Lecture: Trabeculectomy: The Technique and The Thought

Trabeculectomy is, and will be for a long time to come, the most commonly performed surgery for glaucoma. The outcome of the surgery, in terms of its efficacy and adverse effect profile, can be enhanced by a consistent, careful and conscious surgical technique. In this webinar, I would like to share my technique of performing trabeculectomy, the way it has evolved over the years, and the thought process behind it.

Lecturer: Dr. Siddharth Dikshit, DNB, FICO, L V Prasad Eye Institute (LVPEI), India


DR DIKSHIT: Hello, everyone. And I hope wherever you are, you are safe, healthy, and happy, and everyone around you is also good. At the outset, I would like to thank Cybersight for helping me reach you all. And in these times, I don’t know what the situation is elsewhere. At India, we are rarely going out, meeting people. So it’s a wonderful experience to be able to reach out to so many of you, all over. Well, I am Siddharth Dikshit. I am a consultant in the glaucoma and cataract services at the LV Prasad Eye Institute, Hyderabad, and I’m in charge of the residents at the Institute. I have no financial interests or conflicts with anyone. Any financial entity and definitely not with my colleagues. So this presentation and this talk is going to be about my experience over the years, a decade into glaucoma practice and surgery. And how I think I can reach a goal of having a bleb like this, with everything being in the perfect place. Like religion, glaucoma — success in glaucoma surgery is also — can be reached through multiple paths. So I at no point want to state that what I have learned and have adopted in my practice is the only way to go ahead. But I will try to explain to you why I do what I do. Now, irrespective of who the surgeon is, when you do a trabeculectomy, you want to look at a patient who has intraocular pressure of 10, 12 millimeters of mercury, without any medications, from day one to ten years — and why not beyond it? And this is the ideal thing that we want. It does not happen all the time. But happens quite often for us to keep us motivated. What you don’t want: You don’t want any complications. You don’t want even a hyphema or uveitis. But let’s concentrate on complications that are sight threatening and can cause irreversible vision loss. Or failure of surgery or need for repeat surgery. Things like a suprachoroidal hemorrhage, a wipeout, meaning the patient loses the entire residual visual acuity immediately after the surgery. A bleb leak, blebitis, endophthalmitis from a thin cystic bleb will need a lot of intensive care and possibly repeat surgery or surgeries. And a failed bleb. So this is not what we want. And the root cause or a common cause of the top three complications listed here is hypotony. And while we’re doing a trabeculectomy, we can’t to counter hypotony by countering the extent of hypotony, the suddenness of hypotony, and the duration of hypotony. The more is the extent, suddenness, and duration, the more likely are we to meet these complications that we definitely don’t want to meet. So let us see how, during our surgery, or during the journey to the surgery and while performing the surgery, can we avoid these complications. The journey to the surgery actually begins before the surgery. And I cannot undermine the importance of what we are going to do before the surgery. But I will keep it brief, and concentrate on a few specific things. If I’m going to operate on a patient with a visual field like this, or a macular program — you know this is advanced glaucoma. And these patients have a very sensitive eye. And a risk for higher complications, like wipeout or have very little tolerance for fluctuation of intraocular pressure. In these patients, it is best to reduce the intraocular pressure as much as possible, preoperatively, for a sustained amount of time. Because the physiology or the natural vasculature of the choroid, which can lead to many complications, takes time to adjust. So just giving mannitol prior to the surgery may not help, as much as a prolonged and sustained pre-op control would. Now, we are operating because the pressure is not under control. So this is a little counterproductive to talk about. But control it as much as you can. Don’t leave the patient on just one medication, because you are in any way going to do a surgery. Use acetazolamide, use glycerol syrup. And try to get it under control as much as possible, until the time of surgery. And on the day of surgery, for advanced glaucoma, respite of intraocular pressure control, I use pre-op IV mannitol. Which I give at least one hour before surgery. So that it has maximum effect when I start operating and incise the eye. As we have identified people with risk of wipeout, we should identify people who are at risk of suprachoroidal hemorrhages. I can remember one patient very clearly, whenever I see this term, suprachoroidal hemorrhage, written anywhere — she was an obese lady with hypertension, hyperlipidemia, atherosclerosis, sleep apnea, she was breathless when she sat down and was on anticoagulants, and that lady just reminds me of all these risk factors. So what do you do? You try to control as many risk factors as you can. While it is possible in some patients to stop the anticoagulants in advance, please do so. If not, then we have to just bite the bullet and go forward. Control the blood pressure to something below 140 and 90 millimeters of mercury possible. And use IV mannitol preoperatively. Now, there are situations where hypotony is not only more likely to happen, but either has a prolonged course towards resolution, or can have multiple complications. So this is a list of situations where you should try to avoid hypotony to the best possible extent. And though this may not be complete, these are the most important and common conditions which you usually would meet while operating on a patient for trabeculectomy. When you start the surgery, there are certain things, which are very, very important. Very small things. Like giving a patient a bathroom break prior to the surgery. A patient who has the urge to urinate because of a full bladder will continuously squeeze the eye and cause the intraocular pressure to rise. A heavy speculum will do the same. And large volume of intraocular local anesthetic is best avoided. So far we have seen identifying patients, controlling