Lecture: Penetrating Keratoplasty

DR MICHAEL TARAVELLA: The webinar today focuses on corneal transplantation for the comprehensive ophthalmologist. My goal in this is really to talk a little bit about the lost art of corneal transplantation. As many of you know, we are currently doing endothelial keratoplasty for disorders such as Fuchs dystrophy and bullous keratopathy, and we can do deep anterior lamellar keratoplasty as well for things like keratoconus. However, there’s still a very important role for corneal transplantation. So I hope today that I can share with you my 30 year experience in doing corneal transplants, and perhaps keep you out of trouble when you’re approaching yours. These are my financial disclosures. At present, I do not have any financial interest in anything I’m presenting today. I was a consultant for Surgical Specialties, and helped develop the Ultrafit trephine system that you’re going to see today, but the things I’m talking about really apply to just about any trephine system. So in terms of corneal transplantation, one of the most important things is selection. How do you select your patients? Now, again, today, for keratoconus, we might think about deep anterior lamellar keratoplasty, but for keratoconus with a full thickness scar, that might be an option. So conditions that have a good prognosis would be keratoconus — again, endothelial dystrophies, this is something you would think about endothelial keratoplasty unless you have a full thickness scar. Central scars resulting from infections and ulcers. Where the cornea is not very vascularized. Certain corneal dystrophies. Again, there are other options for these. But what these all share is that they are unvascularized corneas in white, quiet eyes. And I think that’s a very important part of the prognosis. This is an example of keratoconus with a positive Munson’s sign. And an endothelial dystrophy, without scarring. So, again, this might be a better candidate for endothelial keratoplasty. But if there was anterior stromal scarring that ran full thickness, then we would certainly think about penetrating keratoplasty. In the United States, back in 2011, and I think it’s gone up since then, about 50% of grafts in the United States are DSAEK or EK, but, again, you can certainly do a penetrating keratoplasty for these disorders as well. Granular dystrophy is a case where we might think about phototherapeutic keratectomy with a laser, an Excimer laser, to polish the cornea, rather than do a full thickness corneal transplant. But, again, it’s an option if you have a lot of central scarring. So not quite as good a prognosis, but still a good prognosis are corneas that have mild vascularity, where the lesions may involve the corneal periphery. This would include pseudophakic or aphakic bullous keratopathy, and inactive herpes stromal keratitis. So inactive HSV has a good prognosis, especially if it’s well controlled with oral acyclovir. But the keyword there is inactive. We don’t want to work on an actively inflamed eye or one that’s infected. Here’s a case of pseudophakic bullous keratopathy. This is a lens you’re probably not gonna see anymore. It has an iris clip lens. So this is one that you don’t really see anymore, of this style lens, but certainly you can see pseudophakic bullous keratopathy, especially if an endothelial dystrophy was missed. If this had a full thickness scar, again, candidate for penetrating keratoplasty. Otherwise, endothelial keratoplasty would be better. So corneas we should try and avoid are probably heavily vascularized corneas. This would include severe chemical burns, ocular cicatricial pemphigoid, Stevens-Johnson syndrome. If they have active HSV keratitis, then we want to really quiet that eye down. The question always comes: How long should we quiet the eye down? And I would say at least 6 months. So these are patients that we want to cover with acyclovir. And generally, when I start them on acyclovir, I’ll keep them on acyclovir for life. It’s always hard to know when to take them off. But I think it improves the prognosis for recurrent infections. So patients with multiple rejection reactions — these are poor prognosis eyes. Patients with uncontrolled glaucoma. And any patient who has active inflammation. So patients with multiple rejections — this might be a candidate for a keratoprosthesis. Many of the techniques we’re talking about today can be applied to keratoprosthesis. So here would be a case of active HSV keratitis. You can see these beautiful dendritic lesions that are sprouting up here. Again, we would want to treat this with both topical and probably systemic acyclovir before we would consider grafting this patient. And here’s a patient with active herpetic stromal keratitis. Very inflamed. Again, poor prognosis. We wouldn’t want to graft this patient, unless there was a perforation and we really had no other choice. And a very severe alkali burn. You can tell this because the cornea is totally opacified. Can’t see any iris detail at all. And look how extensive the limbal ischemia is. Almost 360 degrees. So this would not be a good case to do penetrating keratoplasty. So what’s our definition of success? Well, I guess fortunately the definition of success with penetrating keratoplasty is rather modest. The main thing is to get a clear, compact, thin graft with no signs of rejection. We would like to see an improvement of vision of 2 or more lines, and ultimately, so a patient can get back in glasses, we would like to see low astigmatism, less than 3 diopters. What do we talk about, when we talk about donor selection? Well, in general these are guidelines. You can certainly use older donors, but I like them when they’re under 65. I think we do want an endothelial cell count, if possible, greater than 2500. The death to preservation time, ideally, would be 8 hours, but I’ve certainly taken them longer, especially if it’s a good donor. So if the corneas are cold immediately, put on ice, it can easily go up to a day before you would have to preserve them, from the donor. The storage media that we prefer is Optisol. From the time you put them into the storage medium to the time you graft — you can generally get at least 3 to 7 days. The closer to 3, I think, the better, because the grafts will often swell, and it will take a long time to deturgesce if they’re stored in Optisol longer. So ideally from the time the donor dies to the time you transplant, I think the ideal window is 48 to 72 hours. Again, if you can’t do that, and you have Optisol, you can go out a little bit longer. So the preoperative examination is pretty straightforward. We want to try and get an idea of what the patient will see afterwards. We want to do vision, visual acuity, and oftentimes what I recommend is doing an overcorrection with a hard contact lens. This neutralizes a regular astigmatism optically, so it gives us an idea of what the retina is capable of. I check the pressure, the intraocular pressure. I like the Tono-Pen, because the small applanation surface on the Tono-Pen is more accurate in an irregular cornea. You want to perform a complete slit lamp examination, especially looking for trichiasis or lid disease, exposure, things like that, that might be a problem after surgery. We want to try and address those. Look at the retina. Make sure that you’re not dealing with a retinal detachment, and if you can’t see the retina, then certainly an ultrasound would be indicated. If you have trichiasis or exposure on the lids and lashes, that should be addressed before you do the transplant. And last but not least, I think an ocular surface assessment — I don’t rely on the Schirmer’s test much anymore, but I do use fluorescein and lissamine green to determine if a patient would benefit from the use of things like cyclosporin, topical cyclosporin, preoperatively, or punctal plugs, or tarsorrhaphy, even. If their ocular surface is compromised by dryness or exposure. Special tests that we use can certainly be an ultrasound, looking for retinal detachment, but a poor man’s ultrasound is simply projection. So if a patient can project in all four quadrants, it generally means they’re not detached. If they