Lecture: Penetrating Keratoplasty: Preoperative Planning and Intraoperative Steps

During this live webinar the preoperative and operative aspects of Penetrating Keratoplasty, including indications, tissue selection, anesthesia choices, and intraoperative steps are discussed.

Lecturer: Dr. James Lehmann, former Orbis staff ophthalmologist (2005) and currently a cornea surgeon at Focal Point Vision in San Antonio, Texas, USA.


DR LEHMANN: Good morning, everybody. My name is Dr. James Lehmann. I’m gonna be sharing my screen here in one sec. There we go. Pull up my PowerPoint. Okay. So can everybody see my slides there? Okay. So good morning, everybody. My name is Dr. Lehmann. I’m coming to you from San Antonio, Texas, right here. I’m in private practice. I do cataract, cornea, and refractive surgery. No relevant financial disclosures for this talk. If I forgot to mention it, we’re going to be talking about penetrating keratoplasty today. I’ve done a lot of work overseas teaching cornea transplants, most recently in Jerusalem, Peru, and China. So before we get started, we’re gonna do some poll questions for the audience. Just so I have an idea about the experience of the audience, the first question would be: I have performed penetrating keratoplasty: Number one, never. Number two, 1 to 20 cases. Number three, 25 to 50 cases, and the fourth would be 51-plus cases. So just penetrating keratoplasty. And Lawrence will tally those up, and we’ll get a result. Okay, so it looks like the audience has limited experience, probably, in the 1 to 20 or never cases. So what we’re gonna do with this presentation is kind of give you an overview of cornea transplantation, and not so much detail into the mechanics, because that kind of takes some live surgery to do, but we’ll go over all the preoperative considerations and intraoperative steps. Another question, before we get started. This is one of the questions we’ll address in the lecture, but which of the following is not a contraindication to penetrating keratoplasty? Ocular cicatricial pemphigoid, untreated exposure, keratoconus with scar, or active graft versus host disease? We’ll submit those, and Lawrence will give us a result here. All righty. Looks like the audience got that one right. So we’ll go into some of these when we talk contraindications. When performing penetrating keratoplasty, which of the following is true? The donor trephination should be larger than the recipient, or the recipient trephination should be larger than the donor? Submit your answers to that, and Lawrence will tally those up. All right, looks like the audience was on the spot with that one. The last question: If the patient has a corneal scar and mild cataract, the surgeon should perform a PK3, or the surgeon should just perform the PK and then months later do the cataract surgery, or take out the cataract, then months later do the PK, or the surgeon should perform a DMEK. We’ll go into this later in the presentation. So a little bit of question on this. We’ll talk more about this one. A little overview of the talk. First we’re gonna talk about the background of corneal transplantation, then patient selection, how we choose a donor, and then how we plan for surgery, how we do the surgery, and how we deal with any problems during the surgery. So in terms of background, this is a photo of a patient who had a penetrating keratoplasty back in the 1960s, in New York, with Dr. Castroviejo. It’s a square transplant, you can see. And at this time they didn’t have absorbable or nylon sutures. They would use steel, sometimes wire to do this. The patients would be in the hospital. The graft was about 100 years old, based on the time it was transplanted in the ’60s. So what we’ll be talking about today is the evolution of that surgery, which is PK, which stands for full thickness replacement of the cornea. Obviously the goal of this is to clear up the visual axis and give the patient usable vision. Just a little overview. In the United States, there’s about 50,000 grafts done each year, and if you look back to 2005, the vast majority of those were penetrating keratoplasty. If you follow my line here, we’re down to under 20,000 full transplants a year. We do more endothelial transplants than full transplants now. And in terms of indication for transplants, if you look in 2016, the majority of them are for keratoconus and repeat transplants. Okay? When we talk again about the indications for PK, in the US, at the top of it is keratoconus. And then if you look right here, we have repeat corneal transplants and other causes of corneal dysfunction or distortion. This differs in different countries. In the United States, it’s with keratoconus, repeat grafts, and perforations. But if you go to India, for example — they do about the same number of transplants as the United States each year — those are for therapeutic grafts for corneal ulcers, that don’t respond to medications. And then regraft. And I did a little work in Colombia for this article. The number one indication was bullous keratopathy, and then therapeutic for an ulcer, and then corneal dystrophies. When we say therapeutic, we’re talking about putting tissue on the eye to stop an infection or a perforation. Oftentimes the tissue might be of marginal quality that might not provide years of adequate vision. So normally that’s done to stabilize the eye, and then an optical graft is done. In the United States, we don’t always use that same distinction, because of the availability of tissue, but in the rest of the world, that’s the terminology that’s used. So in terms of patient selection, there’s certain no-nos. Right? Anybody who has active inflammation on the eye, so if you look in this bottom picture here, that’s cicatricial pemphigoid. If someone has active cicatricial pemphigoid, no graft is gonna do well. Even if it were dormant, you would have problems. The bottom line is you have to get this inflammation under control. These are all bad things. Bad dry eye, Stevens-Johnson syndrome, limbal stem cell deficiency, exposure, this is cicatricial ectropion causing exposure. A graft wouldn’t do well, because it wouldn’t epithelialize nicely. More contraindications. Active infection, unless the goal is to fix