Lecture: Glaucoma Surgery: An Evolving Art and Science

Glaucoma surgery is rapidly evolving. While glaucoma filtering procedures and tube shunts remain the gold standard in glaucoma surgery, newer procedures and surgical devices are being introduced. This live webinar reviews the spectrum of glaucoma surgery and factors that might influence patient selection and outcomes.

Lecturer: Dr. Louis B. Cantor, Professor of Ophthalmology, Indiana University School of Medicine, Indianapolis, USA


DR CANTOR: Well, thank you, and hello, everyone. I want to first thank Orbis and Cybersight for bringing us all together. They do a marvelous job with education, and just looking at the registration, it’s impressive, the number of time zones that are represented here today. So I want to thank each of you for taking the time to participate. I’m Lou Cantor. I am the Jay C and Lucile L Kahn chair and professor and director of the glaucoma service at the Indiana University School of Medicine, and I’ve also served for many years with the Academy of Ophthalmology. Our topic today is glaucoma surgery, certainly an evolving art and science, and a field that’s been expanding greatly. We’re going to discuss all facets of glaucoma surgery today. It’s a broad topic. We have a lot to cover. So some of this I will go through somewhat quickly. And then we will be answering your questions at the end. We are due to conclude the webinar at 10:00, but I’m certainly happy to remain on and answer any questions, for any who might wish beyond that time, for as much time as we need. Let me get the slides. So first of all, my disclosures here. I have research support. I’ve served as a consultant for Zeiss and Santen, and have a small investment in a drug development company for drug delivery. I don’t serve on any speakers’ bureaus for any of our industry partners. To start our talk on glaucoma, I wanted to start with glaucoma laser surgery. We often jump to just the incisional surgery aspects of glaucoma, but there’s a lot to discuss with regard to laser surgery. More as a reminder about how effective laser can be, if you have laser available to you. I’ll go through this section rather quickly, so we can focus on the incisional aspects of glaucoma surgery, but I think there’s a few things that we need to sort of think about, remind ourselves about, and review. First of all, laser peripheral iridotomy. Angle closure is common in many, many areas of the world. Much more common than perhaps in other areas. And certainly in some areas of the world, it’s much more common than it is here in the United States. Laser iridotomy or iridectomy — the terms are often used interchangeably — has several indications. Pupillary block, angle closure, prophylaxis, and even sometimes when there’s reverse pupillary block, as a mechanism that’s pushing the iris posteriorly. There are certainly a number of contraindications to laser. Not having a clear cornea. If the chamber is too flat or shallow, and if the angle is already closed with synechiae, then an iridotomy may not be of much benefit. It may actually be contraindicated. Just as a review, preoperatively, we often want to treat these patients before laser with something to lower the pressure a bit. Maybe to constrict the pupil. Certainly topical anesthesia. And we have different types of laser to consider. Some feel that the argon laser may be a little bit more effective in brown irises, and the YAG laser for more light colored irises, but it depends on what you’re comfortable and what the eye looks like, and it’s useful to have some modalities for some patients. Where perhaps you have difficulty with the YAG laser, and argon or another laser might be effective. We often try to look for a part of the iris that’s already thin, such as a crypt in the peripheral iris. There’s been a lot of discussion about where to place these iridotomies. To avoid some of the light reflex and other issues that some patients may have. I still perform these superiorly, between 11:00 and 1:00. You can do them temporally or nasally, but I found that I’ve had no lower incidence of patients being able to see a little light reflex, if I put it superiorly as anywhere else. So I still like to keep the iridectomies superiorly, between 11:00 and 1:00, often just avoiding 12:00, in case there are bubbles during the treatment that might get in the way. We often use a lens such as the Abraham lens, which can concentrate the energy and help with penetration. There are different settings that can be used for different aspects of laser. If you’re doing an argon, more thermal laser, if you want to just contract the iris, you use a large spot size with longer duration and lower power settings, if we’re trying to punch a hole through and create an opening, we go with a smaller spot size, shorter duration, and generally higher energy levels. Sometimes with argon, it can take a lot of shots to get through. And this is a typical-looking laser iridotomy, done with the argon laser. There’s usually some surrounding atrophy of the iris, from some of the thermal damage surrounding the iridotomy. With a YAG laser, our energy levels are usually anywhere between 3 to 10. We start lower and then increase the energy level as needed, to obtain penetration. One or two pulses per burst is usually fine. I usually just use one. And oftentimes, especially if we can find a good crypt, you can get through in very few shots. Sometimes even one. And then you do a few more shots, just to sort of clean it up and enlarge it. And this is the appearance of a typical YAG laser opening. Now, any laser can have complications with blurred vision. Maybe some monocular diplopia from a second image, glare, if the chamber is too shallow or out of focus, you can damage the cornea, cause a little bit of inflammation, and some pigment dispersion, but most of these are generally short-lived, and not of significant consequence. Here’s a picture that’s showing where the cornea actually suffered a thermal injury, with an endothelial burn in that area. That may cause some focal opacity in that area, but generally doesn’t expand and doesn’t cause anything more extensive. So it’s limited. You can get hemorrhage, pressure spikes, lens opacities, and what we worry about most often is closure of the iridotomy site over time. This is just an example of the typical type of bleeding we often get with a YAG. It’s usually limited and self-seals. We get a little string or strand of blood that comes down, and it stops, but I have had cases, particularly in patients on anticoagulants, where there was more extensive bleeding that actually formed a hyphema. Postoperatively, we want to make sure the pressures don’t spike. Use steroid drops. And we want to reexamine in one week. We want to look and see if the iridotomy is patent, but the most important thing to do, postoperatively, to make sure that an iridotomy has been effective, is repeat the gonioscopy, and see if the angle has changed. The