Lecture: DMEK Techniques for Beginners to Advance

Good morning and good evening to those of you tuning in to our webinar on DMEK techniques my name is Samara Andrade, and I’m the director for clinical training at SightLife. I would like to start by thanking Orbis for making this webinar possible. During trying times like these, we’re still able to provide educational opportunities to those of you all around the world. Before we jump into this webinar, I’ll take a few moments to give you a little background about SightLife. Our mission is to eliminate corneal blindness by 2040. We do this through a health systems approach, working in these five program areas. The first is advocacy and policy, where we support national governments, and eye health care systems by enabling a healthy environment. This ensures corneal tissue is available and the health system is able to provide access to care to those in need. We also work on prevention and awareness raising. We do this by preventing the progression of eye trauma like corneal abrasions, ulcers, and ultimately blindness. We do this with community health workers and eye hospitals in rural communities. We also support access to clinical training like this webinar today, supporting training opportunities for cornea care providers around the world. We also work in eye banking developments, supporting the dissemination of best practices, and supporting the eye health ecosystem by ensuring that eye banks have access to the types of training information and educational opportunities that help them function at the highest possible efficiencies. We also work in innovation and access. Supporting access to innovative solutions to improve access to high quality, affordable care, empowering local health care providers to treat their communities quicker and more efficiently. Most of you today are probably most interested in our clinical training program. Since 2013, we’ve trained more than 1400 ophthalmologists in low and middle income countries. We do this working with a global network of cornea care providers, which includes surgeon and helps develop curriculums and symposiums in a variety of techniques, as well as courses for other health care providers such as transplant nurses, optometrists, allied optometric personnel, and general ophthalmologists. This global team of faculty also serve as coaches and mentors, for corneal surgeons around the world, just like you. Today we’re absolutely thrilled to have two of these faculty here to share their best practices on DMEK techniques. Dr. Pravin Vaddavalli is located at LV Prasad Eye Institute in India, and Dr. Giegengack is located in North Carolina at Wake Forest University Medical School. We couldn’t be more thrilled to have them here with you today to share some of their knowledge. With that, I’ll hand it over to Dr. Pravin Vaddavalli to get us started.

