Lecture: Trabeculectomy: Technique and Post-Operative Care

This webinar will discuss the place for trabeculectomy in the management of glaucoma. It will outline the surgical techniques in detail. The normal post-operative management will be discussed as will complications and their management.

Lecturer: Dr. Wallace Alward, Director, Glaucoma Service, University of Iowa Carver College of Medicine, USA


DR ALWARD: Hello, all. A pleasure to be with you. I’m Lee Alward at the University of Iowa. Very cold out here. -6 Celsius. And I’m gonna talk about trabeculectomy. And we’ll start off by giving a few quiz questions, just to get us all oriented. And then I’ll talk about a way or a few ways to do trabeculectomy. Really try to emphasize the little things that make trabeculectomy work. At least, in my hands. So let’s go through some questions first. Question one. Which of the following is the mechanism by which trabeculectomy lowers intraocular pressure? Does it bypass the trabecular meshwork? Enhance outflow through an intact trabecular meshwork? Decrease aqueous humor production? Or open the end of Schlemm canal? Let’s move on to question two. Which of the following is a risk factor for failure of trabeculectomy? Advanced age, exfoliation syndrome, inflammatory glaucoma, pigmentary glaucoma? And we’ll go through all these answers at the end. You’re doing great. During trabeculectomy, a surgical iridectomy is most important in which of the following eyes? Hyperopic, myopic, eyes with pigment dispersion syndrome, or pseudophakic eyes? And lastly, aqueous misdirection or malignant glaucoma is most likely to develop in an eye with which of the following refractive errors? -8 diopters, -3, plano, or +5? Great. We’ll go through the talk. We’ll come back to these questions. Most of you did really great on those answers without me teaching anything. I have no conflicts. I’m on the data and safety committee for a surgical device that I’m not gonna mention in this talk. It’s important to know that there are a lot of ways to do trabeculectomy, and if you took a lot of glaucoma surgeons, you would have 300 ways to do a trabeculectomy. So I’m gonna give you concepts on the way that I do trabeculectomy. Certainly not claiming that it’s better than anyone else’s technique. Just to back up through history, why do we have trabeculectomy? How did it get here? When Von Graefe developed surgical iridectomy, he discovered that a lot of the people who ended up with good pressures had developed an inadvertent filtering bleb. And that led to the development of the original filtration surgeries, in which a full thickness scleral hole was made and was covered with conjunctiva. And this created a filtering bleb. And these procedures worked. They led to very low intraocular pressures. Often too low. But they had lots of complications. Lots of flat chambers. Lots of cataract. And not an ideal procedure. So this is a little cartoon of a full thickness procedure. You can see that under the conjunctiva is a hole that’s made with a punch or with cautery. Or a blade. And that leads to uncontrolled egress of fluid from the anterior chamber. To the subconjunctival space. And it worked. This is a patient of mine who, 54 years ago — not by me. I’m not that old — but had a full thickness procedure done and it has worked for 54 years. Kept his pressure under remarkably good control. The trabeculectomy was designed to have a surgery without a bleb. And the idea and the reason it’s called trabeculectomy is the idea was to cut through trabecular meshwork, expose the ends of Schlemm canal, and allow fluid to leave without the complications associated with full thickness surgeries. However, it turned out that the only eyes that did well were the eyes that developed filtering blebs. So while it wasn’t really initially designed to make a filtering bleb, that’s what it does. So it’s just the same as a full thickness procedure, except it has more control. And throughout this talk and I think those of us who have done quite a bit of glaucoma surgery, the word control comes back over and over again. So this is a cartoon of a trabeculectomy. You can see now over that hole is a flap that you’ve created. And that slows down the flow of aqueous, and by having sutures in that flap, you have some control of the speed of outflow from the surgical site. So we call this a trabeculectomy, which makes it sound like we’re removing the trabecular meshwork. But really, that’s not an accurate term for what we’re doing. We’re basically making a hole — usually anterior to the trabecular meshwork. I think most of us would enter through clear cornea. But the name has persisted. And the complications associated with full thickness procedures are reduced with trabeculectomy. But they’re not eliminated. So we continue as we all know — as we read a lot about MIGS and other surgeries, we continue the hunt for a blebless glaucoma surgery. But trabeculectomy is right now still a very important part of our armamentarium in taking care of people who have glaucoma. So when do we do this? People with poorly controlled glaucoma. Usually people who have already been treated with medicines and trabeculoplasty. Maybe they had a MIGS procedure performed already. When I talk with my patients about trabeculectomy versus trabeculoplasty or drops, with all of those other procedures, we’re trying to get the balance between aqueous production and outflow more favorable. We’re trying to make the body’s trabecular meshwork work. And in this surgery, we’re abandoning the trabecular meshwork. And creating a new way for the fluid to leave the eye. Some people use this in patients who cannot comply with medical management or adhere with their medical regimen. If you feel that they’re not gonna take steroids, for example, postoperatively, then I think a trabeculectomy is a bad choice in them, because without steroids, trabeculectomies — it would be hard to get them to work. And in those patients, a tube shunt might be a better option. Because it really doesn’t require the post-op medicines as much as trabeculectomy. In my practice, I like trabeculectomy if I need to get a very low pressure. Lower than episcleral venous pressure. So we know a lot of the MIGS procedures, the dual blade, the GATT, are designed to flow into the trabecular meshwork, or past the trabecular meshwork, but still go through episcleral venous system. By bypassing all of that, we can get pressures that are lower than one can get if one relies on the episcleral outflow network. And so I see a lot of normotension glaucoma in my practice. I have a lot of patients whose target pressures are under 10. So I do a lot of trabeculectomies. Contraindications — obviously we don’t operate on blind eyes. If somebody has poor conjunctiva, they’re not a good candidate for a trabeculectomy. You really need quite mobile, healthy conjunctiva. I will sometimes, if I’m in doubt, use a cotton tip applicator at the slit lamp in the clinic just to make sure the conjunctiva moves. If someone has had a 360 degree peritomy for a scleral buckling procedure and the conjunctiva was not approximated well, they’ll probably not do well with the trabeculectomy and I would be thinking of more like a tube shunt procedure in that patient. There are a lot of reasons that people would be at more risk for failure. Aphakic patients. Anybody who has a wound in the limbus, in the old days, extracapsular cataract surgery