 It's like it's eight o'clock, which is the Wichita Gower. It means we're going to go ahead and get started. I'm Randy Olson. I'm Chair of Ophthalmology here, CEO of the Moran Ice Center. And this is our first group of resident candidates coming through. Always exciting time of the year. We'll get a chance to chat more. I'll meet with each of you individually. And so we're excited to show you what's happening here at the Moran Ice Center. And of course, this is the morning that we always have our grand rounds. We have a special guest today. And with that introduction, I turn it over to my good friend, Kathleen DeGree, who will introduce our esteemed guest. Good morning. Great to see everybody here. It's my pleasure to introduce Dr. Joyce Liao, who grew up in Taiwan but moved to Texas. And then she went to Harvard and got a degree in biochemical sciences and went on and got a PhD in neuroscience, and then did a residency and fellowship at UCSF. And then she's been at Stanford University and is currently the director of neuroophthalmology there. She's also the fellowship director of neuroophthalmology. And she's now also the vice chair of academic affairs. And Joyce has a lot of research interests. And we asked her to kind of catch us up to speed on some of the hot topics in neuroophthalmology. And she is going to talk about eye and brain diseases. And Joyce, we're really thrilled that you could be here today with us. And thank you so much for taking the time to come here. So Joyce. Thank you so much, Kathleen. Thank you for having me. It's such a pleasure and honor. I'm really jealous of the Moran Eye Institute. So I want to especially welcome the applicants. Hopefully, there will be no occasion where I might pick on you. So today, there are a lot of topics, but today we're going to focus on opting neuropathies. So I have no financial disclosure. And there's been some generous grant funding as well as philanthropy that has resulted in this research. I'm probably telling a group that's completely sold, but vision turns out the most important of our senses. This is a table, a figure from a recent article in JAMA, where they looked at in UK about 250 adults of a wide range of ages and asked some, which of the senses do they value the most and partly related to sort of their age and the length of time and the amount of time they're willing to live with disability? And vision was number one. Hearing is number two. And balance, number three. There are a couple of people who felt temperature sense was the most important to them all the way on the right. So I want to talk about the EyeBrain Network, which is the heart of neurophomology. So I'm going to illustrate it with some slides and videos. So when we look, this is a picture of Sanford. We fixate. And we basically put the most sensitive part of our eye, which is the phobia, and align it directly with the area of interest. So if I overlay a Humphrey visual field map of the right eye, you'll see that the center of vision is placed right on the Memorial Church. And then the blind spot is where we don't see. So when you move your eyes, you basically repeatedly capture this visual information using eye movement. And that allow you to see the world. So this is a video of one of my favorite paintings. It's called Las Meninas by Velazquez. The circles are the fixations. And the lines are saccades. The circles, the larger they are, the longer this person pause in that area. And so you'll probably notice that the princess in the middle tends to get the most attention initially. We tend to look at whatever is right in the center. This is true when you're watching TV or movies. And it's very clever how they design these things, including ads. And then you can see that the path sort of takes you all over the place, looking at visually striking things, and then land at the dog, at the right lower corner. So basically, this is how we see. There's a tension map of our visual path. If there's no hot spot, we actually did not see. So how we plan our eye movement in order to see determines what we see. And the purpose in which we use to look around the world determines what we actually see. So here's just an example of the Incredibles. This is a bunch of middle schoolers. So each circle is a middle school student. I had no trouble recruiting subjects for this study. And so you can see that they follow moving objects. And most of the time, the circles are cut in the middle. And so we've looked at this type of video to compare controls versus patients with eye movement disorder or a visual field defect. And you could get a sense of how the pattern of eye movement could change depending on disease. So foveation. We align our fovea, our visual axis, with whatever is important. And that gives us vision. The information comes through the pupil. The pupil needs to be open. It is captured by the retina, transmitted through the optic nerves of the brain through the retinal geniculo cortical circuit. And that allows us to process the information. And like I said before, the eyes move in order to repeatedly capture visual information. So this is basically everything you need to know about neurophthalmology. All right. So we're going to talk about two stories today. Thanks, Joyce. Well, you know, you've got to start gentle, right? One slide, this is all you need to know. All right. So the first story is about ischemic optic neuropathy. And I'm going to talk about our animal research inspired by our patients. And then I'm going to talk about optic disjusion research. So it's a