Ex-Press Mini Shunt Update
Chat Highlights – June 5, 2013
Guest Speaker – Dr. Michael Pro
Lorraine Miller, Editor, Chat Topic Researcher
Moderator: Good evening! “Ex-Press Mini Shunt Update” is tonight’s topic. We would like to welcome, Dr. Michael Pro, once again as our subject matter expert.
P: What is an Ex-Press mini shunt?
Dr. Pro: The Ex-Press mini shunt is a small, surgical, stainless steel device that was developed to allow more predictable glaucoma surgery results. It is currently being marketed by Alcon.
P: More and more trabeculectomy patients are also having the Ex-Press mini shunt added to their surgical procedure. Why is this shunt becoming so popular?
Dr. Pro: Some glaucoma surgeons believe that the Ex-Press shunt can give a more predictable flow of aqueous humor under a scleral flap. The Ex-Press is a modification of a standard trabeculectomy surgery in which a scleral flap is created. Traditionally, at the base of the scleral flap, a punch of scleral tissue is removed. Aqueous fluid goes from the anterior chamber through an ostium, a hole in the sclera, under the flap and then fills a pocket of fluid under the conjunctiva. The difference with the Ex-Press is that a small stainless steel device is placed under the flap. The tip of the Ex-Press goes into the AC (anterior chamber).
P: Are there certain types of glaucoma that respond better to implanting an Ex-Press mini shunt?
Dr. Pro: That is a great question. In my experience, the Ex-Press is particularly suited to surgeons who may have less experience with glaucoma surgery. The device has an internal lumen size of fifty microns, so patients may experience less risk of too much aqueous fluid outflow with very low IOP. I know that doesn’t exactly answer your question, but in my opinion, any patient who is a candidate for standard trabeculectomy surgery is also a candidate for an Ex-Press device.
P: Dr. Pro, based on your comment that the Ex-Press shunt may be better for inexperienced surgeons, does that mean it take less surgical skill to implant the Ex-Press shunt than to do a traditional trabeculectomy?
Dr. Pro: Not exactly. But in my opinion, trabeculectomy surgery takes quite some time to master. The most difficult part for many surgeons is titrating the flow under the scleral flap. This is not to trivialize the correct placement of the Ex-Press, but I do think it can help to give a more controlled flow of aqueous under the scleral flap in the early post-operative period.
P: How long is the recovery from Ex-Press mini shunt?
Dr. Pro: The recovery from Ex-Press is no different from a trabeculectomy. I want to be very clear that the surgery is quite similar to a trabeculectomy. In general, I tell my patients that their vision can be blurry after surgery and that the blurriness can last up to one month.
P: Would you say the same to the traditional trabeculectomy patients, that their vision might be blurry up to a month post-surgery?
Dr. Pro: Absolutely. I think it is important for patients to know that this is a very real possibility. Some patients may have close to their pre-operative vision and some more blurred. It is important that patients expect some change in their lifestyle for about a month after glaucoma surgery.
P: How long can the Ex-Press mini shunt provide an adequate reduction in intraocular pressure?
Dr. Pro: The expected length of success for an Ex-Press would be the same as for a trabeculectomy. We really don’t know the success rate for the Ex-Press except for the past two years because there aren’t any long-term outcome studies.
P: I’ve read that the Ex-Press has been around for more than ten years. Why haven’t there been more studies on its effectiveness?
Dr. Pro: It can be difficult to do long-term studies due to many reasons. Cost may be the largest factor along with other issues such as patient retention. It is difficult to track patients for such a long time. The use of the Ex-Press has really only increased in the last five years.
P: Does the Ex-Press shunt replace or is it in addition to the traditional trabeculectomy surgery?
Dr. Pro: It does not replace a trabeculectomy. As I mentioned before, the Ex-Press is a modification of the trabeculectomy surgery technique. The outcome is the same. A filtering bleb is created by both. Some surgeons prefer to do trabeculectomies and others prefer the Ex-Press.
P: Can an Ex-Press shunt be added during the combination cataract trabeculectomy surgery?
Dr. Pro: Yes. I think there remains some confusion regarding the Ex-Press. Many patients lump it with other tube shunts, but this is not accurate. It is important to stress that the Ex-Press surgery is nearly identical to trabeculectomy, including the use of mitomycin C to prevent post-surgical scarring and including the formation of a bleb.
P: If cataract surgery is needed for a person with a trabeculectomy, is it best to be done by a glaucoma specialist or a cataract surgeon?
Dr. Pro: It depends. I do not think the presence of the bleb complicates cataract surgery in all cases. Individuals with prior glaucoma surgery sometimes have poor dilation or more complex cataracts. Whoever is doing the surgery has to be prepared for a potentially more difficult surgery.
P: What is the rejection rate for the stainless steel Ex-Press device?
Dr. Pro: These devices do not reject. But they can extrude from the eye if improperly placed or if there is ocular trauma.
P: Can the device be malpositioned and a revision required?
Dr. Pro: Yes, I have encountered devices that were malpositioned and sometimes these devices need to be removed but that is uncommon. If the surgery fails, the device is left in the eye and it seems to cause no harm to the eye. Long-term effects over ten years to the eye are unknown as the device has not been on the market that long.
P: Does each physician insert the device in the eye the exact same way? Where and how does a physician learn the process?
Dr. Pro: Just like with a trabeculectomy, techniques from one surgeon to the next may be similar, but not exactly the same. I think younger surgeons learn to perform an Ex-Press procedure in residency training.
P: Do most insurance companies in the USA cover Ex-Press mini shunts?
Dr. Pro: Perhaps one of the most important questions of the night! Yes, unfortunately coverage of the Ex-Press as well as other novel glaucoma devices like the iStent or canaloplasty can vary from one insurance provider to another even if the procedure is covered by Medicare.
P: Have there been any new updates to the procedure or device?
Dr. Pro: There have not been any recent updates. I am aware of two models, the P-50 and the R-50. The devices are very similar in design and I am not aware of any difference in surgical outcomes between the two models. I think most surgeons use the P-50.
P: Could the Ex-Press shunt cause the same double vision problems as the Baerveldt or Ahmed shunt?
Dr. Pro: The rate of misalignment after Ex-Press is not any different from a trabeculectomy. The rate of double vision after a tube shunt is about five percent.
Moderator: It’s the bottom of the hour. Thank you once again, Dr. Pro, for sharing your valuable insights and knowledge with us.