DR VADDAVALLI: Thank you, Samara, and thanks to SightLife for this opportunity to share some of the things we’ve learned over the last several years. All of you know sometimes that teaching is the best way of learning a lot, just to understand things that I need to teach others as well. Just to give you an overview of what we could be covering today, since we only have about an hour and a little more with us, we’re going to be limiting what we’re going to be talking to you, to the most important aspects. And we thought that I would cover the transition from DSAEK to DMEK, and also a little bit about preparing a donor graft for those of you who do not have access to prestripped corneas from the eye bank. And then Dr. Giegengack is going to be talking about the steps in DMEK surgery, with a focus on loading, delivering, and unfolding the graft, and a little bit about post-op management. In the meanwhile, while one of us is not speaking, we will be available to answer questions on the chat, so please feel free to put in your questions, and one of us will try our best to try and answer that. So the title of what I’m going to be talking to you is actually transitioning from DSAEK to DMEK. And I figured that this was important, because this is amongst the most important steps at which you probably need to understand the subtle variations between doing DSAEK and then transitioning to DMEK. So we also have a number of audience poll questions, as we go along with the presentations. So it would be really nice if you could have your responses ready, so all of us get to know where you’re at, and we can actually change the focus of our presentations, based on some of your responses. To start off, this is the first question that we had for you. To understand what kind of practices you’re involved in, and what percentage of your endothelial transplants currently are DMEK. Would that be 0%, up to 25%, 25 to 50%, up to 75%? I hope nobody says 100%, but still, we have to have that in there. So please go ahead and send in your responses. And let’s see how the distribution is, depending on potentially the kind of access that you have to tissue, and the kinds of patients that you have access to as well. So get your devices, your computers, or your phones, and please select your response. In a couple of seconds, we’ll share the response. That is a pretty interesting statistic. So 0% is more than 50% of the attendees today. About 30% is up to 25%, and I have 1% who is 100% DMEK surgeon, which is really nice. So let’s talk about the basics. This is a really nice metric to have, because we’re going to be focusing mainly on trying to transition between what you’re doing to DMEK. Why do you need to transition? And what are the reasons you think of transitioning to DMEK from DSAEK? There are several reasons I could think of, and I’ve listed them down here, but actually to go through each of those individually, with evidence showing that each of these are important reasons to consider transitioning from DSAEK to DMEK, in appropriate cases, of course. Firstly, DSAEK, you would notice, is not anatomically as natural as DMEK is. You’re going to take out only the Descemet’s membrane, in some cases not even that, and replace it with larger tissue that includes stroma from the donor, as well as Descemet’s membrane. If you contrast with DMEK, you’re not really changing the anatomy of the cornea, because you’re replacing it with exactly the same layers in the eye. So it actually makes a lot more sense to be anatomically more natural than to add in tissue that potentially is not required inside the eye. The second and potentially for me one of the most important reasons is the fact that DMEK has been shown to have a much lesser risk of rejection after a transplant, compared to DSAEK. In fact, it seems that DMEK has eight to tenfold reduction in the potential for rejection after a transplant, based on this article from Francis Price’s group a couple of years ago. And this is important, because not only do we consider this as an important piece of information, for patients undergoing transplant, but also for post-previous keratoplasty who need a second transplant. Where typically rejection risk is higher. DMEK can reduce that risk, because of the reduction in the total amount of antigenicity or antigenically stimulating tissue that you’re transplanting inside the eye. Number three is better vision quality. I have not seen a surgery that gives better vision from the perspective of a corneal transplant, compared to DMEK. And because of the fact that it is anatomically so neutral, the potential for the patient achieving a complete visual recovery, as well as having exceptionally good visual quality, is much higher than most other surgeries, where there might be sutures involved, or tissues that potentially are not wanted in the eye. And that’s the reason why you see a very high percentage of patients with 20/20, and some patients with 20/16 vision as well. Number four: If you’re combining your surgery with cataract surgery as well, you have a much more predictable IOL power. Typically, DSAEK, because of the thicker edges of the graft on the periphery, will result in a hyperopic shift of about 1.5 diopters in the early post-op period, and this reduces to about a diopter and sometimes less than that, in about 3 to 6 months or so. But then again, this is dependent on the thickness of the peripheral tissue, because it changes the posterior curvature of the cornea. Compared to DMEK, DMEK results in a very little or minimal shift in the refractive power of the eye, and an average shift of hyperopia of 0.5 diopters is what is expected. So you need to ensure that you correct for that when you’re implanting an IOL, and in most of the patients after DMEK surgery, they’re refractively quite neutral from the point of view of spherical error. Visual recovery is very quick after DMEK as well. This might not be very important for most people, because people are willing to wait after a transplant, but it is important especially for people who potentially are dependent on the eye in which you’re operating, and potentially because pathology is bilateral, usually they have poor vision in the other eye as well. So this is pre-op of a patient with pseudophakic bullous keratopathy after cataract surgery, previously had Fuch’s dystrophy, this is day one, where the air bubble is still partially visible in the eye. On day three, the cornea is near normal, compared to what you would expect, at the end of one month. So the visual recovery is much faster, as compared to any other surgery. And people are seeing pretty well in about three to five days after the surgery. Refractive predictability is another reason why DMEK goes over DSAEK, because if you look at the kinds of incisions we make for DSEK surgery, especially by using injectors, the average incision size varies between 3 and 3.5 millimeters, and typically, this can result in unpredictable astigmatism. If you compare that with DMEK, most incision sizes are less than 3 millimeters, and you can even use a 2.2 millimeter incision. Wouldn’t recommend that you do that right away. To inject your DMEK tissue inside the eye. And this actually gives you the same kind of predictability as you would get with cataract surgery, to a certain extent. So all of these reasons are reasons why DMEK potentially scores over DSAEK. Now, this is your next question, and please help us with your responses as well. So what would be your primary reason to consider DMEK over DSAEK, depending on what we just went through? Would you think it would be lesser risk of rejection? And potentially the lesser use of steroids and all the antecedent complications that come with using steroids for a long duration? Potentially better visual quality, more predictable IOL powers, faster recovery after surgery, or the ability to have a predictable refraction, including astigmatism, after surgery? So pick up your devices or access your computer screens, and please help us, because this again is an important piece of information that we would love to share with all of you. Here come the results. Most of you think that the lesser risk of rejection is probably gonna be the primary driving force why you would consider DMEK over DSAEK. And that’s a really good reason. In addition to better visual quality. And also refractive predictability as well. So thank you for those answers. Now let’s dive into the second part of what we’re going to be talking about today. And that is that differences in the surgical technique between DSAEK and DMEK. And we’ll look at these at each of the steps of the surgery, from the perspective of a DSAEK surgery. So the first difference actually is in donor preparation. So all of you know that there are several methods of preparing the donor tissue for DSAEK surgery. You can use manual dissection, you can use a microkeratome, or you can use a femtosecond laser. Not used so frequently now. But the method that you prepare the tissue is by dissecting the tissue manually into two planes, or using a microkeratome into two planes, and you try to achieve a donor tissue that’s about 100 to 150 microns thick, that you can inject inside the eye. How do you prepare a DMEK graft? In several countries, especially in the US, thanks to banks like SightLife and CorneaGen, you have tissue that is available to implant inside the eye, and sometimes tissue mounted in a glass cannula that you can inject and implant inside the eye, making it very similar to cataract surgery as well. So how do you actually prepare tissue for DMEK surgery? There are a few things that are important to have. You don’t need a very complex set of instruments. You just need a set of