Lecture: An Introduction to Angle Based Glaucoma Surgery

This lecture will cover the basics of angle surgery for glaucoma management. Topics covered will include the various options for trabecular bypass as well as minimally invasive laser based therapies.

Lecturer: Dr. Malik Y. Kahook, Professor of Ophthalmology – University of Colorado, USA


DR KAHOOK: Good morning, everybody. It is very early in the morning here in Denver, Colorado. And that music was a good wake-me-up, before getting started. I am excited to have this discussion. It’s always great to have feedback from all over the world, with some of the topics that we talk about. And today’s topic is an introduction to angle-based glaucoma surgery. I gave a talk a few months ago, on Cybersight, that touched on these topics, but it was towards the end of the conversation, and we didn’t spend a lot of time on it, and I got some feedback about getting into a little more of the basics, and how we might select which angle surgery we might do in a given patient, so that’s what we’re gonna cover today. These are my disclosures. I work in a few of the companies that are in this space. So we’re gonna start off with a question, just to get an idea of who’s on the call today, and the question is: How often do you perform ab interno or angle-based surgery. I’ll give you a few seconds to answer. All right. So we have a big chunk of people who are listening in who almost never or never do angle surgery, and then another big group that might do it sometimes, but rarely so. This is actually the perfect topic for this group, and we’ll get into some of the basics, and see if we can transition some of the people who never do it into at least occasionally doing some of the procedures. We’ll start off with another question here, and we’ll have another two questions throughout this conversation, and this question is about: Where is the most resistance to aqueous outflow? It takes a few seconds to tabulate the answers. That’s great. So the majority answered the right answer here, which is the juxtacanalicular trabecular meshwork. And that’s where most of the devices that we’re targeting are gonna go through. The real question for today is: Is earlier surgical intervention the future of glaucoma therapy? Should we be thinking about surgery a little bit sooner? Because now we have options that have less complications? A lower adverse event profile? And how is that gonna change our treatment paradigm? And I like to show this slide — I think I showed it in my last conversation, because it does go to show you a little bit of how glaucoma treatment has been thought of in the past. One of our most famous studies is the trabeculectomy comparison with tubes, and we know that tubes are worse than trabs, because eventually we need more medications. Trabs are worse than tubes because eventually there might be more failure, but have you ever considered that many of our trials, our studies, are geared toward which intervention is least harmful. In glaucoma, oftentimes we’re talking about: Which one is least harmful, which one is least hurtful? And this is how MIGS really came to be. It’s an ab interno approach that is minimally traumatic. We want a minimal footprint when we go into the eye. At least modest efficacy that is sustained. It might not be like trabeculectomy efficacy, but we want it sustained. Extremely high safety profile. The majority of the time, when we do cataract surgery, the outcomes are extremely predictable and it’s extremely safe, and we’re looking for a similar procedure for the ab interno procedures we do, and then of course rapid recovery with minimal impact on quality of life. When we say MIGS, oftentimes from a regulatory perspective, we’re talking about device implants. So not all of MIGS would reside within the category of the angle-based procedures that we do, that might be slightly outside of MIGS. And it’s important to say that the umbrella term probably more appropriately is ab interno angle-based surgery, of which MIGS is an extremely big part, and of course the part that has had a lot of innovation over the last few years, led by several of our colleagues. Trabecular bypass devices, like the iStent or the Hydrus, suprachoroidal devices, which we’ll get to at the end, filtration devices — you have a device that sits at the edge of either being a MIGS device or a little bit more than that, towards the trabecular drainage devices, and that would be the XEN implant, and then internationally, not available in the US at this point, the InnFocus shunt. So if you’re thinking about adding angle surgery to your practice, hopefully many of you who answered never are at least thinking about incorporating this. You probably have a population that would be well served by this procedure. So that’s what we’re gonna talk about. How do you think about incorporating it? We’ll talk about patient selection, preoperative, intraoperative, and postoperative, and then some follow-up pearls, including which device you would choose. It used to be when we talked about ab interno or MIGS procedures, we would talk about mild to moderate. Much of the progress in the United States, and subsequently to that, around the world, the focus is really on cataract surgery with MIGS implant, traditionally thought to be mild to moderate, and certainly it has a major role in that category. We all have our devices, and I’ll talk about all of them today. From my standpoint, I think about goniotomy or endocyclophotocoagulation with laser. Sometimes I combine the two. We’ll do goniotomy plus endocyclophotocoagulation. But I don’t want you to think of ab interno procedures as only being relegated to mild to moderate. We also used procedures in moderate to end stage disease, and we found some success in preventing or delaying trabeculectomy or glaucoma drainage devices. In this case, goniotomy has been one of our mainstays, but you can combine it with ECP, you can combine iStent with ECP, and combining the inflow/outflow procedures in some cases has allowed us to stave off trabs and tubes for a very long period of time. We always tell patients in these cases: Let’s try the less traumatic low hanging fruit of doing an angle procedure, and if it fails, we always have the capacity to go and do a trabeculectomy and a glaucoma drainage device procedure. So this is evolving. You can see from a risk to IOP-lowering profile, on the right hand side, we’re still learning. Now that it’s coming to market in the US and in other parts of the world, we’re seeing how it marries with endocyclophotocoagulation, so we can think of it more broadly, how patients might benefit. When we combine with cataract surgery and you’re consenting the patient, it’s extremely important to always talk about plus or minus. What do I mean by that? Sometimes you go and do the cataract surgery and realize that the planned procedure you were going to do with implants might not be appropriate. Maybe the angle just won’t receive the device, or your visualization postcataract surgery is not as adequate as you would like it to be. In those cases, it would be good to have a conversation with the patient, to say that you might not be able to do the ab interno procedure for glaucoma, because of other things that might come up. Just to get them ready. 