reason is not just to put a hole in the iris. It’s to open the angle, which should be reflected in a different appearance on gonioscopy. So that’s very important. And often overlooked. People don’t look at the angle to see if it’s functioning. With plateau iris, you may put a hole in the iris, but the angle still remains occludable. So here’s just a patient, referring a little bit to what I just talked about, who’s had iridotomy for angle closure, now comes in with blurred right eye, vision is down, pressure is 45. What is going on in this patient? Already had a laser iridotomy for acute angle closure. What else do you want to look for? What’s the diagnosis? What’s the treatment in a patient like this? Well, if you repeat gonioscopy, you can see there is still appositional closure of the angle, such as shown in this picture, where there’s a double hump sign, a plateau iris, a very frequently overlooked and misdiagnosed condition that’s not appreciated, and the iridotomy does not relieve the angle closure in these cases, because of the rotation of the ciliary body, and that peripheral iris hump. The laser iridotomy only relieves the pupillary block component that may be present, but not this peripheral hump. For that, we need to consider a different treatment: Iridoplasty. Which can be used in other conditions as well, but primarily as indicated in plateau iris. And there are contraindications to this, similar to any laser. We do similar preoperative assessment for iridoplasty. The laser parameters are a larger spot size, longer duration, and low power. What we’re trying to do is constrict and shrink the peripheral iris and flatten that hump. And this is just a schematic, showing that you place the laser application — this is the thermal argon-type laser, peripherally — the number of spots can vary, depending upon the effect, how much the iris constricts, when you do this, you treat them postoperatively, and regonioscope. Again, complications can occur after any laser procedure, including iridoplasty. Most commonly, this is just a little bit of mild iritis that is short lived. And here are some examples that show appositional angle closure on the left slide, and in the middle, but after iridoplasty, the peripheral iris has been flattened out a bit, and shrunk and the angle has opened. This is another patient. This is a patient now, a long history, 73-year-old, primary open-angle glaucoma. Pressures are somewhat high, borderline-ish. Lots of medications. Progressive visual field defects. What can be the next step? Well, laser trabeculoplasty is a good procedure in these patients, before moving to standard incisional surgery. If you have the laser available. Usually we’re talking about maximum medical therapy or patients with poor compliance. Occasionally we consider laser even for initial therapy, if patients are not good candidates for medical therapy, and maybe don’t have to have surgery right away. We often want to treat pressure preoperatively. These are some standard settings for the laser trabeculoplasty with the argon laser. A 50 micron spot, 0.1 seconds, and then you vary the energy, in order to achieve blanching, and some occasional bubble formation in the angle. Usually I place about 50 spots over about 180 degrees, but I usually treat 360. So therefore 100 spots throughout the angle. And you want to treat that anterior portion of the pigmented meshwork. We use a lens to do that, so that we can effectively visualize the angle and the meshwork. And this is a typical appearance, where we’re aiming just at that anterior border of the pigmented meshwork, with our aiming beam. We generally check these patients afterwards, treat them with steroids, and continue their glaucoma medications, to see what the effect is. It generally takes about a month to know what the effect of laser trabeculoplasty has been. In patients with standard primary open-angle glaucoma, it’s about 75% to 80% at one year, about 50% at best, at five years. There is a failure rate of nearly 10% per year, where the laser wears off. The pressure reduction depends a lot on the initial pressure. Patients with pressures in sort of the mid to upper 20s usually respond best. If the pressure is 30 or 40, you’re not gonna get where you probably want to be, with just a laser. And the laser doesn’t work well in our low tension glaucoma patients, who are already starting at pressures of 16 or 17, for example. Although it can be used and is safe in those eyes as well. It is good for phakic primary open-angle glaucoma patients, patients with pseudoexfoliation and pigmentary. It’s less effective in pseudophakic eyes, younger individuals, and other types of glaucoma. Even though laser trabeculoplasty can work well, for example, in pseudoexfoliation syndrome, pigmentary glaucoma, in more heavily pigmented individuals of African descent, the effect is often a little bit shorter in those individuals, and not as long lasting. Again, the onset of effect takes a few weeks. 4 to 6 weeks is not uncommon. Maybe a little bit earlier for pseudoexfoliation and pigmentary. But again, maybe not as prolonged or persistent of an effect. And this is a typical time curve of the probability of success over time. With laser, as we said. A certain percentage of these eyes are gonna fail over time. And when it does fail, then we start to thinking: Is it worth repeating? Generally with argon laser, a repeat laser is not as effective as the initial treatment, and if the initial treatment was not effective, a repeat is not gonna be effective either. So it really depends. The patients who I consider for retreatment are those who responded well the first time, and got several years of effect, and then maybe it’s worth repeating the laser in those patients, if need be, and we’re trying to avoid surgery. Again, standard complications, the most common of which can be increased pressure, particularly with retreatment. You increase the risk of having pressure spikes and not only not lowering the pressure, but actually making the pressure worse. More recently, we’ve switched more to using the selective laser trabeculoplasty, the SLT laser, when available. It’s a 532 laser, nanosecond pulse. Probably the biggest thing that we notice about this laser is its spot size, 400 micron spot size, compared to the 50 micron spot of the argon laser. This actually makes the treatment of the SLT much easier, because it’s difficult to miss the target. So here’s just a schematic, showing on the left the typical size of the 50 micron argon laser spot, and the 400 micron spot of the SLT laser, which basically blankets the entire angle, so it will be hard to miss the meshwork with the SLT laser. Whereas if you’re a little bit off with the ALT, you can actually be treating in the wrong place, and not getting the effect that you want. SLT and ALT in this study looking at repeat lasers — equally effective. So there’s no advantage in efficacy with a primary laser, or if there’s been a previous