trephines, and you need a punching block. The red stars indicate that these are the bare minimum. The yellow stars indicate that these are the preferred instruments that you would have. So a vacuum punch that you can obtain from any supplier is actually one of the best methods, one of the best instruments, that you’ll need for making or preparing donor tissue. In addition to that, you also need a good pair of forceps. If you can access, there are forceps that have been made for holding or handling Descemet’s tissue, and these are available from several companies. But then again, you don’t need to have all of these. A simple jeweler’s forceps that you have on your table right now would be enough to strip the tissue. So let’s stop there. I’m gonna stop sharing my screen right now. And move over to a video about preparing donor tissues for DMEK surgery. So this it video is a minimally edited video, so you’ll be able to see most of the nuances of how the tissue is prepared. And there are captions in the video to point out the important steps and make sure you don’t miss some of the important points. This is the donor punching block. This is the trephine base that I’m using, and I’m placing my corneal tissue with the epithelial side up to the trephine. I’m drying the epithelium and placing a mark with an ink pen. This is mainly a mark that will help me orient myself from the endothelial site, and does not have any meaning beyond that. The first thing here is the fact that you need to ensure that your graft is well centered around the area where the vacuum holes are present in your donor punching block. This is important to ensure that when you make your trephination, you don’t overlap with the scleral spur or the trab meshwork. So I’m double checking to make sure that the distance is equal. And then when I put my trephine holder on, I also check, and I use a trephine that is a little larger. This is a 9.5 millimeter trephine. That’s a really nice sharp trephine. So I put it down into the trephine holder, ensuring that my centration is good. And once I do that, I use a tapping motion to ensure that the Descemet’s membrane and some part of the posterior stroma is incised. I wouldn’t want to punch it through and through. I just want the Descemet’s to be cut. And following that, I use a little bit of Trypan blue to ensure that I stain the edges of the areas where endothelium has been lost, by contact with the trephine. I try and remove most of the Trypan blue. And you’ll notice here that there are several radial folds around those holes as well, which indicate that this is where the vacuum is present in the donor punch. Then I spend some time trying to remove the peripheral Descemet’s membrane. So what I’m trying to do here is scratch the peripheral Descemet’s membrane, so I can elevate it and remove it completely, and this is an insurance that you don’t have any radial tears towards the center, when peeling your Descemet’s membrane. Next up, I use a sharp chopper or any other specialized instrument to go in to a small area of the Descemet’s area. Preferably you should do it where it is stained, because it is less adherent in these areas. Once I do that, I try to elevate it for one clock hour or so, I hold it with my curved forceps, and try to elevate a frill of Descemet’s membrane all around, to ensure it is free of any adhesions to the stroma as well as to the peripheral Descemet’s membrane. This is actual speed. This is not sped up. This is how quickly you can go, if the tissue is a little older. If you think the tissue is from a younger donor, you probably have to go a little slower and ensure you have no adhesions with the stroma. The next thing I do is release the vacuum that is holding my Descemet’s and stroma back, and I hold the edge of my Descemet’s membrane and start to peel it towards the center. The amount you want to peel you can vary depending on the adherence. But typically I tend to do this in three tries. I do a third, I ensure that I go right to the center, and I turn my trephine around, peel a second third, and finally I’ll do another third after that, to ensure that I’m lifting my Descemet’s membrane right up to the center of the cornea, and ensuring that there are no attachments there. So this is the third part of my Descemet’s being lifted up. You can actually see in the periphery that the earlier frills that I’ve lifted up are actually standing up. After this is done, I ensure that I take off all the fluid from the surface of the endothelium and the Descemet’s membrane. And then I try and center my trephine back in place. One quick point is to ensure that you don’t have too much of a scleral frill, because that can impact centration, and when you place your trephine holder in place, your tissue might get decentered. So ensure that you’re aware of that, and you don’t allow any part of your trephine holder to touch the sclera. And once you have adequate centration, then I will ensure that I put in my second trephine, which is about an 8 millimeter trephine. And then I ensure that I keep touching — keep tapping on the surface, so that I get a little incision on the Descemet’s membrane, and then for a second time I use Trypan blue to ensure I’m staining the inner part of where I’ve trephined again. Once I do that, I wash off all the Trypan blue, with saline, and you can see there’s a thrill of Descemet’s that we handled earlier. There is bound to be some endothelial loss. So then I fold my Descemet’s membrane and ensure I remove fluid from the opposite direction and ensure my stromal bed is completely dry. And the reason I’m doing this is to be able to punch a window using a 3 millimeter trephine, so I can access the stromal part of my Descemet’s membrane later on. Once this is done, I ensure there are no attachments between the 3 millimeter stromal button that I’ve created, and I put it back in place to ensure that there is no (audio drop) the eye. And then I ensure I put I little fluid to make the Descemet’s membrane go back, still in the place that it came from, and dry the bed completely, to ensure it is completely adherent to the back of the stroma. At this point in time I’ve turned my tissue around, found the stromal window, the 3 millimeter punch I made, and then I ensure the Descemet’s membrane, the stromal part, is completely dry, I use a marker, I mark an alphabet — for obvious reasons, I use a P, so I can orient my tissue from inside the cornea when I’m doing surgery, and I place the 3 millimeter window back in place, and now my tissue is ready for delivery inside the eye. So that’s the technique for stripping the Descemet’s membrane and creating a donor. And we’ll go back into the next part of the presentation, which is about the different steps in DMEK surgery, which are different from DSAEK, other than donor preparation. But before we move on, one more question. Again, to understand for those of you who are doing DMEK surgery, do you have access to prestripped DMEK tissue that is available to you from your local eye bank? Or maybe from a friend who will strip DMEK tissue for you, and send it to you, so you don’t have to go through this process of stripping the Descemet’s membrane and preparing the graft before you do surgery? Go ahead and please answer this question again. Because this is important to understand whether there is a likelihood of an increased learning curve to strip Descemet’s membranes, to create your graft, and also potential for tissue damage, when we’re stripping the Descemet’s membrane as well. Again, you don’t need a long learning curve to learn how to make the DMEK grafts. You’ll probably need to prepare about 5 to 10 tissues that are not gonna be used for surgery, and those will be good enough for you to become an expert stripper of DMEK tissues. So go on and answer whether you have access to prestripped DMEK tissue. In India, for the most part, we don’t. Most surgeons would like to prepare their own graft. And so it is an extra investment of time. About 15 minutes extra for surgery. And most of us do it right before we operate. We’ll go ahead and display the results. The majority of you do not. We’ll suggest at the end of the session and later on we’ll share some YouTube videos and links to how to strip Descemet’s membrane and prepare grafts. So thanks for that. For DSAEK, in some cases, you need to strip the Descemet’s membrane. In some cases, you don’t even do that, for keratoplasty. But you would like to strip it in an area so that you have some overlap between your graft and Descemet’s membrane, so there are no bare areas left behind. And here you would want to strip the Descemet’s membrane as much as possible, because you would want to ensure that the peripheral Descemet’s does not impact the adherence of your DMEK graft. So this is what you would do in your typical DMEK case, where you would like to ensure that the stripping is at least 9 millimeters or more, so there is no overlap between your DMEK graft and your area that you strip your Descemet’s membrane. So that’s one step that is different between DSAEK and DMEK. The second step that is different is in the incisions. In DSAEK, you typically would like to have longer incisions, to ensure that your air does not leak out of the eye, and the graft can overlap the internal lip of the incisions. Both your paracentesis incisions, as well as your main incision that you make to access the anterior chamber in DSAEK surgery is usually a little longer than what you would normally make in cataract surgery, because a little bit of an overlap between the graft and the incision is actually desirable, to ensure that you have a hermetic seal of your incisions. Now, look at the length of that incision in DSAEK —