99.9% of the time, you might be able to, but you should be prepared. You should discuss that it’s a little bit different than cataract surgery. So if they had a friend who had cataract surgery, or only had it in one eye, let them know that the recovery might be slightly different, it might take them a little bit longer to get to optimal vision, in some cases you might have microhyphema in the first day postoperatively, which in my opinion is a good indication, and I’ll go into that in a little bit, but just be prepared. Dilation drops — you don’t change your routine when you do cataract surgery combined. And another important point here that we have to be aware of is to discuss positioning with the patient. Oftentimes with almost all of the procedures that we do inside of the angle, we rotate the patient’s head away from us, and we rotate the microscope towards us, and we do that for about 45 degrees each. In that case, there’s a little bit of commotion in the operating room. The patient can hear you talking to the nurse. Not many of the microscopes are self-positioning. Oftentimes the nurse has to help, or you have to get an extra handle, or there’s noise. Just let the patient know that at some point during the procedure, there will be a repositioning that happens, so the patient is aware of it. I’ve found that to be extremely valuable to make sure the patient knows. Rather than after a period of not moving, if you’re asking the patient to move their head, they might be a little confused. Now, in the case where it’s standalone, we typically give antibiotics and pilocarpine preoperatively, to constrict the pupil. It might give us a little bit better view of the angle. Otherwise everything is as above when it’s combined. Now, some pearls that I think would be very helpful intraoperatively, especially for your first few cases, which for more than half of you, it would be your first case that you would do once you get rolling with angle surgery — use a miotic for the first few cases. Intraoperatively, you can use carbachol, Miostat, et cetera. And this would enhance your view of the angle, because you can get a little bit more depth, a little bit more view with trampolining of the iris down, away from your view, and for the first few cases, it might be helpful. Certainly not necessary as you get more experienced. Routine cases and cooperative patients are extremely important early on. When you start doing angle procedures — we’ll go into this more in the next few slides — the positioning is a little different, the surgeon might be more uncomfortable. You’re used to doing cataract surgery but not angle surgery, you might have trained a little bit, but you’re starting your first few cases. Having routine, clear anatomy, being able to visualize very clearly in the clinic, so you know what to expect in the operating room, those are important things. Even though the majority of cases are done with topical anesthesia, for your first few cases, you should consider peribulbar anesthetic. Gives you more control. Your first few cases might take a little longer, so this way you can make sure the patient is comfortable. We want all these eyes to be well pressurized, to encourage flow from the inside to the outside of the eye, rather than any retrograde flow that might occur because you’ve opened up the blockage in the angle. So great hydration, leave the pressure a little bit high on the table, in some cases we leave dispersive viscoelastic, which encourages flow out of the eye in the early postoperative phase. Let’s talk about positioning. A couple of these slides are gonna be familiar if you listened to my talk last year, where we talked about some of the positioning issues that I think are extremely important. If you compare the experience versus cataract surgery, the elbows are at a slightly different position. Depending on your dominant hand, your non-dominant hand will be stretched and holding the gonio lens, whereas your dominant hand would be doing the procedure, and would be much more like phaco in that regard. You’re also working through two different areas. The cornea — in cataract surgery, we’re working with two incisions, whereas in the ab interno procedures, we have one hand inside the eye and the other hand outside. There’s also the thought of bimanual versus intra/extraocular. In the case of angle surgery, oftentimes we have one hand operating inside of the eye and the other not really participating in the maneuvers that are happening inside the eye. And from an operative space standpoint, that’s one thing that most new surgeons to the angle recognize as being different. Instead of having the whole space between the posterior cornea and the posterior capsule when you’re operating for cataract surgery, now you’re operating in a 1 millimeter space and you have to be conscious of the corneal endothelium, the ciliary body, and the iris, and make sure you don’t do any damage to the collateral tissues that are there. This is an image of Shakeel Shareef, who is operating and showing — I think this is a really nice image to look at before starting. Instead of both elbows at the side, you see left hand outstretched with the gonio lens on one side, and there might be a little bit more reaching for the gonio lens part of it. You can tell he’s an experienced angle surgeon. He looks very comfortable here, but you can see very quickly if you’re not practicing before your first few cases, you might be uncomfortable. So practicing is very important. From a gonioscopy standpoint, this is the biggest difference. We have to be proficient at doing gonioscopy in the clinic. You place viscoelastic to couple the gonio lens with the cornea, and I like to put viscoelastic on the bottom of the lens rather than putting it on the cornea. We tend to overinstil viscoelastic if we place it on the cornea. We can save some if we place it on the lens. That moves heme or blood away from the cornea, and any air pockets are negated that way. So I’m in the habit of putting the viscoelastic on the bottom of the lens, rather than on the cornea. You should also make sure your resting your hand, similar