systemic factors, a good intraoperative pressure control can control a lot of things. When you’re planning a surgery like a trabeculectomy, you also think of: Where are you going to do it? Now various surgeons have preferences, and over the years, I have tried multiple things. And my firm belief is that a superior bleb is the one that has the maximum area to spread into. And the kind of diffuseness and the mere size of the bleb that you can achieve with a superior trab doesn’t happen that much with the superonasal or superotemporal trabs. And if you take good care of the conj, it is still possible to do a repeat trab. Either superotemporally or superonasally, depending on which eye you’re talking about. And I have not found… I have very few patients where I have had to do another surgery. But I haven’t had any problems after performing a superior trabeculectomy. Before diving into the surgery, we have to look at how you can prevent the pain happening to the eye. It’s very important that the patient cooperates well and is without pain. Now, while we have a myriad of options, it must be remembered that both a larger volume of the peribulbar block and compression to reduce the chemosis that you happen to have, because of the peribulbar block, reduces supply to the optic nerve. And this itself can cause wipeout. And wipeout may not be just reduction to PO negative status. Significant visual loss can also be a partial wipeout phenomenon. Which you can avoid by taking certain precautions. And reducing the amount of the anesthesia that you give to the eye is a very important part of that. And I typically prefer to do away with the peribulbar block completely. And I typically use a combination of topical and sub-Tenon’s anesthesia with Xylocaine that is preservative-free. I give it even before the draping has started, and I use a 29-gauge needle, go to the posteriormost part possible. Use a 29-gauge needle. Enter an area where there is no blood vessel. Now, that swap is not only keeping the lid away, but it can also be used to diffusely spread the anesthetic agent throughout the area that you’re going to operate. Now, just topical agent is not sufficient, because you’re going to incise the conjunctiva, and you’re also going to perform cautery in that area. So some kind of anesthesia within the ocular structures is required. What happens if we don’t give this anesthesia before the draping? Now, this is a patient where I had given a block after the draping. And you typically end up with a boggy, swollen conjunctiva, which is difficult to handle. Whereas if you do that before the draping, it is not only the amount of time that has passed away, but also the lid closure probably helps in spreading and giving a very good, flat conj, as if there was nothing injected under the conj ever. And that gives much more easier handling to the conjunctiva. So as far as the block is concerned, using minimal volume or a topical block is the way to go ahead. If you have to give a block, a peribulbar block, it is best to use a very low volume, like 3 to 4 milliliter. And inject it inferotemporally. Any peribulbar block that is given superonasally or medially is more likely to cause chemosis and raise intraorbital pressure, which is not good for the blood supply to be optimal. Now, this is very important. Especially when someone is in a learning stage. I’m not talking about exposure to any virus or anything. But only of the area that you’re going to operate on. And while there are multiple ways of doing it, like the corneal transaction suture, with the 6-0 vicryl, or a superior rectus traction suture, I haven’t taken any of these for 99% of my cases for many years. What I use is something I call a rotational grip. So if you see this video, I’m using a Hoskins forceps to hold the posterior Tenon-sclera complex. And just going inside the eye and rotating it forward gives you an excellent exposure. The way to do it is to reach the posteriormost extent that you can. Press a little hard on the sclera. So that you can catch the tissue. And if you look carefully, I’m almost at the insertion of the medial rectus. Superior rectus. So this exposure should be as good as that of a superior rectus traction suture. Without a needle. So to enhance the reach or access of the instrument to the posterior part of the sclera, you can just lift the conj with a crescent or an iris repositor, or any other instrument, so that your toothed or non-toothed forceps has a good access to the posterior sclera. And you can achieve a good anterior rotation without an incision. Now, there are situations where you have to use a traction suture, especially if the globe is very tight, or the patient doesn’t cooperate well, and you have taken the patient for surgery under topical anesthesia. I typically use a 6-0 vicryl for that, and this is a step that you should perform under high magnification. The depth of the suture should be almost 90%. And if you look carefully here, I am zooming in, because I had detached the Descemet’s, and I’m almost at 90% depth of the cornea. I’m going along that end. Possibly you can see some folds appearing on the Descemet’s there. So I have not punctured the Descemet’s, but I’m really at that depth. And this should prevent us from tearing the cornea with our sutures. A finer suture like the 8-0 vicryl is much more likely to tear through the cornea. So a 6-0 vicryl is an ideal suture. But if you are careful and you don’t really pull too hard, an 8-0 vicryl will also do. So the same suture can be used for conjunctival suturing later on. I don’t know why each video is playing twice. But anyway… Now, if you have to operate, you have to reach the area of surgery. And the peritomy, conjunctival peritomy, or conjunctival opening, is the way to go ahead. And I like to do a fornix-based flap so the incision is at the limbus. But even before we talk about the incision and the conjunctival opening, we must know how to handle the conjunctiva. Now, this video will show you how to hold the conjunctiva through the Tenon’s. So you can use a second instrument and fold the conjunctiva over, so that you can hold it from inside out. Especially in such a patient where the conjunctiva is very thin, and take care that you don’t cause too much pull on the conjunctiva. So hold the conjunctiva at every possible opportunity from the Tenon’s side. Tenon’s is a much stronger tissue. And if you