ALT, to doing an SLT. It still works well. This is the typical histology of ALT, which does cause thermal effect, as shown in the picture on your left, with the cratering and coagulative necrosis, which actually causes a small burn, whereas SLT, where the laser is absorbed by the melanosomes, within the trabecular meshwork cells, it doesn’t change the architecture of the angle. And here’s just one study from Archives in 2003, looking at using SLT as primary treatment. You get the same drop in pressure that we expect with trabeculoplasty in general. Now, in our treatment algorithm, there’s lots of rethinking of the sequence of where we do things, and how we do things, and where surgery fits in. For the majority of patients, at least in the US, we’re gonna start with medical therapy, and the majority of the time, that’s gonna be with a prostaglandin analog. Hopefully we’re controlled with medical therapy, or maybe combination therapy. But at some point, we move to laser, and then start thinking about surgery. And where surgery fits in is also evolving, as we’ll talk about more towards the end here. With some of the newer procedures that are being introduced today. So let’s talk about incisional surgery for glaucoma. Our gold standard remains trabeculectomy. There’s a lot of excitement over alternative procedures today. And that’s wonderful. And I think there’s great promise there. But still, when we need good pressure lowering, and effective long-term control, and where we have long-term data, it remains trabeculectomy. This guarded partial thickness filtering surgery, where we create a fistula between the anterior chamber and the subconjunctival space. We typically think of indications for trabeculectomy as when the pressure can’t be maintained otherwise. Now, that’s gonna vary in different parts of the world, depending on what’s available. In some areas, I know that medical therapy is difficult to obtain or maintain chronically. Laser may or may not be available. So how we define when to move to surgery really depends on availability, it depends on a lot of patient factors as well, how likely is a patient going to be able to follow up, how reliable are they, what’s the social structure around them. There’s a lot of things that fall into this. Excuse me. But generally, for us in the US, we’re talking about maximum tolerated medical therapy, which again is variable. How many drops is that? Patients who have failed laser. But basically it’s in patients who are progressing, or who are likely to progress, because of optic nerve damage, if we don’t get their pressure lowered. There are relative contraindications, of course, to any procedure, and certainly trabeculectomy has these. You know, blind eyes, eyes with neoplasms, rubeotic eyes, neovascularization, active inflammation, injury. Extremely thin sclera. I do see patients with very thin, almost blue sclera, who we know are not going to be able to be helped by this type of approach. The techniques vary. We all have our own techniques. So this is where the art — you know, it’s an evolving art. And there’s a lot of different ways to perform a surgery. When we talk about trabeculectomy, we’re not talking about a single monolithic procedure that we all do the same. The conjunctival flap can be limbus or fornix-based, depending upon what you’re comfortable with, and how you learned it. The use of antifibrotic agents, mitomycin and 5FU, varies. How you make the flap. How you create the sclerostomy. Do you perform an iridectomy or not? How do you close the scleral flap? Do you suture it tight, or suture it loosely and allow for leakage? What sort of conjunctival wound closure is used also varies quite a bit. I’m just gonna cover some of these steps, and some of the options. And many of you may do these, or other things as well. There’s no way to cover every possible aspect and alternative to how to approach this. In limbus-based versus fornix-based, if a limbus-based flap — actually, I prefer a limbus-based flap in general — I believe that I get better results myself — you try to make the conjunctival incision as far posterior to the limbus and the fornix as you can. Generally at least 8 to 10 millimeters. For fornix-based procedures, obviously we’re making the incision at the limbus. How much of the limbus you open and how wide you make that is, again, a personal preference, depending upon your technique. Each approach has advantages and disadvantages. Again, depending upon what you’re comfortable with. It is important to note that if you look at studies, the success rates are the same. The IOP outcomes are the same, regardless of how you do it. With your technique. In general, the limbus-based conjunctival flap is a little bit more challenging to do. It takes a little bit longer to close. The fornix-based flaps are easier. How you use a traction suture is different between the two flaps. Whether you use a superior rectus traction suture for limbus-based flap, or corneal suture for fornix-based. There’s more leakage at the end of the flap if you’re doing a fornix-based flap with limbal incision. Placing the mitomycin differs a little bit, where the scarring occurs. And the final bleb appearance does vary a little bit, depending on how you make your incision. So just this very initial part of the procedure — there’s a lot of nuances to it, and a lot to consider. In terms of antifibrotic agents, the ability to attempt to modulate wound healing is really critical, and has changed the face of trabeculectomy quite a bit. Before we had the availability and evidence that these agents were helpful, my failure rates were higher. And it’s now unusual, extremely unusual, almost, to do a trabeculectomy without some antifibrotic usage to try to modulate wound healing. Most often here in the US it’s mitomycin. 5FU can also work as well, in certain circumstances, but mitomycin seems to be a little bit more effective for the majority of patients. There’s a lot of indications for it, but as I said, today, if you ask people in an audience of glaucoma specialists here in the US how often do you routinely use mitomycin in your glaucoma surgery cases, for trabeculectomy, virtually every hand in the room goes up. And I’ve been in rooms where that question has been asked, and it’s rare to see someone’s hand not up. So it’s become very routine. Now, should you do it in every case? Well, you do have to be cautious in some patients. For example, one place where you want to be cautious is in the young myope, because they’re particularly prone to hypotony maculopathy. And in older patients it might be safe to avoid use of the antimetabolite, because the success rate would be pretty reasonable anyway. So there are exceptions, but they seem to be relatively few today, and we’re using these agents routinely. 