little intimidating to come to Moran and talk about optic disjusion. But I'll try my best. And the goal actually is hopefully we could set up some wonderful collaborations going forward. So what causes ischemic optic neuropathy? So the short answer is we don't know. If you fall asleep, you could just remember that. But there's some interesting clues based on a small number of patients that I've seen. So let me start with a case. This is a 48-year-old man who is healthy, extremely active. And he went hiking at Sierra Nevada. So he's done this before, nothing unusual. Three days of vigorous hiking later, he developed some vision issues. So at that altitude, which is not too different from some of the altitudes that you experience here. Hey, it's low by Utah standards. Each breath, he is breathing in 26% less oxygen. So I saw him eight days after the onset of vision loss. At that time, his visual acuity was 20-20 in both eyes, and he had normal color vision. There's an inferior altitudinal visual field defect in the left eye, and a swelling of the optic nerve head. There's a disadvantage on the other side, which is common in patients with non-autoritic interior ischemic optic neuropathy. So we diagnosed him with AIO1 associated with high altitude exposure. He had progression of his vision loss, and he wasn't eligible for any of the clinical trials for AIO1. And so he actually went on to having counting finger vision and generalized visual field defect basically across the fixation. And this is actually typical of the patients I've seen associated with high altitude, whether it is from actual high altitude, hypobaric hypoxia, or sometimes a plane ride. And so in case you don't know, that's actually a moderate high altitude, which I'll show you in the next slide. So associated with visual field loss, early on, he had a dropout of the superior peripapillary microvascular corresponding to the inferior altitudinal field defect. And then chronically, when he has generalized vision loss, there's generalized loss of vessel density. So I have one slide on high altitude hypoxia. So this is sea level, 20% 0.9% oxygen. At Mount Kilimanjaro, which is pretty high, not higher than some of the altitudes here, the you're breathing 10% oxygen. The amount of oxygen in the air is the same, but because of the hypobaric, the available amount of oxygen is reduced. And at Mount Everest, this is only 6.9%. So we're near the valley. It's actually quite a bit higher than Palo Alto, which is 9 meters. So around here is already 1,700. So as a visitor, I'm already working hard. So for commercial aircraft, it's actually up there, 18. So it's pressurized to relative high altitude. And the airline industries have gotten away with this for many years. There are actually studies done in healthy individuals, athletes, to look at performance and the effect of travel. So it has a real impact. High altitude is considered about 2,500 to 3,500 meters. And at the highest peak of the Wasatch Mountains, it's up there. This is when you're probably all acclimated. So some people may get acute mountain sickness and cerebral pulmonary edema. At very high altitude, the symptoms essentially gets worse. And the only treatment is to have oxygen and descent as quickly as possible. So from this patient, we hypothesized that perhaps it's the hypoxia that trigger the AION, because he really did not have any other risk factors. We did screen him for sleep apnea. And there's some very small number of events. His oxygen saturation never really dropped. So we really wonder about the hypoxia, especially with the timing. And this is also the case for the other high altitude associated AION. So the question is, what's the effect of short-term hypoxia, the retina and optic nerve? I'm going to present a work that's done by people in the lab, in particular the first two, Louise and Varun. So we have a animal model of systemic hypoxia. It's basically a hypoxia chamber. And we could dial in and control the amount of oxygen. So we started with something very gentle. Equivalent to going and hiking at a higher altitude. So we pick 10% oxygen for 48 hours. So if we do the analysis, what we see is that there's no loss of retinal ganglion cells after 48 hours of hypoxia. This is a retinal whole-mount preparation staying with a marker for retinal ganglion cells called brain 3A. If we look at the optic nerve and the retina for cell death with an assay called tunnel sting, not much is happening after a 48 hour. There are a few tunnel-positive cells, especially in the outer nuclear layer, but not a whole lot. But what we did find was that the optic nerve oligodendrocytes were the most vulnerable, even with just 48 hours of hypoxia. So there's a significant loss of oligodendrocytes with hypoxia. So how could hypoxia lead to AION when so little is happening? So we wonder about the glia, the role of the glia, because the oligodendrocytes were the only ones that were lost. And we searched the literature. So it turns out that oligodendrocytes are extremely vulnerable to metabolic stress because they have to synthesize a lot of proteins and lipid in order to myelinate and support the retinal ganglion cell axons. They're also selectively vulnerable to hypoxic ischemic injury because of their glumine receptor expression. And then after a lot of glit-surge, I discovered that X-linked charcomery tooth, type I, where there's a mutation in Conexin 32, is actually one of the rare neurological diseases that's associated with decompensation and high altitude. And guess what it affects? It's