are careful, this will help you avoid many conjunctival buttonholes. It is also important to use blunt-toothed forceps. So there are many non-toothed forceps. But what is commonly available and what we use at our center is a Pierce-Hoskins forceps. Where they are blunt and much less likely to tear the conjunctiva than a sharp toothed one. So my recommendation for surgeons, especially if you are at the beginning, is to use a blunt or non-toothed forceps. You need to have some experience to be able to grasp the conjunctiva. So as I told you, the fornix-based incision is at the limbus. But what is important here, why LIMBUS is in capital letters, is because the incision should be really at the limbus. Now, let us see what I mean. So you can see here that I’m using a BS Hoskins forceps in the right hand to make an incision located right at the limbus. Why do I want it right at the limbus? That is the area where the healing will happen maximally. So the limbus is the site of all the stem cells, and that is why the healing at the limbus will happen in the best possible manner. If you look at this video, this has greater details of how to make sure that you have inside the Tenon’s also. The last patient did not have too much of a Tenon’s tissue. So what you need to do here — I’ll just pause this and show you the fold of the conjunctiva. You have to lift the conjunctiva very close to the limbus, in such a manner that you get a fold radiating right from the limbus, and then you start the incision with a Vannas scissors. Conjunctival scissors may make a large tear which may be difficult to close. So you see here you have no notch or relaxing incision at this site. So you constantly see this V-shaped fold and that is enough for you to make an incision without making a relaxing incision. What I’m trying to do now is to make an opening into the Tenon’s so I can get an access to the sub-Tenon’s space. And now I can go on to conjunctival scissors. Create space under the conj for the scissors and make an incision at the limbus. How do you make sure that this incision is at the limbus is by keeping the scissors flat at the limbus. And not let the lower blade rise above the surface. While you are pushing the conjunctiva or the limbal conjunctiva towards the cornea. So that will make sure that you make an incision with no free conjunctiva at the limbus, and that, I believe, enhances the healing of the limbal incision. Just to show how, by putting a pressure or pulling the conjunctiva down, you can ensure that the incision is exactly at the limbus, where I believe it will heal up best, without scattering the conjunctiva posterior to it. Now, contrast this with an incision you would typically use for a manual SICS. I’m not sure how many of you would actually be doing manual SICS. But the traditional incision we were taught for trabeculectomy and SICS was very similar. Here you pull the conj up and create a large fold that is slightly behind the limbus. And you go right to it. So the way you hold the conjunctiva to create this linear fold is also slightly different. I’ll just play this from the beginning, so that you can see it well. You go slightly posterior to the tissue, which is not adherent to the limbus. The anterior limb of the conj is well adherent to the sclera. So that is what you avoid in this kind of incision. But you include that — the initiator incision — right there when you are doing — making an incision without a relaxing component. So you see the conjunctiva is held quite anterior and you’re using very small scissors to make this incision, so there is no component which will require a suture posteriorly. You might be wondering why I’m going on about this incision, and not making a relaxing incision. What I will tell you is: One, if you can’t have the rotational grip or good traction suture, your exposure is not compromised. And you will not need to place a suture that you would otherwise need to place for a relaxing incision. So a relaxing incision means that you need to suture this separately. And whenever you have a suture, there are certain things which come with it. So you typically use an absorbable suture, even if you use a nylon suture for the limbal incision, for a horizontal relaxing incision like this, you typically use a vicryl. A horizontal mattress suture. And that is a problem for me. Why is it a problem? If you look at this bleb, it is a very vascular bleb. No doubt about it. But do you see where there is maximum density of the vessels? It is in this area. And this is the area where you have the vicryl sutures. Any absorbable suture that can absorb fluid and whatever is around the tissue is likely to attract vasculature. And not only that. Being an absorbable suture, there is a possibility that it can give way into the postoperative period, and what we see here is that the horizontal suture has become loose and this part of the incision has become open. Why is this bad? Once you have vasculature, once you have cellular infiltration, it’s a precursor to fibrosis. So having no absorbable suture posterior to your incision line will help you reduce the amount of vascularity that you are seeing in the bleb in the postoperative period. So no relaxing incision is likely to reduce the amount of fibrosis you are going to see in a bleb. Now, this might be a slightly controversial thing. (cell phone ringing) Just give me a moment. Really sorry. I don’t know who is on my mobile. But someone… Now, while it is important to minimize the amount of cautery that you do, it is also important to keep your field of surgery clean. Any amount of bleeding into that area is not something that is going to help you while you are doing the surgery. So we typically use a bipolar cautery. I keep the settings to the minimum possible level where you can achieve a cautery. The key is that after you have performed the cautery, the tissues should remain white and there should be no brown color that you should be able to see. And if you look carefully, I’m cauterizing the vessels. I’m not cauterizing the sclera. And I’m cauterizing only the vessels. And also in the areas where you’re likely to hold it, it is debatable in my opinion whether bleeding will cause more fibrosis or cautery will cause more fibrosis and inflammation in the postoperative period. So I like to keep the area of surgery clean. And if you compare the appearance of this sclera before the