Lecture: Hypotony: How Low Is Too Low?

DR. PANARELLI: Hi, good morning, my name is Joe Panarelli, and I will be lecturing today on hypotony. It’s a pleasure to be here and a pleasure to be speaking to all the attendees. Thank you for sending in questions and showing interest in this topic. As a glaucoma specialist, this is near and dear to me. Try to get through all the questions and the slides in the next 40 to 45 minutes and then take time for Q&A. Let me pull up some slides and we’ll get rolling. All right. Hold on one second. Let me share my screen here. All right. So, let’s get rolling. So, my name is Joe Panarelli, again, I am a glaucoma specialist in New York City. I did my residency at New York Eye & Ear, and then back to New York Eye & Ear and NYU, and started the final phase in private practice, and I have been enjoying it thus far. Over the last 15 or so years, I have encountered a lot of cases of hypotony, and share tips and tricks to help you better manage this when you encounter it. Financial disclosures, I don’t think any are really relevant, though I consult for devices that consult for hypotony. The joys of hypotony, whatever I learned? That’s what I typically title this talk. I’ve learned a lot, I have great mentors over the years who have helped me understand how to treat this challenging problem. In glaucoma, no pain, no game. For the patients, final IOP to prevent from losing vision, we have tos wrestle and dance with hypotony to get that final optimal IOP in the low teens range or sometimes even a single digit. Start off with a quick poll question for those on here. This is one I commonly get, from trainees, from lectures, how do you define hypotony? We see this a lot in even clinical trials. What is too he for an IOP? An IOP less than 8, 6, 4, 2. Just curious. Just curious what the audience thinks, because really there is no right answer for this. We’ll see what the numbers here end up being. But, you know, it’s interesting, when I started as a trainee, I had this higher threshold, and as a specialist for longer and longer, as I shot for lower and lower IOPs, a lot of times a lot of these eyes are okay at lower IOPs. Interesting. I would say I agree that an less than 2 is probably too low. 4 is interesting. I always joke around with my trainees. A pressure of 4, you have a real 4 and kind of a soft 4. There are times when we really are having trouble check the pressure and I think we want to put a number in the chart and so a lot of times I’ll see the pressure is 4. And then go and check, that’s really un-recordable. But there are time which is you check and get sort of a real 4. So, for me, you know, that kind of number is interesting. And that’s really a big cut off for me is when you get to sort of is that number. A pressure that’s sort of a solid 4, often though eyes are gonna be okay. For me often a pressure sort of barely recordable or under 4 is write start to get a little bit worried. Pressures of 6 and 8 are typically okay. They’re typically fairly physiologic. The upper scleral venous sort of floor. But I will say, I have some patients whose eyes are prone to hypotony-related complications once you drop them below 10 millimeters of mercury. Each eye is different, this is general parameters. But clearly eyes are congenital vascular anomalies, those eyes do poorly when you drop below 16 or 18 millimeters of mercury. You have to keep in mind the size of the eye and a few other parameters we’ll talk about. I put this slide together the first time I was giving this talk because these with the wes I had as a trainee, go up to the attendings, and give me the answers to this? It’s hard. It’s really hard. One of the questions I get asked my own trainees, does hypotony only happen with traditional surgeries, tube shunt surgery and glaucoma trabeculectomy. There have been an explosion of surgeries. They’re touted as being safe. We joke around, they’re very safe, but they’re at times minimally effective, even though they’re microinvasive. And the truth is you can get some real deal complications with microinvasive procedures, especially those in the angle, and I’ll talk about what can happen. And then going back to the slide about the question before the number. The number matters, the number doesn’t matter, the number matters sometimes. In clinical trials set a threshold of 6, a procedure is a failure for a pressure under 6 millimeters of mercury. And in truth, I have some of my best outcomes with 6 who have — and then have 6 to 10 with issues. It really doesn’t come down to a single value. It’s how the eye is doing at that pressure. And there’s always the question of sometimes do we miss it? You know, I think a lot of times we’ll get a very low number and we get overly, you know, overly jumpy. Sometimes we’ll get a sort of okay number, but we don’t actually think that the patient’s visual decline can be due to that pressure of 6, 7, or 8 millimeters of mercury when it can. And we can look at the macula, why it’s dropped in the post-op periods. Sometimes we miss it. I will talk about this later. But often when you get OCTs of the macula to look for hypotony, we get horizontal cuts through the macula. And you think about the pathology, coronal folds in the back of the eye when the pressure is too low. Sometimes they’re slicing right in the same plane as those folds. Unless you orient and get vertical cuts through the macula, sometimes you can miss cases of hypotony maculopathy. Then there’s the question of fixing it, when do we fix it? If I leave the hypotony for too long, don’t iron out the creases in the macula, will they be left with permanent distortion? I don’t know. It does vary in each case. I think that a lot of times you have time. This doesn’t need to be fixed yesterday. And often, you know, for a lot of patients, it starts with the pre-op discussion. Have a good pre-op discussion with the patient about the risks and benefits of the surgery. For those with glaucoma, they have to understand that some of the procedures in the fight to get them that very low IOP, there is a chance there can be changes in the vision. I tell patients a lot of times if we’re undergoing trabeculectomy surgery or a non-valved implant some hypotony-related complications or some vision changes are not uncommon. I think that question of the rush to fix it, it is easier handled if you’ve had that discussion with the patient earlier, as they’re going through the post-op period and maybe the vision isn’t what it needs to be, they aren’t pushing you to get this fixed. What happens is sometimes we create more harm than good trying to fix it. Sometimes we get close to the ideal spot or pressure, and in trying to correct the maculopathy, we fail the procedure. This is common with trabeculectomy, we overshoot going in the opposite direction. It can happen with tube shunt