patients. If they’ve already had one filtration surgery that’s failed, young people — one of the questions that came in before the lecture was: Talk about babies and children. I don’t really do trabeculectomies in babies and really young children, because they heal so vigorously, and also we can’t do suture lysis or suture removal without anesthesia. So if I can’t do a goniotomy or trabeculotomy in a really young child, then I would consider doing a tube shunt. Even though you hate to do that in a young kid. But I think it’s more likely gonna work. Inflammatory glaucomas — anything that makes the eye sticky are more likely to heal shut. People who are more darkly pigmented tend to heal more vigorously. People with some secondary glaucomas like neovascular and ice syndrome don’t do great with trabeculectomy. So why do I like trabeculectomy? There are a lot of downsides to the surgery, and I’m completely supportive of trying to develop new surgeries. I think it’s an exciting time in glaucoma now that we’re trying to develop new surgeries. But why do I like trabeculectomy? And I do like trabeculectomy. In my hands, I can get a lower pressure than with any other procedure. And I’ll just present two cases. This is somebody who I saw… I live in a small City, so my patients, often when they’re doing well, they go back home to where they’re from, because it’s quite far away, often. And so we tend to not see patients who are doing well. They tend to go back home. So this person had glaucoma progressing at normal pressures. We did trabeculectomies in both eyes with mitomycin C. And I didn’t see them for 11 years, because they’re back home and doing well. They returned 11 years later to have cataract surgery, and at that time, their pressure was 4 millimeters of mercury in both eyes. That’s a little lower than I would probably want someone to be, but this person was tolerating these low pressures well. And I just wanted to show their visual fields. On the right is the right eye. And this is over 12 years. So this person hadn’t really changed in 12 years, in either eye. One more case. We have a big family, in which we discovered the linkage for juvenile glaucoma in the Myocilin gene, and the man who first presented from that family came to us in 1986. His right eye has been lost to trauma. Struck with a ladder in the right eye. His left eye — this was his visual field in 1986. An octopus visual field. He underwent a trabeculectomy in 1986. At that time, there were no antimetabolites. Just a trabeculectomy. And this is his Humphrey field, 32 years later. And I think there’s very little change there, over 32 years. Which is pretty remarkable. Has a pressure of 11 millimeters of mercury over this period of time. The other thing I like about trabeculectomy, compared to initially doing a tube shunt, is that it leaves me more options. As a glaucoma doctor, you always have to think… What am I gonna do next? If this doesn’t work, what do I do next? And if I do a trabeculectomy, I have the chance to do a second trabeculectomy. Which I would only do if the first one worked for a long time. But I also have tissue to do a tube shunt or even a second tube shunt. If I start with the tube shunt, I’ve pretty much closed the door on trabeculectomy. So for me, it’s generally the first operative step. Once you get past drops and lasers. So prepare, as I said, examine the conjunctiva. Use a cotton tipped applicator to make sure that it’s mobile. I like to stop anticoagulants, if it’s possible. I do a lot of the surgeries with them on anticoagulants. Because if they atrial fibrillation, I think it’s safer to leave them on anticoagulants. Than to risk a systemic problem. If the pressure’s extremely high, in the 50s or so, then it should be lower early or before the case. So one can use intravenous mannitol. That adds a lot of complications. Needing a catheter, et cetera. I usually would just start the case by doing a very early paracentesis and letting just a very little bit of fluid out, and then as I’m working, I just keep going back and letting a little bit more, a little bit more out. So that by the time I enter the eye, the pressure has been low for at least a little bit of time. I find that works pretty well in my hands. Anesthesia — most people, I think, do this with retrobulbar block. I do not. I use what I call topical. I have it in quotes there, because it’s not entirely topical. And I’ll demonstrate that for you. Retrobulbar is perfectly fine. So this is before the patient’s prepped. Put a drop of — a numbing drop in. And just with a 30-gauge needle, inject a combination of marcaine with epinephrine and mitomycin. I rinse that out, then we have the patient prepped and draped, and by the time we come back, the eye is numb in that region. The advantage to me — multifold. One is that they don’t need to wear a patch. Another, that they can move their eye around during surgery. And most patients are cooperative enough that if you say… Could you look down? They’ll look down. And so I don’t need a traction suture in most of these patients. So if you do need a traction suture, you use a 7-0 vicryl suture in this case. I usually mark with a marking pen, 12:00. And I’m putting my traction suture in a position where it will guide me as to where I want to make my flap. So I’m right-handed, and so I tend to make my flaps at 11:00. And by having this traction suture here, and this dot here, I know where I’m going to make my flap. That sounds a little bit elementary, but if you ever get a little bit lost and make a flap and it ends up too far nasal or too far temporal, then you can get a bleb that’s really uncomfortable for the patient. Again, it’s optional to use a traction suture. If I don’t use a block, then I mostly don’t use a traction suture. You can tell whether you need it, just asking the patient to move their eye around. One can make, then, an incision in conjunctiva. This can be limbus-based or fornix-based. I think most people do fornix-based incisions. I tend to like limbus-based. The advantage of a fornix-based incision is that you don’t need as much help to do the surgery. And in some studies, in some groups, they find that the blebs are more diffuse, fornix-based, than they are limbus-based. I like limbus-based, because I hate leaks. I hate dealing with leaks early after surgery. And so I don’t see those with limbus-based surgeries. But it is a little bit more tedious to perform. I think both are fine. So this is a limbus-based procedure. Just making an incision. It’s sort of as far back as I can. Through the conjunctiva. And then I go through Tenon’s — every layer I go through, I go a little bit more anterior. Trying to not bring heavy Tenon’s tissue forward. And eventually this patient has a fair amount of Tenon’s. You can see I go underneath conjunctiva. I want to make my Tenon’s incision wider than my conjunctival incision. And that brings us down to the surgical limbus. And here I’m just using a gill knife. To expose the surgical limbus. You can see that nice gray line there. And that’s where we want to be. But you can see that I have an assistant with a Weck-Cel sponge. So it does take a little bit more help. Fornix-based incision — I’m making an incision here. Close to the limbus. This is somebody we’ve done a combined procedure. You can see that they’re dilated and they just had their cataract surgery done. A little bit more sloppy mark at 12:00 here. This blue mark is