cautery began and now, you will not see any brownish coloration of the sclera. And that is what the endpoint of cautery should be. So minimum cautery is likely to prevent vascularity and fibrosis by preventing the amount of bleeding that you have. Now, do not forget… The step that I see postgraduates missing most, when they talk about steps of trabeculectomy is subconjunctival dissection. And I think the importance of this is very underestimated and understated. So what do you mean by subconjunctival dissection? Once you have made the peritomy, you need to go posterior and open up the subconj space, superonasally and superotemporally, on either side of the superior rectus. Don’t go over the superior rectus. It may damage the muscle pulleys. But definitely do go on either side of the superior rectus. You will go and dissect the areas that you want your bleb to form in. You don’t want your bleb to go sideways. So leave that area immediately adjacent, perilimbal, subconj area. But you go and dissect the areas, superonasal and superotemporal. And it’s important to take care that you don’t enlarge the opening while you are doing the subconjunctival dissection. How you can make sure of that: While you go in, you go in with the closed scissors. While you are inside, and the fulcrum of the scissors is near the incision, you open it wide. It will dissect the posterior subconjunctival space while not disturbing the incision. And while you are coming out, close the scissors again. So that will keep your incision from extending. So subconjunctival dissection is likely to determine the area of your bleb. At least in the long term. And is likely to prevent an anterior localization of the bleb. So while every other factor is important, all glaucoma surgeons believe that the scleral flap, the kind of flap, the size of the flap is the most important determinant of the trabeculectomy. And I like to make a scleral flap that is rectangular in shape. I make a 5 to 4 millimeter flap. And I use a crescent to shape the same. And the reason why I use the crescent is because it’s the sharpest instrument in the operation theater. And a sharper instrument is more likely to give us good control over the incision than a blunt instrument. Once the incision is made, you also dissect the flap with the same instrument. Preventing the need for an additional instrument. And you will notice that the scleral — the crescent knife is just visible. So this gives you a half thickness scleral flap, when you can just manage to see the edges of the sclera. And a rectangular flap is much more likely to give you a posteriorly directed flow. Which can also be achieved through a large triangular flap, where the incision does not reach the limbus. So the incision not reaching the limbus and designing the flap and sutures in such a way that the flow is directed posteriorly is very important for preventing an anterior bleb and achieving a diffuse bleb. For the same reasons, mitomycin, though infamous, is our most important instrument in countering fibrosis. And we must ensure that the application of mitomycin is made over a wide area. We use surgical sponges soaked in mitomycin and placed as much to the posterior extent as possible, as suggested by Serpenko. And this is the area where you want the bleb to form and this is the area that you should irrigate with mitomycin or apply mitomycin. It’s important to irrigate also after you have applied for the duration that you want. I typically use a two-minute 0.04% strength. For two minutes. Three minutes for situations where we have a high risk for fibrosis. Now, before I go and make the ostium, I preplace the sutures. Which means that I place the nylon sutures over the scleral flap in advance. So one fixed suture and one loop releasable is ready to be taken right before the incision is made. Why this is important, this is important to reduce the duration of hypotony that you are likely to meet after you have made the incision. So the duration of hypotony is minimized by using preplaced sutures and paracentesis. The paracentesis also helps us in reducing the suddenness of hypotony. So while you are making a long partial entry on the cornea, you try to leak some fluid out, and after placing the sutures, you make the entry. So the paracentesis serves three purposes. One: It allows you to reduce the pressure inside the eye. Second, it gives you an opportunity to form the anterior chamber, thus reducing the duration of hypotony. And it enables you to perform what is called the titration. The crux of trabeculectomy is making a sclerostomy or the ostium, which I do with a Kelly’s Descemet’s sponge, and I incise the entire length of the 4 millimeter flap to perform the AC as required, I use a 1 millimeter scleral punch and take half micron bites. It may be difficult to visualize or catch the ostium in the camera. After making the ostium, in our population, we think it’s essential to perform iridectomy. So we had a surgeon who was in Canada for a long time. Was not doing iridectomies for our patients. But when she came and started not doing iridectomies, she repeatedly found the iris going and blocking the ostium. So probably there is something in the nature of brown eyes, which tend to have thicker, more floppy iris. And that can go and block the ostium. So while the assistant holds the flap, just pull out the iris, immediately below the ostium. And it should be as wide as the ostium. So very often, you may not be able to even see the peripheral surgical iridectomy that you make after making a small ostium. Now, this is something that I learned from Dr. Paul Palmberg. And for me, it was a game changer. So what happens in titration is: Before you close the suture, you just lock the knots. So the knots — there are three throws, and then you lock it like you would do in a corneal suture. The loop releasable is closed, and a central loop releasable is placed again. So what happens here is that you get an idea of what the equilibrium point of this surgery is. So you have to… You don’t want to ensure that there is a flow happening. What you want to see is: At the point of time when this flow stops, which is the physical equilibrium or the point of time when this flow would stop, and then touch the cornea gently with an iris repositor, you should be able to just indent the cornea without making any flows. If you have to apply force to indent the