Chat Highlights
Antifibrosis Agents
April 11, 2001

Norma Devine, Editor

On Wednesday, April 11, 2001, Dr. Courtland Schmidt, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Antifibrosis Agents." 

Dr. Schmidt:   Hello, everyone.  Welcome to the chat room.  Tonight's topic is antifibrosis (AF) agents. 

P:  What are AF agents?   

Dr. Schmidt:  Fibrosis is part of wound healing, and when a trabeculectomy (trab) heals too well, the trab fails.  AF agents slow the healing process.

P:  Like the 5-FU shot? Is that an AF agent? 

Dr. Schmidt:   5-FU used either during or after surgery is an antifibrosis agent, as is  mitomycin C (MMC).

P:  What does "5-FU" stand for?   

Dr. Schmidt:  Fluorouracil.  Another cancer poison.

P:  How long after a trabeculectomy can AF agents be used?

Dr. Schmidt:  AF agents are best used during the surgery or within, at most, 10 days or so after the surgery.

P:  What are the drawbacks, if any, to using AF agents in trabs?

Dr. Schmidt:  The main drawbacks of AF agents include too low a pressure and an increased risk of infection.  The duration of  MMC usage (between 30 seconds and 4 minutes) increases with the number of risk factors for failure, but there is no magic formula.

P:  What determines whether AF agents are used?  None were used during my trab. 

Dr. Schmidt:  The lower the IOP needed after surgery and the more risk factors for failure, the more one needs AF agents.   Someone with a minimally damaged nerve and no prior surgery might well not need it.  You only expose patients to the extra risks of AF agents if they need the benefits.

P:  Are antifibrosis drugs a family of medicines or a single medicine?

Dr. Schmidt:  "Antifibrosis" just means against healing.  Any drug that slows healing is an antifibrosis drug.  

P:  Does Pred Forte also slow healing?

Dr. Schmidt:   Yes.  Great question. Non-steroidals like Acular also slow healing.

P:  Are AF agents only used as a follow up to surgery?

Dr. Schmidt:   AF agents are used almost always during or after surgery.

P:  Are steroids considered to be AF agents, or is their slowing of healing just an unwanted side effect?

Dr. Schmidt:  That is the only reason to use steroids.

P:  But they are not considered AF drugs, are they?

Dr. Schmidt:  Steroids are definitely a type of antifibrosis medicine.  They slow healing by decreasing inflammation.  But by "antifibrotic" most commonly people mean 5-FU or MMC.

P:  Is it good to heal fast? 

Dr. Schmidt:  Healing fast is good if you break your ankle, but not if you have glaucoma surgery. 

P:  I was given Lotemax following trabeculoplasty.  Is that an AF agent?

Dr. Schmidt:  Lotemax is a steroid.

P:  My doctor is keeping me on Pred Forte for six months after a trab in November.  I am now down to two drops a day.  Is this the normal procedure?  

Dr. Schmidt:  It's hard for me to discuss specifics.  If you have persistent inflammation, Pred Forte might be used for six months.  Most people are off topical steroids within six to ten weeks, but there might be reasons to continue.

P:  Does the use of AF drugs affect only the eye?

Dr. Schmidt:  Yes.

P:  Are AF drugs used in cataract surgery in patients who have had trabs?  

Dr. Schmidt:  Some people feel that cataract surgery in someone who has previously had a trab should be supplemented by some AF.   That is why one uses a lot of steroid in these patients. To date, no good studies show a definite advantage to using 5-FU or MMC in a patient with a functioning trabeculectomy who has cataract surgery.  

P:  I have only had cataract surgery.  Would AF drugs have been used?

Dr. Schmidt:  AF drugs are not used in that situation.  

P:  I had many surgeries on my left eye and recently had a needling . I had some 5-FU shots and am now on Pred Forte. My eye feels heavy and tired and wants to close. Is that normal?

Dr. Schmidt:  A droopy eyelid, or ptosis, is noted two to five percent of the time after even one surgery, so your situation would not be that unusual.

Moderator:  I think I heard someone refer to MMC as a chemo-type drug. 

Dr. Schmidt:  MMC was developed as a chemotherapy agent for cancer. It is extremely potent, and kills many of the cells it touches.  It is handled with care, and placed very precisely.  It is strong stuff, and not for everyone (patient or doctor).

P:  I had hypotony after a trab with MMC.  After a blood injection, the intraocular pressure became normal.  But now, after two years, the hypotony has returned.  

Dr. Schmidt:  MMC slows healing so much that there is almost no resistance to the fluid leaving the eye, so the IOP can be too low. Hypotony is one of the down sides to MMC, which is why everyone doesn't get MMC.  

Moderator:  What harm does MMC do?   