from where I made my paracentesis. So if one is going to close with wing sutures, you can just make this incision right at the cornea. If you’re gonna do a running suture at the limbus, then I would leave a little bit of tissue anteriorly. So the scleral flap — some people go at 12:00. I think that’s perfectly fine. I prefer to go just a little bit nasal or temporal. And I do that at 11:00. The reason I do that is it falls at my right hand. But more importantly, it gives me the opportunity to go back and do a second trabeculectomy. If I do my first one at 12:00, then my second one is going to be farther nasal or temporal than I want. And so that’s why I prefer 11:00. So this is just a 75 supersharp blade. Just a regular blade. The blade is 3 millimeters long. And so that’s my ruler. I don’t take out a ruler or calipers. I make my flap about 2.5 or 3 millimeters at the base. And I make it as a trapezoid. I like trapezoids. I like rectangles a lot. And the main reason for me is that again, it’s control. If I put a suture here, I can put a really tight suture here, and it’s not gonna open up this other side. Similarly over here, a rectangle would do the same thing. If I have a triangle, I don’t like triangles — a lot of people like them, and I can’t argue against them. One of the problems with a triangle is you have a single suture at 12:00. That’s basically an on/off switch. So if the pressure is too high, and you cut that suture, the pressure could end up being very, very low. And then if you have a triangle and you put a suture on the side of the triangle, it gapes the other side. So I’m a big fan of trapezoidal flaps or rectangular flaps. I don’t think that makes a whole lot of difference. As opposed to triangular flaps. But people have strong feelings on both sides. Let me go back, because I need to play that movie again. So these incisions need to be deep. People when they’re starting tend to make little scratches. But these need to be deep, because you want the walls of this to be perfect. And now I’m gonna connect these two. And I’m gonna lift this corner up just with the end of my blade. So that I have something useful to grab onto here with my 0.21 forceps. I don’t just tear the corner off. I have my blade turned up, so that it doesn’t dive. It stays in a plane. And I work from inside out, inside out, to keep working until I get far forward. If I have the blade up, it stays in a plane, and you get this bed. You can see it’s nice and smooth and shiny. You can see that I’m now in the clear cornea. And I tend to be cheap. That means I can do the whole surgery with just this one blade. I use it for the flap. I use it for the paracentesis. I use it for everything. So control, again. You need deep perpendicular walls. Like on the left. Not little scratches where you try to carve it into a flap, and you end up with something that looks like the thing on the right, because the one on the left, you can close this down, if you had a deep flap with perpendicular walls. You could close this down and raise your pressure to 60. Again, everything is about control. You’ll get tired of me saying that. I always do a paracentesis. That was one of the questions people asked. I want to form the chamber through the case. I want to form the chamber at the end, to test my wound. And I also, if I’m doing my, quote, “topical” surgery with just subconjunctival anesthesia, I’ll use preservative-free lidocaine, certainly if I’m gonna have to do an iridectomy, and acetylcholine or Miochol to constrict the pupil. So I think paracentesis is critical. And antimetabolite. I use mitomycin. Some people use 5-fluorouracil. That’s fine. One of the questions that came in is: Well, what about if you don’t have antimetabolites? And certainly that one example I gave of that person with 32 years of follow-up, he had no antimetabolites. So you certainly can get a trabeculectomy to work without antimetabolites. It’s harder, and I think that the change that I would make in my postoperative management is I would be cutting sutures much earlier. We’ll talk about the timing, about suture lysis, later on in this talk. But I would be cutting sutures early, looking to have a very low pressure, very early. With mitomycin, I can have the pressure be pretty high for a few weeks, and I think that just makes for a more comfortable course. So sometimes you can reduce 5-fluorouracil just on sponges. I’ve done that rarely. And again, sometimes you can do surgery without. And you can put this on before the surgery. Before flap creation or after flap creation. I do subconjunctival injections now. I don’t do sponges anymore. But I would say if you’re early in doing trabeculectomy, or you have an eye that has very thin eye, and you’re worried you’re not gonna have a great flap, you might consider making your flap first and then adding the mitomycin sponges afterwards. And the reason that I say that is that if you have a terrible flap, it’s bad to have a terrible flap, you don’t have control, but if you add mitomycin to that situation, then you really dump gasoline on a fire. If I had a really bad flap and I didn’t have great control, I would just abandon the mitomycin, because that’s just gonna make your life more difficult. So this is again using this injectable eye, if it’s marcaine with epinephrine, 50/50 mixture with mitomycin, I make a big bleb here. This is — I’m doing this after this patient’s already had a block. So I’m doing after the block. You can see I’m making this big wheel here. I like to do this before they’re prepped, just to let the mitomycin settle in and get absorbed into the tissues. But this to me is my favorite way of administering mitomycin. I think my blebs look better after this. Plus I am an impatient guy, and sitting there waiting for the mitomycin is hard for me. This is using sponges. These are corneal shields that we’ve cut in two. So using four of them. And I place them — try to surround the operative area with these sponges. This is somebody in whom I’ve already made a flap. It’s a limbus-based incision. And then towards the end… So I’m gonna leave this on here anywhere from two to three and a half minutes or so. Towards the end of that time, I’ll actually put one of the sponges under the flap, for just 20 seconds or so. To see if that helps prevent the flap from sticking down. I don’t miss sponges, since I’ve given up on them. But it’s a perfectly effective way to do mitomycin. So you rinse all the mitomycin away. And now you’re gonna do your sclerostomy. And it’s not really a sclerostomy. You’re actually cutting in the cornea. So again, most of us will have dissected well up into the cornea. And use Kelly punch or knives or scissors to make a block. So I’m gonna push the side of the blade against my flap, because I want to be as far forward as I can, and now I’m biting here with the Kelly punch. And you’ll see… If I can get my little mouse… You’ll see that we’re gonna leave some space here. At the side. Right there. You don’t want to bring it all the way to the edge. You want to make an opening that leaves tissue at the side. Again, if you bite it all the way to the edge, you’ve lost control right there. You might have fluid that’s flowing unabated, and you have to put a stitch in that area. So I always call this a shoulder. So I sort of leave this little shoulder around the outside. This is a Kelly punch. One could certainly do this with the same knife that one did the procedure