surgery as well. These are questions and foundational principles talking about hypotony. We have to understand that each eye is different, we have to understand that we don’t have to rush to fix it, and understand how to fix it. And I’ll spend time talking about how to fix some of the hypotony-related issues, but it all starts with good decision making. If you don’t make a good decision, you won’t get the outcome you want to have. And hypotony with MIGS, microinvasive glaucoma surgery, it’s a game changer in our field, but not without some risk. You can get it due to one of two types of surgery. Post-angle surgery, and following suprachoroidal drainage surge, AKA, I want to make a cleft. It’s not my favorite surgery, we are at least in the use not doing a lot of suprachoroidal drainage surgeries, there are a lot in the pipeline. I will focus on post angle surgery. In the last 5 to 8 years, I have had 10 cases with hypotony after any form of angle surgery. And so, we’ll start off with, again, when does this happen? It’s more common with cutting procedures in the angle, don’t see it with stenting procedures. It’s more common with stripping procedures, the Kahook dual blade, trabectome and other surgeries that are a spin on the same sort of thing. And the key is understanding the pressure, the pressure that’s a low single-digit value is often not you doing an amazing job. Don’t drop below the episcleral venous pressure or the pressure when doing a surgery. Even with coupling with cataract surgery or viscodilation, when you get those lower single digit pressures, there are likely some sort of secondary outflow pathway in those cases. Let’s look at a case. This is a patient who was sent to me, that cataract extraction, multifocal IOLs with Kahook dual blade with hypertension. Patient was on two or three classes of medicine, a reasonable call, and wanted ideal visual outcome and wanted to be off drops. Those are hard promises to keep. The approach was reasonable. The challenge was that the IOP was low and too good. It was interesting because whether you compared it — the patient pickled up on this — compared it to the other eye, it was considerably different. The first eye was running pressures in the low to mid teens on no topical therapy, while the left eye had a sort of low-ish single digit pressure for a while and there was a presumed inflammatory process, and so the patient was given an injection to raise the pressure and quiet some of the inflammation. And then sent for a second opinion. And clinically on examination, these are not always the easiest to pick up, but psych there was a cleft, whether you did a UBM, you can see the longitudinal muscle from the scleral spur, and you can almost make the diagnosis from the OCT of the optic nerve, disc edema is classic for a cyclodialysis cleft. And through the macula, especially the vertical cuts, you can see the undulations in the choroid. What do you do in the situations? Surgical repair? Time? Can you atropinize the patient? Steroids and hope the inflammatory process takes cake of itself? For myself, these need to be lasers a lot of times. I use a lot of energy, 800 to 1,000 milliwatts and apply anywhere from 6,000 to 1,000 spots into the cleft, paint the sclera, the iris root and even the iris itself with a good amount of laze we are varying spot sizes. The key is to create inflammation, get PAS in the area and close the cleft off. I will block these parents in clinic to do this, because it’s not the most comfortable procedure. They’re tolerating this procedure well, it often an means you’re not using enough energy and not getting enough burns to get them there. I was able to successfully close the cleft, I was proud of myself. And the problem was persistent IOP elevation. When you have closed the cleft, it’s — when the cleft is closed, go from the low single digit pressure to something very high. We think it’s because of this, you know, the TM is kind of in this shut down state, this disuse state. When the cleft is closed, the fluid is not actually making its way through the TM, and the pressure will go up to as high as 50 to 60, and patients very symptomatic. And often, tap the patient, start them on suppressants, and often times the pressure fixes itself. In this case, it stayed persistently elevated, probably due to the STK injection. We cut away, and gave a 50/50 shot of working, and the IOP improved quite quickly after the steroid was removed. Fortunately after all was said and done, nice pressures, focal PSA, but still had distortion long-term. This was a photographer, and wasn’t super-thrilled with it. You have to be careful. The challenge with these cases, these are not very sick eyes. These are not eyes that have visual field loss. These patients, the bar is a little bit higher. Having a complication like this may be acceptable if you’re doing surgery on somebody who has a visual field with, you know, a VFI of 40 or less percent where you’re trying to get very low pressures, but for a patient like this who has relatively healthy discs and ocular hypertension, an outcome left with permanent distortion is far from ideal. Let’s move on and talk about hypotony with tubes and trabs. And I’m 15 minutes in, the first third talking about this, the second third with this. And hopefully leave you with pearls and nuggets. This is one of the biggest pearls and this is one I always talk to my trainees about: Whenever you are pre-oping a patient for surgery, and they’ve had surgery in the contralateral eye and they will you there were some hiccups with the surgery, do a thoughtful clinical examination and make sure you review the prior records, even if they’re hard to get. If you can’t get the records, do a careful examination. This patient, the left eye, had troubles with choroidal effusions. But if you look at the right eye, that fundus photo, you can see old sort of watermarks there, you can see where the patient –, and the patient had a tube in the right eye, complicated by effusions in the early post-op period that did resolve with conservative management. But when you see that, you almost know with certainty, you’re gonna have a similar problem in the other eye if you undergo the same operative procedure, and sometimes, you know, you need to undergo the same procedure because you need to get this patient a low final IOP. Look although amount of disc damage this patient has, this patient needs some sort of traditional glaucoma surgery. Battling hypotony is very common in these situations. And often I say, there’s a question I’m going to address later, you know, what eyes are prone to hypotony. I’ll show you a clinical study that we did that looked at preoperative risk factors and demographics. The eyes that are sicker, with more advanced disease to me, typically have greater risk of developing hypotony. I think it’s