5FU is really a pyrimidine analog. And it inhibits — excuse me — it inhibits fibroblast proliferation. These are the typical doses that are given. You can apply this with a sponge underneath the conjunctiva, or by injection. The advantage is you can titrate a little bit. The disadvantage is you often need multiple injections to make it effective. Mitomycin is an alkylating agent, and it actually kills cells. So as opposed to 5FU, which just stops cells from dividing, mitomycin is cidal. It actually kills cells. There’s a lot of different concentrations. There’s no standard agreed-upon way to administer this drug. And again, it depends a lot on your personal technique. What you’re comfortable with, how you do your surgery. It’s hard to isolate any one step in glaucoma surgery, and say: If you do this, your outcomes are gonna improve. Because the whole surgery is a symphony. And just changing one measure in the middle doesn’t necessarily change the entire symphony of what you’re doing with this procedure. Typically, for me, for my standard patients, I’m gonna do 0.2 milligrams per CC concentration. For two minutes. That’s sort of my starting point. If someone has a lot of risk factors for failure, then I’ll go up on the concentration to 0.4. If someone has a very low risk for failure, or someone I want to be conservative with, then maybe I’ll shorten the time and only leave it on for a minute. But these are all individual decisions that are made with whatever experience you have with these medications, based on your technique. You can also deliver this by sub-Tenon’s injection. As well, and avoid just the intraoperative application. So it’s a one-time for this. You avoid the multiple injections. But we are relying on these sponges, or now some injections, and it’s rather imprecise where it’s going or how we do it. Remember, sponges are not drug delivery devices. They’re soaking up devices. So they’re not really designed to deliver drug, and they don’t necessarily always do so in a controlled manner. So we can cut shields in half. We can cut sponges. We can stick a whole sponge under there. Very effective to use. How do you do the scleral flap? In general, I try to make the scleral flap about half to two thirds scleral thickness, but what’s really important is how easily is it going to leak around it, based on your sclerostomy that’s underneath. So how big you make your sclerostomy and the relationship of that to the scleral flap is what really matters, because that’s what determines leakage. It’s not the shape of the flap, whether it’s triangular, trapezoid, rectangle, whatever you want. The size of it doesn’t necessarily matter that much, as long as it’s big enough to leak. That’s what you want. And it’s the relationship to the underlying sclerotomy that determines that. And wound healing. How you make your sclerostomy — it’s really for the most part more of a keratectomy, where you’re usually just removing peripheral cornea to create the sclerostomy, and trying to be anterior, so we don’t get into the ciliary body, reduce bleeding, and in some areas the ex-PRESS shunt is used, as opposed to making a scleral flap, to allow for that sclerostomy to be created. And these are just pictures of inserting the mini-glaucoma shunt, rather than making a sclerostomy. Various studies have been done. This is just one. Using the ex-PRESS to create the sclerostomy, versus using a punch or a blade and scissors to create the sclerostomy doesn’t really affect outcome. So there’s no advantage to the ex-PRESS. If this is something you like in your technique, that’s fine. It is an additional expense, and on the cost side, the cost effectiveness of surgery, there is some debate here, but the outcomes are the same, whether you use an ex-PRESS or something else. If you do your surgery, is an iridectomy important? I like to perform an iridectomy, because I’ve had too many cases where I’ve had an iris, if I didn’t do an iridectomy, find its way into the sclerotomy, and obstruct it internally. It also reduces pupillary block from potentially happening in the future, if there’s synechiae that develop around the pupil, for example. You do have to avoid the ciliary processes, and avoid the zonules, and the hyaloid face, so you don’t want to reach down too deep, but an iridectomy is a standard part of what I typically do. And I typically create the sclerostomy with a blade and with scissors rather than with a punch, but again, it’s however you are comfortable and whatever technique makes sense and works for you. The scleral flap closure can affect outcomes as well. How many sutures and how tight you want it, and whether or not you do releasable sutures, or plan or suture lysis — personally, I put in only usually a couple sutures on my flap, and leave them rather loose, as I like the sclerostomy to be leaking at the end of surgery, as I would like for it to, long-term, in order to avoid shallowing or flat chamber, I leave some viscoelastic in the eye, however, so that usually buys me some time for things to start healing. If you don’t have viscoelastic available or that’s not part of your technique, you may need to suture a little tighter, but plan to have less filtration and higher pressures and a deeper chamber, but you may need to release those sutures, by cutting them, lasering them, or releasing them, if they’re releasable sutures. Lots of ways to handle the scleral flap closure. And finally the conjunctival closure. There are a lot of different ways to do this. If you’ve performed a limbus-based flap with a fornix incision, then I typically — this is what I do — I typically close conjunctiva and Tenon’s separately with a running suture, absorbable suture, like vicryl. For fornix-based flap, being closed at the limbus, usually there’s wing sutures placed on the sides. With some central suturing, the closure — there’s different ways to do that. There’s the technique of a running closure called a Condon-Wise technique, and other closures for closing at the limbus. This just shows closing in the fornix with a limbus-based conjunctival flap. You can see the trabeculectomy here underneath this, and we’re fairly far back here. This isn’t stretched out. But we’re probably at least 10 to 12 millimeters back from the limbus. And this is showing with a limbal incision, with a fornix-based flap, and we’re starting our closure here, and then we’ll wing it at both ends and run a suture anteriorly, to try to minimize the leakage. That’s that Condon-Wise technique. What I always tell patients when we do glaucoma surgery of virtually any type, but certainly trabeculectomy and tube shunts, which we’ll talk about in a minute, is that the success of the surgery — half of that success depends on what we just did in the operating room. The rest of it depends on what we do postoperatively, to achieve success, and how we handle these eyes, and how we manipulate them. There’s a lot of postoperative care required. And maybe it’s releasing sutures. Maybe there’s massage. Maybe we need to supplement with some antimetabolite. Suture lysis can be attempted with various lasers and various lenses. Hoskins lens, Blumenthal, you can