can see gross color vision, like a red pen light or a blue pen light, or a light shining through the red bottle cap, that indicates to me they have gross color vision, and there’s probably some macular function. You want to look for optic nerve cupping. If you can see the optic nerve, you can sometimes see the cupping on ultrasound as well. And again, that will give you an idea if the patient has a poor prognosis for vision, in terms of glaucoma. Visual field testing, oftentimes, is not practical, but if you can get it, it’s helpful. A projected acuity meter — sometimes these corneas are so densely scarred, again, not usually that helpful. So let’s get into operative technique. One of the first questions that comes up is: Should we put a Flieringa ring on the eye or not? This is a ring that’s used to stabilize the eye, since once the cornea is off, we’re open sky, and you can get scleral collapse with forward movement of the intraocular contents. I think especially if you’re a beginner, a ring is a good thing to use, because I do think it helps stabilize the eye. I think other things we want to talk about are the choice of speculum. My current choice of lid speculum is something that doesn’t push down on the eye. So that’s again up to individual surgeon preference, but I like the Shapiro speculum. Because I think it’s one that does not put a lot of pressure on the eye. Again, causing positive vitreous pressure when you’re open sky. Trephine and punch selection — we’ll talk a little bit about that. I do use a spatula to help transfer the graft, and I’ll show you a video of that. Forceps. We’ll talk about those. One set of forceps, double-prong forceps, they’re called Pollacks, and they’re useful for the first bite, when you have sort of an unstable situation, and you’re trying to create that first bite of the cornea. And then scissors. We use Troutman scissors, both to the right and to the left. They’re highly curved scissors. Any corneal transplant scissors or scissors designed for corneal transplantation will work. But my preference is Troutman-Barraquer scissors. So when you’re suturing a ring on, I generally use 6-0 vicryl suture on a spatula needle, no more than 2 to 3 millimeters back from the limbus. The reason for that is that, if you go back 3 millimeters from the limbus, you’re really not going to hit retina. You’re going to be over the pars plana. So if you do perforate, as you’re trying to pass a suture through the ring, then I think it’s just a safer situation. The idea is to avoid perforation, suture towards the cornea, avoid excess tension, and the reason to that is to avoid astigmatism. And this is just an illustration of suturing the ring. You can see that this is evenly spaced around the cornea. This example has 8 sutures placed. Notice that we’re suturing towards the cornea. And this is a pass through the conjunctiva and through the sclera. The other useful thing about having a ring on is you can put traction sutures in 12 and 6. In fact, you can leave the 12:00 and 6:00 suture long, after you make the pass. You can tie it and leave one end very long, and you can use that as traction sutures to move the eye right, left, or whatever movement you need to get good exposure. So then this is a nice picture of a support ring, and good exposure. Again, the idea with the support ring is once you’re open sky, especially if you have other procedures you’re doing, or if the eye is aphakic, or oftentimes with children, this really helps to prevent scleral collapse. My own personal preference right now is for pseudophakic eyes — I generally do not do it. For aphakic eyes, I will. And again, sometimes it’s useful for keratoconus, but many times for a keratoconus patient, I will not use it. Let’s talk a little bit about technique. I think one of the first and most important things about penetrating keratoplasty is to mark the center of the cornea. So I usually use calipers to find the center of the cornea, and then use a marking pen just to put a central mark. The other thing is we use an 8 or 12-incision RK marker. The suture pattern of preference for me is a double-running suture, but I would think, when you’re beginning, using 8-incision RK marker and placing 8 individual sutures is probably a better way to go. And then follow that with an additional 8 sutures, for a total of 16 interrupted sutures, especially if you’re a novice. Once you get that 16 interrupted suture pattern in, you can put a running in between, and that’s a good way to transition from an interrupted pattern to a running pattern. I think, while you’re preparing the cornea, the donor cornea, it’s a good idea to, after you’ve marked the cornea, place a Weck-Cel sponge over the cornea and central cornea to keep it moist as you’re preparing the donor. Now, the RK marker, the usefulness of that is it helps us guide future suture placement. So useful a radial keratotomy marker placed on the cornea, dipped in gentian violet, as I’ll show you, just shows you how you might be able to mark the cornea and get a good idea where your sutures are going to go. So let’s look at this video. So, again, this is one particular system, but what I’m talking about will apply to other systems as well. So you can see here — we’re measuring the cornea with calipers. We’re trying to find the geometric center of the cornea. I will take that dot and move it just a titch nasal, because that’s where the visual axis is. So that’s what we’re really trying to do, and one of the cardinal sins of corneal transplantation is not centering your trephination. So I think it’s very important to get a center trephine. So then we just put a little mark on the center. This will be useful when we’re actually doing the trephine. Especially if you’re using a suction trephine, and you’re sighting down the barrel. Here’s an RK marker. This happens to be a 12-blade RK marker. And the idea with this, again, is it will help guide suture placement after trephination. So the next thing is looking at the donor. The donor tissue is warm to room temperature, and then transferred to the field. Generally once we open the donor container, I will have the nurse hold the container over the field, being careful not to touch the sterile field, but the idea is that the graft falls — as you’re making the transfer, it falls onto a sterile field and not onto the floor. Unfortunately, I’ve witnessed that one. So you just have to be careful with transferring the donor. I generally use a large-toothed forceps, such as a 0.3 or 0.4, to grasp the donor by the sclera, and then place it directly in the trephine block. You center and then trephine from the endothelial surface. And when you’re doing that, you want to use light pressure, then hard pressure. So light pressure tends to take some fluid out of the stroma and centers the trephine. It keeps it from slipping as you’re doing the donor trephination. So first light, then hard pressure, and coat it with viscoelastic. So this shows trephining the donor cornea. And it’s using a vertical guided punch. It shows firm pressure. Once the endothelium is touched. And then you complete the cut. So the idea is to try and get as vertical a cut as possible, and I’ll show you different models of trephines that can be used. And again, this just illustrates trephining the donor. So I think we can stop for a polling question. Larry, I think you have those, if that’s possible. Can we put up one of the polling questions now? So I don’t know if you have those or not. But… If we can, we’ll put up a polling question, and see if we can get a response. Well… I’m not seeing it come up. So we’ll just keep moving on. Then we’ll get to those as we can. So this just illustrates how to trephine the cornea. And one thing I actually like to do is to trephine under the surgical microscope, because I think you can see this a lot better. This is a guided punch. Again, this is the UltraFit system, but what I’m talking about here applies to any guided system. So you brace the cornea with your left and your right hand. And then you center the blade. Once you touch the endothelium, you can’t come off. You press easy, and then you press very hard. And then we’ll just remove the top