with. I used to always do iridectomies. I don’t anymore. I certainly would always do them in a hyperopic phakic patient. So if somebody is hyperopic, for a lot of things these are the harder surgeries. Right? These are the eyes that are more likely to develop malignant glaucoma. These are the eyes that are more likely to develop pupillary block. But I would always do an iridectomy in those patients. I don’t really do them often anymore in myopic patients or pseudophakic patients. And part of this is because I tend to tie my flaps down quite tight. So I almost never see shallow or flat chambers, postoperatively. But if you do, if your chambers are shallow postoperatively, then I would do iridectomies in everybody. So I’m gonna grab the iris. I’m gonna pull it away from my scissor, engage the iris, and pull it back from the scissor. I do it in a two step manner to get an iridectomy that’s wider than my sclerostomy. So let me show that to you again. I’m gonna grab the iris a little bit anterior, pull it away from my scissor, engage it, pull it back, and that way I get a wide iridectomy, but it doesn’t go towards the pupil. It’s just wide. And I think there’s really no way iris can get into that wound. And then the flap closure. I am looking for dryness here. So in the old days, before mitomycin, we would want to have the flap so that there was always a little bit of flow. There’s always some fluid coming through. I always called it the two Fs. Form and flowing. That’s not what I’m looking for. What I’m looking for is that it’s dry. And when I push next to the flap, I can make it burp. So I call that being burpable. I can get fluid to come out if I ask it to. But I don’t want it to come out spontaneously. I want the pressure on day one to be 26. I don’t want it to be 4. Because I have lost control if the pressure is 4 on day one. And that’s different than the old days, where you really want it to be low. Because before antimetabolites, the pressure would just gradually climb. With antimetabolites, you have a very long window where you can cut stitches. So I like a high pressure early on. Not 50, but some 22 or 19, something like that. To me, that’s ideal. And I always do four sutures, at least. I do two primary sutures that are gonna control the flow. So after those two primary sutures, the pressure should be great. And then I put in what I call safety sutures. I put two sutures in parallel to my tight sutures, and I have them there so that I can safely cut sutures early after surgery. So if the pressure is 35 on day one, and I can’t get it to come down with a massage, I can cut a stitch on day one. And I can do that safely. If I had a triangular flap with one suture at the apex, there’s no possible way that I could cut a suture at day one. Safely. So here’s my trapezoidal wound, I’m putting my 10-0 nylon suture in. Unfortunately the video — for whatever reason, it’s getting a little bit jumpy here. So now I’m gonna fill the anterior chamber through my paracentesis. And I’m gonna just inspect and make sure that I don’t have any flow. Check the pressure with the Weck-Cel. Make sure that there’s a normal pressure in the eye. And this is dry. And that’s what I want. And I really don’t want it… I don’t want it to be flowing at this point. Now I’m happy with those two stitches. If I’m not, I’ll put in three, four, five stitches, but rarely do I need more than two. And that’s because I have these nice deep perpendicular walls. Right? So there’s the safety stitch. This is a little looser than the original stitch. And this is the end. So for me, I always have four stitches at the end. And now I’m gonna push next to it, and I can get it to flow. And I’m a happy guy. So two tight stitches at the apices there. And two safety stitches. You can use releasable sutures that pass out onto the cornea if you don’t have a laser available, or if you have somebody whose conjunctiva is just very thick. Too thick for suture lysis. And I borrowed this from an article in the Journal of Glaucoma. But this is the way that I do my releasable sutures as well. So I’m gonna be going backhand here, come out of the flap, leave a big — leave a loop — and then come out onto the cornea. And then I’m gonna put four throws, and snug this down with four throws. And it’s hard to control yourself, but don’t put a locking suture. Then it’s no longer releasable. The next step is to take this and make a second pass through the cornea. Just so that the suture just lies flat on the cornea, and it’s not swaying around, tearing off the corneal epithelium. And then, when you want to release this suture, you just take a 30-gauge needle. Lift this up. It will slide the suture out from the cornea. And you just pull with the tying forceps, pull slowly, and that will unravel. So this is a great technique. I use this a lot. Unfortunately I don’t have a good video of me using this. I use it in people where there’s too much scar tissue. Somebody who’s very young with very vigorous tissue. It’s a really nice technique. And again, if you’re in a situation where you don’t have access to a laser, that would be a really good technique to use. And so if I was gonna use these, I would put a releasable in both corners, and I would put safety stitches without them being releasable. Because this does take a little bit more time. And then conjunctival closure — most people would use a running suture. I don’t like the running suture, because there’s so much tension on these little points, and especially if you have somebody who’s very old, very thin conjunctiva, the advantage of a running horizontal mattress suture is that there’s suture along the outside of both sides of the wound, the entire length of the wound, and that would allow — that would prevent the sutures from tearing through. So I really like this closure. It’s a little bit more tedious to do. So I’m gonna start on the inside of the wound here. This is an 8-0 vicryl. And I’m gonna go from inside out. And then outside in. And what this is gonna allow me to do is — that will bury this first knot. I’m sorry. The videos are a little jumpy, playing them on this platform. I apologize about that. But it makes it slower, so I guess that’s probably not so bad. So I’m gonna tie this down. And now every pass that I make is gonna be… I’m gonna come from inside out, and then outside in, and I’m gonna try to have the whole… The tension distributed along the outside of this closure. You can see this patient has very thin conjunctiva. You can see the flap and the sutures so easily. And for me to close this conjunctiva with just a running suture, I would worry that it would break down. So this is a technique. It takes a little practice. It’s not hard. But it basically at the end… The only suture we’ll see at the end of this closure is the knot here. The rest of this will look like it’s been welded closed. And so now the surgery’s done, pressure’s good. I’m just gonna form a bleb. By pushing with a cellulose sponge right next to my flap, and I have a nice bleb like that. I’m a happy guy. You can do the same thing if you have a fornix-based incision. You can do this running horizontal mattress suture at the limbus. Usually for that, we would have left a little tag of conjunctiva on the anterior margin. Or one can just do wing sutures and pull very tightly across the limbus to close this. If you’re doing a fornix-based incision. So this is a running horizontal mattress suture at the