something about the bad protoplasm, something about these eyes that are sicker and that’s what makes them a little bit more prone, and probably the fact that we’re targeting lower final pressures. So, very important to review prior history and do a good, thoughtful clinical examination to at least make yourself aware of the post-op period. And for those that do a lot of different types of surgery, I’m curious to see what people see more hypotony with, more with your trabs? Microshunt? Preserflo or Xen, valve shunt, theoretically shouldn’t get more hypotony. And more hypotony, nonvalved, Baerveldt or the Molteno, I’m looking forward to having that implant in the US at some point in time. It is your approach, trabeculectomy, shooting for lower targets, you’re more likely to encounter hypotony. However, I make a tight flap and use sequential laser suture, quite slowly, I have a more controlled drop in the pressure. I think microshunt theoretically, not see as much hypotony with because of the controlled, regulated flow, not perfect. Valve surgery, Ahmed, when you have a precipitous drop in the pressure. President Ahmed, you have a high pressure to low teens, single digit, you can get early hypotony. But more commonly with the nonvalved tube when the ligature releases, and interesting, more common with trabeculectomy. Wonderful to see a lot of people around the world doing trabeculectomy. I feel like we’re seeing less and less of that being done in the United States. I think if you polled some of, you know, my colleagues just in the New York area, I feel like we see it with D, but it is definitely very common with A. I think it’s just a matter of how much you’re doing trabeculectomy at this point in time. Probably we all should be doing more of it. And talking about this because I want to get these two questions out of the way. This will help me give a better lecture. The best treatment for choroidal effusions or hypotony is — anterior chamber reformation with viscoelastic, observation, steroids, cycloplegia, drainage or effusions. Probably shouldn’t put best, the best for persistent choroidal effusions or hypotony –being selective and recognizing what you need to do. I did a lot of viscoelastic injections, trying to get the eye to turn the corner for eyes are low IOPs. But for I fusions and a normal-ish IOP, the answer is observation. For others, steroids and cycloplegia. For others, you need to go and drain the effusion. Just curious what people tend to do more of with it. It’s interesting, it’s a nice breakdown, what I was kind of hoping to see there. And, you know, and again, steroids and cycloplegia versus observation, you know, it just depends. More as increasing your steroids and being more aggressive with cycloplegia versus purely doing nothing. It’s not the most perfectly-worded question, but set the stage for talking about how we deal with hypotony. Let’s tab hypotony or effusions with tube shunt surgery first, and then move on to trabeculectomy. I spend a little bit more time on the tubes because it’s a little bit more nuanced and there are different paths you can go with tube shunt surgery and how to correct the hypotony. With trabeculectomy, there’s only one or two courses of action you can take. This doesn’t just apply to tubes, it does apply to trabs as well. Is the pressure low? Or normal? And sometimes you cannot trust the tonometer, you have to trust digital Pam palpation. I come out of the room, and the fellow will say, the pressure is 4. I go in, that’s not 4, that feels rather firm. And at times an over-read, the pressure is 18, and it really is because the chamber is shallow and the lens is getting close to the cornea and there really is no chamber. It is often hard to know exactly what the pressure is, but you do need to actually get comfortable with digitally palpating the globe, and having the eye, is this soft? Squishy eye? Or feels normal or slightly firm considering I don’t have much of a chamber. In those cases, it’s more of a pushing mechanism for why you have a shallow chamber. Where are the effusions and how big are they? Large bullous effusions obscuring the posterior pole. Anterior effusions, which are sometimes hard to see on clinical examination. You have to do a thoughtful exam with a 90 diopter lens, and look into gaze, and get an obtuse image, these can pick up very anterior effusions that often rotate the anterior chamber forward. They have a chamber that’s clearly not as deep as you expected it to be, despite the fact that you don’t see gigantic effusions, they are anterior and how many quadrants, are they kissing? Opposing? Do I need to drain them if they are touching. Really by definition most effusions are appositional areas, and touching. And they’re not gonna stick, don’t worry about it, you have time. That’s often a question from trainees, how fast do I need to drain the effusions, don’t let months go by, but weeks to a month or two is gonna be okay. The question is why am I battling these effusions? Talk about how to battle, what we’re battling and why I’m battling. This is a paper I did with a med student, Stephanie Ying, a med student now. And trying to identify risk factors for who had effusions following tube shunt surgery. What worked. And these patients often did fine, 91 of 110 patients with intra-camera elastic. And the patients who had effusions following GDI surgery, the risk factors for those who needed surgical intervention, a prior GDI. If you have a GDI, and you have a sick eye, shooting for low IOPs. SLD, or implantation of a BGI-350. Most patients in the surgical group, or more patients in the surgical group actually lost vision. What was interesting, had a lower medians are IOP at the follow-up. For a lot of patient who is battle hypotony, if you can get through it, they often end up with a fairly ideal pressure. Hopefully the ones that have hypotony or have effusions, the hope is that they get through it without you needing surgical intervention and they sort of end up in this nice low teens, single digit IOP range. So, hypotony with tubes. So, we’re gonna try to break it down into — so I would say it really is three types of patients. And so, group one — for patients who have a low IOP, but no effusions, with both valve and nonvalved implants, you often do nothing. So, you can just monitor and observe these patients. Pure observation. Don’t have to get crazy with more aggressive cycloplegia, up and the steroids. You can do nothing. This happens in the first few days with an Ahmed implant, and for non-valve, typically around weeks 5 to 6 where the ligature releases and you have an immediate rush of fluid from the anterior chamber into the reservoir. That’s group one. You know, for group one patients, if they are monocular and are concerned that their vision is down, or if the peripheral effusions start to develop