of that, take a look at the donor, and you can see — I like to inspect the rim, just to make sure I trephined in the center of the donor. And before we actually transplant that donor, we’ll coat the endothelium with a little bit of HEALON. So when I trephine the recipient, I generally use a suction trephine system. I center under the microscope. I don’t like handheld trephines, because the one thing you can be sure of, if you’re cutting with a blade or Castroviejo system, is it’s very hard to keep the trephine vertical with respect to the iris plane. The iris and limbal plane. Much easier if you have a suction trephine. So there are many different models of these. Again, the one I’m using here was developed by Sharpoint. I think it’s handled currently by Coronet. But the Barron-Hessburg trephine by Katena also is out there, and there’s many similar to this. So what I’m talking about with these suction trephines applies to all of those. And that just shows you an illustration of a suction trephine. Note that the suction is applied by spring-loaded syringe. One important concept is the fact that, on most of these suction trephines, 3/4 of a turn equals 0.25 millimeters. So it’s just kind of a depth guide, in terms of — if you want to do a partial trephination, I’ll show you how to set the trephine to zero. But once you start spinning the trephine counterclockwise, you’re cutting into the cornea. And that certainly would — it’s a useful number to have if you don’t want to go all the way through the cornea. In general, I don’t mind trephining all the way through. So let’s just take a quick look at that. It’s very similar. Now, you notice that it has 3 cylinders on the suction trephine. The inner two cylinders act as the vacuum chamber. What I’m doing here is advancing this by turning it clockwise, to make sure that that inner blade is level with the inner cylinder on the trephine. That’s the zero point. Then I’ll back off about 6 quarter turns. Then I engage suction. Notice that we’re looking down the barrel, and you can see the dot that I made earlier to ensure that the trephine is centered. So we’re gonna back off 3 quarter turns, or even 6 quarter turns from the zero point, before we actually trephine, so that we don’t — as you engage suction — you don’t want to start cutting the trephine before you mean to. Then you advance back to the surface. If you’ve backed off 6 quarter turns, you generally advance 6 quarter turns. Now, it turns out, when you apply suction, some of the cornea gets pulled into the trephine itself. So you might actually start cutting before you get to that 6 quarter turns that you backed off initially. Each quarter turn — 3 of those is 0.25 millimeters. Now, you can see the right hand is doing the cutting. The left hand is actually bracing this trephine. So it’s bracing on the surface. You really don’t have to press down hard, once suction is applied and you have good suction. So then, when you think you’re through, sometimes you’ll see a little burst of aqueous coming to the center of the trephine. And then I’m going to just show you, before I enter the eye, that this is really a good trephination. It’s well centered. It looks like we entered the eye near the 12:00 position. And it’s very evenly — the trephine is very even, well centered, and that’s what you really wanna see. The trephine size that you pick is generally going to be 7.5 to 8.5. That’s sort of the sweet spot. If you get under 7 millimeters, you start inducing more astigmatism and irregular astigmatism. If you start getting out around 8.5, you get too close to the limbus, encourage blood vessels to grow into the cornea after surgery, and increase your risk of rejection. So then I’ll enter first into the eye with a microsharp blade, allow the eye to decompress. The thing we’re trying to avoid is a suprachoroidal hemorrhage. The idea here is to use corneal transplant scissors first to the right and then to the left. I’m very right-handed and dominant with my right hand, so I usually will start to the right, go almost all the way around to the 9:00 position, and I’ll show you a video of that. The idea is to keep this cut very perpendicular, and you want to probably leave a slight rim at the bottom of the trephination, to keep the iris from incarcerating and protect the iris. And this is just an illustration of cutting the cornea. So, again, I’ll usually enter the eye here. In this particular instance, in this video, I’ve entered up here. But generally I’ll try to enter here, and I’ll go all the way around to about here with my scissors. Again, because I’m dominant. My right hand is very dominant. So I’ll go from roughly 3:00 to 6:00, all the way to 9:00. And then I’ll come back in the other direction, 2 to 3 clock hours, with scissors to the left. So let’s look at that. You can see that I’m using this blade to create an opening just big enough for my corneal transplant scissors. And these are Troutman-Barraquer scissors. Again, I have no financial interest. I believe they are manufactured by Bausch and Lomb Storz. But you can see they’re highly curved. So then I lift with that inner blade to make sure I’m not engaging the iris. Notice that I’m also pulling the cornea a little bit, so I can see where those scissors are cutting. So I’m actually grasping the cornea and pulling it towards the center of the eye a little bit. So I can really see the bottom of the trephination. Lifting on that inner blade, leaving a slight rim. And I’m going almost all the way to the 9:00 position. Then we’ll come back and cut it with the other eye to the left. Now, if you have work to do in the eye, sometimes you can leave one clock hour hinged, and just flip the cornea over. This allows you to close the eye quickly, in the event of a suprachoroidal hemorrhage, something you always have to be on the lookout for. We’ll talk about that under complications, a little bit. So then you transfer the donor to the field. You want to make sure that the endothelial side goes down and not up. Unfortunately, I’ve seen that one before, so you have to be very careful to put the endothelial side down. So you want the correct side up. If you’re using a suction trephine, sometimes it’ll leave tiny marks on the epithelial side, and it’ll allow you to see the epithelial side and make sure that it’s facing up, or the endothelial side is facing down. So let’s, again, look at a video showing how to transfer this (inaudible). So using a Paton spatula. It’s kind of like a little slotted spoon. Note that the endothelium has already been coated with a little bit of HEALON. And when you have a case like this — this is a anterior chamber lens, which is well centered, well supported, so I elected to leave it alone. I usually put a little HEALON directly over the anterior chamber intraocular lens as well. So suturing, again — the most important is the 4 cardinal sutures. The first two have to be 90 degrees apart, in terms of astigmatism inducement. For beginning sutures, surgeons, novice surgeons, I recommend 16 interrupted, 10-0 nylon bites. As you become more advanced, more comfortable with your technique, I think you can transition from 16 interrupteds and put a 16 bite running in between. This gives you really good wound apposition. It also allows you to come back later in 2 to 3 months, as you’re removing sutures, and do selective suture removal, to control astigmatism somewhat. I think the least forgiving technique is one single running suture, 24 bite suture. This is least forgiving, because if you develop loose loops or vascularized quadrants of the cornea, where 10-0 nylon running suture can become loose, then you may have to remove it prematurely and risk a wound dehiscence. So I would say do not begin with a single running suture, but start with 16 interrupteds, and if you want to do a running, put a running in between those. And how deep should a bite be? Some people advocate a 90% bite. I like the idea of a 90% bite. Sometimes it’s hard to tell if you’re 90% or full thickness. In general, if you have a full thickness bite, it’s not harmful. Usually does not end up with epithelial ingrowth and infection. But I would say go as deep as you can, to try and