limbus. Postoperative of course is really important. Frequent corticosteroids. I use every two hours for three weeks, and I slowly taper. I give atropine in the operating room to everyone, and I use postoperatively in anyone who has angle closure or is hyperopic. Again, I’m worried about malignant glaucoma in those patients. And then I give an antibiotic steroid ointment at bedtime. That’s the only antibiotic that I use for trabeculectomy. I see them every week for six weeks. I really want to have control over this. I want to be able to adjust the sutures. Cut the sutures, if needed. Usually if the pressure’s too high, I’ll just do some massage through their upper eyelid, watching at the slit lamp as the bleb forms. And I’ll do that for the first three weeks, unless I’m really forced to be more aggressive. I begin suture lysis at three weeks. Some people do this… One of my partners does this much earlier. I really hate low pressures. So I tend to start at three weeks, unless I’m forced to go early. And I’ll do this with a lens. This is a Hoskins lens, we see here. I usually use red light. Especially if there’s any blood around. It’s nice to use red. A small size. I think the main key is a really short duration. I usually use 0.02 seconds because you don’t want to heat up the suture and burn back to the conjunctiva. And I do my postoperative notes in a table, in our electronic record. I find this really helpful. Because I can see their entire course without flipping back and forth. So this is somebody who has normal tension glaucoma. You can see that their pre-op pressure was 13 millimeters of mercury. Right here. So on day one, the pressure’s 22. For me, this is perfect. I just do a little massage. It drops to 14. When I get out to week three, the pressures bounce back to 22. So I do my first suture lysis at that point. Pressure drops to 6. And you can see that after doing two suture lyses, the pressure now at week six is 7, and the patient’s doing really well. And if all goes well, you have a bleb that looks like this. It’s diffuse and elevated. Not thin. When you look at these blebs with the slit lamp, you can see that they’re elevated, and you saw all these little microcysts, and they may not transmit through the internet well. But you see these little microcysts where there is fluid transudating through the sclera — through the conjunctiva, I should say. I try postoperatively to have them avoid things that increase the risk of surface infection. Contact lens wear. Swimming in lakes and rivers. If somebody works in a really dusty, dirty environment, I probably would not do a trabeculectomy on them. I would probably do a tube shunt. Early problems. Pressure is too high. Usually that’s just tight sutures. Massage. Suture lysis, as we talked about. Sometimes iris can get stuck in the sclerostomy. That’s pretty uncommon. Actually very uncommon, thankfully. Pressure too high with a flat or shallow chamber like this eye, not what you want to see on day one. You could have pupillary block. And that usually — you would have the central chamber, which you can see in this picture here, the central chamber is deeper than the periphery. So this is someone with pupillary block. You can take care of that with an iridotomy. If you have aqueous misdirection, then it’s a uniformly flat anterior chamber. So these again are people who are having surgery. Typically are hyperopic, angle closure glaucoma patients. Kind of beyond the scope of this to talk about dealing with aqueous misdirection. Suprachoroidal hemorrhage, another reason to have a flat chamber with a high pressure. The thing that denotes suprachoroidal hemorrhage is pain. They can tell you exactly when this happened. And obviously you can get an ultrasound, and you can look and see a suprachoroidal hemorrhage. Be really careful that if somebody is hypotonous and their implant lens or their crystalline lens is up against the cornea, you can get a falsely high pressure reading, because you’re applanating the lens. So in that case, just touch their eye through the lid to make sure that it’s not soft. Because obviously your treatment is gonna be very different for that situation. Pressure is too low, usually that’s overfiltration. And that’s hard to deal with, because the temptation is to back way down on the steroids, to have them heal a little bit. But in my experience, once they start healing, then they keep healing. So I try really hard not to back down on steroids. If the pressure is very, very low, you might need to take them back to the operating room, or some people will pass a suture through the conjunctiva, another 10-0 nylon suture. And while that sounds like a frightening thing for people to do who have done that, I have not done it — I find it works well. Obviously leaks are the bane of our existence as glaucoma specialists. Usually early leaks we’ll just stop. Late leaks that develop months later or years later are difficult to manage. And this can lead to SHA*L or flat anterior chamber, effusion, which can lead to suprachoroidal hemorrhage. Hyphema is usually self-limited. People talk about snuff. They used to think snuff was common, especially when you operate on somebody who had fixation splitting field loss. I will say thankfully I’ve seen very little snuff in my career. You always worry a little bit about it, but I think it’s an uncommon problem. Failure. They can form Tenon’s cysts. Usually you can treat these with aqueous suppressants, hoping that they’ll soften up. Here’s an eye with a Tenon cyst. This eye has a bleb around it, but you can see the border of the cyst right there. You can treat these with aqueous suppressants. You can needle them. Cysts are a little bit of a challenge. Leaks need to be repaired. You can see we tried to repair this one and it’s still leaking. Infection is uncommon. But they’re always at risk for an infection. I always tell people if they have a bleb that we need to see them right away if they have redness or discharge. And then I describe for them what I mean by right away. If you have an appointment at 8:00 am tomorrow and it’s 2:00 am, you don’t wait until 8:00 am. You come in as soon as you can come in. Usually if it’s in the bleb itself, you can treat these with fortified antibiotics. Again, they need to be instructed to come back right away. And very rarely you can get infection in the eye, endophthalmitis. And obviously that is a much poorer prognosis. The blebs can migrate over the cornea. That was a bigger problem with full thickness procedures. And weirdly, you can just cut that bleb off. I did that on this patient, thinking that that was crazy. But it actually worked, and it didn’t leak. Which is amazing. If you have a steep rise of the bleb at the limbus, that can make the eye uncomfortable. That can lead to Dellen formation. Or they can have this thing called bleb dysesthesia, bubble dysesthesia, where every time they blink, they form a little bubble over the bleb. That sounds innocuous, but these eyes are really uncomfortable. I’m gonna try that again. For whatever reason, that didn’t show the bulb. There. You can see the bubble there. And so you have this very steep interface between the bleb and the cornea. And sometimes you just need to put a big X suture over there, just to change the shape of the anterior surface. Tears will help. But those eyes are remarkably uncomfortable. And so if you have somebody who’s complaining of discomfort, look for