Late Bleb Leaks
Chat Highlights
June 14, 2006

On Wednesday, June 14, 2006, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Late Bleb Leaks."

Dr. Rick Wilson:    Hello everyone. I hope you've had a good week. I was speaking to the Peruvian Glaucoma Society last week and enjoyed it thoroughly.

Moderator:    Welcome back, Dr. Wilson.

P:    Did you visit Machu Picchu?

Dr. Rick Wilson:   Not this time, but I was there in 1973 and 1982.

Moderator:   Tonight the discussion concerns bleb leaks. Dr. Wilson, about how often do they occur after trabeculectomies (filtering surgery)?

Dr. Rick Wilson:   Bleb leaks are said to occur at a rate of about 1% a year; that is, after 10 years with a functioning bleb, 10% of the patients would have had a bleb leak.

Moderator:   Hasn't the use of 5-FU and mitomycin increased the rate of bleb leaks?

Dr. Rick Wilson:   Yes, but fornix-based conjunctival flaps (that is, the conjunctiva is dissected from its attachment to the cornea to allow the surgeon to get to the sclera to perform the trabeculectomy) have a much lower rate of leaks than if the conjunctiva is incised back from the cornea and then sewn up afterward.

P:   Do the leaks happen right after surgery?

Dr. Rick Wilson:   There are leaks that occur right after surgery, but the leaks I have been talking about usually occur years later.

P:   What causes blebs to leak?

Dr. Rick Wilson:   The leaks occur when the area of the bleb (the ballooned-up conjunctiva over where the scleral drain was made) constricts.  The force of the fluid being drained from the eye is then concentrated in a small area.  The fluid pressure thins the conjunctiva - - like blowing bubblegum. If the conjunctiva gets too thin, a hole forms, and the fluid that is draining from the eye leaks out into the tear film.  The danger is not only that the IOP can drop too low, but also that bacteria from the eyelids and tear film can enter the eye and cause an infection.

P:   Are bleb leaks related to the patient's age?

Dr. Rick Wilson:   No.  They can happen at any age, although if the conjunctiva is excessively thin, as it is in some aged adults, a leak may be more likely.

P:   Can a patient cause a bleb to leak?

Dr. Rick Wilson:   Yes.  Blunt or sharp trauma can tear a thin bleb and cause it to leak or even rupture it.

P:   What would be considered blunt trauma?

Dr. Rick Wilson:   Being hit in the eye with a tennis ball, rubbing the eye too hard, etc.

P:   How are bleb leaks managed?

Dr. Rick Wilson:   The flow of fluid to the hole can be reduced by giving medicines to suppress the fluid or by diverting the fluid from the hole.  That is done by cutting through the scar tissue around the bleb, so the fluid can drain elsewhere and reduce the pressure on the hole to allow it to heal. If those methods don't work after six weeks or so, then the patient's blood can be injected under the hole to see if it will occlude the hole and allow it to heal.  Alternatively, a conjunctival patch graft can be done, moving healthy, normal-thickness conjunctiva from the bottom of the eye and sewing it over the leaking bleb.

P:   Can a patient detect when something is wrong with a bleb?

Dr. Rick Wilson:   The patient often notices excessive tearing or a lot of fluid in the eye under the eyelids that floods out when awakening in the morning.  Occasionally, an infection will be the first indication that something is wrong; especially if the patient has a dry eye and the eye actually feels more comfortable with the leak supplying needed liquid.

P:   What does a thin-walled, avascular bleb look like to the clinician?

Dr. Rick Wilson:   It is elevated off the sclera by fluid, with a thin and clear conjunctiva.

P:   Please describe what "avascular" means in a "thin, avascular bleb."

Dr. Rick Wilson:   Avascular means that there are no vessels visible in the bleb. Mitomycin can minimize the vessels, and just the pressure over time causes the vessels to disappear when the conjunctiva thins.

P:   I'm a 43-year old male.  I developed a bleb leak after a trabeculectomy with 5-FU. I was told to use Cosopt in the affected eye.  Apparently, the bleb leak healed. Is that possible?

Dr. Rick Wilson:   It is possible for the leak to heal, especially if the force of the fluid being pushed through the hole is lessened; as it apparently was in your case by the Cosopt.

P:   Can I do anything to prevent (or reduce the risk of) a bleb leak?

Dr. Rick Wilson:   Probably not, except to always have clean hands and do not be rough when touching the eye or eyelids.

P:   I'm concerned that my sister is not using digital ocular compression (DOC) correctly and could cause harm to her eye.  With her eye closed and looking upward, she's trying to press on the lower part of the eye.  Would you please describe how ocular digital compression is performed?

Dr. Rick Wilson:   There are several methods in use today.  The one you describe is one of them. I, personally, have the patient look straight ahead, press slowly and firmly on the cornea over the pupil till the right intraocular pressure (IOP) is attained, and then count for the prescribed number of seconds before slowly releasing the pressure on the eye.