the white matter. So you get MRI lesions. And this protein is only expressed in the central oligodendrocytes. So really compelling for the fact that if you have high altitude and hypobaric hypoxia, that you could get a decompensation of glial function which then leads to an axonal and neurological disease. So revision of the hypothesis. Hypoxia leads to metabolic stress, possibly in the glia or other cells leading to AION. So we previously reported that experimental AION is associated with increased endoplasmic reticulum stress. So this is part of the unfolded protein response, one of the most important and earliest cellular endogenous responses to stress. So it could be intracellular stress, such as oxidative stress, mitochondrial stress. It could be environmental stress, such as hypoxia, ischemia, diabetes. You name it, this is the common pathway that acts really early on. And what happens when it acts is there is a bunch of adaptive mechanisms that will return the cell to homeostasis where the cells would survive. Or if there's prolonged ER stress, then you could have activation of the proepoptotic pathway and leading to inflammation and cell death. And one of the hallmark of that pathway is a transcription factor called CHOP. So we show that in AION, in animal model, there's prominent expression of this molecule. So let me tell you about the model a little bit. We basically take the Pascal laser that you use for patient care and shine a low-energy laser spot via photochemical thrombosis and induce a local optic nerve head ischemia. It's a very nice model and actually quite easy. You get whitening consistent with loss of perfusion. We do serial in vivo imaging as well as histology to analyze what happens. So we look in the retina and within one day after AION induction, you could see a significant increase in the CHOP expression in the ganglion cell layer. And this is both retinal ganglion cell body as well as the astrocytes that are in that layer. The quantification show that there is a significant increase. So there's a very early increase in significant cellular stress in the retina after AION. And this is not just isolated to area near the nerve, but it's actually quite diffused. If we look at the optic nerve, so this is just a section showing oligodendrocytes in the optic nerve which is labeled with a marker called Olig2 that labels all oligodendrocytes. What you could see is that in control, there's no expression of CHOP. And then within one day after AION, it's like the Christmas tree lit up. So lots of CHOP expression that overlap with oligodendrocytes, but there's actually a substantial population that's specifically in astrocytes. So you have to remember there's no neuron in the optic nerve. So all the cell bodies are glia or blood vessels. So the optic nerves composed of axons of the retinal ganglion cell, all the glia elements that's supporting the axons and the blood vessels. So this significant increase both in the retina and the optic nerve is quite striking and indicates that there's kind of a diffuse and acute stress in AION. So with that in mind, what happens to 48 hours of hypoxia? Did it induce this pathway? So what we see is that in the retina, so it's kind of a complicated slide, but in the retina, you see a clear increase in CHOP expression in the retinal ganglion cells after 48 hours of hypoxia. And if you look at the optic nerve, it's actually pretty striking how the increase is mainly in the unmyelinated portion of the optic nerve. So you have to remember at this area, the lack of myelination means action potentials are being passively propagated. There's an incredible energy demand and a lot of mitochondria and mechanisms that are necessary to make this happen. So essentially the optic nerve lights up like a Christmas tree when there's hypoxia, just 48 hours of Mount Kilimanjaro equivalent, hypoxia. And if you look at different parts of the optic nerve and quantify that, what you see, it's true that there's really no change in the CHOP expression in the myelinated portion and there's, which is in yellow, and there's an increase only in the unmyelinated. So just to remind everybody, the unmyelinated portion is basically all astrocytes and there's some really unique optic nerve head astrocytes that some people have been characterizing. And then in the myelinated portion is a combination of astrocytes and oligos which are connected to provide support for the axons. So if we look at gliophibrillary acetic protein expression, we also see an increase in the expression in the retina as well as the optic nerve head and that's consistent with gliosis or astrolyosis which people debated whether reactive gliosis is a positive or negative or both, but essentially 48 hours of hypoxia is already sufficient to induce all of these changes in the glia. So even though there's no tunnel staining, very little, no cell death in the retina, there's no cell death in the optic nerve, there's a lot of activity happening under the surface inside the cell. So we looked at the cytokine profiling because one of the hallmark of increased cell stress and a path to cell death is inflammation. And this is a seven day hypoxia, same chamber, 10% oxygen. And what we find is that there is a significant increase in the multiple different cytokines, 18 actually, and within one week of hypoxia. And if we were to take the animals out of the hypoxia chamber and let them recover for essentially 12 to 18 hours, the cytokine expression actually already dramatically reduced by that time. So it really