to when you’re doing capsulorrhexis, when we’re using any of the devices with the inserters or the handles. Don’t use the lens to direct your eye. This is something you can teach, but until the surgeon recognizes that they’re doing it, they’re not gonna know how to address the situation. There’s a human tendency with the hand that’s holding the gonio lens to direct the eye away or move it side to side, to get better visualization. In essence you’re just depressing the cornea and causing stria. We don’t want that to happen. We want the gonio lens to float on the viscoelastic, so it’s barely touching or not touching at all. And of course, zoom in. You see on the upper right hand side the image of the trabecular meshwork. Your image of the trabecular meshwork should be extremely zoomed down, so you can see all the intricacies of the anatomical regions within the angle, so you’re treating the appropriate tissue. Extremely important. With cataract surgery, you might be zoomed out a little bit more. In this case, we want you to be zoomed in. This is a video showing a surgeon practicing, out of South Dakota, showing that this is a great way to practice. Before you do your first few cases, in standard cataract surgeries, if you’re doing phacoemulsification, at the conclusion of the case, you can take the microscope, take the standard chopper, whatever you’re using for cataract surgery, and just learn to move the device side to side. You’re not touching the trabecular meshwork, but you’re getting used to the gonio lens, with tilting the patient, and you’re getting the operating room staff used to what happens at the time with the tilting of the microscope. Extremely important. One thing that’s overlooked here is wound construction. I think it’s extremely important to not get into the limbal vessels. If you have oozing vessels, which is something that many cataract surgeons do — they place their wounds slightly posteriorly — in the case of combined cataract surgery with ab interno surgery, if you have oozing vessels, that will make its way into the corneal surface and the viscoelastic, and may make your view a little bit more difficult with angle surgery. So we always go a little bit more anteriorly, and get away from the limbal vessels, when we’re doing combined procedures. All right, so putting it all together. This is a patient who just had cataract surgery, tilted the head, tilted the microscope, in this case, the patient is getting goniotomy, you can see the view is great, maybe the surgeon could have zoomed in a little bit more, so they’re seeing more details of the trabecular meshwork, but in this case, you see not a lot of movement, not a lot of striae in the cornea, so the surgeon is not using the gonial lens to direct the eye, the lens is floating on top of the viscoelastic, and at the conclusion of the case, just grab the strip of trabecular meshwork, and you’re off and running. You’re done with the procedure. So just an idea of how to put everything together, to make it look smooth. I also like to mention this. At the conclusion of almost all of the MIGS procedures that we do, we like to blanch the vessels, if at all possible. So if you look in the upper left hand side here, you see some of the surface vessels blanching, when we inject BSS into the eye. So we’re inflating the anterior chamber, increasing the pressure, increasing the outflow, and oftentimes I tell the patients that we saw this sign that we’re looking for postprocedure. In this particular case, it’s postgoniotomy. We’ve unroofed 3, 4 collector channels, and you can see that the blanching is significant. Always a good sign to know that the distal outflow system is patent. One common question that comes up — should I do the MIGS procedure or the angle procedure before or after cataract surgery? And we just completed a study on this. We presented in some of our national meetings. It’ll be published in JCRS pretty soon, in the next few weeks. And what we did is we had the surgeons evaluate photos that were taken of the angle, before and after cataract surgery, to see if there’s a change in the view. Would it be better to do it before cataract surgery, because of visualization, or after? And in the case in our study — we did it across multiple evaluators. Three different surgeons evaluating the photos. We actually found no consistent difference. Sometimes you can say that the visualization was better before cataract surgery. Sometimes it was after cataract surgery. We didn’t find any predictive points for any of these. So do what you prefer. I prefer to do it after cataract surgery. I like to get the cataract surgery done, and open up the angle a little bit more. My colleagues like to do it before the cataract surgery, which is ultimately completely fine. Now, how do we do it postoperatively? Think of it very much as cataract surgery. Antibiotics, steroids, non-steroidals, if you like to use them. You could use pilocarpine to keep the angle open, if you’ve done incision of trabecular meshwork with goniotomy. What I recommend is, while the patient is on steroids, to make sure the patient is using another steroid drop, but if it’s standalone, you would do exactly the same thing, maybe minus the NSAIDs, and just use a glaucoma drop, along with the antibiotic and steroids, and see the patient back, postop day one. Week one, what you would typically do for your cataract procedures. Some follow-up pearls I mentioned. Steroid response is not uncommon with ab interno procedures. It might be counterintuitive, because we just said that most of the blockage happens at the juxtacanalicular trabecular meshwork. So for EyePass — if we’re removing the trabecular meshwork, why do we have steroid response glaucoma? We just don’t know. There might be effects happening at the distal outflow system, at the level of Schlemm’s canal or collector channels. A lot of imaging is done to figure out how responsive collector channels might be to different stimuli. We’re still learning. In the mean time, until we figure it out, please use a glaucoma drop while the patient is on steroids, especially if they have more advanced disease, so they don’t have spikes. You can stop all medication if the pressure is below 15 and the patient doesn’t have advanced disease, but watch closely, and keep on medications as needed, depending on nerve status, as I mentioned, and then you can restart meds as needed if you aren’t at the pressure that you were hoping for. We’re gonna get into another question here. Sorry, my screen is partially blocked. I’m gonna try and move that around here. Is steroid response glaucoma something that is still possible here, after angle-based surgery? So I’m gonna… So in this case, it’s