"Am I a candidate for new glaucoma surgery?
Chat Highlights
June 2, 2010

On Wednesday, June 2, 2010, Dr. Michael Pro, a glaucoma specialist at Wills, and the glaucoma chat group discussed "New" Glaucoma Surgery.

Moderator: The topic tonight is "Am I a candidate for new glaucoma surgery?" Dr. Pro, what are the new surgeries under consideration.

Dr. Pro: It's a great topic, I think. Let's talk about the ECP, Canaloplasty, ExPress Shunt, and Trabectome if time allows.

Moderator: OK. Do you want to start at the top with ECP? What is ECP?

Dr. Pro: ECP (Endocyclophotocoagulation) is in an interesting subset of glaucoma treatment modalities. See, with most glaucoma surgeries you are working on the outflow side of the equation. So, the IOP is too high and you are basically making a new drain. That's what we do with trabs and tube shunts, but ECP belongs to the subset of "cycloablative" surgeries where you are trying to reduce the amount of fluid that the eye naturally makes, basically "turning down the faucet". ECP is a special probe that is inserted into the front of the eye, most often during routine cataract surgery, and on a monitor the surgeon applies laser energy with the probe to shrink the glands that make aqueous fluid. These glands are called the ciliary body and are located right under the iris.

P: Can ECP follow a failed trabeculectomy or shunt implant surgery? Is it a “last ditch”plan?

Dr. Pro: It can be. In a sense right now we see the ECP used in two ways. First, it is frequently used in patients who are undergoing routine cataract surgery. A patient may have early glaucoma or ocular hypertension and be on one or two drops. ECP can be done during surgery in the thought that the IOP could be controlled post-op and the patient may not need more drops. Second, ECP can be used in patients with "refractory glaucoma." These are patients who have had several glaucoma procedures. Perhaps there isn't really room for another tube shunt and the ECP can be considered as an attempt to control the IOP.

P: Can ECP be done as a stand-alone surgery or is it always in conjunction with cataract surgery?

Dr. Pro: It is most often done with the cataract surgery, but it can be done as a stand-alone. It is technically easier to do at the time of cataract surgery as the view of the ciliary body through the probe is often clearer than in an eye that had cataract surgery years ago.

P: Can too much ciliary processes be effected and the eye not produce enough fluid post ECP surgery?

Dr. Pro: Yes, hypotony (a low IOP) is a possible adverse outcome. It is more common with the predecessor of ECP which is trans-scleral cyclophotocoagulation (TSCPC). That procedure is a non-cutting surgery where a probe delivers laser energy through the eye wall to shrink the ciliary body. It is often reserved for more poorly sighted eyes.

Moderator: Shall we discuss canaloplasty?

Dr. Pro: OK. Canaloplasy is a newer procedure, more like a trab in the sense that you are trying to improve on aqueous outflow. It is limited to open angle glaucoma. It is often performed as a stand-alone procedure, but can also be done at the time of cataract surgery. The approach is a bit like a trab, but in this surgery a fiberoptic cannula is advanced through the Schlemm's canal, a collector channel that runs around the eye. A fine suture is tied off in the canal and this dilation of the canal improves the outflow of aqueous fluid from the eye. In addition some aqueous fluid percolates out from where the flap incision is located at the top of the eye.

P: What makes a good candidate for canaloplasty?

Dr. Pro: Well, you need to have an open angle. Angle closure patients won't work because their natural drain is scarred shut. Also we don't yet have great data comparing this surgery to standard trabeculectomy, so it might not be as good at getting the IOP quite as low as in a trab. Persons with normal tension glaucoma who need a really low IOP might do better with a trab. It might be better for someone with early glaucoma, or someone who would do better without a high bleb (like a person who insists on continuing contact lens wear after glaucoma surgery).

Moderator: Excellent. Let's move on to ExPress shunts.

Dr. Pro: OK, the ExPress shunt has been around for a while now, but is getting more traction these days. It is a small stainless steel device that is used to augment standard trabeculectomy surgery. The device is seated under a scleral flap and may help improve post-operative success by creating a more controlled aqueous flow under the flap. Some surgeons also feel it helps create a more desirable bleb development.

P: What is the benefit of this shunt in combination with a trabeculectomy? What determines when the ExPress shunt is used in combination with a trabeculectomy and when a trabeculectomy should be performed without the shunt?

Dr. Pro: Well, there are no hard and fast rules. Some surgeons like to use the ExPress shunt when a standard trab has failed. Instead of moving on the larger tube shunt, an ExPress shunt can be tried. The thought is that maybe the patient would have a better outcome, with less chance of failure.

P: Will an ExPress shunt added to the trabeculectomy provide a lower IOP than just a trabeculectomy?

Dr. Pro: No. In fact one of the advantages of the Express may be that it prevents some cases of too low IOP which can be seen in standard trabeculectomy.

P: Is anyone at Wills Eye Institute trained in the ExPress shunt?

Dr. Pro: All of us are familiar with it and I would think just about all of us have used it. I perform ExPress shunt surgeries occasionally. Some of my colleagues are big proponents.

P: Dr. Pro, have you heard about the Gold Micro Shunt (by Solx)?

Dr. Pro: Yes, this is a device that has been in development for years now. It tries to improve outflow by shunting aqueous flow to the supraciliary space (a potential space between the vascular plexus within the eye and the eye wall). Newer generations of this device have been developed and are showing promise to lower the IOP. We need more data on this device, but it may be a promising new surgical option.

P: Dr. Pro, do you want to say a word about trabectome? There's a lot to discuss in each of these new surgeries! What is a trabectome and who's a candidate?

Dr. Pro: Briefly, the trabectome is a new device which revives an old procedure. Angle surgery is usually done on congenital and pediatric glaucoma. The theory is that there is a membrane which is blocking aqueous outflow to the Schlemm's canal. In one technique a needle is passed into the eye and the membrane is opened. This can be very successful in pediatric glaucoma, but showed much less success in adult glaucoma. The trabectome is a device which is passed through the eye and which cuts through the eye tissue covering the Schlemm's canal. This “unroofs” the canal and has been effective in many patients. It can be done as a stand-alone procedure or at the time of cataract surgery.

P: Which new surgeries, when done, make it impossible to do a trabeculectomy or add a shunt in the future?

Dr. Pro: The canaloplasty needs a large superior conjunctival incision and may make another trab difficult to perform. So would the gold shunt or ExPress shunt.

P: How many trabs and/or shunts have you ever seen in one eye?

Dr. Pro: I have seen three tubes in a single eye, with several failed trabs.

P: Is there data on the life of a trab with a shunt compared to just a trabeculectomy?

Dr. Pro: No, not yet.

Moderator: That about wraps it up! We're out of time.

P: This has been a lot of information. I think sometime in the future it might be nice to just have a discussion more in depth about one or two of these subjects.

Dr. Pro: I think that was a good chat! Thanks for all the great questions. Good night.

On July 6, Dr. Hsu discussed "The Retina and Glaucoma" in the Chat room. Click here for highlights of that meeting.

Click here for the most recent glaucoma chat highlights and links to the chat archives.

Click here for upcoming glaucoma chat events.