Bleb Complications and Repairs
Chat Highlights
January 18, 2012

On Wednesday, January 18, 2012, Dr. Michael Pro, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Bleb Complications and Repairs".

Moderator: Tonight's topic is “Bleb Complications and Repairs.” Dr. Pro, can you start by explaining what a bleb is for those who may not know?

Dr. Pro: A bleb is the end result and intention of glaucoma surgery such as trabeculectomy, Express Shunt, and even some non-penetrating surgery such as canaloplasty. A bleb is an aqueous-filled cyst between the conjunctiva and sclera under the upper lid.

P: What is a bleb complication?

Dr. Pro: The bleb allows the IOP to be controlled by allowing a steady egress of aqueous from the anterior chamber of the eye to this subconjunctival space and back to the systemic circulation. So a bleb complication can be some derangement of this intended drainage of fluid or some other problem.

Like other surgical complications, it is best to talk about early and late post-operative complications. Perhaps the most feared complication is a bleb infection which can take place at any time after the surgery. Studies suggest infection risks to be from 0.1 percent to one percent. So it is rare, but can be devastating if not treated promptly.

A good reminder for the patient is RSVP, meaning call the office or come in immediately if you have redness, sensitivity to light, vision loss, or pain.

Other complications include bleb leaks, bleb encapsulation or failure, bleb overgrowth on the cornea, bleb over-filtration and hypotony, bleb hemorrhage, chronic bleb-related discomfort and dry eye.

P: I am scheduled to receive a trab surgery in early February and am very anxious. Please advise how I can prevent the bleb being closed.

Dr. Pro: Good question, and one that I am often asked. In general, success of this surgery is between 60 to 90 percent. Some patients still need glaucoma drops after surgery. Failure of the trabeculectomy surgery is indeed due to scarring and failure of aqueous outflow. This is in fact the normal healing response of your eye, as it is not a normal physiologic situation to have drainage of aqueous to a bleb.

Healing is modulated during surgery by the application of anti-scarring medications and after surgery by the use of the post-surgical drops (steroids). So it is critical that you use the drops as directed by your surgeon. Also your surgeon will need to see you periodically after the surgery to inspect your eye and perform interventions on the bleb as necessary, such as cutting sutures.
I hope this is helpful and good luck!

P: What is the time frame for early post-operative problems?

Dr. Pro: Early post-operative problems are typically in the first one to two months, but there is no strict definition. After that they would be considered late post-operative.

P: How are bleb complications managed by non-surgical interventions?

Dr. Pro: It depends on the complication. So, let's take a bleb leak as an example. Bleb leaks can happen in the early post-operative period or many years after surgery. Very early leaks may more often be treated by a return to the OR, but late leaks may be treated conservatively at first.
So, one may try bandage contact lenses, aqueous suppressants (the theory being that reduced aqueous flow through the leak will enable it to heal), ointments and any combination of the three. Some may try cautery in the office. If these fail, a trip to the OR to fix the bleb leak may be in store.

The danger of a bleb leak is that it predisposes an individual to a bleb infection, so we generally try to repair them as I discussed above.

P: Can a bleb have a stitch put in so that I can get pressure in that eye? My doctor said he tried it on a patient a week prior to my surgery and the eye was like mush and he had to patch the bleb and put tubes in for drainage. I have double vision now because the one eye has a pressure of one and the other eye has a pressure of twenty-five. What is a solution as I don't want to lose all my vision in that eye?

Dr. Pro: That can be a difficult situation and one that I do face from time to time. The thing here is that every patient is different. Compression sutures can work in some, but not all patients. Also, each surgeon may have a preference for a particular technique. Especially true in this situation is the fact that there is no single right answer. The course that your doctor has described is one that I have done in the past. I hope this is helpful.

P: What is a scleral patch graft and why would it be used?

Dr. Pro: A scleral patch graft is a section of sterile tissue (often pericardium, but also sclera or cornea) that is used to cover a scleral defect (i.e. an trabeculectomy flap that has melted) or a tube shunt. In the case of a bleb revision, a patch may be needed to either close the trabeculectomy site or reduce the aqueous outflow.

P: Doctor, when you say the trab procedure has a 60-90 percent success rate, does that mean no complications? Or do you consider the procedure successful even if there are complications? I guess I'm asking how you define "success."

Dr. Pro: Success is defined generally by a reduction in the IOP by at least 30 percent or an IOP lower than 18 or 21. Obviously "success" increases when the IOP target is set higher.

There is a movement in the research community to be more consistent in our IOP target (18 not 21). Anyway, success would mean the IOP reduction, even if glaucoma drops were still needed in the future. Sometimes we sub-divide a complete success (no drops) and qualified success (drops).

Anyway, you could have a transient complication, such as a leak or low IOP, and still have a successful surgery in the long run. Serious complications such as an infection reduce the chance or surgical success obviously, but fortunately serious complications are the exception.

P: What is the success rate of a scleral patch graft?

Dr. Pro: Generally success after a bleb revision due to a leaking bleb is about 60 percent or so. I think the numbers are too small to quote success after using a scleral patch during a bleb revision.

P: If a scleral patch graft is successful, how much time does it add to the longevity of a bleb?

Dr. Pro: Hard to answer that one as I doubt there is any study on it. I guess it is more of a case, by case situation. In my experience, most revisions that have a scleral patch have higher IOP over time and may often need glaucoma drops, but the number of cases is too small to have a firm answer.

P: Can you wear contact lenses with a bleb? I wear rigid lenses and am very nearsighted and my vision is better with contacts than with glasses.

Dr. Pro: Wearing contacts is generally contraindicated because it may increase your risk of a bleb infection.

P: Long term, is the most common problem after a trabeculectomy from the IOP slowly increasing and once again being too high, or from developing leaks and the pressure being too low?

Dr. Pro: You really know your glaucoma! The long term problem by far is a gradual increase in IOP. Leaks are much less common.

Moderator: Thank you Dr. Pro. We're out of time. It was an informative chat.

Dr. Pro: Thank you all. Good night and take care.

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