that infection. Things like HSV. Doing grafts on patients with HSV. They need to be on systemic antiviral medication like Valtrex. The eye needs to be quiet several months before you do the surgery. Another one that is kind of under the radar are uncontrolled glaucoma. So if a patient has high pressure, you want to get the pressure fixed before you do the transplant. The graft will fail because of high pressure. It will inhibit epithelialization, and muddy the waters in terms of is the swelling from rejection or pressure. So it’s very important to control the glaucoma prior to doing a penetrating keratoplasty. These two would be multiple previous rejections. So if someone has had multiple corneal transplants, and you’re doing the fourth one, you know your chance of success is very small, and you may need to consider a different modality, such as K-pro. And last is the inability to care for a patient. If you’re never gonna see them again or they’re gonna move far away, that’s not a good recipe for a successful transplant. A transplant is a lifelong connection between the doctor and the patient. The patient needs adequate follow-up. They need to steady follow-up to look for things. And most eye surgeries, you can do the surgery and the patient doesn’t really need to return on a schedule, because they can feel if something is wrong. But with a transplant, and also kind of with glaucoma surgery, you need to have interval follow-up, so you can be sure the graft is doing okay, the sutures are good, et cetera. So again, some indications. Here’s a fungal keratitis. This would be more common. As the number one indication in India, for example. In the United States, we do therapeutic transplants, when patients don’t respond, because there are some fungi that just won’t respond to any topical, intrastromal, et cetera, medications. Here’s the picture of a failed graft that’s very vascularized. This is probably the second or third graft on a patient, and another graft would probably end up the same way. So in this situation, you might be looking at another modality. I received some questions prior to the webinar. One was from Milos. And he asked: Is PK or DALK better? What is deep anterior lamellar keratoplasty? You can see here, we’re putting on a recipient in which the endothelium and Descemet’s have been removed. A DALK is probably superior in keratoconus, and the reason is you have less chance of rejection. You can get stromal and epithelial rejection, but you don’t get endothelial rejection, and that’s a big plus. There’s probably less susceptibility to traumatic dehiscence, if the patient suffered trauma. The main thing is that if you have a problem, you can kind of bounce back from it with a DALK. Whereas in a PK, it’s not so easy to bounce back from a rejection episode. Or for getting their drops, getting a wound dehiscence, et cetera, something like that. So the answer to your question, Milos, is that DALK is better in keratoconus. So let’s talk about donor cornea selection. Here in the United States, when I’m gonna plan a penetrating keratoplasty, I send a notice to the eye banking organization, and in this instance, it’s KeraLink. I tell them what day I’m gonna have the surgery, what the age of the patient is, and then they send me a sheet like this. And the sheet is very nice. It has all the statistics. There’s a lot of stuff on here. So for many of you who don’t have experience with corneal transplants, I’ll kind of run through the pertinent statistics. Number one, the age of the decedent. That’s the person who’s died here. Okay? We generally like to use corneas age 15 to 65. And we try to match the donor age to the recipient age, for obvious reasons. If you put a 90-year-old cornea on a 20-year-old… So you also look at the date of death. That’s here. You want to calculate the difference between when the patient died and when we do the surgery. You want that under 12 days, generally. It’s FDA approved for up to 14, but there’s data suggesting that under 12 days would be the best. I’ve used them up to 14 and it’s totally fine, but there’s a small trend towards improved outcomes in DSEK for under 12 days of use. The last is the D to P. That’s the death to preservation time. That’s when the decedent died, and when the corneas were harvested and put into solution. Oftentimes, they are cooled, the body is cooled, so if the patient or the decedent dies in the hospital, they can cool it in the morgue. You want the body cooled, if possible, and the accessible D to P is somewhere between 15 to 20 hours. If it’s cooled, you can go up to 20 hours, no problem. Lastly, we want a cell count. Just the number itself is not terribly helpful. It’s better to see the picture of the endothelium itself. We can get microscopy images on these, so you can verify — because this is just a small snippet in the middle of the cornea of the endothelium. You don’t have an idea of the entire endothelium. You can have bad things in the other part, but at least it gives you an idea of the uniformity and the size of the endothelial cells, and you want to look for about the same size, and you want these nice hexagon-shaped cells. Lastly, you look at the clear zone. If the donors are older, they’ll have a lot of arcus and limited clear zone. If you need a graft that’s 9 centimeters, but the clear zone is only 7.5, you don’t want to choose that cornea, because the recipient will have while the lines around their graft. So this is on the sheet here that gives information about the patient, et cetera. Another question here: What do you consider as good tissue for a PK and what will you not accept? That’s kind of what we’re talking about here. I wouldn’t accept an 85-year-old cornea. I wouldn’t accept a date of death that was 14 or 15 days. If the death to preservation time were greater than 20 hours, I wouldn’t take it, and if the cell count were less than 2500, I would be reticent to take it. Those are the stats that I use as my baseline. Every surgeon uses a different one, and there have been big studies to help to sort it out a little. As you remember in ophthalmology residency, there are some big studies, so there was a corneal donor study 20 years ago, looking at the outcomes between 12 to 65 and 66 to 