rare. Sorry, that word was covered. Steroid response elevation in IOP is rare after angle surgery. True or false? Changes the answer slightly. I’ll see if I can move the blockage here. All right, so the answer is that it’s not rare. So the answer in this case — I’m gonna close this box here — is false. It is not rare. And this is a really important point. If you’re operating on patients, and you’re doing ab interno procedures, keep in mind that steroid response glaucoma is possible, and you have to be vigilant for that, especially in this population, as you know. So what is the case for goniotomy? I want to talk a little bit about that, because I spend a lot of my time in that arena. So the ramp is critical in the case of the goniotomy procedures that we do. Placing the trabecular meshwork on stretch allows for a more precise cut. It’s not enough to go in and try to incise the trabecular meshwork, because the tissue will bunch up. In our case, we attempted — in the development of devices for goniotomy — multiple different scenarios where we saw a lot of bunching up, like wet tissue paper, of the tissue as we were treating it. And so we eventually came up with the idea of doing the ramp, which resulted in the tissue elevating to the dual blades, and leading to an excision of trabecular meshwork. So we’ve taken this into the clinic. This has been around since 2015. This is an example of taking average pressure from 17 to 12 with one-year follow-up, and with medications also seeing a significant decrease of 1.6 to 0.6. The reason I show this is because there is a significant potential for IOP lowering with not just goniotomy procedures, but many of the procedures that we do in the angle space, and I think we should keep that in mind. We shouldn’t relegate this to the mild to moderate. In some cases, it can work extremely well. From a surgical technique standpoint, this will leverage all the information we just covered earlier in the discussion. The zooming in on the trabecular meshwork, making sure that the lens is floating, that we’re not directing the eye, and you can see it could be a very straightforward procedure. It requires a skill set, of course, and that’s why we’re trained as ophthalmic surgeons. But if you put it all together, you can get many open collector channels, which you see here, with these red dots, and a quite successful procedure, that is streamlined with cataract surgery. I also like the fact that we can take trabecular meshwork tissue, and this is great from a feel-good standpoint. When you do surgery, you feel more like you’re doing something. But also from a research standpoint, you can put the tissue into a tissue library and study it over time, and we’ve done a lot of histology on the trabecular meshwork, and we’re learning things we didn’t know before. One thing is: How does the trabecular meshwork respond to different procedures? We really don’t know a lot about trabecular meshwork healing. And in this case, I received some tissue from Davinder Grover and Ron Feldman, to analyze after they had performed GATT procedure, which is again, an incision, creating a flap of trabecular meshwork, and they had scarring, far down the road, after doing the procedure, and they went in and did an excisional goniotomy, and sent the tissue to the University of Colorado, and we were able to do the analysis, and we saw what for me was the first time to identify fibrosis, postincisional goniotomy. This is something that can happen with all procedures. It can happen postexcisional goniotomy. It can happen post-any of the implants, and we’re starting to recognize this more and more. We’re looking for it, and also analyzing the tissue. I’ll show you an example of that here. This is a case where I had implanted an iStent two years previous, and I could tell that the iStent was moving away from the canal, not in the position it should have been, and the pressure was going up. We took the iStent out and performed an excisional goniotomy. During that excisional process, we noticed a film that was over the site where the device was, as well as over the trabecular meshwork. You see the strip of trabecular meshwork there. But you see this film that we’ll indicate with some arrows here in a little bit, and it was quite tightly adherent to surrounding trabecular meshwork, where the device was sitting, so we took the tissue, excised it, and did some analysis on it, and what we found was a great deal of fibrosis. The whole film was a fibrotic sheet. There was a lot of pigment on one side, low pigment on the other, with trabecular meshwork cells, but this sheet of fibrotic tissue. And this is something we continue to learn about. We published this last year in the Journal of Glaucoma, a series of patients, and we’re continuing to collect tissue, and we’re seeing the same thing. Anything you do in the angle could potentially lead to fibrosis, but we have to learn exactly what the process is, and that’ll help us stop it. These are some examples of harvested tissue post-stent placement within the trabecular meshwork. They all look the same. Less trabecular meshwork cells, less pigmentation, fibrotic sheets that cover the device. So I’m ready to start angle surgery. Which one do I choose? This is really a hard question, and I’m gonna try and answer it a few different ways. In my opinion, glaucoma is becoming a field where the past best patient experiences are now becoming the expectation. Patients want a safe option that provides IOP lowering, and they want the added benefit of decreasing medications. Most of my patients want to be off their drops if at all possible. Surgeons want something that’s predictable, safe, and economically feasible. The economic pressures all around the world are really driving some of the training we’re doing, some of the decision making we’re doing, but we want to be safe and effective, of course. Here’s an example. 