cornea, it means the pressure is slightly high. So the flow has stopped here, and I touch the cornea and you see a mild indentation there. For me, this is a pressure of somewhere between 10 to 14. And by using this technique, if you see a tighter globe, you loosen the sutures. If you see a globe that is not well formed, you tighten the sutures. And then do the test again. So for me, titration and use of releasables is a must to be able to avoid hypotony. And then coming on to a step which I think is very, very important, because you don’t want your bleb to leak… So the technique that they now use is that of a buried 8-0 vicryl. So what you can see here is contrary to what the traditional teaching has been. The first bite is taken from inside out. And the second bite is taken in such a manner that it pulls the — and catches a part of the conjunctiva and pulls it down to the limbus. What happens here is that with one suture, if you don’t have a relaxing incision, you can pull one side of the conjunctiva entirely down. And using a similar suture, you can get a very secure closure by typical wing sutures. The great part of this technique is: Once you put these loose ends under the conj, these will not come out. With the loop releasable and this technique of suturing, you don’t have any suture on the surface. Which typically collects a lot of mucus and invites inflammation in the postoperative period. While it is important to perform this surgery correctly, it is also very important to take care of the patients postoperatively by multiple techniques, I think, that can be an issue, that we can deal with in a separate class completely. But to summarize, it’s very important to identify patients who are at higher risk of suprachoroidal hemorrhages, wipeout, control the systemic factors, and preoperative intraocular pressure. Use topical plus subconjunctival anesthesia while you can, if you have to give peribulbar block, use a low volume anesthesia inferotemporally. Preferably without adrenaline. To prevent the duration and extent of hypotony, use a paracentesis and preplaced sutures. Titrate to prevent postoperative hypotony. By preventing hypotony, you can eliminate the chances of suprachoroidal hemorrhages and wipeout to the extent possible. For getting a posteriorly directed bleb, it is important to have a posterior flow using a large rectangular or triangular flap with the incision not reaching the limbus. And wide area of mitomycin C. Subconjunctival dissection and releasables will help you counter fibrosis in the postoperative period. So I think I went quite overboard. But I wanted to go really slow, and I think for the purpose of the class today, webinar today, I think this is how I wanted it to be. I will be very happy to answer any questions. I think there are questions. Right. The first question is: Why trabeculectomy numbers are reducing year after year? Actually, you see trabeculectomy numbers are reducing only in places where MIGS is paid for by insurance companies. It is not reducing everywhere. MIGS is not for every situation. Most of them will give you an intraocular pressure of 18 to 20 millimeters of mercury, which is much higher than what you get with a trabeculectomy. So if you have an advanced glaucoma, especially that is not open-angle, MIGS are not an option. There you have to do a trabeculectomy. For milder glaucomas, where you will be happy to just reduce the pressure by 3 or 4 millimeters, or eliminate one drug, MIGS are a very good option. Advantages of a V-shaped flap over the traditional rectangular? It depends on where you come from. I saw most of the trabs being performed with a triangular or V-shaped incision initially. We thought that Serpenko has propagated, and I believe that the rectangular flap is more likely to give you a posterior flow. The mechanics is such that if you can recall the diagram, the rectangular flap with the draining part being much more posterior, is much more likely to give you a posterior flow. While I try to answer the other questions… What I will do is I will leave you with that diagram. And answer the next question. Now… Using a single sponge is something that we are not very comfortable with. Because it is very difficult to ensure a posterior and uniform reach with a single sponge. Multiple sponges, especially those that are placed posteriorly, is more likely to give you a posterior spread. Saurav is asking: We go subconj, we don’t use cautery, so what about Tenon’s? Should we not remove Tenon’s? Tenonectomy used to be a standard practice in a previous era when mitomycin was not there. We really need the Tenon’s for a good bleb. In the postoperative period. Cautery — without cautery, I think I would find it very difficult to visualize the sclera well. And I think it’s dangerous. It might not be very safe for the healing of the bleb, and not… Ending up in a thin, cystic bleb. Injectable mitomycin — let us just wait. We need to wait for longer follow-ups. There is a paper from Europe which showed that within a year of injectable mitomycin, 20% of blebs turn thin cystic. So I think over a period of time, we will know whether it is actually safe. A recent paper by Paul Palmberg published in Ophthalmology showed that patients who received injectable mitomycin C versus those treated with mitomycin sponges had equal outcomes. I don’t see much of an advantage, except that you save two or three minutes during the surgery. How large should I consider my triangular flap? I don’t do triangulars. I do 4 to 5 multiple rectangular flap. Technique. I will not go into combined surgeries. I think it’s a completely different thing. How do you titrate this suture? Okay. Now, this is something… I’ll just… Try to rush to the slide where I was showing titration. Now, if you want to understand titration, imagine an eye that is there, say 2, 3, 4, 5 days after trabeculectomy. What will decide how much is the pressure of the eye? The factors that are going to decide the intraocular pressure is the relation between the scleral flap size, the apposition that the flap has been prepared, the tightness of the sutures, and fibrosis. Now, fibrosis is not something that you can control entirely. What you can control very well is the tightness of the sutures. Now, if you see here, this is while I’m titrating. I think this is very important to understand. Slightly more difficult. So if you take… If you just lock the