and are enlarging, you can fill the anterior chamber with a viscoelastic of the slit lamp and hope to achieve three things. You want to stop or slow the flow through the actual tube. You want to add volume and you want to transiently raise the IOP to try to break that cycle with this low pressure. Often I will start with a cohesive viscoelastic such as Healon, and fill the chamber until it moves slight — and I have a helper and I concentrate on getting the needle into the eye. Often these are soft eyes so it’s hard to make that entry into the anterior chamber. I like to concentrate. I have a fellow or a technician push the viscoelastic and I’m watching the needle the entire time. Sometimes I have shallowing of the chamber. These are hard to do in eyes that are phakic, that are soft. These are in patients with low IOPs, or no effusions, or start to develop new effusions over time. Then there are the patients who have bullous serous effusions and their IOP is not low, but it’s started to normalize. But the effusions are rather large and starting to obscure the posterior pole. For these, I’m starting to lose the posterior pole, and they’re noticing shadows and their vision is concerning. I will often drain these effusions and fill the anterior chamber with a cohesive viscoelastic, but not touch the tube, not re-tie it off, give it more time, stent it, do anything different. Purely drain the effusions to try to turn the eye around, leave the eye with a full viscoelastic fill and a lot of times this will get the eye moving in the right direction. The key is to do a B-scan ultrasound of the implant and the amount of fluid or the surrounding capsule. Whether you do the ultrasound, what you will often see is fluid collecting above and below the reservoir. You should see echolucency, then echodensity, the implant, and another area of echolucency. And what that means is you have a capsule that’s formed. These patients should be okay. That capsule may be highly-permeable and why the pressure was a little bit low. But often the pressure normalizes, and the patients do well with drainage of effusions. Then you have patients with bullous serous effusions and the eye has really collapsed. It’s a soft eye. When you do the ultrasound, the globe has deformed. And it’s interesting, these eyes don’t always develop bad effusions, sometimes it’s involution, they start to collapse on themselves. These are the eyes, come out, I got a pressure of 4, but you really didn’t get a pressure of 4 with the eye care, and it was a squishy 47. If the IOP is very, very low, there’s likely little or no encapsulation, and the plan here is to swap the implant out for a valved implant, or you can cork the tube with a 3-0 braided sue cure, typically a supramid in the two. Show you some videos. These are patients that have the bullous effusions, but a near-normal IOP and a capsule that you can see on ultrasound. In these situations, I like to do the drainage myself. I will often make an inferior temp coral cut down, make a mark 5 millimeters posterior to the limbus and often have a 3 milliliter long scratch. And what I’ll do is sort of milk the wound with 2.12s, and can’t get enough out, as you saw, take a cyclodialysis spatula, and lift up the edge. Plus and minus, sometimes a Kelly punch to remove a small piece of sclera, some people are worried about exposed uvea. And you have to have a maintainer, watch the position of the lens. Often once you make that opening into the suprachoroidal space, there will be a decompression of the eye and you have to be ready to fill the eye. Now if the pressure is very, very low and the eye is kind of collapsed, that’s here. The key is the kyphosis. That’s not inflammatory, that is actually fluid that is going through the tube, permeating out through whatever very permeable capsule there is and collecting 360 degrees. That’s the straw, yellow-colored fluid that should actually be in the capsule million it should not be surrounding the entire globe. So, I’m gonna go back here for one second, I just to want show this for a minute here. If we go back and look, it’s interesting, look at — back here. Cutting, go back here. That comes out way too easily. There is almost no encapsulation, and this patient was almost 2 months out. In these situations, re-ligate the tube and try to wait 6 weeks, but in my opinion, you’re not going to get encapsulation. Something about this patient’s wound healing is lets than ideal. In this case, put an Ahmed in. And you can put a braided one in and cork it, I will show that for a different patient. And what about hypotony. Some patients develop hypotony late, in older patients with non-valved implants, and exfoliated glaucoma. They have a single digit pressure, aging into the 80s or 90s, start to see the pressure go from 10, 7, 4, 2. Sometimes they’ll have some corneal endothelial compromise. For these patients, one of two things, I will either plug the lumen of the Baerveldt with the 3-0 supramid, or a clip n ‘snip, close the Baerveldt with a 7-0 proline, clip the wings off, and reopen the implant 6 to 8 weeks later. Again, this is the supramid, this is the 3-0 braided nylon. Plug the tube with it. This is a situation, I was closing it off with proline far period of time. This issue patient had effusions and I was going to laser it open. The key is to maybe put the right amount going through there, slow the flow, but don’t totally restrict the flow. It’s easier said than done. Keith Barton is a pro, and I pick his brain, as well as Angela Tana. And if you have a Baerveldt, close it and remove the wings of the implant, and take the 250 or 350 mull meter end plate and cut it down to 100 millimeter. You have to be careful because you have the fibrous stalks that grow into the little holes here. You can do that on each side and release that proline ligature 2, 3, 6 months down the road. It ups and tricks, not common cases with hypotony. So, we talked about different cases of hypotony. We talked about low IOP with no effusions, low IOP with effusions that are starting to obscure the posterior pole. Talked about when the pressure normalizes, but obscuring the posterior pole, need to drain them, talk about the collapsed eye. Most have lowish or low normal occupy ownership. This is a different beast, annual choroidal effusions. I think when this is hiding with this is a great mimicker of malignant glaucoma. You have a shallow anterior chamber, but a rather normal IOP. And these effusions are hard to see on clinical application, UBM, imaging, or a thoughtful examine, patients looking into extremes of and use a 90 diopter lens. You can almost diagnosis it across the room. Come in, very teary, lid edema, it’s really a massive choroidal expansion. Over time some develop larger effusions. But to me, it does not respond well to reforming the anterior chamber