use the Zeiss lens, and argon laser works well for this, to help cut sutures if you need to increase flow. It’s also important that we understand for both short and long-term how to manage filtering blebs. We developed a grading scale called IBAGS, the Indiana Bleb Appearance Grading Scale, which is represented here, which looks at what I think are the key characteristics of a filtering bleb. It’s height, it’s horizontal extent along the limbus, in terms of clock hours, how avascular the bleb is, versus vascularized, and whether or not there’s any leakage of a bleb. And leakage — we can have no leak. We can have no streaming leak. But a lot of blebs kind of sweat, and they get these little pinpoint leaks, as shown down here, or we can have a full positive Seidel with a streaming bleb leak. There’s lots of complications, early and late, that can occur after glaucoma surgery. And it’s important to understand your complications. And if there’s one chart I always tell our residents to make sure and memorize, it’s this one. So if you have a shallower, flat chamber, in the early postoperative period, the next thing you look at is the bleb. Is it high or is it low? The next thing you want to look at is: What’s the pressure? Is it high or is it low? If you have a low bleb with low pressure, then you already know what you’re looking for. There’s either leak, choroidal effusion, or some overfiltration with the leak. If you’ve got low bleb but high pressure, you’ve got aqueous misdirection or pupillary block. Your diagnosis is gonna follow from that. If you have flat chamber with a high bleb, if it’s low pressure, then you’re overfiltering. If it’s high pressure, chances are you need to take a good look in the back, because you’ve got a suprachoroidal hemorrhage. So just understanding the differential of a shallow or flat anterior chamber based on the bleb and the pressure really leads you to diagnoses and subsequent treatment very quickly, so that you can manage these patients effectively postoperatively. For a bleb leak, whether it’s buttonholes from surgery or thin avascular blebs, these are problems that we often have to deal with, in our standard filtering surgery. There’s lots of ways to manage these eyes. Pressure patches, aqueous suppressants, usually I do lubrication, and try to get these patients off steroids quickly. And hopefully they’ll close on their own. If not, then we may need to manage it differently. There can be glue. There’s other ways of handling a leaking bleb. Compression sutures. Lots of different techniques. I don’t have time to really go into — but we have a lot of options at our disposal. This is just one example of an eye where we did an autologous blood injection. Just took a few tenths of a CC of blood out of the hand from a vein, and injected it into the bleb, as shown in the upper left picture, and here’s the resolution of the blood over time. And the final bleb, and the pressure came up. The hypotony resolved, just by causing a little bit of fibrosis within the bleb, by a blood injection. Here’s glue on the eye, which I’ve sort of stopped doing, because it’s so uncomfortable. Because if you put glue over a leaking bleb, you have to cover it with a contact lens and then wait for the glue to fall off. So I’ve largely abandoned this technique. It’s also important to separate what do you mean by shallow or flat chamber. If there’s just iridocorneal touch in the periphery, most of those eyes are gonna reform spontaneously. If you observe them, maybe add some atropine and pupillary dilation. But if there’s corneal lenticular touch or corneal IOL touch, the cornea can decompensate, you can get anterior synechiae, cataracts, so those eyes need more urgent management. There’s lots of ways to reform a chamber. Most often what I do is viscoelastic. But you can inject air, BSS, other fluid. And you also have to look for choroidal effusions to see if there’s drainage that might be indicated. The effusions occur from hypotony and inflammation. They’re generally not there right away. They take a few days to develop, unless it’s something like a hemorrhage. But just choroidal serous effusions usually occur 3 to 5 days postoperatively, they start occurring, if you have persistent hypotony, especially with inflammation. And this is an example of what a choroidal looks like. And some of the signs and symptoms. It can occur after any surgery. Certainly if there’s a choroidal hemangioma, in a patient with Sturge-Weber, anophthalmos, or increased pressure for any reason, an effusion risk is increased. These we can typically observe and they’ll go away, with steroids and cycloplegia. But we may need to treat. We may need to drain, if the chamber stays shallow. The choroidals have been there a long time, they’re not going away, we may need to consider drainage of choroidal effusion, which I do occasionally. Hypotony maculopathy I see in younger myopes, particularly younger male myopes. They seem to be predisposed. Here’s an example of the choroidal folds that you can see in these patients. You have time to manage these. Generally these choroidal folds are reversible, if the hypotony is treated within six months. Most times within 12 months, even, the choroidal folds will resolve and go away. But the longer they’re there, the more likelihood that they can become fixed and permanent folds that affect vision. Suprachoroidal hemorrhage is of course something we all worry about and want to avoid. It occurs in the first 4 to 5 days, generally after surgery. There’s a lot of risk factors. Glaucoma being a big risk factor. And we’re doing glaucoma surgery. But advanced age, vascular disease, aphakia, myopia, previous vitrectomy and so forth are all risk factors. We’ve managed these similar to effusions, and if there is clot, as is shown in the picture, in the suprachoroidal space, you can’t really drain it right away, because it’s clotted. And clot lysis takes four to five days to start, and may take 10 to 14 days for that entire clot to become liquefied. But sometimes we do have to drain these, if there’s severe, intractable pain, uncontrolled pressure, persistent flat chamber, or other reasons. Failed blebs we can deal with in many ways. But what I want to encourage you to do is, if the bleb starts to appear to be failing, do gonioscopy, and look at internal sclerostomy. We often miss that there’s been some scar tissue or iris that’s affecting the internal eye. We’re treating the outside of the eye, but not the actual problem. Late bleb failure from episclerosis is the most common reason why filtering blebs fail, and we have to look out for it. Blebs can become encapsulated, but most of these will resolve. This is a typical Tenon’s cyst. And we can manage these usually conservatively. Rarely do they need surgery. And lastly, just bleb-associated infections. We all have to be on the lookout for, and warn patients about, particularly in thin avascular blebs. We need to treat lid disease, if patients have