avoid a posterior wound gape and get good wound apposition. So our goal with suturing is to get good anterior and posterior wound apposition. We want deep bites. The ideal bite length is about 1 millimeter on the donor side and 1.5 millimeters on the recipient side. Try to avoid dulling the needle tip or bending the needle. Again, we’ve used that radial keratotomy marker to help space bites and make our bites even. And your brain is very target-oriented, so it’s nice to have those marks on the cornea as a target for future suture placement. When you tighten a running suture, try to do it carefully. Don’t pinch the suture and don’t overtighten the suture. And this is also including — even with interrupted sutures. We want to really approximate. Don’t strangulate. Sometimes I will use a double running suture. It is harder to learn, but it gives you really excellent anterior wound apposition, because of the criss-cross pattern. And it also creates an antitorque pattern. When you put in a running suture in one direction, it creates a slight torque or twist on the graft. If you put a running suture in the opposite direction, it relieves that torque, and again, that criss-cross pattern — I’ll usually go, instead of going in the same direction, go counterclockwise on a first running suture, and then clockwise on the second running suture, being careful to make sure that you don’t cut the first running with the second running suture, as you’re putting it in. I think the idea here is good wound apposition, but again, I don’t recommend that technique for novice surgeons. This illustrates putting in the first two cardinal bites at 12:00 and 6:00. Let’s just look at that. Intraocular lens appears to be well centered and well sized. So again, that’s just saying that the lens — if the lens is unstable, then you have to replace it. The options of replacing might be a glued in or sutured in intraocular lens, or a better fitting anterior chamber intraocular lens. But this one looked really good. And note that there is HEALON on this graft. On both the anterior chamber lens and the cornea itself. So this is the Pollack forceps I was referring to. Notice that they have a space, and it allows you to pass the suture right between the prongs. And that allows you to get a very stable bite on your first bite. Now, generally, the Pollack forceps I will only use for the first bite, and then I’ll switch over to Colibri forceps or 0.12 forceps for the rest of the suturing. I use a 2-1-1 pattern. I’ll illustrate that. Primarily because I can control the tension on it, and it’s easy to bury. The idea with these knots is they’re gonna have to come out sometimes, so if you make a really big knot, sometimes they’re hard to get into the eye, to bury them. But they’re very hard to get out as well. And we’ll trim it, leaving a little bit of a tail. Notice that I’m kind of seeing how the graft is going to fit, and it fits very nicely. So when you trephine, I usually will trephine slightly larger than the recipient trephine. So in this case, the recipient, I believe, was 8 millimeters. So the donor was 8.25 millimeters. So use maybe a quarter millimeter larger on the donor than on the recipient. Now, what I do is stop after that second suture, and I look. And I’m looking for a gap to the right and a gap to the left. So that suture right there — what I’m looking for is: Is it well placed before I pull it through and tie it? I really want to know if I have good alignment of my graft. And this shows you the order of suture placement. So 1 and 2, and then 3 and 4. So usually we’ll go — here’s the surgeon’s 6:00 and then the 3:00 and 9:00 position, and then in between. And that’s your first 8. Now, if you’re gonna do 16, then you can come around and put interrupteds in between there. And again, the idea here is 1 millimeter on the donor side, 1.5 millimeter, if possible, avoiding the limbus, on the recipient side. Again, this just illustrates the 2-1-1 knot. It’s easier to bury than 3-1-1. So you have to make sure that these throws are in opposite directions, so it squares the knot. But this is a very good technique, in terms of creating a small knot. And notice here that we have really a deep bite, and again, we’re trying to avoid a posterior wound gape. This shows tightening the suture, but in general, I don’t like to pinch the suture as you’re tightening it. You can lift with one prong in the forceps. I’ll usually start 6:00. March slack all the way up to here, while holding that end. Then grab it here. Again, march slack all the way up to here, while you’re holding this end. The idea is not to pinch, but just to lift. A Sinskey hook works well too just to lift and remove slack from the suture. So this just shows tightening a running suture. And again, it’s going to be tight here. With the knot buried, if possible. And the idea here, again, is not to pinch the suture and create weak spots. So start at your surgeon 6:00. Tighten by lifting, not pinching. Again, a Sinskey hook or one side of a tying forceps. I will usually — it doesn’t matter which side you start on. Just be consistent. The goal, again, here, is to remove slack. Do not overtighten. This is just going to show placing a double running suture. Now, this happens to be a 12-bite double running suture, so I used in this particular case — I used 6 cardinals. Did a running bite in one direction, and coming back in the other direction. And putting a running suture through as well. Now, the idea also, as you’re doing a running suture — very important not to touch the tip of the needle. If you touch the tip of the needle, as you’re passing this through, you touch this part, as you’re passing this through, what will happen is you’ll dull the needle. And you’ll notice that right away, after just several bites. It becomes very difficult to pass. So be careful how you grasp it. Now, this, if you notice, this is a double running suture, so one suture ran counterclockwise, with the knot not tied near the 12:00 position. The next suture ran counterclockwise. Yeah. Counterclockwise first time. Clockwise the second time. You notice that nice criss-cross pattern? Again, that creates good wound apposition, with the idea of trying to avoid anterior and posterior wound gape. The way I tie those knots is I will usually start my knotting — start my suture bite on one side, and finish on the opposite side, so that as you tie the knot, it’s automatically buried. Now, this is a beautiful single running suture, but it is a very unforgiving pattern. And the reason is — if you get vascularization here or loose loops, then you might have to take that suture out early, and risk wound dehiscence. So this is not something I recommend for novice surgeons. Even for advanced surgeons, I don’t use this particular technique. My preferred technique right now is 16 interrupted sutures with a running in between. So next, when you’re done, we want to refill the anterior chamber. We’re looking for wound leaks, but we’re also watching the iris carefully. We’re trying to avoid incarceration. If you have a little viscoelastic inside the eye, some of it will come out, as you’re irrigating at this point. A little bit of viscoelastic is okay. A lot is not. Sometimes that’s a judgment call. If you leave too much, you’re gonna get a pressure spike after surgery. So this will show you how to fill the chamber. Just go in between your sutures. Fill the chamber, look for wound leaks. If you are not sure, then one thing you can do is put a little fluorescein around the edge. I usually check very carefully with the Weck-Cel sponge. If you have an area that even with a double running suture — sometimes you’ll get tiny leaks — you can pass a — carefully pass — an interrupted suture in that area. And again, looking at the iris, to make sure it’s not incarcerated. So now we’re done with surgery. What’s next? Subconjunctival injections. You can use those. I don’t really use these anymore. Cefazolin is what I would recommend. Another option would be to inject a little subconjunctival steroid. I usually do not recommend gentamicin, because the risk is, if you get that inside the eye, you can get some very severe retinal toxicity, and