Dr. Schmidt:  It causes harm if it's used too aggressively in someone who doesn't need the very low pressure, or makes your pressure too low, or increases the risk of infection. The bleb after MMC use may be more cystic and elevated, and possibly more uncomfortable.  As with any treatment of any kind, one has to use the benefits to justify the risks.

P:  Why does 5-FU  come in such a large vial?   

Dr. Schmidt:  5-FU is packaged for chemotherapy, not eye surgery. Because the vials are "single-use," we end up wasting most of it.

P:  Do you have a pressure in mind before you do a second or third trab? 

Dr. Schmidt:  You should set a pressure goal for every patient, whether it's for  drop therapy or surgery.  That goal depends on all kinds of factors, such as age, amount of nerve damage, life expectancy, risk factors for scarring, etc.  

Moderator:  How long has MMC been in use?

Dr. Schmidt:  It has been used about eight years or so.

P:  When a patient signs an informed consent form for a trab with either 5-FU or MMC, does the doctor wait until operating to decide which one to use?   

Dr. Schmidt:  That's rare, but can happen if the doctor has to judge the scarring, and therefore the risk for failure, at the time of surgery.  

P:  Three years ago I had a trab,  followed two years later by a successful blood injection.  Now the effect of the blood injection has worn off.  Why? 

Dr. Schmidt:  The blood injection  temporarily increases outflow resistance, but then wears off.  The effect of MMC is profound, and often hard to counteract.

P:  So the effect of another blood injection will also wear off? 

Dr. Schmidt:  Good question.  We still don't understand why they work in some people but not in others.  We need a better way to predict failure.  Perhaps a gene assay.  We can hope. 

P:  What do you mean, the "effect of MMC is profound?"

Dr. Schmidt:  The effect of a blood injection not uncommonly wears off.  MMC is great at preventing scarring, because it is so good at killing almost every cell it touches.  It can be very difficult to fix a bleb with too great outflow due to MMC.

P:  Should one know whether 5-FU or MMC was used during a trab, or are they comparable? 

Dr. Schmidt:  They are different.  MMC is more powerful and therefore useful in some, but not necessarily all, patients.  Antifibrotic agents might be used in a first trab if very low IOP is needed, or if there is a high risk for scarring (inflammation), as in the black race. 

P:  My first trab was without MMC.  

Dr. Schmidt:  That is the most common way.

P:  My first trab was with MMC.   

P:  Is there a need to know whether MMC or 5-FU was used if the trab seems to be successful after four and a half months?  

Dr. Schmidt:  No, only if it fails,  because if 5-FU had been used, then you could use MMC. 

P:  If the first trab was done without MMC, can a second one be done without it, too?  

Dr. Schmidt:  Yes, but it is likely to fail if the first one did.

P:  By failed trab do you mean any time it has failed, even after 15 years? My first trab was successful, but is getting old.

Dr. Schmidt:  Age doesn't matter if the trab is working.

P:  I  read in the April 4th chat highlights about several things that can go wrong with a trab.  You can lose vision, have macular puckers and rippled retinas from hypotony.

Dr. Schmidt:  Those are all possible and are among the reasons you don't expose someone to the risks of MMC who doesn't need the benefits.

P:  How low an intraocular pressure is too low? 

Dr. Schmidt:  Some people see great with an IOP of one; others have optic nerve and retina swelling at an IOP of twelve. 

P:  What complications can a blood injection in the bleb cause?   

Dr. Schmidt:  A blood injection can cause blurred vision, bleb scarring, discomfort, and irritation.

P:  Is it common for all the stitches to need to be removed within a couple of months after a trab because of increasing pressure?  

Dr. Schmidt:  That is not at all uncommon.  

P:  I will soon have a cornea transplant.  Will the MMC used in my trab last September affect the transplant? 

Dr. Schmidt:  No, the MMC was washed off your eye after being applied during the surgery.  Remember, everyone, to ask questions of your doctors, whether about AF agents or drugs.  Good luck to you all.

P:  First, you have to know TO ask about MMC!

Moderator:  How true! I had no idea about MMC.

P:  Me either.  

P:  This was a good topic. There is a lot of controversy about it in the literature.

P:  Sometimes we don't know what to ask our doctors and the information is not volunteered.

P:  That is why this chat room is so helpful.  We don't know the questions to ask and our doctors certainly don't tell us anything.  Being in this chat room helps me learn the questions to ask and get the answers.  

P:  I agree.  I have learned so much since joining in this chat.

P:  This was again a good learning experience for me.  I did not know much about antifibrotic drugs like MMC. 

P:  Doctor, this has been most informative, as you can tell by how we held onto questions on this topic. Thank you very much for your time.

On April 18, Dr. Henderer discussed "Difficult Glaucoma" in the Chat room. Click here for highlights of that meeting.

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