75-year-olds. And essentially the results were that, at five years, there was no significant difference in the outcomes. And so this is kind of what opened up the door to using older tissue. Now, a lot of cornea surgeons are still reticent about it, but you can have quite good success. And as we do more endothelial keratoplasty, sometimes older donors are more useful. For example, in DMEK, it’s easier to unscroll the Descemet’s membrane in an older patient than a younger. Oftentimes patients ask me if you have to have blood type or HLA matching like for solid organ transplantation. We tell them no. There was not a huge study, but a study done in the ’80s, looking at this, at high risk transplants, and if you matched up the HLA, and there didn’t seem to be any benefit at three years from that, so we’ve gone away from that. In Europe, I think there’s a little more of this, but I’m not familiar with that. What does the cornea go into? Many different solutions, but in the United States, the most popular one is this one, Optisol. And this was invented in the late ’80s. Before then, you had to keep it in short-term storage. Either a moist chamber or the MK medium. So you had to use the cornea pretty fast. Now we can save it up to 14 days. Essentially it’s a buffered solution that has nutrients, antibiotics, and there’s been a push to put amphotericin in there, to help decrease the chance of a postop fungal keratitis. It’s strange, but in penetrating keratoplasty, fungal keratitis is not a huge issue, but it is in endothelial keratoplasty. It seems like in DSEK and DMEK, there’s a higher incidence of this. So there’s been new exploration of putting amphotericin into the solution. It’s done in Europe, but in Europe, they do organ culture, in many eye banks there. Anyway, the bottom line is that the intermediate term solution is the most popular. It’s this one. In India, it’s called Corneasol. At the current time it doesn’t have amphotericin, but it does have antibiotics. These long-term storage — organ culture is where you keep the tissue warm, at kind of physiologic condition. You can use it longer than 14 days, or you can freeze it or do gamma radiation, but then you don’t have any more endothelium. So when somebody passes away, they want to donate their corneas, there are some things we have to make sure they don’t have. Review the medical and social history, and we do serologic testing. Serologic testing is basically for hepatitis, HIV, and syphilis. What’s not required is what’s listed here. For solid organs, you have to test for these, but not corneas. HTLV, EBV, CMV, Chagas, West Nile — these are not routinely checked for in corneas. In the United States, in 2014, 10,000 corneas tested positive for communicable diseases, and the majority were hepatitis, hep B or hep C. Why were these tested if we don’t routinely test for HTLV or West Nile? The reason was that the donor was also a solid organ donor, so they were tested for at the same time. And eye banks don’t just give you the cornea. They investigate it and make sure it’s okay. Using a viewing chamber and a little mount on a slit lamp, they look for exposure, infiltrates, clear zones, anything that may rule out — for example, if the donor, the decedent was in the ICU on a ventilator, and developed exposure keratopathy with subsequent infection, you would see a little white line in the cornea, possible infiltrate. You wouldn’t want to use that cornea, even for endothelial surgery. And then lastly we do donor specular microscopy. And Conan has devised a gizmo like this, with a viewing chamber that takes beautiful pictures. For those of you not familiar with specular microscopy, this would be a beautiful scan here. You see uniform endothelial cells, these are bigger cells, moving to take up the space, so this has a lower cell count. This may be borderline. Here you see pleomorphism, heterogeneity of the cells, suggestive of hypooxygenation or another condition that means the cornea is not in great shape. And here you see guttata, as would be present in Fuch’s corneal dystrophy, so you wouldn’t want to use this cornea there. So we have a lot of toys at the eye bank that make us able to plan the surgery a lot nicer. Preoperative planning. So there are several things you have to think about. The first is: What kind of anesthesia will you use for the patient? The next is: What are we gonna do with the lens? Are we gonna leave it alone, or do we need to do something with it? Lastly, there are some unique situations. One would be a previous failed graft, and you have to decide: If I’m redoing the PK, am I gonna repeat the trephination, or remove the current one? Or do I want to do an endothelial transplant on them? Or move to a different procedure, like a Boston keratoprosthesis? So anesthesia for penetrating keratoplasty. Different parts of the world use different kinds of anesthesia. Okay? The goal is obviously that the patient’s comfortable and that the eye is not moving. There is some added risk involved with penetrating keratoplasty, as the globe is open for at least 10 to 15 minutes of the procedure. So you really need to have good akinesia. And the patient needs to be comfortable. They can’t be coughing, they can’t be wiggling around, they can’t be doing Valsalva. So you really need to kind of get to know your patient and make sure that you choose the correct type of anesthesia. So most of the cases I do are with retrobulbar anesthesia. But there are some cases of general. If the patient is younger or I don’t feel like they can stay still during the surgery, and at the end of the case, if we’re doing a general, I do give a peribulbar block to help with analgesia. So as I was saying, what kind of anesthesia for the PK? You need to make sure the patient can lay still, you have to make sure they understand — so if the patient has any kind of hearing issues, moderate mental — dementia, something like that, or if they have moderate or low IQ, where they can’t really follow orders, you need to maybe go for general anesthesia. You also have to consider: Do I need to be doing more things? If I’m gonna suture in an IOL and I’m doing external manipulations, I need the eye still, I’m gonna reduce the risk of suprachoroidal hemorrhage, so