sutures, you square the knot, and leave the knot untied, so three throws, pull, and then just leave it like that… And the loop releasable on the corner being closed, and what you see here is by this technique… You will see very shortly: I fill the eye. You will see a pouting sclera here. So what it means is that there is a good amount of aqueous under the sclera. There is a good aqueous lake that will form and the sclera will not oppose completely. It’s very important that the aqueous reaches the subflap scleral lake. And then only it can go into the bleb. Now, the tightness of the sutures is not going to change ever on its own. You take off the releasables, do a suture lysis. So whatever is the intraocular pressure at this point, if the other factors don’t change, is going to be the intraocular pressure of the eye. So if the flow at one point stops, though you’re not measuring the intraocular pressure, you’re judging the tension, what I’m doing here is just letting the iris repositor fall onto the cornea. And from experience I have learned that if the iris repositor — there without any external force pressing on the cornea — can cause indentation but no force, does not require any force to form that indentation, that is a pressure between 10 to 14. Where you want to land. And this can help you eliminate hypotony from your practice. And it is much easier to prevent and tackle high pressures. Especially if you use multiple releasables. In a standard manner, I do use releasables now. And this came from Dr. Paul Palmberg, from Bascom Palmer, has helped me almost eliminate hypotony from my practice. Yes, slow is good, always. But not while you’re writing your exam. Now, the technique for suturing with 10-0 nylon and 8-0 vicryl is different. If you use wing sutures, which are not buried, and leave the 10-0 nylon, it becomes very uncomfortable for the patient. I was with a consultant as a resident who used to use 10-0 nylon. And I did not like sutures which are exposed. So even vicryl, though it’s a very soft suture, I bury it under conjunctiva. And there’s a huge difference in the amount of comfort that the patient is going to have. So if you use 10-0 nylon, you need to use the Moorfields technique, available over the internet, very clearly. How much mannitol do you give? Depends on the intraocular pressure. Something like 1 milligram per kilogram body weight is what I typically use. And I give one hour prior to surgery. I make sure that the eye is soft, when I am taking the patient into the operating theater. Just make sure that it happens — it typically would take somewhere between half an hour to one hour. Some patients where the intraocular pressure is higher, I also give something like 150 to 200 milliliter, if the eye does not become soft. I don’t want to go into an eye that is hard and cause a sudden decompression. I think that’s a very major risk for wipeout and suprachoroidal hemorrhage. So if we can avoid that, nothing better than that. Mitomycin is not available? Oh. So there are situations where I could not use mitomycin. Such as a patient with very thin sclera. Typically. Or a patient who has very bad uveitis. You don’t want to use mitomycin for the risk of hypotony. I have used amniotic membrane in such cases. So that has helped. I think we can discuss in a later place about how to use amniotic membrane. You can also reach out to me. My details are available on the Cybersight website. Yes, the dissection has to be below the sub-Tenon’s space. So you remember when I was discussing the peritomy of the conjunctival opening — I was pointing out the fact that you must go and incise the Tenon’s. You cannot be between Tenon’s and conjunctiva. That space will close very fast. When do you prefer trabeculectomy over deep sclerectomy? There are multiple surgeons I keep speaking to. I have not… I’ll tell you what. I am not well versed with the technique of deep sclerectomy. Not something that I can comment on. Which instrument under the scleral flap that you use? I use them in the arcade. In children or young adults, the Tenon’s tend to prolapse out. It should not prolapse out. It can be confused with the aqueous lake that you have. And you have to prevent that by taking care that if you don’t manhandle or pull the Tenon’s too much — just make sure that you push it in, before closing the conjunctiva. Even if it has prolapsed out, make sure that you push it in, before you close the conjunctiva. 0.2 milliliter subconj mitomycin before peritomy can be used routinely if the conj or sclera is not too thin. Subconj application during intraoperative — I’m a little conservative. For me, 0.04% of 4mg/ml is very fine. I have not had problems. So I would use mitomycin to the minimal extent possible. First day post-op… I think we’ll leave this question probably for another forum. Antiglaucoma eye drops — do you stop or no? I was just saying that you should get the best possible intraocular pressure before the surgery, so that the extent of hypotony — so a pressure drop from 40 to 10. Imagine how different it would be from 20 to 10. And as far as the washout period of the medications is concerned, most intraocular pressure reducing drugs have a washout period of almost a month. So stopping it for one week will not really help you. But only reduce the chances of complications. Removable of releasable sutures… One I now release at two weeks. Others only if there is a need. How to decide whether to perform bleb revision or repeat trab. Anything early, a needling is the answer. Anything late, you have to look at how the trabeculectomy was behaving in that eye. A trabeculectomy that failed very fast in an eye means that there are risk factors — you can’t find any fault with your technique in that surgery. So document your surgery very carefully. What you did. If you did anything different for that eye that may have within a risk factor. If you observe anything postoperatively that was a risk factor. I think if the first trab has worked quite well for a long time, I would go for a repeat trab. Later bleb revisions in the longer term… I’m not a very big fan of that. I would do a needling in the first two to three months. MMC I use after the scleral flap. I definitely use homatropine in the postoperative period. I have seen in our population — I am from India — the prevalence of angle closure is very high. If you don’t use homatropine, I see a lot of pigment