I doubt if dilating the eye would cause a lens to shift.  Bleb needling might, if your IOP dropped suddenly or got too low, putting pressure on the lens from behind.

P:  What is the proper way to use eye massage to lower pressure after a trabeculectomy?

Dr. Rick Wilson:  Every doctor has his or her own way.  I have my patients look straight ahead, close the eye to be flushed, push in gently with the clean pad of the index finger and increase pressure until the eye is uncomfortable, but not painful and hold for the instructed number of seconds.  The technique, amount of pressure, and the time should all be demonstrated and written down by the doctor for you.

P:  Since my trabeculectomy two months ago, I have had four shots and will probably have more.  What is the purpose of the shots?  

Dr. Rick Wilson:  I assume the shots are 5-FU.  If so, they are  intended to slow down scarring.  After two months,  I doubt that any more shots, if they are indeed 5-FU, would  help.  Shots of 5-FU are most effective postoperatively from day 2 to day 7 or 8.

P:  How certain is it after filtering surgery that IOP above the established target is a cause of progression?

Dr. Rick Wilson:  Half of the patients in a study at Bascom Palmer Eye Institute who had had surgery, but continued to have IOPs above 15 mm Hg, showed progression after the surgery. 

P:  Can you tell me where I can get hard data about an infant's target IOP?  Last week I discussed the target IOP for my baby with her doctor and he said 20 mm Hg was okay.  I don't agree.  

Dr. Rick Wilson:  I'm not sure if there is anything in the literature on target IOP in infants.  The usual IOP for infants according to  Dr. Roberto Sampaolesi is about 8 to 10 mm Hg.  The pressure rises to the low teens throughout childhood.  What we don't know is if babies can resist the effects of IOPs in the upper teens -- an IOP that would be fine for adults with healthy optic nerves.  In adults, damaged nerves require a much lower IOP than healthier nerves to prevent further progression.  My impression has been that younger patients, even those with badly damaged nerves, show more resistance than aged patients.

P:  Who is Dr. Sampaolesi? Where does he work?

Dr. Rick Wilson:  Roberto Sampaolesi is a famous glaucoma specialist in Buenos Aires, Argentina.   At least at one time he had a very large congenital glaucoma practice.

P:  How common is it to repeat SLT (Selective Laser Trabeculoplasty) in both eyes four months later?

Dr. Rick Wilson:  Very uncommon.

Moderator:  I know it's late, but do you have time to answer a few more questions?

Dr. Rick Wilson:  Wish I could, but I have been working since 4:30 a.m. today and tomorrow I start at 7:30 a.m. in New Jersey.  Have a great week.

Moderator:  We understand.  Thank you, Dr. Wilson. 

End of highlights for August 11, 2004.

On August 18, Dr. Wilson discussed "Patient Compliance" in the Chat room. Click here for highlights of that meeting.

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