with viscoelastic, it doesn’t do well with drainage of the effusions, they often come right back. These cases, you have to hit them hard with cycloplegia and steroids. And start hard, 40 of prednisone, a few weeks, and aggressive from switching, and I will put them on atropine at least twice a day. These are patients where you sometimes have to sit with a very uncomfortable shallow anterior chamber. It’s interesting because at some point in time, they will often just break. These effusions will — the silver body will rotate posteriorly, the chamber will deepen and you don’t have to do much. I have played tug of war and tried to deepen the anterior chamber, only to have it come back shallower the next day. I will put a piece of viscoelastic, reform the chamber. But often the pressure goes from 8 to 12 to 48, and the next day, come in, and they’re more shallow. And I think I’m upsetting the ciliary body even more this these are interesting effusions you have to be careful with. Finally, hypotony with the trabeculectomy, it seems like that was one of the more common things that the audience member requests have seen. And so, hypotony with trabs typically happens after your final laser suture lysis. So for me, I do a trapezoidal flap, 4 sutures in the flap every time. I do a fornix spaced, and like to have no flow for a week so the edge can heal. And release the sutures, one at a time, or two in one sitting. I don’t often have problems until the first month, I’m sitting with the pressure that’s not quite where I want it to be, and I know I need to cut that last stitch, but I’m worried about what’s gonna happen. The key with trabeculectomy, I think, is good massage of the eye before you cut that last stitch. If you gently apply some pressure to the eye, and that web becomes massive and the pressure drops to 2, you probably should not be cutting that last ditch just yet. Maybe bring the patient back in a few days or a week before I cut that. On the flipside, massage and the pressure is down to 6 to 8, probably a good time to do it. But I personally have made the mistake of not massaging beforehand, and just cutting that last stitch, I was four weeks out, and saw the pressure down to 2, which is in the case. One thing to be careful with, when I have low IOPs with trabeculectomy, I don’t often love filling the anterior chamber. I find as you put more volume into the anterior chamber, sometimes you open up the flap even more. I have found they often have made the hypotony worse. I don’t love fulling, observe. Versus tube shunts, more likely to insert viscoelastic to turn the ship around, I don’t often do that with trabeculectomy. So, you cut that last stitch, pressure goes down to zero, that eye starts to look like it’s gonna collapse. There are not too many things you can do in this situation. To try to stabilize in the office, a lot of times you need to replace the eye with fluid. BSS first followed by viscoelastic to try to get that eye to turn it around. Often the viscoelastic, there’s just not enough volume and a lot of times it will go through the flap and collect in that sub conjunctival space. If that’s not working, a lot of times you have to go back and re-suture the flap. This is a big call. This is different from tube shunt surgery, I’m not worried as much about jeopardizing the long-term success of my surgical procedure. Whether I do a tube shunt and I have to re-ligate or drain effusions, you know, I’m not as worried about that procedure failing. When I have to go back and reopen up the conj in an eye that’s inflamed, re- suture the flap and resort suture lysis, I’m worried it’s not going to work as well as it was able to. That’s a concern and sometimes why I sit on things more. This is a patient, you know, I went back and you can see — one of the eyes with hypotony is when you see that — whether you see a 360 bleb, that’s never a good thing. This is a tough eye. I had to go back, traction stitch in, trying to fill this eye, I just can’t get the eye well-pressurized. I really had to put all four sutures back in the flap before I could actually re-form this globe. And it’s interesting, you see the eye already starts to look happier by the end. The key is you have to be comfortable in these situations in suturing in a very soft eye, which is sometimes easier said than done. You have to be careful and make sure the patient is well-anesthetized. You can’t rush and can’t go back and do the revision in 5, 10 minutes. That can sometimes take longer than the initial surgery because the circumstances of the situation is less than ideal. And then the question is afterwards: More steroids? Less steroids? How do I — how do I manage this patient so that I don’t fail this trabeculectomy? How do I do my suture lysis? Am I more aggressive? Am I less aggressive? I often tell the patient, I’m still gonna keep my foot on the gas. I think they have a higher risk of scarring after I do this revision. I will get back to cutting those stitches pretty quickly in the first few days. You can see sometimes these eyes that are hypotonus, they’re angry, and more pro-inflammatory. And we have been low IOPs, very quickly they can turn into eyes that end up failing down the road. Those are pearls with trabeculectomy and some of the hypotony that you see request them. So, suprachoroidal hemorrhage. Try to tie all hypotony into one lecture, which is tricky. One of the questions is why do I need to reverse the hypotony? What is wrong with it? The hypotony is not good if it’s causing maculopathy and vision issues. But the bigger fear is, if they stay hypotonus for too long, bend over, pick up something heavy, you worry about a suprachoroidal hemorrhage. Mass every, typically with the post-op period, the first night after a trabeculectomy or a tube shunt, get out of bed and come in with a disorganized-looking eye. The back of the eye, can’t make heads or tails of what’s going on, the chamber is flat, those are hard. What I see is patients with serous choroidal effusions, but bleed into the effusions. Walking around with bug louse effusions, they bend over and bleed into these effusions. Those tend to drain a bit better. But regardless for me, I’m of the thinking that I don’t wait a week or two for the blood to liquefy. For my patients, especially the monocular patients, I like to drain the hemorrhages immediately. I go into the OR for one to three days. And tell the patient, I may not get a ton out, but a lot of times, decompress, re-form the chamber and get the eye moving in the right direction. It is often not great if those eyes stay collapsed with the blood that’s loculated. I like to go and let them know I supply to take them again in a week. And so much like, you know, my drainage of serous effusions, I do a similar approach. I use a traction stitch. Go in the interior temporal quadrant. Numb the