Trabeculectomy/Shunt Combined Surgery
Chat Highlights – February 6, 2013
Guest Speaker – Dr. Anand Mantravadi
Lorraine Miller, Editor, Chat Topic Researcher
Moderator: Hello, Dr. Anand Mantravadi. Welcome to the chat. Tonight’s topic is “Trabeculectomy/Shunt Combined Surgery.”
P: How long has a trabeculectomy with the option of an EX-PRESS shunt been performed? What are the results for this type of combination surgery compared to a traditional trabeculectomy?
Dr. Mantravadi: Using an EX-PRESS shunt during the procedure is a modified trabeculectomy. A large scale prospective randomized controlled trial has begun. The recruitment for the study has been completed. The data pertaining to the success rates has not been published. Success rates will probably be similar for both the trabeculectomy and modified EX-PRESS shunt trabeculectomy.
P: How is an EX-PRESS shunt different from a Molteno or Baerveldt shunt?
Dr. Mantravadi: The EX-PRESS is a titanium shunt that is a part of the trabeculectomy procedure. The EX-PRESS standardizes the size of the hole and how much fluid can flow through the device. Flow can be obstructed downstream from the device. The EX-PRESS functions like a traditional trabeculectomy and is susceptible to the same risk factors for failure and success. A trabeculectomy is a filtration procedure that enables the flow of aqueous humour from the front chamber of the eye under a flap in the wall of the eye. It collects under the outer lining of the eye or conjunctiva. A hole is made in the sclera for a trabeculectomy so the fluid can flow.
A Molteno or Baerveldt are aqueous drainage devices that can achieve success in eyes with pre-existing scarring. They can also be used as a primary filtration procedure. They are different devices with the same goal of lowering intraocular pressure.
P: When and why is the EX-PRESS used over a traditional trabeculectomy?
Dr. Mantravadi: The EX-PRESS is not a superior procedure but it does standardize parts of the trabeculectomy. The goals for both are the same. Some surgeons feel it is better suited for some patients.
P: How painful is the post surgery period after an EX-PRESS shunt/trabeculectomy?
Dr. Mantravadi: I do not expect pain to be a significant part of the postoperative period. A temporary, mild foreign body, scratchy sensation is common.
P: Can the mini shunt be seen post surgically by others at a conversational distance?
Dr. Mantravadi: No, the shunt can only be seen with a microscope.
P: What is the recuperation time of a trabeculectomy with an EX-PRESS shunt?
Dr. Mantravadi: Activity restrictions, such as lifting, are in place for one to weeks. After two weeks, people can return to their normal routines. I generally expect post-op stability between one and two months.
P: What is the effect on vision?
Dr. Mantravadi: People return to within one line of their pre-operative vision. Some are sooner than others, but most by one to two months.
P: Does the EX-PRESS Shunt surgery produce blurry vision? If so, how long does the blurriness last?
Dr. Mantravadi: The goal of the operation is to preserve vision that can be irreversibly lost with uncontrolled glaucoma. Vision returns at the same rate as a trabeculectomy. It is variable but should return to within one line of pre-op vision in one to two months.
P: Is low pressure a problem after this surgery?
Dr. Mantravadi: Low pressure is a potential consequence of any glaucoma surgery. The rate of lower pressure is not significantly different compared to a trabeculectomy.
P: Do patients with the EX-PRESS shunt have cataracts develop more often post surgery?
Dr. Mantravadi: This has not been studied long- term given the recent emergence of the device.
P: What happens when the shunt allows too much fluid to escape and how is this problem corrected?
Dr. Mantravadi: Mother Nature and time often corrects a majority of these situations. As the body heals, the pressure will spontaneously rise as scar tissue develops. To help facilitate this, your doctor may prescribe a few topical medicines or even instill some medicine within the eye. In the rare event that this does not spontaneously correct, a surgical revision may be necessary.
P: Does intraocular pressure (IOP) fluctuate with an EX-PRESS shunt as it does with a Molteno or Baerveldt shunt?
Dr. Mantravadi: When a Baerveldt, Molteno, or a trabeculectomy is functioning well, I’d expect little fluctuation.
P: Is the surgery that includes an EX-PRESS shunt different than a traditional trabeculectomy?
Dr. Mantravadi: Trabeculectomy and tube shunts are different procedures. The first involves implanting a device that facilitates drainage of aqueous humour, and the latter procedure involves creating a new drain out of the wall of the eye.
P: I need a trabeculectomy and have visited two doctors capable of doing the surgery. One is offering the EX-PRESS shunt with the trabeculectomy and the second is comfortable with performing a traditional trabeculectomy. What factors should I consider in making the decision as to which doctor should perform my surgery? What should be the most important consideration in my decision-making process?
Dr. Mantravadi: Great question! Different surgeons have different preferences when it comes to surgical techniques. Some favor one approach over another based on their personal experience. Data is helpful to shape the decision, but each decision is individualized. There can sometimes be more than one right answer.
P: Which surgery usually fails first, the procedure with the EX-PRESS shunt or the filtration surgery without the shunt?
Dr. Mantravadi: Success rates are similar. Direct comparison study results are forthcoming.
P: What causes an EX-PRESS shunt to fail?
Dr. Mantravadi: The same factors which cause a trabeculectomy to fail. The most common factor is excess scar tissue around the new drainage site which can occur regardless of the presence (EX-PRESS) or absence (traditional trabeculectomy) of the device.
P: Does a patient know prior to surgery if they are having a shunt included with their trabeculectomy procedure?
Dr. Mantravadi: Yes, this is a part of the informed consent process.
P: Does this surgery benefit all types and stages of glaucoma?
Dr. Mantravadi: Chronic angle closure, neovascular glaucomas, and others are not typically good candidates for EX-PRESS devices. Open angle glaucoma along with pseudoexfoliation and pigmentary glaucomas are better candidates.
P: When stitches are released, does this process increase or decrease the pressure?
Dr. Mantravadi: The pressure decreases.
P: Can the EX-PRESS shunt be used in combination with cataract surgery? Can a trabeculectomy with an EX-PRESS shunt be performed after cataract surgery?
Dr. Mantravadi: The EX-PRESS can be used in combination with or after cataract surgery.
P: How many EX-PRESS shunt trabeculectomy surgeries does a glaucoma specialist need to perform to be considered skilled at the procedure? Over what time period are you making the estimate?
Dr. Mantravadi: For surgeons adept at glaucoma surgery, it may not take many surgeries at all.
P: When can needling help a failing trab?
Dr. Mantravadi: When a trabeculectomy is failing or insufficient filtration exists, it is due to scar tissue around the area of the drainage site. A bleb needling can be performed and your doctor can use adjunctive anti-scarring medications (antimetabolites).
Moderator: That was an interesting topic. Thank you, Dr. Mantravadi for your expert advice.
Dr. Mantravadi: Good night.