 For those who don't know me, hopefully, you've all met me before. My name's Chris Smith. I'm one of the cornea fellows working here for the year, stepping on y'all's toes. Don't worry, it'll be over sooner than you hope. I'm gonna talk about a project I've been working on and hopefully will be submitted, or hopefully publishing soon with Dr. Abu Shusha. He was my senior at St. Louis University and now he's a cornea faculty at Baskin Palmer. And will this advance? Maybe not, maybe this one. Sounds good. Oh yeah, there you go. He'll clap on. So this is the statistics I got. I'm very proud of the cornea world and how far they've come from 2005. And these numbers of 42,000, full thickness, now down. It's cut in half almost to 2015. 19,000 was the statistics there. And mainly for the more use of endothelial transplants. These were the indications, mainly keratoconus for full thickness, transplant, but also for other things like trauma. It's still endothelial dysfunction. Some people are doing that. We have a ways to go still with our graft survival. This is the, about 60 to 80%, they're quoting as far as long term rates. And so this is kind of where we kind of wanted to branch off with this idea and our thought process on looking at these grafts post-operatively. These are some of the reasons why they fail. Usually the highest is nonimmune, just kind of failure of the graft, but also it can be immunologic rejection. This is still the most and probably best way we can evaluate these grafts after transplant. We're not attempting by our research to replace this, a slit lamp examination, looking at corneal edema, looking how well the graft is doing under the slit lamp. This gives us a better idea of how to taper our treatments. But another kind of imaging modality that's highly published is this confocal microscopy, looking at endothelial cell density. And you'll hear a lot of this of what's the cell count. And we always worry about what the cell count is. And preoperatively, it's a great tool, see how, before we transplant. And then, so it also, this was a study done and it gives good six month, the six month endothelial cell density was a good indicator of how well your graft was gonna do. They found higher numbers, 2,500 in greater, only had a 2% failure rate, but while lower numbers in the less than 1,700 had a 13% failure rate. In five years. Also, they saw central corneal thickness was there was a kind of a good threshold. This line here is 600. And there was quite a big, quite a bit drop off when this CCT was greater than 600. So these are two things, two different imaging modalities that's currently being used to evaluate these PK graphs after transplantation. Another one is polymegathism, which doesn't have a lot of research for it. This is the coefficient of variation. If you average the size, the cell size under a confocal microscopy, and if the bigger variation, we suspect that there's a lot more disease there and the graft isn't gonna do as well. But this one isn't as highly published. We propose in our research a new tool using anterior segment OCT to measure decimate, we call it decimates membrane complex thickness. And it's using anterior segment OCT, you can with calipers measure this thickness and I'll show you how we kind of came about this. This was published in 2010. The top is a healthy 25-year-old cornea, the middle is kind of a 65-year-old healthy cornea and then the lower has fused dystrophy. And if you look, there's kind of two hyperreflective bands here, which, can I get this? And this is where we go. So there's a hyperreflective band if you can appreciate that here. So the images sometimes it's easier to, we built a software that can actually pick up this transition in the density. And if you measure the thickness from the two hyperreflective bands to the end, that's kind of the complex and we suspect that's the start of decimates membrane all the way through endothelial cell. And this with age, it was statistically thicker with just age from our healthy 25-year-old to our 65-year-old but also with this disease cornea, there's, you can tell it's a lot thicker here. So that was, we wanted to take it one further and this project we did, we evaluated this complex and compared it to a more common imaging modality of endothelial cell density and see which is better at predicting which one correlated with the slit lamp examination, a clinical examination better. So what we did is we took 42 graphs and they each got both of the imagings as well as a slit lamp examination by a cornea trained specialist. And we divided these after clinical examination, they were divided into ejection in a clear group just on what they looked at at slit lamp exam. And then after that, this is just an image of what a cell count would look like. And this is the best way to do it. A lot of, you'll see a lot of cell counts, they just kind of click as fast as they can. But if you really want a good image, you have to outline these cells and it'll give you an accurate area over how many cells. This is called a variable frame technique. And then also we measured central corneal thickness and decimates membrane thickness. If you can see these arrows, here's that hyperreflective band all the way to the end. And then they were compared under receiving operating characteristics curves to see which has more specific or to which diagnostics is more specific. We started as well this math equation and this, if you think one argument might be that if the whole corneal is gonna fail, it's gonna suck up fluid like a sponge. So of course decimates and central corneal thickness is gonna get bigger. So we made this index to see how much more decimates membrane