DR VADDAVALLI: All right. Next slide, please. Sorry about that. So what I was saying is that the area you would like to strip is generally larger. And the incisions in DSAEK, as you can see in the video here, are typically a little longer than what you would make in DMEK surgery. Next slide, please. So the main incision as well is something that you would like to make longer than normal, as compared to cataract surgery, in DSAEK, to have some overlap between your tissue and your incision. Next slide, please. And if you compare that with DMEK, can you play the video, please? You’ll actually see that in DMEK surgery, the size of your incisions is usually a little smaller. The paracenteses are shorter, because you don’t want to have overlap between your graft and the internal lip of your incision. And the main incision that you make as well is usually a little shorter because you don’t want your graft, again, to overlap the internal lip. Because if you tap on that graft, it is possible that your graft might extrude from the eye as well. So see the length of that incision is usually a little shorter. Thank you. Next slide, please. The other important thing about the differences between the two kinds of surgery are the fact that you also will need to — can we go to the next slide, please? Yes. The fact that you will also have to mark your graft. In DSAEK, in the early days, when you used to fold your graft like a taco and deliver it inside the eye, marking was mandatory, because you would not know which side it would open up in. But nowadays, in DSAEK, the majority of surgeons don’t mark their grafts. Next slide, please. So if you will notice in DMEK surgery, like I showed you, in the donor prep, the marking usually is quite mandatory. Next slide, please. So in DMEK surgery, unless you mark your graft, sometimes you actually can get confused by the orientation of the alphabet inside the eye. Especially if you’re operating on corneas where visibility is not very good. And so it is really important to ensure that you have a mark, and you also check that the mark is oriented correctly, at the end of your surgery. Next slide, please. So we’ll go on to the next slide. Great. So the next difference between DSAEK and DMEK is also in loading the graft. The majority of current techniques of loading and delivering the graft in DSAEK involves some amount of either pulling or pushing the graft, and physically, actually, holding the graft. This is an example where we’re using sort of a light to deliver the graft inside the eye. So whereas in DMEK surgery, you don’t use any physical contact between the graft and your instrument that you’re using to deliver the graft inside the eye. So the majority of delivery techniques in DMEK will involve ensuring the graft is oriented correctly, sucking the graft in a glass tube to ensure it’s always bathed in fluid, and then delivering it into the eye along with the fluid to ensure it’s not touching any of the instruments that are used to handle the graft inside the eye. Next slide, please. So for DSAEK, there are any number of delivery devices that you can use to insert the graft inside the eye, and Dr. Giegengack will also take you through some of the delivery devices for DMEK surgery. Next slide, please. But for the majority of the DMEK surgeons, the default instrument to insert tissue inside the eye is a glass tube. You have different types of glass tubes. But then the reasoning behind this is the fact that you want minimal contact between your DMEK tissue and your plastic in the periphery, and that’s why most surgeons prefer to use a glass tube. Next slide, please. The other important difference between DMEK and DSAEK is the manipulation of the graft inside the eye. Next slide, please. In DSAEK, most of the movement of the graft or the manipulation of the graft is done physically, by actually holding onto the graft. Whereas in DMEK surgery — next slide, please — you will see that most manipulation occurs externally. So manipulation will end after you deliver your graft inside the eye. And after you form the anterior chamber. And once this is done, most of your maneuvers are done externally, rather than internally. So that’s a change from the point of view of a surgeon who is used to doing DSAEK. When you transition to DMEK, this is probably the single biggest learning that you will need to tap on the surface to get your graft to listen to you, rather than directly handle the graft and ensure that it opens inside the eye. Next slide, please. The last difference between DMEK and DSAEK from the surgical perspective is the attachment. In DSAEK surgery, most surgeons are happy with a partial air bubble inside the anterior chamber. And this air bubble is good enough to actually achieve good centration, as well as attachment, even if you have some fluid spaces between the graft and your host. Next slide, please. But unlike DSAEK, DMEK is very different in this aspect. Again, several surgeons use gas inside the eye instead of air. Next slide, please. What we use is air. And the difference is that the air bubble needs to completely fill the anterior chamber at the end of surgery, because if it does not, premature absorption of the air can lead to detachment of the graft. Next slide, please. Next slide, please. So we’ll keep going on. Yes. The next slide, actually, is a question for you again. If we’ll move on to the next slide, please, Lawrence. Yes. This is the last question that I had for all of you. And again, I would be interested in understanding: What would be the primary reason for the majority of you not already transitioning to DMEK? Would it be because of limited access to tissue? Would it be because of lack of instrumentation and availability of instrumentation? Would it be because of the fact that most of your patients are not suitable for DMEK surgery? Would it be because you’re worried about visibility during surgery? Or you’re worried about graft manipulation and unfolding? Please, again, access your devices. And help us answer this question as well. Well, there you go. Limited access to tissue seems to be the primary reason why most of you haven’t transitioned to DMEK. And that certainly is something that can be addressed. Graft manipulation and unfolding — hopefully after you listen to Dr. Giegengack’s talk next, you’ll probably become pros at doing this as well. Thank you for answering the question. Moving to the next slide… The reason I’ve been talking to you so far is visiting all the reasons why you should look to transition at least in a few cases over from DSAEK, because it does have its advantages. Next slide, please. All of us go through a learning curve. And on average, it seems that it takes about 10 cases — we can keep going, clicking through this slide, to ensure that — it takes about 10 cases or so to make you comfortable with the different steps in DMEK surgery. So on average, about 10 cases — that exposure will allow you to become a very good DMEK surgeon. Next slide, please. So what I would like to leave you with today — next slide, please — is the fact that you don’t need to do DMEK in all your patients. There are still some cases where you should still do DSAEK. And that would include patients where visibility is really poor, and anybody would struggle to do the DMEK surgery. Where you have patient comorbidities, where the patient cannot lie flat for a long time, extensive peripheral anterior synechiae, like an ICE syndrome, or in certain conditions, maybe where the IOL is unstable, if you have a very poor posterior graft-host junction, DMEK is not a good choice in cases like that. And the most important thing I have learned over time is: Do not try to do DMEK in an eye where it potentially may not make a difference to the patient. Because DMEK has specific indications where it can potentially impact visual acuity. But in cases where visual acuity is going to be limited, then doing DMEK over DSAEK might not be of any advantage. So thank you very much for answering all the questions. And I apologize for the slides going off somewhere in the middle. Hopefully I’ll be able to answer questions while Dr. Giegengack is speaking. So I would like to invite Matt to go ahead and teach us all about handling the DMEK tissue inside the eye. Over to you, Matt,