I have seen cases referred to me where vision was lost due to inadvertent injection of gentamicin into the eye, due to retinal necrosis and retinal toxicity. Another really nice way that I like is to just use a collagen shield soaked in moxifloxacin and dexamethasone. Put 5 drops of each of these in a solution, make sure both sides of a collagen shield are covered. It delivers a very high pulse of these medications into the anterior chamber, so you patch the eye and leave the collagen shield on at night. Usually use a 12-hour shield, so by the next day, it’s gone. So let’s talk a moment about combining procedures. The most common one that we will do is a cataract. You can do this open sky, and if you do this, you have to do an extracapsular technique. Generally it’s very difficult to do a capsulorrhexis open sky, so I usually tell people to try a can opener-style capsulotomy. It’s also very good if you have a soft eye, when you’re trying to do a combined procedure. So for combined procedures, I would recommend things like mannitol, a good retrobulbar block, good massage, maybe Diamox, get the pressure low and the eye soft. If you’re going to do a combined procedure, open sky. The opening has to be usually about 8 millimeters, or it’s difficult to get the nucleus out. Probably the more difficult part, when you’re doing open sky techniques, is removing the cortex, because you have to be very careful not to rupture the posterior capsule, if possible. If you’re planning on putting in a posterior chamber intraocular lens in. I use a manual technique, using a Simcoe irrigation and aspiration cannula to get the cortex out. And then, if we can, we’ll put in a posterior chamber intraocular lens. So this just shows prolapsing the cataract out of the eye. Usually it comes out pretty easily. You can use a combination of irrigation and spatulas to get behind the lens nucleus and deliver it out in toto. And then irrigate the cortex out — again, with a Simcoe manual irrigation and aspiration technique. However, my preferred technique at present is to try and combine — if I’m going to take a cataract out, I’ll usually do the phacoemulsification part first. Now, this depends on how opaque your cornea is. But if you have a good view, then I think it’s a nice procedure to try and do penetrating keratoplasty first. Your view might be compromised, because you’re probably doing this for a corneal scar anyway, but sometimes you can work around it enough. You can use techniques like chandelier illumination, which has been described like a light pipe inside the eye, so that you have good visualization. Staining the capsule. All those things help with this particular technique. The nice thing about this is you do the phacoemulsification first, get a good capsulorrhexis, which means your intraocular lens goes in the bag. You can decrease your open sky time, which is the most risky part of the corneal transplant. You don’t have to worry about endothelial damage during the phacoemulsification part, because you’re going to remove the cornea and put a new one in. And you can bring nuclear fragments into the anterior chamber to phacoemulsify, again without worrying about endothelial damage. So again, when possible, I try and combine phacoemulsification with penetrating keratoplasty. The downside is it increases the surgical time. You may not have an adequate view. And the phaco time — the phaco wound has to be placed in the periphery, and maybe even sutured before you can do your trephination. Because the phacoemulsification incision can interfere with trephination. This shows putting a wound in open sky note. This first — one has kind of snuck in the capsule. You can see that this was a can opener capsulotomy. The first part of this 3-piece intraocular lens is in the capsular bag. The second loop — you’re doing open sky — really has to be compressed, and sometimes it doesn’t hurt to press down on the center of the lens to make sure that this haptic, if possible, can slip into the capsular bag. And again, this shows just insertion of an open sky technique. What about intraocular lens exchange? As I showed you in this particular case, if you have a flexible loop anterior chamber intraocular lens, you can leave it alone. A posterior chamber intraocular lens, if it’s well positioned, scarred into the bag, can be left alone as well. If it’s unstable, then you may have to remove it. This is both for a posterior chamber and anterior chamber intraocular lens. So what are your options? You can put in a flexible loop anterior chamber intraocular lens. I will do this if you don’t have a lot of peripheral anterior synechiae and you have good iris support. And you have a properly sized anterior chamber lens. You can also put a sutured-in or glued-in intraocular lens. I’ve done both those techniques. I won’t cover how to do those techniques today. I think there are well illustrated videos, if you want to look at those techniques. The main thing about suturing in an intraocular lens in this setting — sometimes it’s a blind passage of a needle, and you can get bleeding, tilt of the lens — I think it’s a more difficult technique. But I’ve done both suturing and a glued intraocular lens technique, where you couldn’t really get a good anterior chamber intraocular lens, and you had angle pathology. The remaining thing, again, with the sutured-in technique, is there’s a risk of hemorrhage, tilt, and exposure of those sutures. This is probably one of the more common things we have to do, if you have a pseudophakic or aphakic eye, and the capsule is not intact, and that’s an anterior vitrectomy. So we really want aggressive removal of any vitreous in the anterior segment, in contact with the iris. You use a dry technique. So as you’re doing the vitrectomy, it’s not necessary to have irrigation at the same time. I like an automated technique. So you can use the same vitrector that’s usually hooked up to your phaco machine. You don’t really need a retina machine. So I will use, for instance, for me, the Alcon Centurion has a really nice vitrectomy setup, and I will use that to remove the vitreous. And this just shows that you’re removing the vitreous open sky. The idea is to get as much vitreous in the central core here as possible, until you see these iris leaflets drop back, and there’s no anterior chamber vitreous or incarceration of the vitreous in the anterior chamber at all. Sometimes it’s very hard to see it, and you can use triamcinolone, a little bit, open sky, just to stain vitreous, and that way it can help you with removal. I do tend to remove synechiae, but I don’t spend a lot of time removing them. I will usually use a blunt spatula and scissors, and gently try and peel these back from the cornea as much as possible, if present, and unfortunately, in a lot of these cases, you’ll run into synechiae. The idea is to try and avoid bleeding, which sometimes can be very difficult. Does it really help? A lot of times they’ll just recur anyway, but in general, I will try and move synechiae to the back of the cornea, to try and create as much room as possible for your graft and try to avoid iris touch, especially to the new cornea. I am not a fan of combining glaucoma procedures with penetrating keratoplasty. I do think the pressure should be well controlled, so if possible, do your glaucoma procedure first. Do your trabeculectomy or valve first, and get your pressure down. It also helps eliminate potentially toxic medications. So it’s a good idea to try and get the glaucoma under control before you do your penetrating keratoplasty. The other thing, of course, if you’re trying to combine a procedure, and you end up with a flat chamber, you can compromise your corneal transplant. So postop care — usual regimen. I will see them 1 day, 1 week, 1 month. My antibiotic of choice is a fluoroquinolone or a Polytrim, which is polymyxin/trimethoprim. If they’re not sulfa allergic, it’s very good against MRSA. I usually cover them with a fairly strong steroid. Prednisolone acetate 1% is okay. I’ll start them on at least 4 times a day — sometimes more or less, depending on the amount of inflammation. And that will really go over a very slow taper over the