blepharitis, and tell patients if they develop a red eye or conjunctivitis, even if it doesn’t seem concerning, they should always let us know. And here’s a couple examples. These are the risk factors for bleb-associated infections. Most of these are preceded by a bleb leak, but we don’t always see that right away. These are the common organisms, but that can vary where you are in the world. This is what they look like. Here’s various examples. They are often leakage. I sort of grade these. Stage I would be where it’s just a localized bleb infection, with not a lot of spread internally. Stage II is where we’re having anterior chamber reaction, and stage III is where there’s vitreous involvement and a full endophthalmitis. Stage I and II we can often treat with aggressive antibiotic therapy. Stage III will usually require vitrectomy, or at least a tap and inject. Of intravitreal antibiotics, to try to save the eye. The incidence of bleb associated infections is not insignificant. There’s been several studies that have looked at this. In general I tell patients that over their lifetime, again, depending upon age, if it’s a 50-year-old who’s getting a bleb, that’s very different from an 80-year-old. But there is a risk of having this happen, and I tell patients about the issue of developing a red eye, and our patients know well to call us, if they start to develop anything that might be a sign of a bleb leak or bleb infection. We usually can manage these with antibiotics, as I said, topically, initially. And again, stage 3 requires more aggressive management for endophthalmitis. Now, to mention tube shunts here, tube shunts are great alternatives when standard surgery has failed, or for other eyes, where you expect a trabeculectomy to fail, such as an uveitic eye, or an eye syndrome, for example. We have multiple types of tube shunts. Non-valved, such as the Molteno and Baerveldt in the US. Valved, the most common is the Ahmed, which is also available here in the US. But there may be other types of shunts available throughout the world. They all do about the same thing. One of the important factors with these shunts is: What is the implant size? What is the area for filtration? And there’s been several studies that look at this, and actually around 250 square millimeter area is about the maximum that a single quadrant device can effectively work in lower pressure. I don’t use the Baerveldt 350 for that reason, because you really don’t get additional pressure reduction from that larger size, versus the 250. And the other valves are somewhat smaller. So you don’t get as much on average either. So for me, the Baerveldt 250 has sort of become the standard tube shunt, and I use the others, such as an Ahmed, if I’m trying to be more conservative in someone with risk factors such as a suprachoroidal hemorrhage. Lots of ways to implant these devices. And the key factors, though, are to get the device itself, plate, well posterior in the equatorial or postequatorial region of the eye. Too many times I see these shunts put in, and they’re too anterior. And they work less well, and they are more prone to erosion and exposure, if left too anterior. Multiple steps to the surgery, again. These are a little bit more standardized, perhaps, than trabeculectomy. But there are still a number of steps. One of the decisions is: Especially for the wider devices, such as a Baerveldt 250, should you make an attempt to push it under the muscles? Can it be on top? Can it be intra-Tenon’s? The answer to all of that is yes, and they all work the same. It just depends on what your technique is, and what you’re comfortable with. Typical medications postop. If you tie off the tube or occlude it somehow, or if it’s a valve shunt, you may need to use something for pressure postoperatively, initially, and then always be on the lookout for hypotony. These do have some benefits. If the patient is a contact lens wearer, they can wear them. And they do work well, but they don’t work quite as well as perhaps long-term — here’s a study that was done, the trab versus tube shunt study, which showed similar long-term results, but initially trabeculectomy seems to work better than a tube shunt. So it depends on what your goal is for pressure. This is also looking at trabeculectomy versus tube shunt and failures. There seem to be a little bit higher proportion of failures in the trabeculectomy group over time, but when you took those out, then again, the results were similar. And here’s looking at the different pressure goals from those studies. A lot of postoperative complications still possible from all of these procedures, including tube shunts. Now, just for the last couple minutes here, there’s been a lot in terms of new glaucoma surgeries and the MIGs procedures. This is the current, probably most common definition for a MIGs procedure, these microincisional procedures that have a high safety profile, minimal tissue manipulation, and so forth. There’s been lots of ways to divide up the different types of MIGs. This is just one example from Steve Vold. Part of this is trying to take advantage of the outflow pathway. And particularly the canal-based procedures, to really recover and use the canal, the collector channels, and the episcleral venous plexus, to get at where the site of resistance is, but there are a variety of devices. We have a variety of MIGs-based procedures and non-device procedures, that cover either a small area of the canal, such as a micro-bypass shunt, where it’s just a very focal, to 360-degree viscodilation and trabeculotomy-type procedures, where you open up the entire trabecular meshwork, to try to allow fluid access to the canal. We are still sorting out how these various procedures work, but they are becoming a more common part of our glaucoma therapy. There are attempts at suprachoroidal-based MIGs procedures, to drain into the suprachoroidal space, CyPass and iStent is under development. And there’s translimbal MIGs. I might mention that the CyPass in the US was recently withdrawn from the market because of issues regarding endothelial cell loss concerns. And then translimbal-based MIGs, that are clear corneal procedures. The XEN is the most common here in the US. There’s also the InnFocus Microshunt, which is still in clinical trials, which offer different clinical approaches to translimbal-based MIGs. And there are ciliodestructive procedures as well. I mentioned canaloplasty. It’s not a MIGs procedure, but it’s an older procedure I liked and got good results with. We’re doing it less, but what I did — and I’ll highlight — is that you can alter the anatomy. If you look at Schlemm’s canal here on the right and on the left, you can see dilation of the canal and collector channels on this high resolution ultrasound, showing how it can impact the outflow system, and we can do the same things with our MIGs procedures. So here’s our trabecular stents. Trabectome I don’t use much anymore, but it opens up a few