patient, this is a 92-year-old, had a Xen, minimally invasive safe, this patient I thought was a great idea, XFG. Ended up with a massive suprachoroidal, and light per situation to 280, and it’s nice to have a fellow, hold both sides of the wound open, take a 75 blade for a super-sharp and cut down to the suprachoroidal space. This is quite satisfying when you see the drainage here. This is really bleeding into serous effusion. This tends to drain a lot better. It’s amazing how often you need to drain. Sit there and sit there and sit there. I have anterior maintainer in trying to keep the eye pressurized. And watch the lens, those effusions are draining, there’s a pressure differential, that eye will catapult backwards. Make sure that the fluid moves around the zonules into the vitreous cavity. And this patient did rather well, but it was guarded, the prognosis, for a while there. So, you know, as I roll here, I’m pretty close at 43 minutes, hopefully I’ve answered some of your questions about hypotony. I will stay on for the Q&A. I think the big thing to remember is you don’t have to rush to fix it, but you have to have a thoughtful approach how to fix it. Good he pre-op is important. And letting them know it’s a battle. And changes in the vision. So, they’re not pushing you to fix this quicker than you have to. Even with macular-related issues, the vision will get better over time and you don’t have to rush to fixing it. You know, the effusions, it’s a hard wall when to drain them, when it’s tubes, trabs, and what to do. I think with trabeculectomy, you often have to go back and re-suture the flap and start over. But be careful, I think those eyes are a greater risk of failure. tube shunt, sometimes it’s putting viscoelastic in the eye, sometimes it’s drainage of effusions along with sometimes it’s swapping the implant completely out. It depends on what the eye feels like, looks like, the degree of encapsulation. A lot of questions you have to be pretty thoughtful, and doing a lot of these procedures, you get a better feel. Don’t be afraid to ask someone else for help and guidance. I can’t tell you how many times I ran to Steve Getty, Rich, Paul, and can you look that the patient with me, I’m not 100% sure what to do. I think sometimes getting a second set of eyes is smart in these situations. You know, with that, thank you. This is my pride and joy, my daughter, my son and our new little doggy here. So, I’m gonna stop the screen share, go to the Q&A and try to just take a breath here for a second and answer some of your questions. But thank you. All right. So, we’ll start here ping I — good amount, like 18 to 20 questions here. I’ll try to get through each of them here. My Zoom is telling me I should avoid using hand gestures. post-op week one, Ahmed, pressure is greater than 0, flat AC, hypotony maculopathy, what will you? Conservative with cycloplegia or steroid or inject to AC? Good question, it says the pressure is 4 millimeters of mercury. I got to say this: Flat ACs are not as common due to over-filtration. When you have a flat AC, it’s often pushing, it’s choroidal expansion. Those cases don’t really do as well with re-forming the anterior chamber. There is some maculopathy there. And this is great to bring up with the question here, which eyes are prone to maculopathy? The eyes that are bigger and have thinner scleral walls, they are more prone to maculopathy. So, you know, it’s interesting, you know, at this point in time, probably given the low pressure and the shallowing of the chamber, I probably — I might at one week give this patient a little bit of viscoelastic in the anterior chamber and see what response is. Sometimes when I inject the viscoelastic, the pressure will go immediately up to the 20s or even 30s, and that tells me I’m fighting a pushing mechanism. In which case I want to go more with steroids and cycloplegia and just time. Sometimes viscoelastic in and go from 4 to 4.5. In which case, okay, there’s probably some over-filtration going on here. That’s how I differentiate what’s going on, see how they respond to the viscoelastic fill. And with an Ahmed, a lot of times if I have them good on day one, I will often see them at day three. I often never see somebody day one and week one, there’s a lot that can go on in that period. I would say for a lot of my shunting procedures, I like to see them a little bit more regularly. So, let’s see. Will low pressure make worse visual fields? Actually, those patients who end up a lot of times I find with a low final IOP, I often find they have more stability in the field and improvement long-term. As long as the eye can handle the low pressures, I like getting the pressures pretty low. When the pressure is low, there’s no evidence of any systemic abnormality or I’m wondering if that just means there’s nothing wrong with the eye, how do you treat it? This is a question in general. We have a lot of lectures where you see a case somebody presents where they do all this work because the number was low, but the vision was okay, the macula was okay, if you have a low number, even a number of 3 or 4, and that patient is — you have to worry they could develop effusions, they could have a hemorrhage. But if that eye manages to remain stable over the month or two, you have just done the perfect surgery. I don’t think because you have a low number that you have to do anything. You can observe the low number as long as the eye is tolerating that low number. And long-term the eyes learn to acclimate, and never at risk of a suprachoroidal hemorrhage because it’s at 2, 3, 5. What’s the difference between — let me see here. Go to the next one here. What is the most common mistake glaucoma surgeons make when evaluating hypotony-related choroidal effusions? The big mistake is rushing to do something about it. I think a lot of times effusions are absolutely fine to see. I actually sometimes — I have a slide I remember giving once to retina docs. Happy face, sad face. I don’t mind creating a little bit of hypotony where I get some mild diffusions. That tell mess I have gotten the pressure a little low where I want it to be. And a lot of times, good final IOPs. It’s fine do get effusions. I’m happy to see them. Digital palpation, I’m not great at it. But it’s one of those things where, you know, try a few different things. Take out a pen, check the pressure over the sclera, see what kind of numbers I’m getting. And you have to be careful. When you don’t have the a deep anterior chamber, a lot of times these pressure measurements can be pretty skewed. And so, you know, sometimes a B-scan ultrasound helps, you can see the contour of the globe a little bit better. Sometimes when you’re questioning, is this 4? Is it really 10? I’m not sure. Do an ultrasound. You’ll see. When you see the wall of the eye kind of look like it’s caved