I might want general anesthesia. Patients in their 20s and 30s are not very good with just local anesthesia. The anxiety and things. So you have to get a feel for your patient, and I would suggest to many of you if you haven’t done transplants definitely in your first several cases, you want to do them under general anesthesia, so that you’re not pressured during the suturing of the donor. When we do retrobulbar anesthesia, we use this needle. It’s called an Atkinson needle. As you know, it’s blunt at the tip. There are risk factors with retrobulbar anesthesia, as you know, all of these listed here, but generally it’s safe. If you’ve done thousands of them, you do a good job, and the eye is akinetic and the patient doesn’t have any pain, one thing I’ll mention is we do use hyaluronidase in our blocks. The blocks are normally lidocaine, 2% without epinephrine, and bupivacaine, that’s a more active agent, and we put hyaluronidase to help diffuse the block, and that gives you about 2 hours of a rock solid globe, and 6 hours of analgesia. Presurgical planning. Lens management. Here’s an intraocular lens. And here’s a case where the patient has corneal scarring and a cataract. There’s different scenarios here. One would be the patient just has a mild cataract. The other one would be the patient has a very bad cataract. And these kind of fit together. Does the patient already have an IOL and it’s not in good position? Obviously if it is in good position, you’re gonna leave it alone. Does the patient have an ACIOL that’s not fitting correctly? Or do they have a lens that’s rubbing against the iris, causing uveitis and glaucoma? Or are they aphakic? We’ll go through a few of these scenarios. Obviously in your first few transplants, you want to leave the lens alone, because it does add an element of difficulty to it. So if somebody has a mild to moderate cataract, obviously in this picture, a lot of scarring, before and after, this would be the most common scenario. Maybe a 40-year-old with keratoconus, or a 50-year-old that has some kind of cataract. In this situation, you want to leave the cataract alone. It makes the case go faster, it’s safer, and you can get a better result long-term if you do the transplant, you perform the suture management for 6 to 9 months afterwards, and then you come back and do phacoemulsification on the patient. Any kind of refractive error, especially spherical, you can correct with IOL six months later. The astigmatism that would be present — I would hesitate to put in a toric lens, because the graft astigmatism can change over time, and if they ever need a different graft, you have to remove the lens that you have. So a question from the audience that was submitted prior to the webinar was from Rajashree Das, about the management of postop astigmatism. I’m gonna go briefly into that, because we’re not talking too much about post-op stuff, but this is the graft suturing technique that I use. It’s 12 interrupted sutures, like the hours on a clock, and then there’s one running suture that goes around. I experimented with a different type of sutures, and most of my colleagues nowadays just do 16 interrupteds, but I like this the best, because you put these interrupteds in first, and they’re tighter than the running suture, and then about 4 months after surgery, after the eye is healing up, you bring the patient in, and we do topography on them. You can see here would be January 2013, four months post-op. I have these interrupted sutures and here’s the running suture. We do topography, which isn’t the best in the world. You can see the irregular surface. This is common in a transplant. You don’t get the greatest topos. And it’s telling me I have 3.75 diopters of cyl. Generally in this direction, okay? So we remove some sutures. You remove them on the steep axis and you remove the interrupted sutures, not the running. Okay? And then you bring the patient back in a month. Now we’re February the 19th. Now we’re getting some better pictures, and you can see the sutures that are still present. There’s one here, one there, one there, and look where the cyl is. The cyl now is 8 diopters. You’re getting a prettier picture, so I know I need to remove some sutures. I probably remove these two, and then you bring them back. This is now 6 months postop, this is March, and you’re getting a better shape here. The astigmatism is still irregular, measuring 2 diopters, so I would stop at this point and let the graft heal. I would leave in the running suture for the patient’s lifetime, unless it broke. That provides a safety measure, and if for example you have removed all the interrupted sutures and you still have high astigmatism, that would be for a different lecture, but at that point I would remove the running suture and do any kind of arcuate incisions or anything needed to improve the shape of the graft. So again, that’s a little brief tutorial in astigmatism management, after PK. Another question from the audience was from Manjunath Natarajan in India. What are the advantages and disadvantages of continuous interrupted sutures? This is the most common technique, 16 interrupted sutures. And here’s my technique with 12 and 12. There’s a couple reasons why I like a combination of the two. The first one is that I can do suture removal earlier. I can start removing sutures at 4 months, because I have this running suture in between, to help maintain graft integrity. If you have 16 bite and you remove one, you’ve got a big space there. Or if you have a loose suture, you’re much more likely to have a wound leak than you will in this scenario. At an aesthetic level, look how much prettier this looks than this. If somebody sends you a patient for a corneal transplant and they see them back and you just have these sutures like this, they’re gonna say… Man, I can do that. But if you have a pretty running suture like this, they’re gonna say… Wow, that was a good job. I know that’s tongue in cheek, but in a sense, it’s much prettier and I think it’s safer. If this is looser than the interrupteds, you can remove the interrupteds and still keep the running suture for years and years as a safety measure. The next scenario would be: What if the patient has a dense to mature