dispersion. The amount of flare you will note without strong cycloplegia will be very significant. Not atropine. I think that is not required. The allergy we have in our country is very common. So I use homatropine in the first postoperative period. Kelly punch, without Kelly punch. If you want to make a scleral incision that is not reaching the limbus, you have use Kelly punch. For the situations when you don’t have a Kelly punch, I use an MVR to create that window. So I wish I could… I had the time to share that with you. But basically… Basically make sure the anterior chamber is well formed. Hold the edge of the scleral incision. Either retract the flap with the suture or ask your assistant to do that with an instrument. And then gradually mark the opening or the ostium going from inside out. If you go from upward down, you are likely to cause a sudden shallowing. But if you are going from the sclera towards the cornea, down to up, inside to out, you are likely to create a partial thickness ostium that gradually becomes full thickness. Intraocular Xylocaine before iridectomy? No, I don’t use. With the subconj anesthesia I use, I have never had a patient complaining of pain with the iridectomy. Shape — I think I have already answered the shape of the flap. Control the IOP after surgery. You have to look at the cause. Why the intraocular pressure is raised. The intraocular pressure can be raised because of problems at three levels. Either the ostium is blocked. So you have to tackle with that. Or the scleral flap no longer has the subscleral aqueous lake. Because of tight sutures. Then you go to do suture lysis, or releasing the releasable. If it is late, and that has not worked, probably a needling to raise the scleral flap. If it is fibrosis, increasing steroids, doing needling, using injections can be the general guideline. Let me be very clear: If the subconjunctival space shows fibrosis, the height of the bleb is decreasing, and you see a lot of vascularity, increase the steroids, use bleb massage to keep the bleb formed. A bleb that you can keep formed for six weeks is likely to stay that way for a very, very long time. So repeated massage, frequent follow-up. If you see the patient at one week and see the patient at six weeks, then the opportunity is gone. In such patients, you have to do a more frequent follow-up and tackle depending on the cause. Shallow anterior chamber during surgery. Correct. So I make a paracentesis exactly for that reason. A shallow anterior chamber is not a problem in itself. But it can be a precursor to aqueous misdirection or malignant glaucoma. Precursor to suprachoroidal hemorrhage, choroidal detachment. So that is why I don’t like this situation and I make a paracentesis and reform the AC. If you don’t make a paracentesis, you can use the ostium and the flap itself to reform the anterior chamber. I don’t like a shallow anterior chamber, either intraoperatively or postoperatively. Yes, we do have an international fellowship program. You can approach our website for that. Okay. While washing the mitomycin with the conj… Okay. This is a great one. And that used to be a problem. So this will not happen if you don’t use the cannula. If you don’t use the cannula, and go under the flap, and you use the hub of the syringe only, this will not happen. The hydration of the Tenon’s. And make sure that you use a forceful 30 milliliter irrigation that is going right up to the posteriormost part of the area that you have dissected. Where do you exactly get the rotational grip? It is in the posterior sub-Tenon’s space where you would see some thick Tenon’s and sclera that is still adherent to each other. Near the superior rectus. And you can go and grab that and do away with need for any traction suture. Trim thick Tenon’s — I am not very comfortable. When I was in Africa for a very short time, I was very surprised to see the amount of Tenon’s that I saw there. And when we have many patients visiting from Africa, the Tenon’s… Thickness, I think it varies from race to race. I was a little worried about leaving Tenon’s in such patients. And young patients initially. But I don’t think it affected the outcome over the long term at all. So I just leave as much tissue as nature wanted there to be. Do the minimum that you need to do. No tenonectomy for me. Midriaticum eye drop? Midriaticum is what drug? If it’s something that causes mydriasis, I do put a drop of homatropine at the end of the surgery. Initiation of scleral flap — if you say we entered too deep and see uveal tissue, how do we proceed? Excellent question. What we will need to do in that case is one thing: Judge the expertise of the surgeon. If you have done scleral tear suturing earlier, what I would do in this situation is: One, not use mitomycin. Mitomycin, going into the suprachoroidal space, is very dangerous. I would just create a flap above the present flap, and suture the initial… So you will have three layers. The scleral bed, the flap that you have, the bottom of which you started initially, and then a flap that you had created. So the bottom flap should be sutured to the bed. And you can proceed with the surgery. If you have the patience and the skill to do that. What is ologen implant? For the previous question, if you have any doubt, just close it. It’s not worth the risk. Because suprachoroidal space is not a space that an anterior segment surgeon should be routinely dealing with. Ologen — I think multiple textbooks can answer that question. Early failed trab, what is the frequency and duration of… So once again, we have to look at the cause of failure of trabeculectomy. So steroid response can be a cause, but you have to exclude all other causes before calling it a steroid response. So if there is inflammation, subconjunctival fibrosis, more steroids are required, if you see raised intraocular pressure in both eyes, other eye being on same medications, then it can be a steroid response. You need to change it to a low potency steroid. Then reduce the frequency also. Use of Visco with trab. I know many surgeons like to do that. But when viscoelastic remains in the eye, after a cataract surgery, we call it low fibrotic or inflammatory. I am not someone who is in favor of using viscoelastics with trab. Just titrate your flaps well. And you will not need… How long is that visco going to remain in the eye? What happens when it is absorbed? You’re