Repeating Incisional Glaucoma Surgery
Chat Highlights – August 6, 2014 Guest Speaker – Dr. Robert Barnes
Lorraine Miller – Editor, Chat Topic Researcher
Moderator: We are privileged to have a glaucoma specialist, Dr. Robert Barnes, with us from Chicago, Illinois. He is a Professor at Loyola University, Chicago with offices in the suburbs of Aurora and Glen Ellyn. We would like to welcome you, Dr. Barnes, to our moderated chat this evening and look forward to the knowledge you have to share. Our topic tonight is, “Repeating Incisional Glaucoma Surgery.”
Dr. Barnes: Thank you for having me.
P: What are the causes of a failed first filtering surgery?
Dr. Barnes: Great question! If we knew all the causes we would fix the situation and not have failures. Patient’s age, type of glaucoma, previous surgery, and ethnicity all affect surgical outcomes.
P: What factors are considered by the surgeon when determining if a trabeculectomy or a tube shunt should be performed as a repeat surgery?
Dr. Barnes: Age of the patient, type of glaucoma, history of previous surgery such as cataract, retinal detachment, or muscle surgery all affect how much virgin tissue remains, which is needed for a successful outcome.
P: Surgeons are advised to use rigorous patient selection to ensure surgical success when performing a repeat trabeculectomy. What patient would not make a good candidate? What medical intervention would then be used to control IOP?
Dr. Barnes: Ideal patients have good virgin conjunctival tissue remaining to make a new trabeculectomy site. They do not have a history of a systemic disease like diabetes or a bleeding disorder caused from aspirin or Coumadin. Neovascular glaucoma would probably push a surgeon to do a tube surgery.
P: Eyes with a failed first incisional surgery have a higher risk of failure from a second surgical procedure. Why is this true?
Dr. Barnes: Normally trabeculectomy surgeries have a success rate of anywhere between 85-90% but can fail if there is significant bleeding, inflammation, or if a dosage of 5-FU or Mitomycin was used. Previous surgery as well as the surgical technique has an impact on the success rate as well as how patients follow post-op medications and directions.
P: Does the reason for the failure affect the success of the second procedure?
Dr. Barnes: Many factors come into the decision tree for a surgeon. If there was extensive bleeding the first time and not the second, if more chemotherapy such as 5-FU or Mitomycin was used, if more steroids were used, or if a suture was cut earlier are all considerations for the physician.
P: I’ve had a trabeculectomy and two bleb revisions in one eye, and I have two iStents in the other eye. Why can’t the iStent be used in closed-angle glaucoma?
Dr. Barnes: iStents are a snorkel tube in the angle to allow direct access to the meshwork and Schlemm’s Canal. You need to be able to see an open angle to place it, but with a closed angle you can’t see it. But they are sweet when they work! In the United States, most insurance companies only pay for one stent, but most people really need two stents. They are coming out with a larger one in 2015.
P: Are bleb revisions or bleb needlings always attempted prior to a second filtering surgery?
Dr. Barnes: It depends on how the bleb looks. If it is too thin then we might go with a bleb revision. If the scleral flap looks closed then we would proceed with needling. If the bleb looks cystic and not diffuse, then we would also needle it.
P: At diagnosis, my pressure was 68 and I had a blood vessel occlusion. In three years, I have had a trabeculoplasty in each eye, a trabeculectomy in both eyes, and two Baerveldt tube shunts in my left eye and one Baerveldt tube shunt in my right eye. I am currently on three eye drops several times a day. My IOP is steady in both eyes between 20 and 40. Recently, my specialist suggested another tube in my right eye due to high pressure. I am hesitant as I developed a cataract in my left eye after the second tube surgery. What advice can you offer for the mental preparation for continued surgeries? At what point can we increase the dosage of eye drops from twice a day to three or four times per day to avoid or prolong surgery? I am 36 years old.
Dr. Barnes: My prayers are with you and your family. You have to have faith in your doctor. You can get another opinion. Obviously, you have probably one of the worst cases. Best wishes.
P: If the first incisional surgery fails, under what conditions would diode laser photocoagulation be performed as the second procedure?
Dr. Barnes: Most physicians use the diode if the vision is poor such as 20/400 with only finger-counting and hand-motion. There are doctors using it on eyes that see well. I have used the diode many times on patients with good vision but they have had serious medical conditions or issues with another trabeculectomy or tube and still have had very nice results. The diode has its own risks, though, so it is an option to ask about when talking about a second operation.
P: If episcleral fibrosis caused the ultimate failure of a trabeculectomy after three needlings, could another trabeculectomy be performed? Would adding an Ex-Press shunt to a repeat trabeculectomy decrease or control scarring?
Dr. Barnes: Two great questions! Episcleral fibrosis causes all failures or is part of them. ExPress shunts are an option. I usually use them in second operations if a tube is too much and the eye still has some good conjuctiva remaining, but they are not always successful either. I have used them as primary and secondary surgery. I am not convinced they are any better than a standard trabeculectomy so I am not sure how to answer that. I think scarring is the same, but after three needlings, you probably need another surgery.
P: How much vision is lost with the second surgery? What visual disturbances are caused by the second site?
Dr. Barnes: Vision loss in glaucoma surgery is a loaded question. We have to consider if there is a cataract, if there is bleeding behind the eye in the retina, how much nerve damage is already there, how high the pressure rose during the post-op period, and how much astigmatism was induced by the sutures or the wound site.
P: Can two surgeries be performed without the need of an IOL within the first three months post-surgery?
Dr. Barnes: Sure if a visually significant cataract does not form.
P: Is it better to have a glaucoma specialist or a cataract specialist extract a cataract in an eye with a working second trabeculectomy?
Dr. Barnes: Well, I am biased. What can I say? But let’s be fair, there are many great surgeons out there. General ophthalmologists have performed some of the most beautiful trabeculectomies I have seen. Probably having a glaucoma person who is accustomed to dealing with trabeculectomies and cataracts is best.
P: Should a second surgery be performed by another physician or is there a benefit for the same doctor performing a second surgical procedure?
Dr. Barnes: That is a tough question. If you have confidence in your doctor and you feel that you were treated well, I would stay with someone who has been in your eye. The information gained from the first surgery helps in how you approach the next surgery.
P: Are some types of glaucoma more prone to failed first surgeries than others?
Dr. Barnes: Yes, great question. Neovascular and inflammatory type of glaucomas have a higher failure rate. Congenital glaucoma probably does too, depending on the age of child.
Moderator: Our time is now up. Dr. Barnes, thank you so much for taking the time to do this chat. Your answers have been very informative. We hope it has been a good experience for you, too.