first 6 months. If you have high pressure in the early postop period, medications like Alphagan and timolol, brimonidine and timolol, are very good to help control the pressure. I think it’s also important to try and keep the ocular surface intact and healthy. So using preservative-free artificial tears is also important. So my current recommendation would be to use a fluoroquinolone and prednisolone acetate, 1%, 4 times a day for the first several weeks. Probably stop the fluoroquinolone in 1 or 2 weeks. I like a fourth generation fluoroquinolone, but certainly a third generation fluoroquinolone like ofloxacin works quite well. The fourth generation I like is Vigamox or moxifloxacin, because it’s unpreserved. So I will use that up to 4 times a day. And again, Polytrim, I think, is a very good choice. It’s not expensive, and it really has good activity against a lot of Gram positive organisms, like methicillin-resistant staph or MRSA. I think it’s especially important to use it preoperatively in patients who are health care workers, that you suspect might be colonized. All right. Let’s talk a little bit about intraoperative complications, and then we’ll talk about some early and late postoperative complications, and we’ll be done. First intraoperative complication and most dreaded one for me is an expulsive choroidal hemorrhage. This occurs in about 0.5% to 3% of patients. The risk factors are high myopia, long axial length, advanced glaucoma, and hypertension and advanced age. So I think the main key to prevention is to try to have a soft eye and slowly decompress the eye. So we want to try and minimize the pressure gradient from opening the eye to the atmosphere as much as possible. And we do that with mannitol, massage, Diamox, if necessary. A good retrobulbar block. And then when you enter the eye, allow it to decompress for a minute or two, before you proceed with any other additional work. If you have one, they can be very difficult to manage. What I will do is generally have my assistant put the finger directly over the eye while I’m preparing the donor. You can use what are called tacks to get the donor out quickly. This simply is something like 6-0 vicryl suture with the suture ends trimmed short, so you can tack down at 12:00, 6:00, 3:00, and 9:00, and then put sutures in between. So you kind of just do a partial pass of that suture, and the suture — the needle itself you have four tacks or sutures that you can use to get the cornea donor on quickly. The idea with that, again, is to try to get the eye closed as quickly as possible. Can you do a sclerotomy? Yes, you can do a sclerotomy, but generally you have to close the eye first, and you have to know what quadrant the blood started in — or the bleeding started in. If you’re going to do a full thickness sclerotomy, it should be done about at the equator, which is generally where the rectus muscles insert, about 7 to 8 millimeters back. And you would have to recognize the quadrant of that the hemorrhage is starting in. So one of the more common early problems I run into is epithelial healing. So I usually will patch the first day. If you’re really noticing that by one week out, you’re not getting much in the way of healing, then again, minimize medication toxicity, perhaps put them on antibiotics, if there’s no sign of infection. Add preservative-free artificial tears — and I can’t emphasize the word preservative-free enough. Think about punctal occlusion. Think about a tarsorrhaphy. Think about a bandage contact lens. But it is important to get the epithelium to heal as quickly as possible. If you have a wound leak, don’t hesitate to go back in and resuture it, if it’s not getting better with conservative measures such as a patch or a bandage contact lens. I think it’s very important to monitor intraocular pressure. So I will generally use a Tono-Pen, because of the small applanation surface. It’s more accurate. The glaucoma medications I prefer are oral carbonic anhydrase inhibitors, if the pressure is very high. If it’s moderately elevated, then you can think about brimonidine or timolol. I don’t like to use pilocarpine or Xalatan, because they tend to kick up inflammation, and there’s been some case reports that Trusopt, or dorzolamide, and topical carbonic anhydrous inhibitors, especially, might have some endothelial toxicity. So, again, oral carbonic anhydrase inhibitors, alpha-adrenergic agents, such as brimonidine and timolol. It’s very critical to get the pressure normal for the success of the graft. One of the key factors for graft failure is uncontrolled intraocular pressure. If you have poor wound apposition, suture if necessary. If you have astigmatism at about 3 months, start removing sutures selectively, based on topography or keratometry, or if they just look tight, it’s okay to pull them. But normally I’ll wait about 3 months. If you have a wound gap, then you may have to suture it, rather than remove a suture. And this can certainly be a cause of astigmatism, and it’s known as a microdehiscence. I generally don’t recommend adjusting 10-0 nylon, because of the risk of breaking it at the slit lamp. It’s a technique I used to use, but I really don’t use it anymore. So really, in the first year or so, I’m just selectively removing sutures to try and minimize astigmatism. The most feared late complication is probably rejection. So an eye that’s becoming red, vision is dropping, patient has pain — you’re seeing typical keratic precipitates on the endothelium — this has to be treated immediately, and generally you treat with very strong topical steroids. You can consider a burst of systemic steroids, such as IV pulse of methylprednisolone. That also helps get things under control rather quickly. Especially if you have a patient who is not very compliant. Can you use cyclosporin topically? Yes, if you have it available. It’s not really been proven to decrease the risk of rejection or treat an active rejection. Now, you can reject both the epithelium and the endothelium. If you notice in this case of epithelial rejection, you get these nodular infiltrates on the surface of the cornea. These look a lot like adenovirus. But they’ll be confined to the graft. So that’s one way to tell. They won’t spread beyond the graft-host margin. And then for endothelial rejection, you’re going to have corneal edema. Notice this nice Khodadoust line here. That will kind of march across the cornea. Notice that the cornea above the Khodadoust line is relatively clear. Below the Khodadoust line — this is the graft-host margin here. Below the Khodadoust line, a lot of edema. So edema, keratic precipitates, drop in vision, inflammation, all of that — confined to the graft, especially. That is an endothelial rejection. Again, you treat that with intense topical steroids hourly, until it starts to resolve, and even systemic steroids, if necessary. Other complications — you can certainly get endophthalmitis. This is why I’m a fan of culturing the corneal rim. Because generally, unlike a phacoemulsification patient or cataract patient, where the source of the bug is usually the patient themselves, with corneal transplantation, the source of endophthalmitis is usually the donor. And so it’s nice to culture the donor rim. If you treat it just like any or endophthalmitis, if you get one — which includes intravitreal injection such as vancomycin and amikacin, and if necessary, perform a vitrectomy. Primary graft failure is sometimes hard to diagnose, but if a graft never clears, stays hazy in that first few weeks, that’s what you have — the only remedy for a primary graft failure is to replace it. And last but not least, if you have sutures and steroids, then certainly you can get a corneal ulcer. And these can be difficult to treat. The question always becomes: Do you remove the sutures? If you think you have a good scar between your graft and host, yes. And you can even culture your sutures. You might be able to find the bug. But this has to be treated with intense topical antibiotics, even fortified antibiotics. Note that there’s two foci here. I usually will culture these as well. Use fortified antibiotics. Do you back off on steroids? Yes, but you