cataract? You remove it at the same time as the transplant. Here’s a patient I took care of who had trauma and cataract as well. So we’re gonna plan to do cataract surgery as well. This is the lens I like. You can do silicone three-piece lens. What you don’t want is a one-piece acrylic lens. So a three-piece lens or a one-piece PMMA is fine. With the technique to remove the cataract, you’re not always certain you can put it in the capsular bag, so you don’t want an acrylic one-piece lens in this scenario. A three-piece silicone is perfect, or one-piece PMMA. So you measure the axial length, you use that most of the time for the calculations, and 45/45 is the average K. You need to use a Flieringa ring, and the technique is called open sky extracapsular cataract extraction. You don’t phaco it. You can, but it seems like overkill. I’ll show you that technique later. Here is that patient again before and after. I also did some iris repair. Here’s that 12 and 12 pattern, here’s sutures from the original scleral rupture or corneal laceration, and a nice clear visual axis. If the patient is gonna be aphakic at any point in the procedure, meaning they’re aphakic or you’re taking out a cataract, you need to use these Flieringa rings, 1 or 2 millimeters posterior to the limbus, sutured to the episclera with silk or vicryl sutures. They help to maintain integrity, position the globe, and decrease the posterior pressure once the lens has been removed. So it’s kind of like a box kite. The question from the audience submitted before was from Bayanda Mbambisa. The question is: What is the advantage of using the Flieringa ring? When you take the lens out of the eye, the eye shrinks down like a deflated balloon, and the ring gives it some integrity. It’s like a box kite. So you make your life easier when you put it on. With my travels to different countries, I find in many places they don’t use these, but I find that it minimizes the grey hairs. So here’s an example of lens management. This case has a decompensated cornea, with some vascularization, and then it has a one-piece acrylic IOL in the anterior chamber. So this is a no-no. This lens needs to be removed. You could debate whether the patient needs a PK versus endothelial keratoplasty. Without examining them, it’s difficult, but let’s assume they need PK. I would recommend general anesthesia, Flieringa ring, removal of this IOL, and sutured-in IOL at the same time as doing this PK. If you could do endothelial keratoplasty on this patient, I would recommend a two-stage procedure, where you suture in the IOL, remove the lens, and a second procedure doing a DMEK. In this scenario, what do you use to suture in that lens? There are two lenses people use in the United States. One is the Alcon CZ70BD, and the other is the Akreos. I prefer using Gore-Tex suture. This is off-label use of Gore-Tex, which is not designed for the eye, but it doesn’t have a break, so this is the best thing. If you’re suturing with 10-0 prolene, you’re gonna have some suture breakage. There’s renewed interest in the Yamane technique, and I presume this could be done at the same time as the PK, but I have not done that. This is gonna be on the horizon, and as you go to meetings, I’m sure you’ll find expert surgeons doing this, in combination with open sky-type procedures. But again, take out the bad lens, suture in a new one. You could choose either of these lenses and use the Gore-Tex suture. If somebody is aphakic, it’s essentially the same. You look at this picture down here, decompensated cornea, no iris, this patient would benefit probably from the Human Optics artificial iris. Maybe you could get away with endothelial keratoplasty in this patient, but if they had to did a PK, Flieringa ring, sutured IOL, perhaps sutured iris, and then PK. Okay, so a couple of unique scenarios here. If somebody has a failed transplant, you have a couple of options. You do another transplant, you either do endothelial keratoplasty, or you do something else like the Boston K-pro. So the first decision is: Do you need to do another transplant, or can you just replace the endothelium? Let’s say the failed PK has an opacified cornea and they were seeing well prior to the graft failure. So if they were seeing well with glasses or contacts, prior to the graft failure, and the cornea has a good shape on astigmatism, there’s only edema, there’s not a lot of scarring or vascularization, then I would recommend endothelial keratoplasty in that case. But if somebody has a failed graft, and then you look at the graft, and it’s got a terrible shape to it, they weren’t able to wear contact lenses or glasses, and they were just kind of hanging around with that cornea, then you need to repeat the transplant. If it has lots of scarring and vascularization, either repeat transplant or K-pro. So if you’re gonna repeat the transplant, you’ve got two options. You can either trephine again, outside the area of the previous graft, or you can remove the graft. Okay? That’s there. Now, if it’s really a long time ago, or the graft is very small, or lots of scarring, I like to trephine again, outside the area of the original graft. But if the dissection was done recently, like you have primary graft failure, and it’s not even scarred in there, I wouldn’t retrephinate. I would just remove the one that’s in there. Okay? So that’s a little bit higher level surgery, but just kind of talking through that. Let’s look at two scenarios here. This is a patient with good previous vision, and they have graft failure. You see a bulla right here in the central cornea, you see some vascularization, the eye looks a little angry. There’s minimal scarring. So here, I think endothelial keratoplasty would be the treatment of choice. Either DMEK or DSEK. This is a different case. This is a vascularized, scarred graft. We don’t know how many grafts they had before. Let’s assume two or three, okay? If this is the first graft they rejected, one could do another PK. If this is the second or third, you need to do a K-Pro. So for those of you guys who don’t know what a K-Pro is, this is what it looks like postop. You have a rim of donor cornea, and then inside of it is a PMMA cylinder, that gives you a clear central optic, and