bubbles. They’re not lying to you if they say that they’re uncomfortable. So let me go through the questions again. Hopefully that is a helpful introduction to you, on just what to think of when doing a trabeculectomy. Again, think about control. That’s the number one thing to be concerned about. So which is the following mechanism by which trabeculectomy lowers intraocular pressure? Bypassing the trabecular meshwork, enhancing outflow through an intact meshwork, decreasing aqueous production, or opening the end of Schlemm canal? And most of you got this right the first go-round. Waiting for the results here. I didn’t see the results. There we go. 84% are correct. Some people — 10% said open the end of Schlemm canal. That was what it was designed to do, but it doesn’t. What it does is it bypasses the trabecular meshwork. Which of the following is a risk factor for failure of trabeculectomy? Advanced age, exfoliation, inflammatory glaucoma, or pigmentary glaucoma? Right. So almost everyone — 93% of you got inflammatory glaucoma. Advanced age actually puts people — makes people more likely to have a successful outcome. And neither pigmentary nor exfoliation really are big risk factors for failure. Question three. During trabeculectomy, a surgical iridectomy is most important in which of the following eyes? Hyperopic, myopic, eyes with pigment dispersion syndrome, or pseudophakic eyes? Almost everyone got that correct. Hyperopic eyes — 92% of you are correct. You worry about aqueous misdirection. You worry about them getting pupillary block. Pigment dispersion is kind of thrown in there. Sometimes there will be iridotomies for pigment dispersion early in the course of the disease to try to get at the underlying pathophysiology. But they have deep anterior chambers, of course. Lastly, question four. Aqueous misdirection, malignant glaucoma, is most likely to develop in an eye with which of the following refractive errors? -8 diopters, -3 diopters, plano, or +5? Right. So most of you got that correct. A -8, you worry about doing those eyes because they’re thin, a little bit. But people who are hyperopic are a concern, going to the operating room. And I would leave them on atropine postoperatively, because of my concern of aqueous misdirection. So key points. Trabeculectomy bypasses the meshwork. Creates a bleb. It can generate very low pressures. Sometimes too low. It has associated complications. And antimetabolites increase the success rate, but also the likelihood of complication. I mean, if a trabeculectomy fails, that prevents you from having bleb leaks and other issues. So I have a curriculum website, the Iowa glaucoma curriculum. I have almost this exact same lecture on there, if you want to listen to me again. So now I’m gonna move on to some questions.\

DR ALWARD: Okay. So question one is… Why are blind eyes a contraindication? Usually any intraoperative surgery is contraindicated. I think there’s a very small risk of getting sympathetic ophthalmia in the fellow eye. And so I would never put somebody through the long bumpy postoperative course of a trabeculectomy for a blind eye. I mean, I’m talking no light perception blind. I’m not talking somebody who’s legally blind. That’s unfortunately part of our patient population. Question two is: Do I always use mitomycin C? And I do in my practice. As I said before, if you’re early doing this in your career and you have a flap that’s not well controlled, you can abandon mitomycin C if you have a patient who is really old and has very thin conjunctiva and you’re more worried about suprachoroidal hemorrhage than you are about failure. Then you can use very little mitomycin or none at all. That one example that I gave, 32 years, that guy had no mitomycin. So it’s not essential. But it certainly has changed. For those of us who did surgery before mitomycin, it completely changed the way that surgery has gone. It allows us to close things up tighter, so we don’t have that early postoperative hypotony. Knock on wood, I have not seen flat chamber in years and years. So I do like mitomycin. Let’s see. What is the place of trabeculectomy in normal tension glaucoma? That is the surgery in my mind for normal tension glaucoma. I sometimes will do tube shunts if I have to. But they don’t get the pressure as low. I think it’s the best surgery. I think the MIGS surgeries that rely on episcleral venous pressure are not gonna get you the best practice. So if you want a pressure less than 11, trabeculectomy in my mind is the only way to go. What is my opinion about subconjunctival injection versus 5FU? And what antimetabolites have I used over the years? I was part of the 5FU trial, which was twice a day injections for a week and once a day for a week. That was hard on the patients. It was hard on us. I think it changed the course of glaucoma management. Mitomycin is much easier because you only have to do it one time. And as I said, I moved from sponges to injection. But I think the sponges are perfectly fine. Question about mixing anesthesia with mitomycin. Yes. So that’s exactly what I do. I use marcaine, a long acting anesthetic, mixed 50/50 with mitomycin. So it’s a volume of 0.2 ML. In my hands, that’s been by far the best way for me to do the surgery. I guess that answers to these questions. One question. I’ve convinced them to do trapezoidal flaps. Was doing triangles with a rounded apex. No. I’m mostly talking about just a triangular flap. Pointed at the end with a single suture in the end. For me, I don’t feel that that’s a comfortable way for me to do surgery. For the reasons I said. If you put a single suture in, then it’s fast, but then you have so little control over the pressure. I really like my four sutures, because I can… I have a lot of control over 6 or 8 weeks about what the pressure’s doing. And mitomycin doesn’t put me in a hurry. I’m not in a rush, because I can cut stitches three, four, five weeks out. Can one use absorbable sutures for the flap? I would not. I think again that you lose control. So I would not use an absorbable suture. One doctor said: My concern from the video is… It’s a long question here. Concern that the traction suture is close to the visual axis. So no, it’s not. And that’s just, I think, the way it looks on the screen. It’s quite peripheral. And it’s not full thickness. Can it cheesewire through as part of this? Absolutely, if it’s too superficial. But it just takes a little bit of practice. Sometimes if it cheesewires through, it’s no big deal. You just pass it again. If it’s too deep, then I would pass another traction suture. I would take it out and pass one more peripheral to that. And that’s one of the reasons I don’t go all the way at the limbus. Partly I don’t want to hit the conjunctiva. But it gives me room to put in a second traction suture, if I’m too deep. But you don’t ever even see any residual of this postoperatively. There’s one here about which resource would I recommend to learn visual field? That’s a little off-topic. But my curriculum site… If you go there, there are chapters about how to interpret visual fields. Question about… Can you use amniotic membrane instead of conjunctiva? I would say no. Amniotic membrane is great for some things. But it can’t replace the conjunctiva. I think if you have a defect in conjunctiva, people have had success closing bleb leaks with amniotic membrane. I must say I’m not one of those people. I haven’t been dazzled. I don’t