probably can’t stop them. So I will continue to use maybe — if your patient was on 4 times a day Pred Forte, then you should really back down to maybe once a day. This shows a corneal ulcer in a rheumatoid arthritis patient, in a relatively quiet eye. But again, this has to be treated systemically. If you have a patient with rheumatoid arthritis that starts going into a melt. What about stitch infiltrates? Generally — are they infectious or are they sterile? And the answer is you don’t know. So I generally treat a stitch infiltrate as if it’s infectious, and bump up the topical antibiotics and steroids both, until they resolve. I watch them carefully. If I feel they’re infected, then you might have to pull them prematurely. That can risk the wound a little bit. So I’m always hesitant to remove a suture. But I will give it a chance to resolve with topical antibiotics and steroids. One of the big issues we have is astigmatism. Generally for this I will try — this is when all the sutures are out. You can try astigmatic keratotomy. There are two different techniques. You can go right into the graft-host margin. I generally go inside the graft-host margin, about 0.5 millimeter, with a diamond knife set probably not to 90%, but maybe 85% of measured corneal thickness with a pachymeter. This is in the axis of astigmatism, so if your axis was 90%, you just go inside the graft-host margin at that — above and below, at the 12:00 and 6:00 position. My arc length — I will generally start — there’s not a good nomogram. The main thing I will tell you — it’s a very powerful technique. So don’t exceed 60 degrees, in terms of the arc length of the cut. I would generally cut it with a 45-degree cut first. Just kind of get a feeling for if the patient’s going to respond. This is really for high astigmatism, greater than 3 diopters, that you can’t really fit a patient with glasses. You can also certainly fit a contact lens. This works well. I will, again, wait — you can actually fit a contact lens with sutures in. I will usually wait about 3 months, until the patient is off antibiotics and I begin to decrease their steroid dose. I like a mini-scleral lens, because it doesn’t actually touch the cornea. And oftentimes, you can leave the sutures in for a prolonged period of time, if you get a good contact lens fit. The fitting can be difficult. Sometimes it’s trial and error. So one of the really great boons to all corneal surgeons is to have a good fitter in your practice. A good contact lens fitter. Corneal topography can be helpful with fitting. I don’t like soft lenses, because they will tend to induce blood vessels. Well, that’s it. I know we had some polling questions, and I’m sorry they didn’t come up in this particular version of this talk. I don’t know if we can get those polling questions to you or not. But that’s pretty much it, so we’ll open it up to questions, and kind of go from there. So I am gonna show you some polling questions. I think we can go ahead and do those now. I guess I didn’t run this well, so we’re going to go ahead and launch some polling questions. So which of the first questions — which of the following diagnoses has the best prognosis for successful penetrating keratoplasty? And it gives you four choices. HSV keratitis with active inflammation, a highly vascularized cornea with central scarring following a chemical burn, a case of pseudophakic bullous keratopathy, or keratoconus with a dense central scar but minimal blood vessels in the cornea? So we’re gonna go ahead and launch the poll. And we’ll give it about 30 more seconds. Okay. It looks like most of you responded keratoconus with a central scar but minimal blood vessels. I think it’s a close call between pseudophakic bullous keratopathy. Again, just depends on how vascularized and inflamed the eye is, but generally the keratoconus eye is going to be a white, quiet eye with minimal blood vessels. So that would probably be my choice for the best prognosis. And by best prognosis, I mean least likely to have an immunologic rejection reaction. And also, actually, to get the best result with visual acuity. All right. We’re gonna go to polling question number 2. And that is: What is the definition of success for corneal transplant? And it gives you three choices. I’ll go ahead and launch the poll. Looks like all of you got that. So that’s good. Glad to see you’re all paying attention. A thin compact graft with less than 3 diopters of astigmatism and improvement of visual acuity of 2 or more lines, which is kind of a modest definition of success, if you think about it. An endothelial keratoplasty — many times with Fuchs dystrophy, we can obtain 20/20 vision. But again, with penetrating keratoplasty, a little bit more modest, in terms of success. Okay. Next polling question: All of the following factors are considered in donor selection, except… We’re gonna go ahead and launch the poll. Looks like people are still voting. So, you know, I think cell count tends to be important. We want a cell count greater than 2500, if possible. Just makes sense if you start with a lower cell count, your likelihood of success is not going to be as great, in terms of graft failure. Even if you don’t have an immunologic rejection reaction, endothelial cells tend to dwindle over time. So typically, a clear graft, at a year to a year and a half, may have 1,000 cells per millimeter, when you started with 2,500 cells per millimeter. So, again, you’re gonna have that natural attrition. So the more cells you have to start with, the better the prognosis. Death to preservation time and how long the donor has been in storage solution, I think, can be important factors. Again, 8 hours would be ideal, but up to 24 in Optisol, before you put it in Optisol, for death to preservation time — I mean by that death of the donor — and how long the donor has been in storage solution — generally ideally no more than 72 hours, but with the newer storage solutions, you can go out a little bit farther than that. And the last one — cause of death. This can be somewhat controversial, in terms of should you take, for instance, a patient who died from cancer? If it’s a solid tumor, generally yes. Heart disease is not usually going to affect the prognosis on the graft. If somebody had an infection, with septicemia, probably not a good choice to use. If they were HIV positive, not a good donor to use. If they had dementia or prion disease, not a good donor to use. So those things come into play, but if it’s heart disease, you’re probably okay. So which of the following is true, in terms of suturing a corneal transplant? That’s the next polling question. Looks like people are still voting a little bit. I think an interrupted technique is best. If you get a running technique, again, if you have a running suture, especially if you have a heavily vascularized quadrant, you can end up with loose loops of suture, and you can risk a wound dehiscence. So individual sutures, on the other hand, if they become loose, and you get differential wound healing in that circular wound, you can remove those interrupted sutures early with very little risk to the graft. 7-0 vicryl is not a good choice for suture material for a corneal transplant, because it really will be too reactive. Cause a little bit too much inflammation. It may be a good choice for suturing in a Flieringa ring, as we alluded to previously. It may be a good choice if you have a graft that you’re trying to get on quickly, and you want something with high tensile strength, in the event of an emergent situation such as a suprachoroidal hemorrhage. But in general I would not use 7-0 vicryl. 