DR GIEGENGACK: Thank you. Thanks, Pravin. Thanks, Samara. Thanks, SightLife, for having me. I’ll move on from here. There’s a little bit of overlap in what we’re talking about, and I’ll try to skip over the stuff that Pravin already answered expertly. I’m medical director for CorneaGen. I put that on my disclosure. One of the things I noticed on the questions was that a lot of you are people that are not yet — surgeons that are not yet doing DMEK surgery. And I want this talk to be encouraging, to have you go out and try it, because of all the reasons that Pravin was saying. That it’s the right thing to do for your patients. And this slide here — I think DMEK surgery is a lot like cataract surgery. In that there’s more than one right way to do it. And that’s kind of daunting, if you get on the internet, and you start looking up ways of how to do DMEK for your patients, and you see some guys like to do it this way, and some guys like to do it that way. That’s true. There’s more than one way to do it. But you shouldn’t try to learn every way at once. You don’t want to go into that first DMEK surgery thinking: There’s 10 different ways I can do this. You want to go into it saying: After I did my research and preparation, I’m gonna try to do it this one way. And today, I’m gonna present my way of doing it. And maybe that will ring to you, and maybe that’ll be the one that you might go off and try when you try it yourself. Or maybe you’ll pick a different one. But pick one. Don’t pick them all. And then just like Pravin was saying, don’t start off with complex cases, just like you wouldn’t with a cataract surgery — you wouldn’t start with the worst cataract. You would start with one what was manageable. And know that not all cataract surgeries are the same. Also not all DMEK surgeries are the same. So be prepared for some variability in the way your patients respond to what you’re doing. So this is probably a little bit redundant. But it’s a poll question. You guys can answer that, and I think it’ll probably give us a little similarity to the first question that Pravin gave us. Maybe we don’t have to spend too long on that. So again, most of you are folks who aren’t doing a lot of DMEK and want to do more. I’m hoping my technique talk will be helpful for that. I wrote out every step I do in DMEK, and that’s kind of daunting, because there’s 22 steps or so in there. But I pulled out the ones that are different between DMEK and DSAEK. So if you’re a DSAEK surgeon, you know how to do a lot of DMEK. There’s only a few things different that you need to do. Preparing the donor is a scary one, and unfolding the donor is a scary one. So I’m gonna talk about how to unfold the donor. And the other ones I put in the second column are things I do differently. But they’re not anything that anterior segment surgeons have trouble doing. They’re not novel to us. So I won’t spend too much time on that. Just really quickly, when you do a DMEK surgery versus a DSAEK surgery, usually you’re leaving more air or gas in the eye at the end of the surgery. And the risk of pupillary block is higher. And so when I do a DSAEK surgery, I don’t make a PI, a peripheral iridotomy. But when I do a DMEK surgery, since I’m leaving more SF6 gas in there, I make a PI. That’s a different step from DSAEK, and it’s an important one. Because you can hurt people with pupillary block. If a DMEK fails because you didn’t put enough air in there, or if it detaches, you can fix it. But if they get pupillary block, that’s a potentially blinding condition. So that PI is important. As you’re doing a new surgery, anything you can do before the day of the surgery, making the day of the surgery easier, is better. So if you have access to a YAG later, doing a PI with a YAG laser maybe a couple days before can be good. If not, a vitrector is a really good way of doing it, and if not, then I use a needle. I have a video on how to do that. I’m gonna skip that. I can come back and show it later, but you guys know how to make a PI. So here is a question for you. If you’re doing DMEK, what method are you using for injecting the tissue? Most folks that are doing it are using the IOL injector, which makes sense, because it’s inexpensive. There are some advantages to the glass cannulas, and I like to use a Geuder cannula, which I’ll talk about. I realize in the USA, we’re spoiled with the disposables that we can use. There are people who are reusing the glass cannulas, which makes them comparable in cost to the IOL injector. But I get that. Just know that there’s more than one method for injecting the tissue. And they all have their advantages. I think the advantage of the IOL injectors is that they’re inexpensive. And you probably already have one. And most people in the United States are using glass cannulas, which have the advantage that you can see through them and see the tissue in there. The glass is thought to be more gentle on the tissue. And then the one that I’ve settled on is the Geuder cannula.
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Which I like more than the Jones tube. For a few different reasons. I get my tissue preloaded now. Again, spoiled. But I used to have to strip it briefly, until they started to do that for me, and I used to have to load it into the cannula. And now I get it preloaded into the cannula. But even if you get your tissue preloaded, you want to know how to load it, in case it ever comes out. And what I like about the Geuder cannula is that if you’re looking at the picture of it there, there’s a skinny end and a fat end. Unlike the Jones tube, where you load the tissue and inject the tissue through the same end, with the Geuder cannula, you load the tissue into the fat end, and then inject it into the eye through the skinny end, and that allows you to gently load the tissue without squishing it, and then it also allows you to put it into a small incision on the cornea. So that’s the one advantage of that, loading it in this end and injecting it with that end. I like the glass. Some people say you can look inside a glass cannula and see how the tissue is oriented and twist it so that you’re shooting it in with the proper orientation. That’s hard to do, because sometimes it spirals as it comes out, but it’s a neat trick to try. The Geuder cannula — this fat end is designed to screw into a syringe nicely. And it seems to do that reliably every time. And then it can go through — it can even go through a 2.2 incision. I put it through a 2.4 incision. That’s what I use for my cataracts. I like the length of the skinny part and the bevel, because you can get it past the pupil, you don’t have a fear of injecting it into the pupil, and because it’s tapered, it fits the wound snugly. Here’s a video of me assembling the thing. So that’s the 5-cc syringe that I put a few ccs of balanced salt in. And it comes with the tubing. If you’re reusing the glass thing, which of course the company doesn’t recommend, but I know people do it, you could use just IV tubing for that. And then you put some fluid through it, so it doesn’t have a big air bubble in it. And this video came from when I was getting my tissue already stripped, but not loaded, so it’s in this Optisol here, all stripped and stained. Pravin fixed it for me. And then you can aspirate it through the fat end of that, without squishing it at all. And of course, it’s got a bunch of Optisol in it, so what I’m gonna do is drop it into a thing of BSS. Now, if you were stripping your own tissue, you would just stain it and put it in a medicine cup with some saline in it. Sterile saline. And then aspirate it into the fat end of that Geuder tube. And there it is, inside the tube. And then you’ve got to gently remove the tubing off. And I’m gonna screw the syringe into the back end. There’s a little air bubble usually on the back end of it. You want to drip a little fluid — I’m gonna drip a couple drops in there, to get rid of that little air bubble, and screw it on there. And you don’t have an air bubble in there. And that thing is ready to inject. Very easy to do. Doesn’t take long. You can see it in there. You can kind of see how it’s oriented already. And then the injection — like most tools that you put in the eye, it has a bevel line on it. And you go and bevel down, but before you inject it, you turn it to bevel up. It’s stopping for some reason. So you get it just past the pupil, you turn it bevel up, and then you know you’re not gonna inject it into the pupil. Because it goes through a 2.4 wound, you can kind of just pull the cannula back out, without worrying about it refluxing out, which used to be a problem with the bigger injectors. There are some tricks to that, and I’ll talk about that, but it’s a pretty straightforward injection method. All right. So we got the tissue in the eye. And now we’re gonna talk about the unfolding of the tissue, which is the part of the surgery that most people get the most nervous about. And when I’m teaching it to folks, I kind of give some cheerleading things at the beginning. I say: It’s not that hard. It’s different from anything you’ve done in other surgeries. But it isn’t that hard. You can do it. I always remind people: If you mess it up, you could always repeat the transplant. So in your worry to get it unfolding, you want to not do damage to the eye because you’re getting frustrated, or know that in the worst case scenario, you couldn’t get the thing unfolded, and you could come back another day and try again. I know tissue is short in lots of places. But first, do no harm. And then the other thing that I tell our patients — they’re awake and listening to us. And in the beginning, especially, I would tell my patients: Hey, there’s this funny step in this surgery, where I’m gonna be unfolding this thing. Sometimes it unfolds really quickly in a couple of minutes, and sometimes it takes longer than that. If you hear me messing around, talking about that, it doesn’t mean anything is going wrong. I also have a fellow sitting next to me, usually, and I warn them that the fellow might be saying things like: Is that upside down? If they know those are normal things to be saying, it doesn’t make them nervous. So take your time when you’re doing this unfolding. With all things that are tricky or complicated, it helps to sort of simplify it. The first thing I do after injecting the tissue in the eye is I flatten the anterior chamber. And I’ll tell you that when you do that, the tissue will assume one of several shapes that will become familiar to you, the more of them that you do. And once I’ve done that, I know that there are three different things that I can do to get this tissue unfolded. And appropriately positioned. I can deepen the chamber if I want the graft to move around a little bit more. I can flatten the chamber. If I want the graft to move around less. If I have it in the right spot and I want it to move less. I can flatten the chamber. And then you can tap on the outside of the cornea. And when you tap on the outside of the cornea, it makes a fluid wave in the eye. And a thing to always remind yourself while you’re doing this is it’s the fluid wave that unfolds the graft. It’s not your instrument. You’re not pushing on it with your instrument. You’re causing this wave to go through the anterior chamber. And that’s what unfolds the graft. And then again, just like I was saying in the beginning, there’s more than one way to do this. But you want to have a go-to technique. And I have these four moves. I tried to simplify what I do into four different moves that I use for unfolding almost every DMEK that I use. That I do. And again, there might be more than one way to do this. But I’m gonna go through these four moves, because I think you can unfold almost any DMEK using these moves. Just a couple things before I go on to show some videos. If it’s unfolding funny, if you flatten the chamber, and the shape that the graft took doesn’t look like one of the ones that you know how to unfold, just deepen the chamber and flatten it again. Because it’ll form a slightly different shape, and maybe it’s one that you recognize, that you can do, so sort of flatten the chamber, look at the shape, analyze it, if you don’t like it, deepen the chamber, and flatten it again. I’ll go over a couple of shapes that I don’t like to see. And I have a picture of them. I’ll talk about orientation in a little bit. If there’s air bubbles in the anterior chamber, maybe some went in when you injected the tissue, they get in the way with the unfolding. So go ahead and go in there with the cannula and remove them. Once the graft is unfolded, it’s hard to move around the anterior chamber, so you want to have it centered before you completely unfold it, and sometimes it’ll get stuck in the angle. If you try to move it around and it’s not moving, maybe it’s stuck in the angle. Deepen the chamber and get it out of that area. The initial shapes. When I put the graft in and I flatten the chamber, I look at the shapes that it’s forming. And usually it’s one of these two shapes. Either the bottom one I would call — this one they call the Goldilocks scroll, where two ends are sort of curving in, and this one we might call sort of a taco fold. And invariably, it forms one of these two shapes. And you can look at it, and it’s hard