think that’s helped me very much. But if you have no conjunctiva, it’s just completely falling apart, I would make an incision far up in the fornix and try to drag conjunctiva down to the limbus, but I wouldn’t use amniotic membrane to replace conjunctiva. What do I do with Tenon’s tissue? Do I preserve it or excise it? That’s a really great question. I used to often excise the Tenon’s tissue. But now… Since mitomycin’s come along, I worry more about too thin a bleb than too thick a bleb. So I would never do a formal tenonectomy where I remove as much Tenon’s as I can from under the conjunctiva. I did in the past, but I don’t anymore. Let’s see. A lot of questions about needling. I don’t do a lot of needling. I know people do. People who do Xen implants do a lot of needling. In my hospital, getting the injections takes a little bit of work. It has to be made in a separate building and shipped over. It’s just a little bit of a problem. In a lot of places, it’s easy to do. So I would do that for somebody with Tenon’s cysts, somebody whose trabeculectomy is scarring down, and I can’t get it to elevate. So usually what I do is a mixture very similar to what I talked about. Marcaine and mitomycin. And inject it a little bit away from the bleb and then use the needle to go — and I don’t have a movie of this. I’m sorry. I should have put that in. To kind of go under the conjunctiva and enter the bleb or the scarred area from the side. So one question here about leaving viscoelastics in the anterior chamber after surgery. I think in Europe they do that routinely. And I don’t think we do, typically. I don’t know anyone in the US who does that. I don’t know why that difference in policy… I never do. I leave it in the AC after an Ahmed tube shunt. I don’t after trabeculectomy. And partly because again, I’m tying things down tight and I don’t typically have flat chambers. Partly because I think it makes it harder for me to judge the outflow, if I have the anterior chamber filled with viscoelastic. What do I do with suprachoroidal hemorrhage? Well, there’s really not much to do in the operating room, right? You basically close everything down tight. If you’re sure it’s a hemorrhage, sometimes you just have chambers that get really shallow and it’s really hard to reform them, and you can’t tell if it’s a hemorrhage, or if it is aqueous misdirection, malignant glaucoma. In that case, I would put a bunch of atropine on. Try to take a look in the back. But usually there’s not much to do in the operating room. You close everything up and it’s something that has to be dealt with later, usually with your retina colleagues. A question. Do I think trabeculectomy will be kept as a first line surgical procedure or one day be obsolete? I think most of us who do a lot of trabeculectomies hope that it is one day obsolete. I think a lot of these new surgeries are really interesting. And I applaud the people who are developing them. It’s an exciting time to be a glaucoma doctor. I think that for some patients, for the foreseeable future, trabeculectomy is gonna be necessary for people in whom you need a pressure of 6. Right now, I don’t see anything else that does that. But I’m hoping that it goes away. Because there are a lot of problems. I like trabeculectomies, but we can do better. Let’s see. We talked about… Some people had questions about flaps. There was another question about postoperative hypotony. I would try to avoid that. Obviously that’s easy to say. But I would try to get used to this concept of having — closing things down tightly, having a pressure that is way higher than your target for the first couple of days or weeks, and gradually ratcheting the pressure down with suture lysis. I think that it’s a much safer way to do surgery. Let’s see. So a question for a beginner: How to select my early patients to favor positive outcomes? Excellent question. I certainly wouldn’t start with patients who have inflammation and are young and are gonna scar. I would find somebody who is elderly, lightly pigmented, thin conjunctiva, kind of everything in your corner. The downside with an elderly patient is that they are more likely to have problems like suprachoroidal hemorrhage. But that’s a rare problem. And so try to pick people who are high chance of success. And then kind of gradually work your way towards harder cases. Do I believe that a peribulbar block can cause snuff-out? No, not really. I think snuff-out is uncommon. I think it’s just most likely the sudden drop of intraocular pressure. But the reason I’ve given up on blocks is because I like not wearing the patch. They can start the steroids right away. I like having them move their eye around. So if you have them look down to put in a suture in the scleral flap, that’s much more physiologic than yanking the eye down with a traction suture. It doesn’t distort the wound at all. So it’s not my concerns about the retrobulbar or peribulbar block. It’s just that I think not using a block is better for my patients. If I have to combine trabeculectomy and cataract surgery, do I do one side or two sides? So that has changed over time. I used to do one side. Certainly when I was doing extracapsular surgery. But I do two site now. I do a temporal phaco first and then do my trabeculectomy up at 11:00. Nice to put the mitomycin/lidocaine early before you’re doing your phaco. It has a lot of time to settle in and get absorbed. What is the success rate of trabeculectomy in my hands? I don’t really know the answer to that question. I feel like it’s pretty high. I think it’s probably… If you talk about unqualified success, in somebody whose pressure is great on no medications, I would guess probably 50%, 60%, and people who are at target with medicines, it’s probably 80% or so. One of the problems I have is my patients live so far away that the ones who are doing well — I don’t get to see them. So I tend to have a bias that I’m not doing as well as I am. We one time did the first mitomycin phaco-trab, using mitomycin, versus a placebo. And in those patients, we had to bring them back and we had really good follow-up. And actually the success rate for both was pretty high. And that surprised me, because again, my patients who were doing well were back in their hometown, 200 kilometers away, so I don’t get to see them. What is the location like to inject antimetabolites in post-op follow-ups? So I would inject them in the same quadrant as the bleb, but far away from the bleb. I certainly don’t want to get antimetabolite into the bleb. There’s usually this ring of steel around the bleb. So especially if you’re having to needle them, I don’t think there’s much risk of getting antimetabolite in it, unless you actually inject it. Let’s see. Do I recommend trabeculectomy in angle closure glaucoma? Yes, I would do trabeculectomy in acute angle closure. I don’t think there’s really a better operation. The chambers are too shallow to do a tube shunt. It’s just you’re way more nervous about that patient, right? Because you have this sudden drop in pressure. That puts them at risk for hemorrhage. You have eyes that are at high risk for aqueous misdirection, malignant glaucoma, so they’re not fun eyes to operate on. But yes, I would definitely do a trabeculectomy. In my experience how long do trabs work? I have people I did trabs on when I came to Iowa 33 years ago. They’re still working. I think once you get past the first several months, they