suggests a model where you have a lot of activity with hypoxia whether it's from going to high altitude for a short period of time, obstructive sleep apnea or other systemic diseases, and then recovery to normoxia, so things calm down again. But the cycle of hypoxia and normoxia may be a critical factor in triggering AION. So hopefully I'll have more to report in the future but we're really excited by this study. So inspired by our patients with high altitude AION, what we find is that in animal model of hypoxia, there is a significant loss of the optic nerve oligodendrocytes consistent with their metabolic demand and vulnerability for metabolic stress. There's no retinal ganglion cell loss with short-term hypoxia, but there's a lot of increase in the activity around there, including this expression of CHOP, a pro-epoptotic cell death transcription factor. Finally, with a cytokine profiling, we see that there is cytokines and inflammation already activated as part of post-hypoxic inflammation. And this could be an important target for treatment. So we're happy to identify some potentially novel therapies and we've already started some testing that I'm not gonna go into today because the human data is so sparse. But in animal model, we've shown that there's a significant rescue of both retinal ganglion cells and oligodendrocytes if you were to lower endoplasmic reticulum stress. And we've only done that in all of one patient because it's very expensive. It's something like, it's an FDA-approved drug for urea cycle treatment and it's something like $180,000 a month. The company is calling me to find out more information. So the new model of AION is such that hypoxia, which essentially is the result of vascular risk factors, sleep apnea, et cetera. That leads to a failure of glia, oligodendrocytes and astrocytes, which work together and triggers inflammation. And this leads to failure of retinal ganglion cell axons, which leads to ischemic optic neuropathy. So let me illustrate it a little bit. There's the orange, which is the single retinal ganglion cell axon, which is in sheath by oligodendrocytes. And the astrocytes, which is in green, are connected through direct communication. So you have lactate, which is one of the main energy source. The oligodendrocytes provide a lot of the energy support for the axons. Goes from the oligodendrocytes directly through channels into the retinal ganglion cell axons, which gives you ATP. So if you fail in the glia, you will fail in the axon, and that leads to AION. So it's possible you have sort of these repetitive episodes of hypoxia, led on by hypo-perfusion, which is historically very well described, as the cause of AION. And this is highly relevant to glaucoma, because as you know, ischemia is a significant component of glaucoma. And this may be one mechanism by which glaucoma also occurs. In case you don't know, Stanford is kind of the land of the glia. And so it's an area that I'm hoping we'll be able to investigate much more. So just to summarize this part of the talk, the eyes bring the world to our brain. The brain gives us vision, and the vision gives us human experience. So the key for us doing translational research is to be cognizant of the long distance pathway between the eye and the brain, with the optic nerve as the connector to deliver this information. And so disease in the eye, as well as disease in the brain, could affect that eye brain network. And so the goal of our research is really to use all the amazing tools that we have now to be able to diagnose patients early, both for AION as well as for glaucoma and other diseases, so that we could intervene, so that we could develop novel treatments. So maybe I'm gonna pause a little bit for questions before I go on to the next part. Fascinating. Having spent a lot of time between 3,000 and 4,000 meters in my life, another profound thing that happens is not just that your partial oxygen pressure drops quite dramatically, but your body wants to make up for it. And so in order to do that, there can be pretty profound respiratory alkalosis. And that's typically what causes a continuum of symptoms from almost everyone, particularly if they go from sea level to 3,000 meters, for instance, are gonna get a headache. And then a lot of people get altitude sickness, which is really kind of a mild form of cerebral edema onto the full edema. And I remember I brought Claas Domen out here in my early career, so he went from Boston to a meeting we had at Snowbird, and that night he got both pulmonary and cerebral edema. So it's really hard. And so have you looked to see how much pH balance maybe also is impacting some of these things? So the questions about respiratory alkalosis, alteration in pH, in high altitude, and whether we've looked in this model. So we have not looked, but certainly pH is a big part of it. There's actually also some literature that pH recovery for the body is actually relatively fast once you go into... Oh, you can feel it. Literally, you can feel it. And I would say, typically, it's about 48 hours. 