Chat Highlights
Life After a Trab
October 11, 2000

Norma Devine, Editor

On Wednesday, October 11, 2000, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Life After a Trab." 

Dr. Wilson:  Hello, everyone.

Moderator:  Hello, Dr. Wilson, the topic tonight is Life After a Trab.  How many trabeculectomies can one eye have during a lifetime?

Dr. Wilson:  Three to four seem possible to me.

Moderator:  Can a trab be done only at the top of the eye? 

Dr. Wilson:  Trabs can be done all around the eye. However, trabs in the inferior (lower) 120 degrees are about nine times as likely to become infected as those above.  Trabs off to the nasal or temporal sides can sometimes result in a dry spot just beside them on the cornea.

Moderator:  Can a bleb become infected years later or is that something that happens right away? 

Dr. Wilson:  An infection usually happens years later, once the conjunctiva has been thinned by years of pressure under the conjunctiva.

Moderator:  What are some signs of an infected bleb?

Dr. Wilson:  The signs of an infection are red eye, usually mucous or pus, blurred vision and pain in the eye.

P:  Except for mucus, don't many of us glaucoma patients suffer from the same symptoms -- red eyes, eye pain, and blurred vision?

Dr. Wilson:  Yes, but an infected eye is redder, more painful, and vision is reduced to light perception.

P:  After a trab, are there specific things we can do to reduce the risk of infection?

Dr. Wilson:  Use careful hygiene around the eye; don't bump or injure it.

P:  Right after a trab, is there an average expected time before the operated-on eye regains actually useful vision (useful for reading or driving)?

Dr. Wilson:  Usually about a month for reading; driving may be much sooner.

P:  What is the longest successfully functioning bleb you have seen in your patients?

Dr. Wilson:  Twenty to thirty years.

P:  At what point should we see our doctor about a possible infection? (Or is it more of an emergency room situation?)

Dr. Wilson:  A red eye in a patient with a working trab is an emergency. Most emergency rooms don't have an ophthalmologist,  though they may be able to call one in. It would be best to call one you know of directly, especially someone familiar with your case.  

P:  What would be the emergency in a red eye that had a trab?  

Dr. Wilson:  If  bacteria get into the eye through a thin or torn bleb, then the bacteria can grow exponentially and destroy the eye and any vision potential.

P:  How long is it before a bleb is fully healed, that is, enough to go swimming?

Dr. Wilson:  I caution folks with blebs that are thin or greatly elevated to use goggles when swimming. Clearly, swimming holes should be avoided.

P:  How does a doctor know how big the bleb should be?  

Dr. Wilson:  Training, experience, gestalt.  

Moderator:  What is a trab revision?

Dr. Wilson:  There are many kinds of trab revisions. One kind is to take conjunctiva from the bottom of the same eye to put over the filtering bleb above, that may be thin and leaking or prone to infection. Re-surfacing the bleb with a thicker conjunctiva helps the IOP come up to a normal IOP and reduces the threat of infection.  

P:  After a trab I had ten years ago, the doctor had to reform the chamber.  Can you explain that to me? 

Dr. Wilson:  If more fluid is getting out of the eye through the trabeculectomy than the eye can keep up with, the front of the eye becomes under-pressurized and collapses. Reforming the eye means putting fluid into the front to re-pressurize it to a normal pressure in the hope that the  eye can then keep up with the new drain.

Moderator:  When someone has more than one trab in an eye, is that considered a revision each time they have a trab?

Dr. Wilson:  No, only if the doctor goes back to the same place to revisit an earlier bleb.

P:  Are people with allergies that cause eye symptoms at greater risk for infections and bleb failures? 

Dr. Wilson:  I don't think they are at greater risk for infections, but quite possibly for bleb failures. 

P:  Once a person has a trab, is it more likely they will have more? 

Dr. Wilson:  It usually means they have worse disease or more intolerance of medication. That may predispose them to greater risk of another trab.

Moderator:  If the bleb is beginning to scar over, do you recommend anything?

Dr. Wilson:   I use digital ocular compression, i.e., pushing on the cornea to push fluid through the drain under pressure and dilate the little duct.

P:  Blebs sound dangerous. I would think some kind of bacteria would eventually find its way in.

Dr. Wilson:   It can be from a week or two to 20 or 30 years.  It's about one percent per year, e.g., 10 years, 10 percent.  

P:  If a trab lasts for about seven years, does that mean if another trab is performed in the eighth year, the chance of infection would be eight percent (the first trab) plus one percent (the second trab) or are the chances not cumulative? 

Dr. Wilson:  No, it's not cumulative.  

Moderator:  What about temporal injections? Are they from a trab and what are they? 

Dr. Wilson:  Temporal injections of what?  Temporal injections just means injections to the temporal side.

Moderator:  Can someone (me) with angle closure and trabs in both eyes take Benadryl?  

Dr. Wilson:  After a working trabeculectomy, you can take about anything. 

P:   Dr. Wilson, I get so confused.  Sometimes I get the message that numbers (IOP) are the most important. Then I am told that as long as my fields are stable, that's the most important. What do you think?

Dr. Wilson:   Everything should be taken together.  The main thing is the continued, unchanging health of the optic nerve and a stable visual field. Watching the numbers helps us achieve the other two milestones.

P:  Is it okay to use Visine?

Dr. Wilson:  Visine artificial tears are okay,  but don't use the Visine that gets the red out. If used chronically, it gets the red in and keeps it there. Artificial tears, like Refresh Tears and GenTeal that come in bigger bottles but without preservatives, are the best in your circumstances.

End of highlights for October 11th chat.

On October 18th, Dr. Rick Wilson discussed "Glaucoma & the Cornea" in the Chat room. Click here for highlights of that meeting.

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