this patient is wearing a contact lens right here. You can see this. And that’s why there’s some air bubbles right here. But again, this is a reasonable surgery that has good results. But a different topic for a different time. All right, guys. We’re about 40 minutes through. I’ve got about another 15, 20 minutes here. We’ll talk a bit about surgical technique. First you have to prepare the recipient, you need to punch the donor, trephine the recipient, there’s a couple special situations, and then you’re gonna suture the cornea in. So when you’re preparing the eye, you need to do the following things: You need to place a Flieringa ring if necessary, measure the corneal diameter, and mark the center. These are gonna help you choose what size of trephine you need, as well as center that nicely. Most grafts I do an 8.25 donor into an 8 millimeter recipient. So there’s that question. The donor needs to be bigger than the recipient. Why is that? Because when you punch a donor, you’re punching backwards, from the endothelium side, so that changes the shape a little bit, and this gives you a better fit. Some people oversize by 0.5, and I used to do that, but I found my Ks were too steep, so I do it by 0.25. So here’s a video of me placing the Flieringa ring. I sized it, and you don’t have to place these radially. They can be oblique passes, and the first one can be through the conj. When you hold this Flieringa ring, you want 0.3 or 0.5 forceps. 0.12 are too fine. You’ll mess up the tips. The first two are hard to get in there, but I’m using 6-0 or 5-0 vicryl. You don’t have to pass them from the center out. You can pass them in whatever fashion you want. Episcleral bites. And you want to get about four of them in there, okay? If the patient, even after the block, has some — the view is not centered like that, you can use another suture, and kind of move the eye around, so the ring is helpful in that scenario. Okay? So there we have the Flieringa ring. All right, so the next step is measuring, centering, and marking. Okay? So once you have the ring on, you want to measure the recipient cornea. And so let’s say we measured it. It’s 12 millimeters. Then you change the calipers to 6, and you mark the central cornea. Then you can measure the vertical diameter, and this helps you to center the cornea. The whole point of finding the geometric center of the cornea and marking it is so when you do trephination, you have a good reference point. Because the vacuum trephine has a cross on it. Now, I additionally like to place another smaller blunt trephine to mark the center of the cornea, so that I know when I’m putting the vacuum trephine on that I’m encompassing that area fully. And then I’m using a marking pen here, just to mark that. So that’s about a 7 millimeter cornea. And lastly, you use what’s called an RK marker. You can buy these at Academy and stuff. And that helps to place the sutures later in the case. Really you only need to mark the four cardinals. That’s the most critical, but with that marker, we’re able to do that. So you have host corneal trephination. Obviously you’ve prepared the donor before you do this. You don’t trephine and then prepare the donor. I’m just showing this in surgical steps here, and then we’re gonna go to the donor. But the next step is generally the donor, okay? This takes an assistant. This trephine here has a little tube that’s the suction, and your scrub tech will push in, and I use those lines right there, and I go on my little dot, I encompass the area that I had previously marked, and then we get suction, okay? And now we have suction, you can tell it’s locked on the eye, every quarter turn is about 60 to 70 microns, but I was twisting that pretty fast, because it was in the air. Now I can feel it hitting the epithelium, and I can see it’s cutting in the stroma. So I slowed it down quite a bit. I trephined down to what I thought was an appropriate distance, and I like to enter in controlled fashion. You can see aqueous right there. Now we’re using viscoelastic to fill the chamber, and the next part involves the use of the corneal scleral scissors. If you have to buy instruments for PK, this is what you have to buy. You probably have almost everything else. What you want to do in this step is excise the recipient cornea. So the way you do it is you use these corneal scleral scissors that have blunt tips, and the bottom of it is longer than the top, and the main thing is you don’t want to cut the iris. So you insert the tips, and then you have to rotate the scissors to be perpendicular to the cornea. Okay? So that you’re cutting up and down. If you’re not perpendicular, you get a little ridge like this, that you can see over here, because I wasn’t up and down. I chose this video, because later in it, I switch to some different scissors. You can see these are curvier. These are easier to use. Those other ones are more for DALK, because they’re blunter. But these more curved corneal scleral scissors are often easier to use. So now we’re removing the final… They’re just kind of big and bulky, and that’s why I don’t always like them. Now we removed it, and the cornea is open sky now. Now here you use Vannas or corneal scissors to remove the little rim I talked about. Sometimes if you don’t cut perpendicular, you get that little rim. You don’t have to remove too much of it, but you do want to remove enough so that the graft sits nicely. All right. So then the donor preparation. This was done obviously prior to the step we talked about. I like to do this under the microscope, and on this punch, I use a marking pen just to mark the inner circle, so that I can center better. But it’s easier to center it under the microscope. If you just try to eyeball it on the assistant’s stand or something, you don’t get as good a result. Using the microscope, I like to center, and I want to see that I have all that purple rim inside the rim there. So once we have it, we punch it. Using the matching holes. This is a bigger graft, 8.75. And so you push down really hard, and you kind of wiggle it, so it punches all the way through. Then you use your 0.3s and you spin it, so that you definitely separate the donor from the donor rim. And so here we are. We put some