to tell if it’s upside up or upside down. It could be one of those two orientations. Things that I try to avoid, that would cause me to deepen the chamber and flatten it again, is if I flattened it, and it looked exactly folded in half. The ones that are exactly folded in half with the techniques I like to use, don’t unfold as well. If I see that, I’ll deepen it and flatten it again, to get it back to one of those two shapes that I showed above. This other one I call double fold — this is sort of a sneaky one. Because it looks like it’s almost there. And you’re like: Oh, I could totally do that. But the second fold on it locks it. And if you see that second fold, that’s not gonna unfold for you, with the techniques that I like to use. So I deepen it and get that second fold to go away. This is an Escher painting. Knowing if it’s upside up or upside down is sort of an optical illusion, and it’s trickier than you think. You’ve got to have some way of determining whether it’s upside up or upside down. We know that the graft scrolls with the endothelium on the outside. And the mark that you put on your graft, the P that Pravin put on there, there are some other marks that I like to use, is essential for knowing upside up or upside down. But sometimes that mark will fade, and you’ve got to have a backup plan if your mark is invisible. And a good way of doing it as it’s sitting there in the anterior chamber — is to put a cannula along the graft, move it out to the periphery, and if you go under the edge of it, you know it’s curled appropriately up. If you go along and you don’t — in this area, if you slide it along and you don’t go under the edge of it, you know it’s curled the other way, so it’s a way of figuring out the orientation without putting a mark on it. Moving to my next question, those of you that are doing it, what do you like as your mark? I should have had a P mark. If you like P, you can click the S mark. S for stroma. Or P for Pravin. The I II mark is the one that I’ve switched to, which I’ll talk about. Good. Here’s a couple shots from my eye bank. One with the S mark, and one with this I II mark. I kind of like the I II mark now. Most of my videos have the S mark in them, because I made them before I switched to the I II mark. The I II mark is maybe a little bit easier to put on, because you don’t have to do that punch. But I’ll refer to Pravin, because I don’t have to strip my own tissue. But we’re looking at it with the endothelial side facing us right now. When you put it in the eye the other way, the I and the II will be in clockwise orientation. I and II, like you would see it on a clock, whereas the S looks like — I think of S for stroma. When I was doing DSAEK. But the S should look like a normal S, when the thing is in the right orientation. The neat thing about the I II mark is that it’s on the edge of the graft, and sometimes when you’re starting to unfold it, the edge of the graft becomes visible before the middle of the graph, so you get an idea of your orientation a little bit quicker. The other thing about the I II mark that I like a little bit better is that sometimes six months after the surgery, you can still see the S in the patient’s eye. Since the S ends up being paracentral, maybe that has some effect on the vision. I think it doesn’t, it doesn’t really matter, but you can see it for a while. The I II, since it’s on the periphery, maybe matters less. The flip. So you put it in the eye, you flattened it, you start to unfold it, you realize you’re upside down. You need to have a way of turning it over. We’ll call this move the flip. You go in with a cannula through your paracentesis, and you inject it and you ricochet it off of the iris, and it makes a sort of circular current in the anterior chamber, and it’ll turn it over. Here is one here. It looks like it’s in a Goldilocks scroll. I feel like I’m gonna be all done in just a minute. And as I start to unfold it, I see this S here is a backwards S. Hopefully you can see that on the video. It’s a backwards S and then I realize — hey, I’m unfolding it upside down. So I’m gonna go in through the paracentesis. And inject some fluid. And you can’t really tell from a 2D video here, but I’m injecting it, I’m bouncing it off the iris, and it makes a current in the anterior chamber. And it turns it over nicely. And here I am, back in that Goldilocks scroll, but in the other orientation, ready to flatten and unroll it. You need to have some sort of a method for centering it. And this diagram is not my best artwork. You have two cannulas, and you tap the surface of the cornea with one cannula, and it makes a fluid wave. And then if you just tap it and let go, the graft will move over and then drift right back again, as the fluid comes back, so you tap it with one, and then you pin it there with the other, and then you kind of alternate, and you can kind of shimmy this thing forward. So when I’m unfolding things, I use this cha-cha technique to center it. The Goldilocks, if you get that Goldilocks orientation of your graft, and it looks like this, these are the easiest ones to open, you tap on the surface with the cannula, and it makes the fluid wave that causes the two edges to flip out. So the first video here is gonna show you a combination of the Goldilocks and the cha-cha. So I flattened the chamber. It formed that nice Goldilocks scroll. I’m tapping in the middle. And it’s starting to unfold. And I don’t want to get all the way unfolded until I have it centered. So there it’s almost unfolded. And then I’m gonna cha-cha it over. Because I want it centered on my mark. That was the cha-cha. And then a little bit more to unfold there. And you can see that frontwards S. And I’ll squirt some gas in here, but I’m gonna… A little air, and you’re done. There’s another move called the Dirisamer. Everyone always shows the Goldilocks scroll, but more commonly it’s the taco, where it’s folded like this. If you want to unfold this one, you do this move called the Dirisamer, where you take one cannula and pin this edge, and with the other cannula, you tap next to it. Not on top of the folded part, but next to it, and it makes a fluid wave and causes it to open up. So this is gonna be a combination of the cha-cha and the Dirisamer. So I flattened it, and I got that taco fold. And I’ve pinned it with the left hand. And I’m tapping it with the right and it starts to open up. And I’ve got to center it before it gets all the way open. Cha-cha, cha-cha, and then… Tap tap tap. Dirisamer. It’s not staying the way I want. I’m trying to flatten it in the chamber to get it to be a little less mobile. I can flatten, deepen, and tap. A little cha-cha to get it in the right spot. There it is. Then we’ll put gas in there. All done. And really, I’ll talk about some different things that can happen. But those are the techniques that I use to unfold almost every graft. And there are things that can go wrong, just like with any other surgery. And you want to know about them, what you can do to avoid them, so I’ll go over the more common ones. Injection errors — most of the injection errors that happen get minimized by using this Geuder cannula, but I’m biased. Here’s a mishap. This is using a Jones tube. The Jones tube used to go through a 3.2 millimeter wound. And you can have a lot of reflux of fluid out that wound. And there it goes. So even if you get preloaded tissue, you’ve got to know how to reload it again, if something like that happens. Which is what you would do if that happens. There’s ways to avoid that. The Geuder cannula goes through a smaller wound, so you get less of the fluid out. But the other thing you can do is, after you inject it, remember, you put a bunch of fluid into the eye, you want to decompress that pressure a little bit. While the injector is still in the eye, you can take the cannula and decompress the chamber through the paracentesis, and that takes a little bit of the pressure off. The other thing you can do is turn the graft sideways, so it’s not lined up to launch out like that. Here’s another thing that can happen, that I think the Geuder cannula helps with. The Jones tube didn’t go very far into the eye. If you angled it down, you could shoot the graft into the pupil. And that’s a tricky thing if that happens. If it happened, you would go in there and just grab it and pull it back out. But that’s poor style points. And the graft is really friable, so if you grab it like that, you could tear it. What I like about the Geuder is that because it’s a small wound, you’re less likely to have the fluid come back out, and because of the way it’s longer, you can get it past the pupil before you inject it. And anything you can do, if you’re worried about it, is you can kind of turn it sideways. So that it won’t come shooting back out. Just a thing about injecting air. After you get the tissue in the appropriate position, you’re gonna inject the air. Your cannula is small, and sometimes when you are squirting air out, you get — there’s a little surface tension on the air cannula. And when you start the air going, sometimes it takes a lot of force to get it to go. So I like to do that outside the eye. But it’ll hiss air for a little while after you do that. You just want to make sure it’s done hissing before you put it in the eye. Because sometimes, just like that, a little bit of air will go shooting back in, and you just sweated out unfolding the thing, and then you squirt that air in there, and you have to start over a little bit, and that’s particularly demoralizing. This little video here on the left here — this is four different DMEK grafts that I was playing around with in the eye bank. And I just wanted to show you how they’re very different. These two look like they’re just ready to go in the eye just nicely. And then this one up here — you see that one? It’s this really tight scroll. And sometimes you’ll get one of those really tight scrolls. Sometimes you’ll get the Goldilocks like the one I’m circling there, and sometimes you’ll get the two making that taco shape. A good tool to have in your tool box is this Fogla cannula. That shoots fluid out the sides of it. I use that if I ever get one of these tight scrolls. Which doesn’t happen that often. But here I’m gonna use the Fogla cannula to open one of the tight scrolls. This one isn’t the tightest, but I line the tight scroll up with one of my paracenteses, and I go in there with the Fogla cannula that shoots fluid out the side. And then opens it. And then there’s my shape that I know about. There’s my taco fold. And I know what to do with that. I can do a Dirisamer and a cha-cha to get that thing going. So that’s a technique for getting that tight scroll to turn into one of the shapes that you’re familiar with. Graft tearing. Again, I don’t have to prep my tissue anymore. They used to give it to me prestripped. But then laid back on the stroma. But I would imagine when you guys are learning how to prepare this tissue that you might ever tear it. And there’s one that tore. The point being… This is a patient of mine where I tore the graft. And I put the bigger piece of it in there. And this is a month post-op, and it looks great. And this picture down here is a picture from a paper by Garrett Melis out there, where he was doing hemi-DMEKs, where he cut the tissue in half and used one piece for two patients. And some of us are doing Descemet’s stripping only, where in some cases you can just take off Descemet’s and not even put a graft. The point being is that: Your donor tissue doesn’t have to be full. If you ever tear one, and you have a big enough piece, you can put it in and probably still get it to work. It might delay the recovery time, because the area that you stripped that wasn’t covered takes a little while to heal. Fibrin formation is a bad thing that can happen. Doesn’t happen very often. But something about the tapping brings out inflammatory mediators from the iris. And maybe the PI has something to do with that too. And sometimes you’ll get this fibrin forming in the anterior chamber. Particularly if you took a long time to unfold it. And it’s a really hard complication to get by. It’s better to avoid it than deal with it when it happens. If it happens, just try to get your graft unfolded quickly, and know that you might be redoing that case somewhere down the road. And people that form fibrin are more likely to form it again. And those folks, you might think about doing a DSAEK if you had to repeat it. But ways to minimize the chances of it are to make your PI beforehand. The other thing I do is I leave the eye at a high pressure, after I get the eye ready for the DMEK, while I’m preparing the DMEK, and I think the high pressure makes the fibrin formation less likely. But it’s pretty rare. I have some talk about post-op management. We’re going over time a little bit. I’m thinking Pravin — what if we made this a talk about unfolding, and what we’ve done so far, and answered some questions now, and know that people are gonna have to look up their post-op management? There is some stuff to think about in post-op management, when do you rebubble, which is something I was gonna go into. And I don’t mind doing that, if we decided that was how best to use this time. What do you think, Pravin? You can unmute and tell me.