is growing compared to the corneal, central corneal thickness. We used 33 because the numbers usually came out to be about one for normal corneas. This is our demographics of the patients we saw. And moving on, the results showed that compared from our clear and our rejection group after endothelial slitlamp examination, we had 15 graphs here and 43 in our rejection group. And so this is the decimates membrane thickness is 15 microns and 43 in the rejection group. And it was highly statistically significant between the groups. Also central corneal thickness was as well as expected as these corneas kind of a lot thicker. And then we also, if you apply our indices, that was significant as well with, it was a lot higher in the rejection group compared to the clear group, which suggests that the decimates membrane is growing thicker than the entire corneal. So this just summarizes the results as well. So looking at the ROC curves, area under the decimates membrane thickness was a lot more, so it showed a lot higher ability to correlate between the two groups, more specific and sensitive compared to the two. Also of note, the disease corneas are really difficult with to get a accurate endothelial cell density measurement with confocal microscopy. With any of that haze, you really need a clear picture to be able to reflect and get a good cell count. So the images were kind of crummy. So we didn't obtain all of the we didn't obtain endothelial cell density from all of our rejected groups, but we were able to, with the anterior segment imaging, it was a lot slicker, a lot easier for something like a, especially a technician to be able to use if you want to use in clinic later. And this is just an example of what the two pictures of a clear and a rejection group, a lot more difficult to get a clear image because of the irregularity of that layer. Further, we looked at these under the histopathology, taking these corneas and measuring them. And this is kind of, we would measure the thickness here and then compare those. And we saw that they're, both the CCT and endothelial cell density were different in the two control rejected graphs, which is expected. But one thing we definitely learned from this, looking at the histopathology, that was helpful. This is just shows the sensitivities higher with the endothelial thickness. But what was really interesting in this part of the study was when you look at the histopathology, we were expecting, oh, there's gonna be this huge retro-corneal membrane. That's what we're measuring if, or is it actually decimates membrane that's growing on these rejected graphs? And it showed that of these 31 rejected graphs in this group, there was only three samples that actually had a retro-corneal membrane and there was still a highly significant change with our decimates membrane thickness was almost double X vivo compared to our control group there. So that was kind of interesting. And this is just a small study and there's a lot to move forward and really understand the utility of this because this is just a step, can we image this? And then I think the next step is how will it change our clinical judgment? Will this change over time? Is it reversible? Is can we slow it down with steroid treatment and whatnot? And so that's kind of our next goal. So you have any questions? What do you envision the clinical utility of this being in the future? That's the next question we're asking. I think if there's any judgment call, if any borderline of where this is going, how is my graph changing over time? Can we reverse that with a certain amount of steroids or hopefully another treatment in the future? I think that is the goal, is it ultimately to taper down our treatments, but that's a lot of questions down the road that we don't have any answers for yet. So this is just the first step. I may have missed it, but what is just the hypothesis for pathophysiology, why is this occurring? Oh, so the hypothesis is just as with any transplant, you figure beginning transplant, some of the first, if you cut it up after a rejection episode, first thing of deposition is usually doesn't, not just basement membranes are getting thicker at the rejection. And so this is the first time where we can actually look at real life in vivo tissue and watch that membrane grow because before usually it's failed, usually the kidney transplants failed and the basement membrane is quite thick in these vascular tissue. You know, basement membrane thickens in endothelial dysfunction. I think Frux is the classic example of that. And so endothelial cells do lay down this extra basement membranes when you've got a dysfunctional endothelium, such as a graph that's beginning to reject that endothelium is damaged for some reason. It starts putting out extra basement membranes. So this is really a marker of endothelial dysfunction in general. So it's interesting that nobody thought of this before. I mean, it's a very clever way of looking at this when you can't get endothelial counts directly through an edema's cornea. And so the interesting to see if you can get correlations on the degree of thickening and can you do anything to slow it down and does that relate to that graph to eventually failing? Those are gonna be the questions that would be really important to answer with further studies of this group of patients. And we hope to be able to correlate it with the more used DSEC and DMEC in the future. Because those ones don't fail as much as full thickness transplants, but as we see the numbers are dropping dramatically with full thickness transplants. I don't see in my lifetime getting rid of full thickness transplants completely, but hopefully we can do that.