clock hours of the canal. Again, the suprachoroidal stents, CyPass, and the iStent Supra. There’s been studies. This is the data that caused the voluntary withdrawal of the CyPass just a few months ago here in the US, because of endothelial cell loss. These are in eyes that had phaco plus CyPass versus phaco alone. Here’s some of the subconjunctival or translimbal stents, as represented in these pictures. Various pros and cons to each of these. What I think is important for us — and I’m gonna show this very quickly here, because the details I want to show you in the graph — but if you look at review studies, and we’re starting to get more and more data on all these various procedures, and here’s the procedures that were looked at in this study, and what I want to show is this graph. So this graph shows — and the individual procedures, I know there’s a lot here, but these are all compared to the clinical trials, of which there were reasonable numbers that had some sort of comparative control group. And the line down the middle would be if the addition of the MIGs device — if it was to the right, versus the left, in terms of how much more effective it was. So if you look at iStent, say, in the second group down, the improvement over phaco alone or medical therapy here — and here’s phaco alone — is about 2 millimeters. Of improvement. And the closer these bars are to the center line, the less effect, and to the right actually suggested higher pressures. So what we’re seeing with the MIGs procedures, we start to get devices that — yeah, they can lower pressure, but it appears to be not only minimally invasive, but for many of these procedures, the effectiveness is also fairly small. But they are very safe. So you’re usually looking to 2 to 4 millimeters maybe of improvement in some of these procedures, but not much more than that. So trabeculectomy still remains our most effective procedure, and just some more data on that. And I want to get to the end, so we can take your questions. But if you look at trabeculectomy in the 21st Century, it’s really quite an effective procedure. Again, compared to Ex-PRESS. We get in many of our patients good sustained long-term control, low teens to even single digits in multiple studies. And as things start to filter out over time, I think we’re getting a dose-response curve on our various procedures. So on the bottom here is phaco alone and what it does. Above that, with the addition of laser, then we’re getting to some of our MIGs procedures here, in terms of percent pressures, but at the top still remains trabeculectomy and tube shunt for when we need good sustained long-term pressure reduction. So the algorithm may be changing, but it hasn’t completely changed yet, until we get more effective MIGs procedures. So with that, I’ll thank you for your attention, and we’ll now turn it over, so that we can get to your questions.

>> Great. Thank you, Dr. Cantor. If you want to stop sharing your screen, you can bring up the Q and A questions. So far, there’s two questions.

DR CANTOR: So first question is: In phacomorphic glaucoma with no light perception and raised pressure, would you rather perform argon laser iridoplasty, when patients refuse to have cataract surgery? I’ll answer that question in a couple ways. First of all, if the eye is truly NLP, and there’s no chance of any visual recovery, I would try to avoid surgery. There’s really only two reasons to treat the pressure in glaucoma, and that’s to prevent pain and preserve vision. So from a vision standpoint, there’s no reason to treat. If the eye is NLP. Now, from a pain standpoint, if the eye is uncomfortable, usually we can control these eyes medically. And even with minimal medicines. Sometimes it may be reasonable to consider laser, but I would avoid an incisional surgery in an eye that’s NLP, myself. And the second question, I think, is a follow-up. How about cyclopentolate drops to maintain the anterior chamber postoperatively? Absolutely. I think that’s certainly reasonable. A lot of these eyes with end stage phacomorphic or other types of glaucoma with uncontrolled pressure — if you can put them on a cycloplegic, cyclopentolate, atropine, that’s all you have to do. So generally in those eyes, less is more. The next question is: Do you believe there’s a place for MIGs procedures in the developing world as a replacement to trabeculectomy? Great question. I think MIGs procedures have an increasing role in what we’re doing, but they are not to the point yet where we can replace trabeculectomy, in my opinion, for the vast majority of people that have glaucoma. What the MIGs procedures, I think, are allowing is if you want to think of it generally… Our treatment for glaucoma has been a one size fits all. You put a hole in the eye or you don’t. Trabeculectomy or tube shunt. Or you don’t. Where the MIGs procedures are more aimed is for the mild to moderate end of the spectrum. So I think that in the patient with mild glaucoma, even if they’re in the developing world, if there were a MIGs option, it may be something to consider for those patients, so that we can preserve the trabeculectomy for if they get worse or if they fail the less invasive procedure. But for the majority of patients, who have more moderate to advanced disease, the MIGs procedures are not gonna probably reduce their risk of blindness right now. And we need to probably get to a trabeculectomy or procedure that’s gonna control them. So it’s an evolving area. I think our MIGs procedures are gonna continue to improve. And be more effective as well. The next question is: Do you trim Tenon’s to avoid encapsulated blebs? I do not. I do not do a tenonectomy in conjunction with filtering surgery, either trabeculectomy or tube shunts. I’ve tried it a few times, and I haven’t found it to be effective. Other authors have tried it, and there are some reports that it actually wasn’t very effective either. I think the increased tissue manipulation with tenonectomy can just lead to more reactive fibrosis. Next question is: What guides your choice of anesthesia? Well, for me personally, I still for the majority of surgeries that I do — which are fairly involved, and often are in eyes that have had previous surgery — I primarily do blocks. And usually retrobulbar or peribulbar blocks. Oftentimes combined with a facial nerve block as well. I do sort of a modified O’Brien by the ear, as a facial nerve block, so that I have good control. I like to have full control of the eye, and I like to have really good exposure. Of the eye. So I most often use blocks. Can you do a lot of the less invasive procedures and MIGs and things with sub-Tenon’s or topical anesthesia? Yes, but those aren’t the patients that I see and get referred to me most often. Next question: What would you recommend for a patient with plateau iris angle closure who has had iridoplasty and persistent IOP rise, despite medications? With plateau iris, presuming that we’ve done the peripheral