DR VADDAVALLI: I think this bit is important. Maybe we should spend a few minutes talking about post-op management.

DR GIEGENGACK: Okay. So I should flip through these slides? Okay. So the graft is in there. You put the gas bubble in there. You’re done. And different people have different regimens that they do for folks, after they do that. DSAEKs — I usually tell my DSAEK patients that maybe there would be a dislocation of their graft, maybe 1 in 50, the way that I do it. With the DMEK, I tell folks that with my technique, there’s about a 1 in 8 chance that maybe there would be some dislocation of the graft afterwards. And need to have something done. When a DMEK detaches, different from a DSAEK, it usually only partially detaches. When the DSAEK detaches, the whole thing might come off. But when a DMEK detaches, usually it’s only one portion of the graft that has some space. And of course, 1 in 8 isn’t all that high, but we would like to avoid it entirely. And the way that you minimize the detachments is positioning. And then air stays in the eye for a couple of days, and SF6 stays in the eye for the better part of a week. So if you have access to SF6, that can minimize or lower your rates of detachment. Although I don’t feel strongly about that. I feel like air works really well too. But for my patients, I use 20% SF6 to hold the graft in place. And I have them lie flat for an hour after the surgery, with their head taped in just the position that I want them to be in. And then I have them go home, and I tell them to maintain that lying flat position, as much as possible, until they see me the next day. Maybe take a 15-minute break every two hours. I’m always a little bit worried about pupillary block. So I tell them, if they were to get a really bad headache, I would want them to sit up a little bit, because the gas bubble would move, and the inferior PI that I would make would lower the pressure. And they don’t usually have to do that, with the amount of gas that I leave in there. About an 80% anterior chamber fill at physiologic pressure is what I like to do. So they lie flat until they see me the next day, and then I check them, and then I usually see them a few days later, and I tell them to try to lie flat for two or three more days, with 30 minute breaks every couple of hours. And that’s hard for some patients. But since the gas bubble is in there, it helps to do that. We’ll talk more about that. The antibiotics obviously — we use some Vigamox drops, or moxifloxacin drops. And then steroids — you know, we talked about how there’s less rejection in DMEK. I put them on steroid drops four times a day, initially, and I get down to once a day over the course of about 4 monthlies, *months. And I stay on it once a day indefinitely. There’s literature out there that shows that steroid drops lower the risk of rejection from 2% to 1%. And we’ll talk about rebubbling. If they come to see you in the first week or two, and there’s an area of the graft that isn’t adherent, and you can tell it isn’t adherent, because of edema overlying that area, you’re gonna ask yourself: Should you put a little more air bubble in there, in the office? Or in your minor room? And there’s some rules that I follow. Because a lot of those detachments kind of resolve themselves. As the endothelium starts to wake up. But here’s some rules that I follow. If the area of detachment is greater than a third of the entire graft, then I usually rebubble. And then even if it isn’t greater than a third of the graft, but the area of detachment is involving the visual axis, I rebubble, because it gets them better quicker. Know that if you need to rebubble, it isn’t an emergency. You usually have about a 6-week window, I think, to do a rebubble. Sooner rather than later, if you think you need it. Just because it gets the patient to the finish line faster. But after about 6 weeks, that tissue starts to get kind of fibrotic. And it won’t go up into its place. So if you think you need to do it, know that you’ve got that window to do it in. And you can do it more than once. I used to do it once, and if it wasn’t working, I thought I had bad tissue, but I’ve seen that some of them need to be rebubbled again. And sometimes it needs to be rebubbled not because anything that the patient did wrong, or anything that you did wrong. If you think about it, a swollen cornea has a different curvature than an unswollen cornea. And you’ll see it happen sometimes that day one, they look great. And somewhere in that first week, there starts to be a little area of detachment. And I think it happens because as that corneal edema goes away, the curvature changes, and it makes a little bit of space. And I see it happen more often in those eyes that were very swollen to start with, because there’s probably more of that curvature change. Here’s a picture that you don’t see very often in DMEK. Where the graft is entirely detached, and it’s scrolled up in the anterior chamber. And that probably means — it could mean that you put it in upside down. That could be a reason for complete detachment. Or maybe there’s something wrong with the tissue or maybe something else. Some people will squirt VisionBlue in the eye and restain that thing, and try to put it back. If I see something like this happen, I usually take it out and try to do another one, again, because I’m spoiled and I have good access to tissue. But it doesn’t happen very often in DMEK. Partial detachments are more the norm. Here is one where you see this area of edema, where there’s a detachment. You can see it on the OCT. And I would say that’s more than a third of the graft. And also involving the visual axis, and that is one I would think about rebubbling. And I would do that in the clinic. I would look at the graft and I would pick an area where it was detached. And I would make a little mark on the limbus, where I wanted to go in with the air. And then I like to do it with them lying flat, when I inject it. Though you can do it sitting up at the slit lamp. But I’ll do it away from the detachment, so I won’t worsen the detachment by the injection. Here’s one that’s a third of the graft and one that I rebubbled. I just like this picture because this graft was a failed DSAEK that I did a DMEK on top of, and you’ll see them detach sometimes at the edge of the scar tissue, where the DSAEK was, and this one detached on either side, and sort of started to scroll up, and for whatever reason, the patient didn’t want me to rebubble, and they did fine. Because the graft covered the pupil, and the edges eventually healed, and you would be surprised at how many of these would resolve themselves, even with doing nothing. Especially small detachments. So if you had a 10% detachment, you might not do anything. Just another one with the detachment. Pupillary block I won’t talk much about. Just to say that it’s to be avoided. I would rather put less gas in and need to do more rebubbles than put too much gas in and never have to do a rebubble, but have an occasional pupillary block. Sometimes you’ll see patients afterwards, where everything looks great. This is a DMEK I did, and he’s not dilated. I probably put too much gas in there and he probably had high pressure in the first day or two, and damage to the pupillary sphincter and permanent mydriasis to be avoided. You can add to that section if you wanted to. I kind of blitzed through that.