24 to 48 hours, and you can all of a sudden feel it. That headache is going away, and you're getting a little more energy. So you're right, that does not take very long, but it certainly is profound. And I think the acute changes, like pulmonary edema and cerebral edema, are probably a lot of it's related to that pH change. I think we should work on that. And the pH in the central nervous system, there's some data suggesting that there's a relative delay in that pH recovery in the central nervous system. So I didn't show this data, but we actually looked at the retina using OCT, hypoxia, and then with recovery. And what we see is within one day of normoxia, there is a dramatic swelling of the retina. And so it's actually quite striking that such a short, sort of a hypoxia normoxia recover it can lead to such a prominent edema. And we've looked at different molecules, including aquaporn for, and a variety of molecules that seem postulated to be important for edema. But basically, if what we see in the retina is what's happening in the brain, it's quite dramatic. And just the other one, and Kathleen and our other group, I mean, it seemed to be epidemiologically to support your hypothesis that by looking at a group of people who regularly are backpacking and spending time above 3,000 meters, of which we have a whole bunch of people, and compare what the overall incidence of NAON is with that group versus people who typically are living at sea level and is there a difference in incidence would support your hypothesis? Do we have that kind of data that? We don't, no? Wouldn't it be the people at sea level though that would have these events, right? Because we become like acclimatized to the altitude. So when we go up higher, we'd be less likely to see it versus someone coming from sea level experience. Well, if I understand what you're saying in association with this, not necessarily, well, anyway, if we could compare that or a group of people who regularly go from sea level and go and come climb in our mountains, there's certainly a lot of those too, who fly here all the time, they regularly are spending trips at higher level. That would be, where's Brian's stag? We got Brian here. Did you talk population database? We have kind of a cool, have you heard about that? Oh, yes. This is partly why I'm here. Yeah. Hey. So if you come like the altitude where the person lives, do you think that would be helpful? Like the variation in altitude here, like some who lives at lower altitude in Utah versus some who lives at a higher altitude in Utah. Do you think there'd be a difference in risk as far as risk of development of having an AI at one? So those studies would be helpful for sure. It will take thousands of patients. The Utah population database is now somewhere like 30 million different people in it now. Yeah, cause you wanna look at who got AI. So it's a difficult study actually. A easier study would be to do what you propose, which is to look at before and after. And we have a grant to look at cytokine profiling, but we've also looked at some of the other components of the blood. That's the most easily accessible fluid to us. And so there are clear biological activity within the plasma. So that for example, if we were to apply human AIO in, plasma isolated either plasma lung or extracellular vesicles carrying components, it induces vascular formation. And basically the beginning of vascular genesis. If you're on a supplement here, we ought to meet the skeptical genealogy this morning. That'd be interesting to study. Yes. Yeah, just to amplify on that a little bit. Yes, it's the blow off of the CO2 with the hypoxia that is actually, the optic nerve is much more susceptible to this than the rectus. But what's also, I think, implicated in this, even small amounts of sleep apnea at the end of each hypoxic apnea episode, there is a reprise that consists of much more breathing, but also a huge peak in your blood pressure. So this can aggravate that injury. And then a question, have you ever tried erythral port, intraocular erythral port for non-autority ischemic optic nerve? It's demonstrated to protect not only neuronal protection, but all lago dendral sitting protection. Think about it. Yeah, so I haven't done it personally. There's clear animal data supporting, it being neuroprotective for retinal ganglion cells. I believe the drug is actually in clinical trial. I'm not sure, it's not for ischemic optic neuropathy, but for glaucoma potentially. And it has to be the form that doesn't induce, it doesn't have to hematologic effect, of course. Or intraocular protection. There was a small human study of erythral port as well. And as with most studies with AION, it was, but you need hundreds and hundreds of patients for AION to prove any kind of either benefit or non-benefit. The other confounding factor for travelers here is that you really have to control for other vascular risks. There might be, one could hazard, that those who have a propensity for doing crazy things at high altitude might be overall more fit than those who choose to kind of hang out in the valley. Well, it'd be interesting to look at the effect of exercise in those. But yes, it's a difficult study that requires a lot. So I think it's almost better if you were to identify specific theory, you know, what might be working in animal models and then go and really look at the human data. I think Kathleen, you had a question. Oh, I don't know. Go ahead. Based on the, on your data, do you throw a crap or not into those extremes or get on a plane in the near future? So in the short term, I ground all of them. And in the long term, I don't have the data to tell them not to do it. And so I just asked that they bring the portable CPAP machine just in case. So that patient that I presented actually has chosen to continue his lifestyle. And in fact, one day his dream was to hide the John Muir Trail, which anyway, he's been okay so far without the second I involved. And so hopefully we'll have treatment before anything happens to