Optisol in there, and we cover it, and we go and do that preparation. So two little side notes: Sometimes you have to put on a temporary K-pro if you’re doing surgery with a retina colleague. Here are the numbers for that. And if you have to remove a cataract, this is a case I did with Orbis in China. Here we put on the ring, removed the donor, and you can see the cataract is fairly dense. So we’re drying off the bed there and putting some vision blue to help stain the capsule, we’re removing the vision blue, and you can do a can opener-style capsulotomy here to remove the anterior capsule. You can see me talking through… I think this is done by the trainee at the time. If you’ve never done a can opener-style capsulotomy, you should, because it’s a good skill to have, and you kind of want to go right around the edge of the iris, and you make little cuts, kind of bringing them in. What you want to avoid are radial tears that externalize. Here we’re going all the way around. And that’s the free anterior capsular leaflet. Almost free. And then I’ll rewind here a little bit. You can see the lens — once you remove the anterior capsule, the lens just wants to come up. Even though the iris isn’t as big as the lens, it will dilate a little bit. So I’m using the cystotome to elevate the pole of the lens, and then we’ll kind of spin it out. We’ll spin it this way. So we kind of push here. So pretty easy there. Get that bad boy out of there. You look here, it looks pretty clear. This lens didn’t have any cortex, so we didn’t have to do cortex removal. We’re putting a viscoelastic in, basically elevating the side of the iris so you can put this three-piece lens in. You can’t get into the bag, so you want to put the haptic into the iris, and then do a technique in which you bend the trailing haptic forward, get this edge under the iris, and then torque your wrist up, release the haptic, while pushing down on the optic. Now you put a bunch of viscoelastic, and you can proceed with the donor cornea suturing. This was a video given to me by Dr. Aldave. The main take-home points here is that the most important sutures are the first four. You start at 12:00, and this is how you want to hold the needle. You want to go almost all the way back, about 3/4, and it’s the tip of the needle holders. This is the pass you want to do, 90% thickness. Not 50%, and not 100%, because you get wound leak, but 90% thickness. Once you’ve passed it through, you always want to do a 3-1-1 knot, a surgeon’s knot, and you want to lock it back onto the cornea. Everybody always asks what kind of tension do you have to put on these sutures. Well, you don’t want them incredibly tight, like the tightest that you can do. Because you’re gonna have too flat of a cornea. You want moderate tension. Okay? And the way that you know how good your tension is comes at the end here, after you passed the first four sutures. So he’s passing another one here, same thing. Pass through, 90% thickness. Uses his forceps here to help pass the needle. You want to go about 1 millimeter onto the donor, and 1 millimeter onto the recipient. Okay? You want to rotate that knot. 3-1-1. And then after you’ve placed the four cardinal sutures, you dry the cornea, and you can see this diamond. Okay? That diamond tells you that you have nice tension all the way around, okay? And that’s the trick. If you have a funny-looking diamond, then you know you have to replace one of these stitches. Okay? The last part we’ll cover just some intraoperative complications. So some bad things that can happen, right? You can perforate the sclera, make the wrong size trephination, you can have bleeding, you can have damage to the iris, et cetera. When you’re talking about anesthesia, as we mentioned before, anesthesia is your friend. Don’t hesitate to do a general anesthesia case, if needed. In the United States, we have some body habitus like this, and if the patient is not set in a reverse Trendelenburg, often the pressure can go this way and you can have increased pressure during the procedure. How to avoid scleral perforation when placing this ring? First, you need to use a spatulated needle or a tapered needle like this. You don’t want a cutting needle like A and B, or you’re more likely to do it. You also need to rotate the eye for comfort, and make oblique passes if necessary. How to avoid improper trephination? Once the donor is cut, it’s too late. So you need to confirm the trephine sizes with your team in the operating room, and make sure that you have the right numbers. You always want the donor bigger than the recipient, and you always have to cut the donor first. If the donor is too small, you get hyperopia, glaucoma, and you have wound leaks. If it’s too big, you get steep Ks, myopia, and exposure. Donor bigger than the host, 0.25 to 0.5 bigger. You just have to find a system that works for you. And how to avoid misalignment? You need to mark the cornea with an RK, make nice medium thickness depth, and confirm that you have that diamond at the end of the first four sutures. If you have bleeding, it may not be possible to avoid, but air is your friend, okay? First in this case I would do something like a peritomy. But just remove the liquid from the AC once the eye is open, and that’ll help to stop the bleeding. You can damage the iris during trephination. It’s fairly common. Especially in your first few cases, you can fill the anterior chamber with viscoelastic, so that you see viscoelastic expressed when you cut the endothelium. Oftentimes you cannot enter the anterior chamber with the trephine. You can just go down a certain depth with a supersharp. And how to avoid trauma to the lens? If you’re doing any other ancillary procedures like iris repair and things, you need to lift the iris when passing the needle, you need to avoid excessive trephination, if you’re not gonna do anything to the lens, you want to give pilocarpine preoperatively, to get that pupil as small as possible. To avoid capsular rupture during the open sky, you need to be efficient and fast. And you need to be delicate. You need to make sure that the can opener capsulorrhexis doesn’t have any radial tears, and you need to avoid excessive manipulation, and when you’re doing cortex