don’t tend to fail. They can, obviously. They can fail 15 years from now. So you never give up on seeing these patients. But there’s not a lot of reason for them to fail late. The reason they fail early is because there’s inflammation, there’s blood, but afterwards, when you get far out, you don’t have any of that. And so once they’re working and they’re on autopilot, they tend to work for a long time. What is my attitude towards non-perforating operations? I guess that’s like a canaloplasty? I don’t have experience doing those. So again, I do a lot of these old-fashioned surgeries like tube shunts and trabeculectomies, because they work pretty well. I am completely excited and on board with developing new operations. I haven’t found one that works as well for this population of patients. But again, because of my practice, because I’m in a university hospital and patients live far away, I tend to see really bad glaucoma, and I tend to see a lot of people with normal tension glaucoma. And so that’s why a lot of these surgeries just aren’t applicable for my patient population. Why didn’t I choose traction suture on the rectus muscle? That’s a good question. I used to do that I would say 30 years ago. You would need to have a block. I don’t do blocks. People without a block would not like you if you did a traction stitch. I also worry about bleeding. So if you bleed from a traction stitch and it gets down in the bleb, that’s kind of a mess. Corneal traction suture is so easy and it’s so benign. I don’t really see a reason to do a rectus suture. Absorbable versus non-absorbable for conjunctival flaps. I use absorbable. I use an 8-0 vicryl suture. I don’t have an objection to using a non-absorbable suture. It’s just that you’re gonna have to go back and take it out later on. And that’s an extra step. It heals fast enough. How do I manage a bleb leak from the area of suturing on the 7th postoperative day? Excuse me. I would take them… We have a minor surgery room in our clinic. I would just take them there and I would put another suture in. I wouldn’t just patch them. That should do really well. Leaks early on are relatively easy. Because epithelium is intact, and so you just put another 8-0 vicryl suture in that area. That’s really not a hard problem, unless just the logistics of taking them back to the hospital, back to the operating room — I’m lucky that I don’t have to do that. I can just take them down the hall to the minor room, just give them a drop of topical anesthesia, and put in some sutures. Do I make a standard count of punches or vary? No, I don’t make a standard count. Sometimes it feels like I make punches until I make it bleed. That’s not what I want to do. But I would usually do two Kelly punches. Typically one doesn’t seem like enough to me, although I don’t have any data to support that. Again, I want to leave that shoulder that I showed you on the side. I want to punch all the way to the edge. Pretty much any size opening is gonna be big enough to handle the 2 microliters a minute that comes out of the aqueous. So I usually use, I would say, two punches, and that’s usually plenty for me. Let’s see. What is the best time to inject 5FU to prevent bleb failure? I don’t really use a lot of 5FU, so I’m not good to answer that. I would probably say after a few weeks. Because you’re really not sure it’s failing that early on. You would be going through massage. You would be going through suture lysis. I think injecting 5FU. Or mitomycin postoperatively to prevent bleb failure… If you see that someone’s scarring down, I think that’s a really reasonable thing to do. In my situation, it’s just logistically harder than it is in a lot of places. What is the concentration of mitomycin C I inject subconjunctivally? So I use 0.2 milligrams per mL of mitomycin. But we have a pharmacy that mixes this up for us. It’s mixed up in our chemotherapy unit of the hospital, since I practice in a hospital. How long after anti-VEGF injection can we plan a trabeculectomy? You know, some people use anti-VEGF with their trabeculectomies to enhance success. I don’t really see a reason that you couldn’t do it soon after. The other was PRP. Sometimes you get choroidal effusions from panretinal photocoagulation. You’re gonna be driven in that situation by how high the pressure is and how urgent it is. I don’t do a lot of trabeculectomies for neovascular glaucoma. I tend to think tube shunts work better. They’re obviously very difficult cases. And even for a tube shunt, that’s even difficult. Usually with neovascular glaucoma, I would put the tube shunt, if I can, in the sulcus. Not in the anterior chamber. Because the neovascular tissue can grow around your tube shunt. If the bleb fails after a while, this is, I think, a really important question. How would you act? How would you repeat the trabeculectomy near the first one? I’ve changed on this over the years. I think I would say if the trabeculectomy worked great, and failed after 5 years or something, that’s uncommon. But if it did, I might be inclined to do a second trabeculectomy, particularly if my target was quite low. More often now I would be inclined to do a tube shunt, if the trabeculectomy failed. If I did it, and everything went great, the patient was good about taking their steroids, and yet they still scarred vigorously, then hopefully I would have learned from that, and I would instead maybe do a tube shunt. Would I perform phacotrabeculectomy for a patient with acute angle closure glaucoma and 3+ cataract? Or do phaco alone as a first step? That’s a good question. Excitingly, the world is moving to doing a lot more cataract surgery hopefully early on for people who have pupillary block angle closure. If there was a way to get the pressure controlled enough that I could just do the cataract extraction, and they didn’t have a lot of glaucoma damage, I think that’s worth trying, by itself. If they’ve been in angle closure for a long time, I think the meshwork is probably… You really don’t have the meshwork to work with. And I probably would do a combined procedure. Can anti-VEGF be used to prevent bleb failure? Yes. They can. There are studies. People using anti-VEGF agents instead of mitomycin or with mitomycin. It’s not something that I do. I’ve been quite happy just with mitomycin. But we’re learning more in an area of development… I don’t have experience with it, but I know it’s something that people are doing. This one we answered. Thank you for saying thanks. I don’t see any other questions here that I haven’t answered one about. Early hypotony. I mentioned that in my talk, I think the tendency with early hypotony is to just really back down quickly on the steroids. And I try hard not to do that. I do do it sometimes, but I try hard not to do it. Because I really… I think what you’re trying to do is to get everything to close. And once it starts to close, to heal, then it just keeps healing. But sometimes you have to. Sometimes you’re a little bit desperate. A question on my experience with ologen implants? I have no experience with that. I’ve certainly read that people are using them. But I have no experience with that. Sorry. I think I’ve answered all the questions. So thank you all for listening. And I hope you do great trabeculectomies out there.

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February 7, 2020


Last Updated: October 31, 2022

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