in a little bit or see some choroidal thickening. Sometimes that pressure is low, versus a really nice contour., you know, sometimes what you’ll see is a nice contour with choroidal thickening. That is probably choroidal expansion, that is normal versus, you know, you see the collapsed eye, that pressure is probably pretty low. Why — so the 3-0 drip cord, before exchanging — great question. You could totally do it. My problem with the 3-0 rip cord or even intraluminal, I don’t use the 3-0 as a rip cord because I just cork the tube with it, I don’t have it come out the back end. Why not do that? It’s a little less predictable for me. I will sometimes put a 3-0 supramid all the way to the plate junction, too much. The pressure is 30 the next day. Halfway, and the pressure will still be 5. Sometimes for me it depends upon the patient. So, if the patient is, you know, if I’m a little bit more worried about, you know, they want — they want this to be done. They can’t handle going back to the OR, switch for an Ahmed, I’m a little bit more certain what I’m going to get switching to the Ahmed. Scarring and worried about the dissection and removing the implant is hard, then yes, the 3-0 and plug in. That’s a great question. It was hard to get into the nuances one versus the other, but you can go either way with it. I think the key with the supramid, need to do more to be comfortable. Sometimes you have to go back in, sometimes remove it. It depends. I would say this: If I feel like there is some encapsulation, but it’s just not good encapsulation, the supramid I can put in and pull out at a later point in time. I can leave a little bit past the tip of the tube and remove it a few months down the road. If I think the case I showed where there’s no encapsulation, those cases I will switch for an Ahmed. That’s what I do. Yes. Have I had a patient who never corrected after hypotony. Yes, it’s a distortion they noticed. What I consider to be anatomical success, it looks great, but there’s probably damage to the RPE photoreceptors. I don’t have a great answer. Was it the length of time? Paul, my mentor, always talked about sometimes some of these patients, need to get the pressure up very high to flatten out the wrinkles back there, otherwise, you know, you’re not going to truly reverse those hypotony-related complications. I don’t know. You know? It’s always easy to second guess and say I should have done this a little bit sooner. But again, sometimes you’re worried about failing the procedure. You’re trying to keep the patients from going blind, there is a risk they are gonna lose some vision. Yeah, so, a trab — that’s a good question. What else can you do in the anterior chamber? I don’t love the idea of putting in viscoelastic. Because I find it sometimes pushes more through, you know, throughout ostium, through the flap, take a flap that’s unhinged and unhinge it. That’s a good question, can you put gas, I have put gas in. But one of my colleagues used to put an air bubble. I don’t think that’s unreasonable. I think they’re both kind of options to slow things down. Truth think, you can do it with a tube. I’ve had patients who have had retinal detachment following a pars plana tube, and they needed gas, it obstructs flow through the tube. Whether it’s a tube or trab, you can use an expansile gas, ask the cornea docs. Something I’ve never done. And I have a few patients with 2 to 4 millimeters of mercury. Some had a thin cornea. Depends on who is checking it, but the pressure is 2, the eye looks great. And in truth, I’ve left them alone. Yeah, have you ever had a suprachoroidal hemorrhage despite control and uncomplicated surgery. Yes. What did learn? It probably is where I started. I probably should have put them on Diamox. It’s about the delta. You start to where you end up. One thing to go from a pressure of 18 down to 4. It’s another thing to go from a pressure of 58 down to 14. You may do an Ahmed in somebody who has an NVG, bad pseudo-X glaucoma. Be causal, those tend to have bad tissue and suprachoroidal hemorrhages and bad starting IOPs. We will not forget, tube shunt, monocular, like you said, seemingly perfect surgery. My partner saw him on day one, 10, he started at 38, came in day three light perception with a suprachoroidal hemorrhage. Ended up doing okay, drained over the weekend. I should have been more aggressive trying to start. He was monocular, rushed him to surgery because the pressure was up near 40. Probably could have added another agent or oral, and hopefully started at a lower IOP. If the hypotony is untreated and they have macular issues, clearly they can develop some permanent distortion, changes in the vision. Earlier on, depending on systemic risk factors, develop a suprachoroidal hemorrhage. There’s always the question of can you end up with kissing choroidals where the retina sticks together. I have not seen that happen, but that is a theoretical risk. Question about suprachoroidal hemorrhages, drain quickly. Knowing it will not be the final trip to the OR, but I like to make the cut, open up the space, and a lot of times decompressing allows me to re-form the anterior chamber. Let’s see here. When a patient has persistently low IOP, but no visual symptoms or structural complications, what’s your threshold? I have — there’s no threshold. Just observe. No visual symptoms, no structural complications, persistently low IOP, I will say it again and again, you have done the perfect surgery. Nothing. Get the patients to not focus too much on that you have to help them it is just a number. I tell patients, I have people going blind at seemingly good pressures and I have people who have pretty high eye pressure and they are okay. And it probably has something to do with the CSF pressure and the pressure gradient or differential as to why these eyes are okay. Something about their scleral rigidity, coronal thickness. Tough cases. I think there’s two questions about AI. Wonderful questions. I hope AI can help me do my job, but I think the trouble with AI is do we have enough information we can feed it that it can help give us, you know, proper guidance? So I think that’s always the question with at least a lot of — a lot of the issues with artificial intelligence and medicine is: Is it garbage in, garbage out? Can we give it enough information that it can tell us, hey, based upon these demographics, these parameters, these bio mechanicals properties, this is what you should do. And fortunately or unfortunately, I don’t know that we have enough cases of hypotony that we can feed it into something where we can identify the right decision tree. Like I said, I tried doing that with a small subset of patients. 