removing, you want to avoid pulling on the capsule or the cortex. If you do have capsular rupture, you can inject some Kenalog and perform an open sky vitrectomy and it’s actually easier to do a vitrectomy in this scenario than a phaco. It doesn’t prolapse forward as much, strangely. And in these situations, you want to use a more rigid IOL that will help tamponade the vitreous. The most dreaded complication would be a suprachoroidal hemorrhage. There are risk factors, like high myopia, multiple surgeries, glaucoma. The older the patient is, any systemic vascular diseases, diabetes, anticoagulation, so this is a good point. I never stop anticoagulants on my cataract patients or endothelial keratoplasty patients, but I do stop it in penetrating keratoplasty patients. I like to stop coumadin, aspirin, Plavix, prior to surgery. Intraoperative factors are things like vitreous loss or sudden decompression. Excessive manipulation of the sclera, passing needles for sutured IOLs, all of these things can increase the risk. Also if the patient has a higher blood pressure, or they Valsalva during the procedure, these are risk factors. You need to communicate with anesthesia, let them know that the eye is open, that they need to be deep under, and not the possibility of bucking on the tube. Here’s a case of posterior pressure, the patient was under a block, and started kind of bucking forward, when iris manipulation came. And it’s not necessarily a hemorrhage, but it’s posterior pressure, expulsion of ocular contents. So you can see the lens here coming forward, and we’re trying to push it back, get the patient under control. Ultimately, you have to put your thumb over the eye. There’s an instrument called a Cobo keratoprosthesis. It doesn’t always work great, but technically this can fill the hole and you can inject fluid in. The problem is, it’s only one size. So if your trephination is bigger, you’re gonna have problems. So anyway, that’s a dreaded complication. Additional questions we had from some of the audience preoperatively, from Shahnawaz Kazi in India: How to avoid suprachoroidal? Look at preoperative risk factors and minimize them, especially the anticoagulation, and what’s the role of Avastin? It does work. The literature suggests that if you inject it subconjunctivally, it reduces it. But the effect is not long-term. You have to keep injecting it. Some doctors laser, steroids are effective long-term in decreasing vascularization. Also Depo steroid in avoiding failure — this is subconjunctival Kenalog. I don’t like to do this at the time of transplant, because you can’t control the pressure. A lot of patients have postop pressure spikes, and if you have this in the conj, you don’t know if it’s coming from the graft or this. And it’s very hard to remove. I don’t mind steroid like dexamethasone subconj right after the case, but the Depo steroid such as Kenalog, I don’t like to do that. And avoiding endothelial loss would be handling surgery delicately enough, using viscoelastic in the bed here, so you don’t have trauma to the endothelium. Another question we had pre-webinar was from Laila Awad in Jordan. What do you recommend to increase the success for pediatric cases? I don’t really do pediatric to pediatric. I’ll do surgery on teenagers, but a pediatric transplant is a whole different animal, and it needs to be done in a team approach, preferably where you have a pediatric ophthalmologist and a glaucoma specialist. If you can get away with lamellar surgery like for keratoconus, I would, because you’re gonna have overall success, but it’s a difficult case. Pediatric keratoplasty, there’s only a handful of surgeons in the United States who do them, because it’s such a niche procedure. So five minutes early. Thank you for your time. Here’s a histology slide of the best part of the eye. So I’m happy to take questions, if anybody has any. And we’ll go from there. So I’ve got a couple of questions here. All right, so we’ll start with one. One of my patients with PKP developed retinal detachment with choroidal effusion 2 months after surgery. He was non-diabetic, hypertensive, pseudophakic with coloboma iris with nystagmus. Many patients can have low pressure, causing effusion without detachment. If you have a choroidal effusion, it means your pressure is low. Number one, you have a wound leak, and you have to fix it, or number two, the eye has some ciliary shutdown. You can get after surgery — just the shock of surgery, you can have the ciliary body stop making fluid. You can get shallowing of the AC and low pressure. That’s treated with dilation, cycloplegia, and intensive steroids, probably oral as well. And then Dr. Shaikh writes: What about suture removal? When should we start removal? Any difference in children and adult? Yes, like I said, I don’t do pediatric keratoplasty, but those sutures need to be removed very much sooner than adults. They get a much more aggressive response to the sutures, not just with the scarring of the cornea, but also with vessels and such. And in an adult, if you have 16 interrupted sutures, I think you can start around 6 months, maybe later. In my process, where I do 12×12, 12-by running, 12-by interrupted, you can start at 4 months. And I showed a little bit in the presentation about using topography to guide suture removal. Any other questions?

>> So Dr. Lehmann, we’ll wait maybe 30 more seconds.

DR LEHMANN: Okay. Dr. Shaikh sends another question: Can we start continuous in the beginning? Yes, the first transplants that were done — not the first, but what was popular in the ’70s or ’80s was a 21-by running suture. However, you still need to place cardinal sutures. You don’t just start with a running suture. That would be bad. Some people use 9-0 nylon, which is easier to manipulate, and you use 9-0 to make the four cardinal sutures. You don’t rotate the knots or bury them or anything. And then put in the running suture. Once the running suture is in place, you remove the four initial 9-0 nylon sutures. Okay! Well, I want to thank you all for your attention. And I hope this was helpful. Thank you very much.

>> Thank you, Dr. Lehmann.

November 12, 2018

Last Updated: October 31, 2022

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