iridectomy, which is always the first step, plateau iris is really defined as an angle that remains occludable, despite a patent iridectomy. But then if you’ve done the iridectomy, and you’ve done iridoplasty, and it may just be that there’s enough either synechial closure, or there’s been enough damage to the meshwork from the previous closure episodes that medications can’t control it. So then I think you have to go on to surgery, and in most cases, probably a trabeculectomy. If there’s no open questions posted right now. If anyone else has a question, I’m happy to address it. Oh, here we go. How long does hypotony last, until it causes maculopathy after trabeculectomy? The hypotony maculopathy develops very quickly, actually. It can develop in the first few days, with hypotony. So it doesn’t take long for it to occur. What’s interesting about the hypotony/maculopathy is that once the hypotony resolves, either on its own or because you’ve intervened in some way, for the hypotony to reverse, it seems to take about as long as it was there. So if the hypotony was there a month, let’s say, before the hypotony resolves, and it causes maculopathy during that month, it may take a month for things to straighten out. If the hypotony had been there for a year, before the hypotony was treated and reversed, you may have to wait a year to see if it’s gonna go away, even once you get the pressure up to a normal range. What keywords to use to convince patients to have surgery? Yeah, well, first of all, I don’t try to convince patients to have surgery. I try to advise them as to what I think is in their best interests and give them the options that are available to them. And it ultimately is the patient’s decision. One of the things that I frequently do, especially for patients who are concerned about the risks of surgery, because there are risks, and we always talk about them, and patients often get in their mind that they have a high risk of going blind from the surgery, which — there certainly is a risk. I tell patients you can lose your vision from surgery. But the other side of that equation is: Without surgery, the likelihood of you losing your vision is 100%, let’s say. Because if the pressure is not controlled and the glaucoma is getting worse, your vision will go, although maybe more slowly. So we do have that discussion. And it’s how you phrase things. But ultimately, it’s providing the patient with the information you can, and the perspective, and what you recommend, but it’s their decision. Now there was a question about how to manage hypotony maculopathy. There’s various ways to manage the maculopathy. Generally it’s from an overfiltering bleb. And usually, first of all, after surgery, if there’s some hypotony and a little maculopathy, and it’s in the first few weeks or month or even two after surgery, I don’t do anything, because most of the time, just with normal wound healing, the pressure will come up. If the bleb looks really big early on, I may taper off my steroids a little more quickly. But if the hypotony doesn’t resolve, and someone has maculopathy, it depends on the appearance of the bleb. Number one, if there’s a bleb leak, you need to fix it. Most of the time, there’s not a leak. It’s just a large bleb. It’s too big. And there’s a couple of ways that I’ve found most effective, personally. But there are a lot of ways to manage blebs, some of which we talked about during the presentation. One way is just to revise the bleb and do a conjunctival advancement flap over the bleb. If it’s very thin, very avascular, you can mobilize conjunctiva around the bleb and deepithelialize the bleb and pull the conjunctiva down over it, and do that. There’s other procedures where I make incisions through the bleb and suture it down. Some people — kind of like a compression suture, but I actually make an incision, if a bleb is very extensive. Let’s say the bleb is covering six clock hours, it’s so extensive. I will go up between 11:00 and 1:00, and make incisions through the bleb, and then suture it down with an absorbable suture, to create a barrier to shrink the bleb. Those are just a couple ways that you can manage an overfiltering bleb that’s leading to hypotony maculopathy. What IOP values do you consider as optimal first day post-op? Is the next question. Again, it depends on how you do your surgery. I typically expect my patients after trabeculectomy, for example, to have a low pressure, postoperatively, because I do not suture the flap tightly, but I leave a high molecular weight viscoelastic in the anterior chamber, usually Healon GV, or something similar. Healon 5, even. Very viscous. To maintain the chamber. And then we get very nice blebs, and it takes a few days for that viscoelastic to wash out of the eye, and the pressure is usually pretty low during that time, but at least the eye is having a chance to start healing, and some of the medications preoperatively are starting to wear off and the ciliary body is starting to function. However, if you like to suture your flap more tightly, then you’re probably aiming for pressures early on to be in the 10 to 15 range. But I find that very hard to control. So then you have to be willing to manipulate sutures. What is the dosage and duration of steroid eye drops we should use after trabeculectomy? This depends on the patient, but in a standard glaucoma patient without a lot of inflammation, where the surgery went fairly straightforward, I would usually use just the prednisolone 1%, 4 times a day. If the conjunctiva was very injected, then we may bump that up to six times a day. But normally, for the garden variety patient, I’ll use 4 times a day prednisolone, 1%. In patients who have a history of any uveitis or iritis, we will certainly bump that up to every couple hours, and I will often give at the time of surgery a sub-Tenon’s injection as well. Even just some dexamethasone, where I don’t expect it to last a long time, but I want to get a lot of steroid on board very quickly, and some of those patients with a history of iritis I’ll often put on oral steroids also. But the average patient, not inflamed terribly, just 4 times a day is usually fine. And the last question is: Do you have any therapy for neovascular glaucoma? Yeah, neovascular glaucoma is tough. Because it’s not only the glaucoma. It’s the underlying disease that you have to treat, whether that’s from diabetes or from vascular disease, a vein occlusion, or some other condition. You need the retinal treatment — is a mainstay of treating any patient with neovascularization. So they need to get that treatment. We will often give an anti-VEGF injection and try to get in laser right away, but for the glaucoma part, we almost routinely will go just directly to a tube shunt procedure. And typically either an Ahmed or Baerveldt tube shunt.

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November 28, 2018

Last Updated: October 31, 2022

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