65-year-old patient with primary open-angle glaucoma. Current pressure is 15. Patient has a significant cataract. No prior glaucoma surgery, on a prostaglandin analog, visual field shows early nasal step that is progressing slowly. The question is: What is your best surgical option? I’ll go through some scenarios. What’s on the menu? What are the choices? You see this table is continuously expanding. We’ve had trabectome, iStent, Trab360, ABiC, GATT, and you see the other choices there. I used to say there were many choices, but a poor understanding of where they fit in, due to lack of data. And that’s evolving. I don’t say that anymore, because evidence-based medicine is increasing, and we’re starting to get data that can drive the decisions. I didn’t have room to put everything on this slide. There are many, many more. So you’ll see a video of the Hydrus implant being placed on the right hand side. My first choice is to go after conventional outflow. It’s safe, physiologic, and it gives us the chance to do a small footprint without placing a device. We can do things like goniotomy. All devices and all approaches have a role, and I think we’re learning how to personalize with the long-term data that we’re getting. I think all of them have a role in mild glaucoma with cataract surgery. In cases of standalone, and perhaps more advanced disease, my go-to is goniotomy, and of course I’m biased in that area, because we’ve done a lot of work in that area. I also like that it’s economically sound. When I’m traveling around the world, oftentimes we don’t have access to the very expensive devices that are implanted, and in this case we can give patients access to the benefits of angle surgery without the expense that goes along with the implants. There’s procedures combined with medications, in-office procedures. There are a lot of things happening in this space. From an outflow standpoint, there’s also the unconventional pathway. This one has had a lot of news recently, as many of you know. Suprachoroidal implants — never was my first choice, because of the unpredictable nature of IOP lowering. And it had a higher adverse event profile, like hypotony, a lot of our patients were complaining of pain, and of course endothelial cell loss, which led to the only device on the market, the CyPass implant, being pulled, and further studies underway to figure out what to do to make the adverse event profile better and potentially put it back on the market. Where does it fit into my algorithm? I would sometimes consider doing it instead of a second tube, if the patient had extensive scarring, but now of course that it’s pulled from the market in the US and globally, we don’t really have access to that, and we’ll have to see with new materials, different designs, maybe combining it with different medications. We have to modify our expectations with the suprachoroidal space at this point. So what’s on the menu for full thickness? We have XEN/Trab/ExPRESS, and in the perhaps not minimally invasive, but less invasive would be XEN. I know there are studies around the world where some of you might have access to it. It’s not my first choice, because my major goal is to avoid a bleb. I’m trying to get away with having a bleb, with all the potential complications. XEN in our experience has a 40% needling rate, which was too high to implement in our practice. And the possibility of treating glaucoma earlier with some of our other approaches pushes off the need for a bleb further and further, so it hasn’t risen up to the top one or two approaches we use. Where does it fit into my algorithm? In the case of XEN, elderly Caucasian patients, lightly pigmented, tend to do better than others. Traditional trab or ExPRESS is typically my choice. If I’m looking for a bleb, we do trabeculectomy, typically. We do many of our XENs ab externo instead of ab interno these days. We’ll see how different designs might work better. And do we have antiscarring strategies? It’s not enough to just do a bleb. We have to do a better bleb. And I don’t think we’re quite there yet. This is a video of ECP being performed. Expectation is that you can get 25% IOP lowering. I’m a big fan of ECP. It works in a lot of cases where other devices might not work as well. You can go through two incisions and get 360 degrees of treatment. Easily combined with outflow procedures. And it’s the go-to when conjunctiva is compromised, in my case. So back to the patient case. 65-year-old with POAG and goal pressure is 15, pressure is 18, no prior glaucoma surgery, nasal step that’s early. In this case, I’m sure you can predict from everything that we just said — I would go to goniotomy as my procedure of choice. It’s safe, effective, exposes several collector channels. But what if I change this slightly, and I say: Prior glaucoma drainage device surgery, maximum tolerance to medical therapy, visual field nasal step progressing rapidly. How would I change that? In my case, I would do 360 ECP and combine with one of the outflow procedures, whether it’s goniotomy, iStent, Hydrus — any of the choices we have. The combo, when you’re looking at advanced disease and doing things more aggressively, that would be the choice. What if goal pressure was 10, no prior surgery, currently on maximal medical therapy, steady progression of nasal step — in this case, we’re still back to traditional trabeculectomy. It’s still my go-to when the target is 10. This is one of the areas that hasn’t changed significantly over the years. We’re still using that as a gold standard for IOP lowering. Maybe some of the new devices that are coming, like the InnFocus, will change that. But we don’t know. Last question. Which glaucoma surgery is most likely to succeed when targeting an IOP level of 10 to 12 millimeters of mercury? And the answer… All right, so we just talked about that trabeculectomy is still the go-to. 5% gave goniotomy. Trabeculectomy is still the gold standard here, when we’re looking for very low pressure. So where are we headed? More choices will further our ability to personalize care, similar to tailoring IOLs or glaucoma medication choices. Head to head data — we’re getting a lot more studies that are comparing devices and approaches to each other. Educational outreach. A lot of the companies that are selling these devices and approaches are training surgeons, residents, and fellows, so we’re getting a lot more education in the field, which is only a good thing. Learning more about combining inflow and outflow, drug delivery will start making an impact. A lot of the meetings I’m going to now used to be very heavy on MIGS. Now it’s heavy on drug delivery. I think that combination will happen. Economic drivers may dictate a non-implant approach to MIGS. Depending on where you operate, what community you might be in, you might not have access to everything that the other surgeons may have, so looking for less expensive approaches might be beneficial. And robust office-based IOP-lowering procedures are the next target. We’re trying to get away from operating rooms and doing things in procedure rooms and even potentially at the slit lamp. I think we’re gonna see more of that in the next several years. One thing I like to talk about is that we now have several options. 15 years ago, when I was in training, we just talked about trabs and tubes, maximizing therapy and going to incisional surgery with full thickness procedures. Now we have many options, which is a beautiful thing. Thank you very much, and I’m happy to take some questions.