going to get hypotony. If the flap is good and you have taken care of titrating it well, you won’t need to leave viscoelastic in the eye. Follow-up protocol… I think we can have a class on that. We can have a full session webinar on that. How do you perform trabeculectomy… In a very deep set eye? Difficult situations are difficult for everyone. And I think it’s just a matter of time before you get used to it. That is a situation where I would like to take retraction sutures, so I have a good exposure. I can turn the eye downwards. And have good exposure. Premature entry… I think I’ll just leave that. That’s a very good question. But if you can find my email ID on the Cybersight website, you can discuss there. No, I don’t remove Tenon’s, even when it is thick. Do you perform combined SICS and trab at the same settings or after some time? If there is preexisting cataract, I would like to take out the cataract at the same time. I do trabeculectomy only in situations where the patient is pseudophakic already or does not have a significant cataract. If there is a cataract, just go ahead and do a combined surgery. Phaco-trab is something I prefer. But very frequently, we need to do an SICS trab also, when the cataract is very hard or a mature cataract. So then I think SICS in my hands — I am friendlier to the endothelium. Post-op hypotony does not require resuturing. The requirement for resuturing is bleb leak. Or are you talking about the scleral flap? If you titrate, you don’t need this. Titrate your flaps. Why would you want air or visco in the eye? They are both going to get out of the eye after a while. Titrate your flaps. You don’t need anything, either air or visco, that is not going to remain in the eye for a longer time. How do you prepare a patient with an acute attack of glaucoma? Basically you’re talking about acute angle closure. Now, acute angle closure — there is a huge body of evidence that is gathering that if there is no disc change that you see, it means that it is not an acute and chronic glaucoma. It’s a de novo acute angle closure. You probably will do better if you do a cataract surgery or a clear lens extraction. Jury is — not everybody agrees with it. But that is what I do if medical control is not possible. Doing it earlier gives better results. So probably within a month, it should be enough time for you to understand whether the medical therapy is going to work or not. AC shallowing when doing sclerostomy with Kelly punch. That is the only time, when you are entering the eye and doing the ostium, the intraocular pressure in the eye is going to be close to zero, if not zero. So it’s very important to reduce the duration of that zero intraocular pressure by doing a paracentesis, by using preplaced sutures. So AC will shallow during — no matter how you make the ostium, how you do the incision. You are going to see a very shallow AC where intraocular pressure goes to zero. Pterygium — I don’t do pterygium surgeries. But when I was doing… I was doing an extensive removal. Accidentally torn? It will depend on — flap is accidentally torn. It will depend on where it is torn. If you can’t suture it, you need to put a lamina scleral thickness patch graft over it. If the scleral flap is torn, it will cause very bad hypotony if it is leaking. So it will also depend on whether the tear is anterior or posterior. But any major tear will need a scleral flap or scleral patch graft, laminar thickness, over the flap that you have made originally. Congenital glaucoma should be operated as soon as possible. You should not wait for any duration. In a patient who has congenital glaucoma. It’s a surgical disease. Only in a very few cases you can succeed medically. This is what we see here. I know for sure that there are areas in the world where you see milder cases of congenital glaucoma. But do not wait if medical therapy has not worked. It causes irreversible damage, in terms of enlarging the globe, increasing the axial length, and the more corneal area you have, the more extensive it is likely to become. Especially if it is unilateral. Don’t wait. It’s a surgical disease. Again, my pleasure, if I could be of any help. I’m sorry. I’ve taken a lot more time than I wanted to. I was allowed. But I had kept time for questions. Okay. In SICS plus trab? Will have to be single site. If you want to make a 5 to 6 millimeter incision, I will make a linear, around 5.5 to 6 millimeter incision. And then perform trab with a slightly different technique. I prefer to do a twin site phaco-trab whenever possible. With temporal incision for the phaco. Twin site. How high IOP is safe to do a trab? What if the IOP is still 50? We are doing a trab because the IOP is not coming down with whatever medications are available. So you try to reduce it maximally by giving topical and oral medications on a chronic basis. If it doesn’t come down, giving glycerol and mannitol once or twice, two or three days before the surgery, sometimes helps. If nothing is possible, you just have to bite the bullet. Pray to your god, the patient’s god, and hope nothing goes wrong. But that is a situation that is very precarious. Very often you get away. But that seems to be a situation where you can have complications, like choroidal detachment, suprachoroidal, aqueous misdirection, especially with angle closure. Thank you, Priscilla. My pleasure. Thank you so much for joining. Thank you so much for joining. What do you do first in combined surgery? Okay. I think we will make this the last question. So for a combined surgery, when I do a phaco trab, I make the flap and then shift to the temporal area. So it will proceed exactly the way I have showed you. I have made the flap. Perform and complete the temporal phaco. Come back and complete the remaining part of the trab, exactly like I showed you. So the technique of trab in a twin site trab does not change at all. It has been my pleasure. I just so much wish that I was… We were all together in some place. And hopefully that will be true soon. Thank you so much.

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June 1, 2021

Last Updated: October 31, 2022

3 thoughts on “Lecture: Trabeculectomy: The Technique and The Thought”

  1. Outstanding lecture! Greetings and heartfelt thanks from across seven seas! Could you please do a webinar exclusively on post op hypotony?


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