10-0 nylon is actually a diameter that I use for suturing corneal transplants. When I trained, we would do a double running suture with 10-0 in one direction and 11-0 in the other direction. So 11-0 nylon I don’t think has enough tensile strength. It looks pretty, but it really doesn’t have enough tensile strength to give you good anterior and posterior wound apposition, which is our goal. I think we’ve got one more question for you. All the following are true with respect to corneal transplant rejection except… I’ll let you read the question. Looks like we have people still voting. Okay. I think this is an important one. Most graft reactions can be reversed, if they’re identified in a timely manner. So I will give my patients that little mnemonic you see in the fourth part of this question. RSVP. Redness, sensitivity to light, decrease in vision, and pain. Those can all be signs of bad things happening. Not just a rejection reaction. But I will tell my patients the magic words to get into my practice are — I’ve had a corneal transplant and I think I’m rejecting. So I try to get those patients in quickly, because many times you can — they may look bad, but you can reverse them, with very aggressive topical steroids, and sometimes even systemic steroids. So your choice of systemic steroids will depend — whether you use them or not — may depend on how healthy your patient is. For instance, if you have a diabetic or somebody who is immunocompromised, using a systemic bolus of IV steroids would not be a great choice. But if you have somebody who is relatively healthy, you can oftentimes reverse a rejection reaction. If you can’t use IV steroids, even a tapering dose of oral steroids. So you can start off with maybe 60 milligrams of prednisone for 3 days, 40 milligrams for 3 days, 20 milligrams for 3 days. I will do that in patients if they have an aggressive rejection reaction. And you would be surprised how many times you can reverse these. So I think the key is to catch them early and to educate your patients about when they might be having a rejection reaction, so they get in to see you. The first one is absolutely wrong. Rejection reaction is a lifelong risk. The most frequent time it’s going to occur is probably within the first year. But it can occur as long as that graft is in place, and that’s what I will emphasize with my patients. And I think we’re pretty much done with all the questions. So at this point, I will see if we can open up to any questions from the virtual audience out there. So I’m not hearing any questions. I don’t know if that’s just because I’m not technically capable of getting them. But I think if that’s the case, I thank you for all of your attention. And wish you luck with corneal transplantation in the future. I’ll hang on for just a bit to see if we can… Just to make sure that we’re not missing any questions from the audience. Well, I left my email up there. So I’m happy to answer questions, if you don’t feel like you’re getting your questions answered about techniques of corneal transplantation. What instrumentation I use, what nylon I use. So again, thank you for your attention, and at this point, I think we’ll conclude the webinar. Well, let me go into Q and A. Actually, I did get some questions there. So we’ll go ahead and go into Q and A, and there are some questions here. So we’ll go ahead and answer them. How long do I use topical steroids is the first question. And I will generally use them lifelong. So I don’t stop them. There has been some recent work by Frank Price and others even in endothelial keratoplasty that using them lifelong may decrease the risk of steroids in endothelial keratoplasty, which already has a low risk of rejection. But what I will do is taper them. So depending on how vascularized their cornea is, if they’ve had previous rejection episodes, I will start tapering right around 6 months, so I’ll go from 4 times a day to 3 times a day to 2 times a day. Then maybe I’ll switch them from Pred Forte to a weaker steroid, such as FML. But generally 1 or 2 drops of FML a day is what I’ll keep them on forever. Next question is: Do I have a video for good double running suture? Unfortunately, I do not. I have my suture video, but now that I know that it’s out there, what I’ll try and do is make one and produce it. I think the main thing with running sutures in general is to practice. For instance, we have a wet lab, and we have the use of animal eyes. So if you have trephines that you can reuse, you can trephine an animal eye and mount that under a surgical microscope in your wet lab. It’s a good technique to be able to practice. I don’t, unfortunately, have a good video of that, in terms of the technique of a running suture. But I think evenly placing the sutures is important. I think another aspect of evenly placing the sutures is to mark. So I use that radial keratotomy marker. And again, if you’re going to use a 16-bite running, use an 8-blade radial keratotomy marker. Place that on your cornea before your trephination. That visual guide is very helpful, in terms of suture placement. Next question I have is: How to do keratoplasty for pellucid marginal degeneration? Can be very difficult if they’re very thin. And sometimes one way to do it is decenter the graft, if you have to, to incorporate the thin area. Another thing you can do, which, again, can be difficult, and is an advanced technique, is you can first do a tectonic patch graft. So a tectonic patch graft can be used. You can take a piece of kind of horseshoe-shaped cornea. You sometimes have to fashion those by hand. Do a deep lamellar resection in the area of thinning, put that in, into the cornea, suture it carefully, come back another day, and do a penetrating keratoplasty, once you have addressed the really thin area. That technique has been described in journals. I don’t have a good illustration of it. But again, for pellucid marginal degeneration, a tectonic patch graft over the inferior part first, doing a deep lamellar graft technique, would be what I would consider. What is rejection, versus failure? Rejection is an immunologic response. I’ve written about this. There’s a chapter in Medscape, if you have access to it, that goes into detail about what rejection is. Versus failure. Failure means that you have basically a very quiet eye, where the graft just becomes edematous over time. And remember, there’s a natural attrition of endothelial cells. So if you had a critically low number, the endothelial cells can’t keep up with demand in terms of pumping out and deturgescing the cornea, so the graft will begin to swell and you’ll get edema. So graft edema without signs of inflammation is really graft failure. Rejection is what I showed you earlier. You’ll have a red eye with inflammation. Usually keratic precipitates on the back of the cornea, and will generally respond to steroid drops. The book that I took those pictures from actually is… I’ll show you a copy right here. It may be out of print, but it’s called Ophthalmic Surgical Procedures, by Peter Hersh. Very good book. It may be out of print, again. Let’s see if I can find out when that was copyrighted. Unfortunately, it was copyrighted in 1988. And it was published by Little, Brown, and Company. But, again, it is Ophthalmic Surgical Procedures, which I think just shows some very nice illustrations of penetrating keratoplasty. The best tool to monitor intraocular pressure. That’s another question. I like the Tono-Pen. And the best way to manage it, I think, first, is medically. But if you can’t manage it with timolol, brimonidine, and Diamox, then that’s really the kitchen sink. Then it’s time to refer to your glaucoma specialist or, if you’re able to do it, put in a valve. I think a valve is a good way of controlling intraocular pressure. Schiotz tonometry doesn’t work as well, so if you have access to a Tono-Pen, because of that small applanation surface, it tends to be more accurate. Okay. I think that is pretty much all the questions that I can see at this point. I appreciate your attention. Again, if you have further questions, please feel free to email me. I’ll try and respond to you. There are some great texts on corneal transplantation. The video part I’ll just have to go back and video some of my cases for you, and I’ll try and give them to Orbis, so that we have a good library of those techniques of suturing. Again, the problem is penetrating keratoplasty is becoming somewhat of a lost art, as some of the newer endothelial keratoplasty techniques and deep lamellar techniques kind of take over. But it’s still very useful, especially in patients who have a corneal scar, ulcer, or you have to get a graft on quickly, to save the eye. Thanks again for your attention.