>> Thank you, Dr. Kahook. We have three questions so far, if you want to open up the Q and A.

DR KAHOOK: Which gonioscope do you recommend? There are multiple gonioscopic lenses out there. There’s the Hill lens, for operating through an incision, with the lens sitting on the cornea, which is something we use frequently. There’s the Volk lens, that has teeth on the bottom, to help with resting and sitting on the conjunctiva rather than the cornea. You also have many disposable versions, so it might be more cost effective to get many disposable versions, rather than what tends to be a fairly expensive investment with gonioscopic lenses. Over time, it might be more cost effective if you’re doing a lot of procedures, but take that into account. There isn’t one lens that is above all the others, and you might have different vendors for the gonioscopic lenses. This might be something to talk to colleagues who are doing surgery in the angle close by, and see what they’re using, because you might have access to those lenses a little bit easier. Sorry for my bad connection. What does ramp stand for? Ramp is actually just the word “ramp”. In this case, ramp is where you start on the bottom and move your way to the top. In that case, the description — the trabecular meshwork sits on the bottom, ramps up to the top, and presents itself to the two blades. That was the big thing for us when designing the dual blade devices. Without the ramp, we weren’t getting consistent parallel incisions to produce an excisional goniotomy. So which is the best procedure for NTG/LTG? Great question from Muhammad Ramzan. In this case, very long conversations have been had about which one would be best for NTG. Whether it’s NTG or regular POAG, if your target is 10 to 12, trabeculectomy is your best bet. However, a lot of NTG patients have a pressure of 16, 18, and in that case, our procedure is doing a goniotomy, plus or minus ECP, and if 13 or 14 is our goal pressure, you can go the ab interno or MIGS route. If you’re targeting 10, it’s still trabeculectomy in our hands. A question from Dr. Pai. Standalone MIGS is an accepted treatment? It is. In my case, about half of my procedures, when I do goniotomies, for example, are standalone. I go in, I do the trabeculotomy or trabeculectomy of the strip of tissue, and in some cases, I tag along with ECP, without having done cataract surgery, if the patient is pseudophakic, of course. In cases of some of the MIGS procedures, the implants — that might be a little bit different. It depends on the regulatory status. In some places around the world, you can only do combined implant with cataract surgery, because that’s how it was approved. But with the goniotomy procedures and others, you have more flexibility. With ABiC, 360, you can do those without having to do the cataract surgery. Question here: Where do non-penetrating deep sclerectomy stand in your management algorithm of treating glaucoma effectively? Many of my colleagues that I’ve talked about this in Europe might shake their heads at this, but I don’t do non-penetrating deep sclerectomy. The reason is that we were not trained on that in the United States. Very few physicians in the United States do deep sclerectomy, and our experience is that trabeculectomy is more effective and more reproducible in our hands. Many of the non-penetrating deep sclerectomies that I tried earlier in my career were most effective when I converted them to traditional deep sclerectomy. This has to do with training. Many of the surgeons I know that do deep sclerectomy do it in a fantastic way. And they would be better at answering that specific question. How do you manage hyphema during or after goniotomy? This is a very important question, and I touched on it slightly in the past. Where when I’m doing goniotomy, and I’m excising a strip of trabecular meshwork, if I don’t see reflux of blood into the anterior chamber, I see that as a bad sign. I want to see reflux. I want to know that the collector channels are patent, that the distal outflow system is patent. And at that time, if you inflate the anterior chamber adequately, let’s say you haven’t completed the treatment, and you want to move some of the heme out of your way, you can inflate with viscoelastic, dispersive or cohesive — really up to your preference — and then complete the treatment. Now, one of the management things to do at that point is: I routinely leave about 10% fill of dispersive viscoelastic in the anterior chamber at the conclusion of all my angle procedures. In the case of goniotomy, for example, whether there is a little bit of trickling blood from the collector channels or not, I’ll typically leave some dispersive viscoelastic, and that encourages the outflow from the inside of the eye to the outside of the eye, and hyphemas postoperative day one are extremely rare in my practice at this point. Occasionally you might see a microhyphema. That resolves after day one. We’ve done a review of almost 300 eyes in our practice, and I believe all of our patients, if there was hyphema, postoperative day one, overwhelming majority were done by week one, and all by month one. Not that big of a deal, if you’re handling it correctly, and adding the dispersive viscoelastic 10% fill at the end of the case will pretty much fix that problem for you. All right, let me see here. Standalone MIGS: Is there increased risk for developing cataract? Most of the standalone MIGS procedures I do in pseudophakic patients. There is increased risk of cataract development if you’re operating in a phakic patient and entering the eye for any procedure. That’s something to keep in mind. Of course, if you cause trauma, bump into the lens, that will make it 100%, but in the case where I’m in, if the patient is phakic, the overwhelming majority of my patients have some degree of cataract if they’re phakic, and if I’m going in anyway, I want to give them the maximal benefit of going into the operating room, and typically combining cataract surgery with the MIGS procedure. You said you perform angle procedure after cataract surgery. What is optimal timing in your view between the two