Moderator:   Not trying to be funny here, but you do mean that the patient should look straight ahead with the eyes closed, right?

Dr. Rick Wilson:   Absolutely.

P:   How does applying pressure to the lower lid with the eye open differ in results from your method, and how does a patient know when the "right pressure" is attained at home?

Dr. Rick Wilson:   The eyelid probably should be closed with either technique to prevent accidentally slipping a finger into the eye.  The results are probably the same.  The doctor should demonstrate the correct amount of pressure in the office and have the patient try it to see that it is effective in the patient's hands.  Usually, the pressure is uncomfortable but not painful.

P:   If I understand you, DOC is only used for bleb problems and is brief. Is that correct?

Dr. Rick Wilson:   Yes, I usually prescribe it to be done twice, from between two seconds to ten seconds, and repeated every one to four hours.

P:   If a patient uses DOC incorrectly, could that cause harm?

Dr. Rick Wilson:   Yes, if the patient pushes too hard or not in the right place, it is possible to hurt the eye.  However, I have used the technique in 2,000 to 3,000 cases and have had very few complications over the years.

P:   Couldn't the increase in IOP caused by DOC harm the optic nerve?

Dr. Rick Wilson:   Because the IOP is not elevated for more than ten seconds at a time, it does not seem to harm the nerve.  We use it most extensively in patients with advanced damage who need a very low IOP to prevent further optic nerve loss.

P:   What if the patient just can't stand to press on the eyeball?

Dr. Rick Wilson:   Then we can't use that technique.

Moderator:   What is the purpose of DOC?

Dr. Rick Wilson:   If the hole in the sclera is starting to heal too much (that is, become too small), by pushing on the cornea and increasing the IOP markedly for a few seconds, the patient can dilate the hole and often keep it from scarring down more.

P:   What does a good bleb look like?

Dr. Rick Wilson:   The best bleb is very diffuse and covers the superior (upper) one-third of the eye and often is elevated 360 degrees around the cornea.  It should not be thin or have too many vessels in it.

P:   I've looked at dozens of images of blebs and have yet to see one that is elevated 360 degrees around the cornea.  Is that because such blebs are uncommon or because I haven't seen enough?

Dr. Rick Wilson:   I usually see about one or two 360-degree blebs a day, but they are uncommon.  Thinner, more localized, blebs are the ones that are prone to leakage.  There is usually a ring of scar tissue around the bleb that walls off absorption of aqueous over a large area, concentrating the eye pressure over a small area of conjunctiva, leading to thinning.

P:   Can a bleb be seen and recognized by anyone besides a doctor?

Dr. Rick Wilson:   In most cases, a bleb can be seen by lifting the upper eyelid and looking at the bubble or cyst-like structure there.

P:   Has ocular digital massage caused any harm to patients' optic nerves?

Dr. Rick Wilson:   Literally thousands of patients have used digital ocular compression without known harmful effects to the optic nerve.

P:   Would there be any harm done or benefit to my bleb if I continued DOC a couple of times a day for years?

Dr. Rick Wilson:   Some doctors suggest that. I have had patients who need very low pressures that continue DOC for years.  One side effect that occurs with long-term use is greater prolapse (falls out of place) of the fat pad underlying the eye and cushioning it.  The fat is easy to remove, but means a cosmetic operation that may not be covered by insurance.

P:   Are any devices available for ocular digital compression? (I know you don't like the term ocular "massage".)

Dr. Rick Wilson:   I don't know of any devices that can be used to improve DOC.  When I have used the term "massage" rather than "flushing," I have had patients kneading their eyes like dough.  That is not a good practice.

P:   Will the daily use and removal of eye makeup on the upper eyelid have any negative, long-term effect on a bleb?  I also have a thin or non-existent Tenon's capsule.

Dr. Rick Wilson:   You should be careful, as mascara can get into the eye and the pigment particles can be infected with bacteria.  Also, using excessive pressure to clean the eyelids could injure the bleb.

Moderator:   What is "Tenon's capsule?"

Dr. Rick Wilson:   Tenon's capsule is the layer of fibrous tissue under the conjunctiva and above the sclera.

P:   Is there any other treatment available that can provide the same benefit to a leaking bleb as digital compression?

Dr. Rick Wilson:   There used to be a suction device that pulled fluid through the drain, but it is outdated and I have not seen it in use in the last 10 years.

Moderator:   Dr. Wilson, thank you once again for your generosity with your time, experience, and wisdom.  It is appreciated by all of us.  Have a good week.

Dr. Rick Wilson:   Thank you all for your attention.  Have a good week.

On June 21, Dr. Wilson discussed "Normal-tension Glaucoma" in the Chat room. Click here for highlights of that meeting.

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