110 patients, the addition tree for three of us that worked similarly, but very, very hard. If you’re not seeing the patients daily, it’s hard to know how quickly they’re gonna turn and when they’re gonna turn. How can clinicians differentiate hypotony caused by central nervous system disorders during assessment. Not 100% sure how to answer it, but, you know, there’s definitely — I’m gonna use that question as a jumping off point for sort of a different question that I saw here. For patients with uveitis, maybe carotid obstruction, maybe issues with hypo– under-production, and, you know, it’s interesting, there are definitely some patients who doesn’t diffuse a lot of fluid in the post-op period. You do surgery on them, and it’s like the eye goes into complete shut down after surgery. Had this several times. I’ve had cases, do a trabeculectomy, put four tight sutures in the flap, and come in day one, the pressure is two. Almost no blood. It’s something about the inflammatory nature of the surgery, they need surgery and some time. I wouldn’t get too worried, as long as you do the surgery the way you wanted to do it. Don’t be surprised, you get patients who will under-produce in the post-op period. Follow the train of thought, I’m going to switch over to tubes. One thing about tube shunt surgery, especially non-valved implants, I don’t like to start in before the pressure closes. And they take time to get out of the system. In 5 weeks, there’s a precipitous drop in the pressure, I don’t love them being on multiple aqueous suppressions. I will use a 10-0 vicryl or nylon wick, find what works for you so you can get good, early IOP control and hopefully not have to start your anti-glaucoma drops in that period. Similar with, you know, with, you know, an Ahmed implant, you know, you want to try to be careful with when you restart aqueous suppression. Really good questions. Hopefully the new implants, like the Paul implant, will help, they will a small luminal diameter. We’ll see. Keep rolling. I saw a question about the C3F8. Again, have not done it, but definitely probably something that does make sense that you could try to do. Got to be a little careful with how much it expands, how long it’s gonna linger for. That’s the trouble. Again, especially with something like trabeculectomy, it’s kind of trying to find that optimal timing. Like how much do you want to do? And again, the problem is with a lot of these cases, the ends are very, very small in these cases so we all don’t have thankfully a tremendous amount of experience. So, it’s hard to try something new, especially if it’s a patient’s good eye or if it’s their only eye. Ciliary body and hypotony, 100%. There’s a role, and toxicity, as to why some patients end up hypo-secreting. And sometimes they have prior myo, do a tube shunt, production can be all over the place. There are certain patient who is after surgery whether you restart their aqueous suppressant, it can have a profound effect on the CB and they can go into sort of a shutdown start. I forget who wrote the initial paper years ago on this. But there are patients who you do a tube shunt, their pressure stabilizes, they develop a hypertensive phase, you restart a beta-blocker or a carbohydrases inhibitor, and there’s a sensitivity to the topical agents. Be careful with that. That’s a tip. I saw that once in fellowship. Let’s see… in resource-limited settings, what should we do to avoid devastating unmonitored risks of post-hypotony. Fantastic question. Hopefully, you know, in those situations — so say we’re talking about something like trabeculectomy. It is probably a tight flap and not getting overly aggressive with ever trying to get that lower — the low final IOP. Probably it’s going things like only doing valved implants, but being aggressive to treat the hypertensive phase. I have found that my Ahmeds get better reduction if I aqueous suppress them when the pressures are getting back up into the double digits. Avoid some of the bigger non-valved implants. one of my colleagues does a lot of hypocoagulation in places where there’s not a lot of access to care. It’s something to keep in mind, it’s trans-scleral, great procedure, no reason it can’t be used first-line in certain places. What precautions to take when patient has controlled low IOP post glaucoma — oh, great question. Love it, love it. Okay. So, you have a low IOP. And you need cataract surgery. So, I know the webinar is probably getting close to ending, but try to keep going here. But I love this question. Sometimes the treatment for low IOP following trabeculectomy is cataract surgery. It sometimes induces just that right amount of fibrosis for that patient. Not so much with tube shunt surgery. For the tube shunt patient, be careful, sometimes it’s tricky when the eye is soft. The best treatment for a patient with a low IOP and kind of on the fence, getting in and doing the cataract surgery. So, okay. What are the most common causes and best intraoperative prevention methods for hypotony? I would say whether it’s tubes or trabs, it’s surgical technique. With tube shunt, making sure the scleral tunnel, entry into the eye is proper sized. Withdrawing the needle, don’t flick to the side and end up with peritubular flow, getting more flow than you want. You can get this with Xen. With trabeculectomy, titrate your flow as good as possible. With water tight closure. Be careful with paracentesis and wounds, make sure you don’t have inadvertent leaks, and I like a lot of — at the end of the surgeries, I think that helps for patients who are prone to inflammation and under production. And I do a lot of sub.Let see, a few more here I want to get to. Should we re-form the anterior patient with the anterior patient — IOP 9 — this is interesting. This is a question of a patient has got sort of a flat chamber several months after a corneal, but no wound leak, the IOP is okay. I guess the question is why does the patient have a flat chamber? Do they have coronal adhesions? It’s hard to answer. Probably want to get a UBM and look a little bit more to make sure there’s not anything else going on. That’s a little bit of a tricky question. Maybe for the last one here, we’re, you know, I just want to touch on hypotony with the Preserflo, in the US we didn’t see a lot of hypotony, in Europe, they were seeing more. We are now in the US trial stenting with the 10-0 nylon suture to slow the flow. It’s hopefully transient and limited, I don’t have a great experience with viscoelastic fills in those eyes. Because those are small diameter tubes. Be careful with how much volume you put in the chamber. I don’t think the viscoelastic goes through the implants within xen63 or 45 or Preserflo as quickly as the Baerveldt, and patient observation, cycloplegia with these microshunts is okay. Great questions, got me thinking. hopefully this was informative, and thanks to Andy and everyone at Orbis and Cybersight for helping to allow this to happen. Hope everyone has a nice morning.