procedures? Thanks for allowing me to clarify. What I meant is that in the same sitting, in the operating room, I’ll do the cataract surgery and immediately after that, I’ll do the angle surgery. I do combine those two. What I don’t do is start off by doing the angle procedure, and then go on to cataract surgery. I don’t do a staged procedure, as we typically do with trabeculectomies. I don’t typically combine phaco trab or phaco tube, because I think the trabs and the tubes do better when I’m not doing the phaco. So I’ll do the phaco first, wait a few weeks or months, depending on the IOP lowering I get from the phaco, and then do the trab or tube. And when I do that, I’m often combining the phaco with one of the angle procedures and trying to push off that trab even more. However, with MIGS and angle procedures, I do them in the same sitting. I don’t separate the two, and I do them immediately after phacoemulsification. How do you decide to do 180 versus 360? This is specifically, I believe, for goniotomy. Yeah. There are two questions that are similar here. It says how do you decide for goniotomy, and then Nuraddeen asked a similar question. I assume it’s also for goniotomy. There’s been a lot of research to see how many clock hours of goniotomy are necessary, and it turns out in our experience and others anything above 4 clock hours of goniotomy doesn’t give you more IOP lowering. You’ve accessed 4 or 5 collector channels, and that gives you adequate IOP lowering. Some would say it’s good to do 360, because if you have some scarring, you don’t have it in all of the 360, so you have a chance of making it work. But my response to that is that I want to do as little as possible to get maximum efficacy. If you’re treating 360, you’re potentially getting more inflammation, and in all instances I know, you’re treating tissue that you don’t have immediate visualization of, if you’re cannulating. I don’t like to treat what I don’t see, so many of those procedures also cause an incision, rather than an excision of trabecular meshwork, so the leaflets that remain can then fuse more readily. At least, in my experience, with the procedures that I’ve done. So we typically do 3 or 4 clock hours of excisional goniotomy, and that’s all we do, and we’ve had great success with that. There’s a specific patient question. My patient, age 29, diagnosed with LTG at the age of 26, on Travatan, IOP 12 in both eyes. I wish we could take a deeper dive. If the disease is advancing, not advancing, what does the visual field look like… But let’s assume the patient is getting worse with a pressure of 12 on Travatan, you can’t use any of the other medications that might be available, and I still think trab is the best choice. If you want to get to a pressure of 9 or 10, that is gonna be the best choice out of all the options we have today. Can we do trabeculotomy as done for congenital glaucoma in adults, as this also involves cutting TM as done with a KDB? This is a very important question, and historically, if you look at some of the work that was done with adult goniotomies, and what you start to see is that the incisional goniotomy, as is traditionally done with congenital glaucoma, with an MDR blade or needle, where you’re just placing an incision, it had horrible results in adults. Almost all of the adults in the series that I published failed to lower their IOP with incision of the trabecular meshwork, and the reason is that the trabecular meshwork leaflets tend to refuse, reanastomose, and cause elevation in the intraocular pressure. So that was actually the major drive behind performing excisional goniotomy. We were trying to limit as much as possible how many microns of trabecular meshwork remained that could then fuse together. And that’s why I think we’re seeing more success in adult patients. So if you look at the historical data from trabectome, with electrocautery of the trabecular meshwork, removing more of the tissue than just an incision, and subsequent to that, KDB, with an excisional goniotomy, using the ramp and the two blades, we’re seeing much more success than we saw in the 1930s, 1940s, with some of the series that were just an incision of the trabecular meshwork. Where exactly do you perform your goniotomy? At the pigmented TM or non-pigmented TM? It depends on the device that you’re using. In the case of KDB, we’re going in and removing as much of the trabecular meshwork as possible, and the blades really take care of it. So you don’t have to aim. As long as you’re in Schlemm’s canal, the blades are taking care of the non-pigmented and pigmented TM. In the case of doing something like a GATT procedure, Davinder Grover and Ron Feldman have talked about this in some of the meetings. I’m not sure if they’ve published on this. But what they’re noticing is that the suture goniotomy is actually causing an incision in the upper part of the trabecular meshwork, near Schwalbe’s line, and that’s the main area where they see the treatment happening. Things like trab 360, OMNI 720, that can cause a tear in the trabecular meshwork, but it’s hard to predict in that case where it will be. It might be different from patient to patient. In which cases do you particularly go for goniotomy? Again, my biases I think are pretty clear here. Because we’ve worked extensively with goniotomy. I tend to use it on a lot of patients. It’s my go-to device. But it has particular success in pigment dispersion, pseudoexfoliation, chronic angle closure, where you can use it to remove some of the anterior synechiae, and do the goniotomy. We usually get home runs out of those. We get a lot of IOP-lowering out of those procedures. And certainly our go to. Primary open-angle glaucoma, NTG with a mid to high teen pressure — we also use goniotomy routinely in those cases, before going to something more invasive. If we can go to something that’s minimally invasive, like goniotomy, compared to a trab or tube, we go for that, and tell the patient in some circumstances: If you fail, we still have the option of doing a trab or tube. So I like to go less invasive before more invasive. 