DR VADDAVALLI: I think that’s great, Matt. I think you have covered what would normally be spoken over a two-day course, in 35 minutes. So I think — great job. I think some of the questions that were coming in, in the chat, and potentially were related to positioning, and also to rebubbling, that’s the reason why I thought that would be good to cover. The other questions were about why you prefer to tap on the eye, and not use fluid jets inside the eye. So would you like to answer that as well?

DR GIEGENGACK: Sure. It’s counterintuitive, the way that graft unfolds. I remember the first couple I did, I thought — well, it wasn’t unfolding. So I thought I would just go in there with an instrument, and sort of pin it with one and unroll it with the other. And of course, I tore it. So you can’t drag it around the inside of an eye, like you would with a DSAEK. And the fluid jets — to move it around the eye with fluid jets through your paracentesis, it’s too much of a wave. It kind of would just jam it over into the angle. The wave that you get when you tap on the corneal surface is a tiny little fluid shift in the eye. And it’s enough to cause it to unfold without causing it to shoot off to the side of the eye, basically. It’s more — it looks less delicate, but it’s more delicate, I think, to what it’s doing to the graft. I don’t know if you agree with that, Pravin.

DR VADDAVALLI: Yeah. I think the other question was about this sign to reassure us that the orientation is correct. Like in DSAEK, we talk about the double ring sign. Is there any sign that tells you — I’m assuming if we don’t have a mark on the graft, that the graft is oriented correctly.

DR GIEGENGACK: There isn’t, I don’t think. It can look very normal, upside down. And that’s why that mark is essential. Not essential, because if the mark is faded, you can still do it. But you have to know it’s unfolding right, before you get it all the way unfolded, if you don’t have the mark on it. It looks identical, upside down, as upside up, unless you have some sort of an orientation mark. Do you agree with that?

DR VADDAVALLI: Yes, absolutely. I think that’s why marking is so crucial. And I think that’s always a game changer, especially if you’re operating in eyes where visibility is not very good. And one other crucial learning is when you’re transitioning from DMEK to DSAEK, typically, we tend to pick cases that would be more challenging. Because you’re worried about the outcome. You probably don’t want to try this technique in an eye that has a very clear cornea. But again, counterintuitively, it’s really important to pick a cornea or a case where the visibility is good, the anterior chamber is normal, and the likelihood of you having a good outcome is higher. Those are the easiest cases, and typically for somebody who is transitioning again — a previously failed DSAEK graft is actually a very good case to start with. Because you have a patient where the vision is not very good, and once you take the DSAEK off, visibility is usually pretty good. And the anatomy, I’m assuming, of the anterior chamber should be conducive to do a DMEK as well. The reason I said that is because: Unless you’re doing a case in a cornea that is really clear, which is very unlikely, marking the graft is very important, to ensure — at least in your first 100 cases — to ensure you’ve got the graft right. Even after, if your edema is going to preclude visibility, I think marking should always be done.

DR GIEGENGACK: Agreed. Yes. Always mark. For sure, yes. I’ve done many. Hundreds, I guess, at this point, but I’m never gonna stop marking. I think it’s the way to go, certainly. And I totally agree with what you just said. DSAEK is a great surgery, and we get good outcomes with that. And if you are looking at an eye, and you think… Could I do DMEK? Or would it be more of a challenge, because of the anterior chamber? Know that you never want your innovation to be worse than the way you were gonna do it before. So eyes with tubes and eyes with unstable lenses and stuff like that — I’m still doing DSAEK for lots and lots of people. Because I get a better outcome with that. DMEK is great for certain eyes.

DR VADDAVALLI: Oh, yes, and there’s a follow-up question as well about pupillary block. You mentioned pupillary block briefly. So the question is: How do you treat pupillary block in a patient who has had DMEK surgery previously?

DR GIEGENGACK: The unfair answer is to say try not to get it in the first place. And the way to not get it is to have a good iridotomy, and to not put too much air in there. And when people goof, it’s because they put an air bubble in there, and they think it’s the right size, but they didn’t test the pressure of the eye. So it’s a big air bubble, and the eye is at a high pressure. And so that’s actually more air than you think it is, or they have a bunch of air that they inadvertently put behind the pupil. So try to avoid it. But if you have it, you go in there — if I get it, in my minor room, I go in there, and I are remove the air as soon as possible. Because the longer the iris stays stuck up there, the more likely it is to have some permanent synechiae. And trabecular meshwork damage. And sometimes those eyes — you break the block and you get the iris down and they still get glaucoma. So fix it fast. Take the air out. Worry about the health of the tissue. The cornea tissue. Later. That’s what I think.

DR VADDAVALLI: I guess we’re pretty much beyond time. So I will let Samara decide what we need to do from here on. But I guess we answered most of the questions online as well. We’ll try and finish up answering some questions that are coming up in the chat. But anything else that you would like to bring in, Samara?

DR ANDRADE: Thank you both so much for taking so much time to answer questions from viewers. We are over time. So if we want to take maybe the next two minutes, just to wrap up, if there’s any urgent questions still left there, and of course, welcome to reach out and contact with us for additional questions that aren’t answered during this time.

>> Thank you all.

DR GIEGENGACK: Thanks.

DR VADDAVALLI: Thank you all, and thank you again for staying all through. And thanks again, Matt, for an excellent presentation. And thanks to Samara, SightLife, for this amazing opportunity as well. I hope we’re all back to doing regular transplant numbers very soon.

DR GIEGENGACK: Yes. All right. Thanks, Pravin. Thanks, everybody.