7-year-old male, -12 diopter sphere both eyes, 0.8 cups, both bilateral microspherophakia with closed angles, IOP controlled with Trac con… Not sure what that is, sorry. What to do? This is a more extensive conversation. 7-year-old male, high myope, and you also have significant cupping with microspherophakia, and the angles are also closed? Depending on the exact examination, what the trabecular meshwork looks like, what the angle looks like, you could try doing a goniotomy first. It could be a suture goniotomy with GATT. It could be any of the choices that you might do. It depends on the maturity of the angle. What does that look like. Is this something that has been longstanding? More of a congenital-type picture or a JOAG-type picture? Oftentimes in patients that have reached the age of 7, we’re talking more — especially in the picture that you describe — we’re talking more of a full thickness procedure. Like a tube in this case. To get better control over a longer period of time. This is a tougher case. It might be worth putting it on the Cybersight discussion board, if you have access to it, and then tag me, and we can go back and forth and I can dig in a little bit deeper with some of the data that I could use to answer that. And I see it’s Travacom. Thanks for answering that. We don’t have access to that in the United States. IOP reduction with KDB is better in pseudoexfoliation/pigmentary glaucoma or POAG? We do have that with POAG and others, but you see this dramatic lowering of pressure with pseudoexfoliation, pigmentary, and you see that more consistently than some of the other processes. For hundreds of eyes that have been done in some of the studies, usually around 12.5 to 13.5 — we can get most eyes to that level, but pigmentary and pseudoexfoliation usually come to my clinic with higher pressures, and that’s why we see that more dramatic lowering. Because most of the blockage in the processes is definitively at the trabecular meshwork, whether it’s plugging or loss of trabecular meshwork cells, in the case of pigmentary glaucoma, we tend to see a more dramatic decrease in pressure, and it’s our go-to with those procedures. We see a lot of success in that. Where is the role of lasers going in the future for POAG, compared to the MIGS devices in the market right now? Those still have a major role in our practice as primary therapy, even before starting medications. What we’re seeing in the US at least is a slight decline in the use of SLT and ALT. Nobody is quite sure whether it’s because of economic drivers or that many of our patients have been treated already with these, and have moved on to different procedures, or we’re retreating less. We’re not actually sure why that’s happening. But in my practice, SLT has a major role. Primary therapy in those who may not tolerate medications or may not be able to instil medications, because of physical limitations or lack of adherence to therapy. There are new lasers that are being tested, different wavelengths that are being tested. SLT is dominant in the US and Europe. And we’ll see how that factors in, in the future. Most procedures are pretty similar to what we’re doing with SLT, so there won’t be much of a differentiator. For how long is goniotomy controlling the IOP lowering? About three years, consistently lowering pressure in the majority of patients. I would say stay tuned. We don’t have the five or ten-year data we have with trabs and tubes, but we have significant 2 and 3 year data, and seeing very similar outcomes to the 6 and 12 month data that have been published. 2-year data is being published fairly soon, in the next two months, so you can see that the numbers look very similar to what they do at one year. All right, primary open-angle glaucoma, microscopy has shown damage to angle structures. Is goniotomy helpful in such cases in the long term? This goes back to the chronic angle closure I just discussed with the last couple of questions. I think in my practice some of the best outcomes have been in chronic angle closure, where I remove the synechiae, remove the trabecular meshwork, and a lot of the damage has been done from chronic contact with the iris. That tends to expose a healthy distal outflow system that hasn’t responded in similar ways to some of the primary angle closure patients, where it appears that a lot of the obstruction might be in the collector channels. In these cases, we do see dramatic lowering, and it might relate to primary damage within the angle structures, particularly the trabecular meshwork, and I think there’s low risk for doing goniotomy in these cases. You can always go to trabs and tubes if needed. Can we repeat goniotomy in one eye? You can’t repeat it. You cannot repeat it in the areas where you’ve already done the goniotomy. But if you’ve done 4 clock hours, and you go in, you can also treat another 3 or 4 clock hours that were not treated initially. I would not recommend that. So the way that I practice is I try goniotomy once. I do 3 to 4 clock hours. If the patient comes in a year later and the pressure is going up, and I have to do something else, I typically go to a trab or tube. I don’t go to a repeat goniotomy. I think the goniotomy has given them a chance to push back before the more invasive procedures, but the eye is telling you that it needs a little bit more than what the goniotomy is providing. Sometimes you see the patients come back, and they have a film over the goniotomy site, whether it was incisional or excisional goniotomy, or the devices I showed you with iStent, previously, and in those cases, you can go in and remove the film, but there’s a tendency for the film to redevelop, if the patient has a tendency for that, so we typically go straight to trabeculectomy or glaucoma drainage devices when the goniotomy has failed. No open questions. I’m happy to answer any other questions if they’re there. If not, I’m happy to sign off, and wish everybody a good morning, evening, afternoon, depending on where they are.

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March 7, 2019

Last Updated: October 31, 2022

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