him. Do you think, have you used in your model just the oxygen with these animals that get these kind of the edema to see whether that would rescue any part of it or keep them from getting worse? Good question. So whether oxygen treatment is helpful. So the only thing we've done so far is just returning them to Normaxia for a short period of time, but not for longer. It's remarkable how the cytokine normalize within that short amount of time, even after a week in hypoxia. So we would predict that there's enough sort of endogenous mechanisms that you're not gonna lose a lot of cells, but definitely the outer nuclear layer is actually where you have the most tunnel positive cells in the two day and certainly increase in the seven day model. These studies on hyperbaric oxygen treatment? Yeah, so highly controversial. And no good data. I would say that in the right patients, I have encouraged them to do it. Basically the idea of bypassing the blood vessels and directly delivering oxygen is appealing. So it's not covered by insurance and patients have to pay out of pocket. I usually tell them, because usually there's not enough time to figure out if they have sleep apnea or not. So I would tell them to do the typical 2.4 hemispheric pressure treatment as late in the day as possible. So that will maintain their oxygen tension for as many hours as possible while they may be more vulnerable. So I have not been impressed by hyperbaric oxygen alone, but in this one patient where we did this drug, expensive drug for reducing ER stress, I wonder whether the combination with hyperbaric oxygen may have played a role. We did see a remarkably relatively improved and less severe for someone with a high altitude, a scheming optimal ophthalmopathy. So the question is the patient I show has progressed the severe vision loss, but the changes in hypoxia were relatively transient, meaning reversible. So that patient did have AION, and so that's a different than just having hypoxia alone. So the idea is how do we figure out, how do we prevent the AION from occurring in hypoxia? And I think your point about the pH is likely a role that there's some selective vulnerability in the CNS, in the optic nerve, quite matters specifically that is contributing to the persistent hypoxic induced changes that then one day goes over and develops full-blown AION. Okay, that's amazing questions. All right, so we're gonna talk about optic disdrugin. So be gentle with me. So optic disdrugin is a cellular deposit located on the optic nerve head in the unmyelinated portion, enteritolamic fibrosis. It's different from the drugin immacular degeneration. So this is what a photo might look like, sort of a lumpy bumpy appearance of the optic nerve head with a lot of texture and the arrows pointing to a large druse. With auto fluorescence imaging, you could see these drusins that are superficial and with ultrasound you could detect that the presence of something that shouldn't be there. So in optic disdrugin, there's obvious compartment syndrome, there's crowding of the optic nerve and abnormal blood vessel. And so you could have a relative degree of prominence at the superficial drusins. We just call it myo-moderate and severe, severe, meaning full of drusin on auto fluorescence imaging, for example, or on color from this photo. Some patients develop vision loss and we don't know why anywhere from 25 to 75% of patients develop vision loss. What changes in that group versus in the group that just has some drusins but never develop any issues? So the idea was to look at this particular connection, what causes enough damage in the optic nerve that the patients will develop vision loss. Sort of a different problem from AION. And drusins, of course, is a significant risk factor for developing a scheming optic neuropathy. So here are just an example of a nine-year-old on the left with drusin and this sort of really tall mountain-like appearance at the optic nerve head. And then on the lower part is both eyes of a 19-year-old with optic this drusin. And so these are really easy to image and the Utah group has certainly been looking at using OCT with enhanced depth imaging to look at these optic nerve head drusins. So essentially after Mueller described it many decades ago, in fact, like 150 years, we still don't know what causes the drusins. It was described histologically and then ophthalmoscopy after it was invented. You could start to see these drusins. So it thought to involve calcification of the mitochondria that's extruded from inter-optic nerve axons, which then forms these sort of nucleus for a process that gives rise to larger and larger drusins. It's thought to be related to some kind of axonal defect, possibly in the metabolism or the axon transport of the axons. So the clinical description, the phenotype is really clear, but the biology is completely unclear. So our question is in patients with optic drusin, we ask the simple questions because we're kind of new to this field. So can we use OCT and OCT-A to image and whether these measurements correlate with vision loss? And is OCT-A valuable in addition to OCT? So OCT and geography became relatively more widely used with the spectral domain OCT since about 2017. And for optic nerve head, you could basically see this area is loaded with blood vessels and we could use this to quantify. So we did a study of 53 control eyes versus 29 optic disk drusin eyes and compare their various measurements. So the data, there's 27 measurements, visual measurement, OCT measurement and OCT and geography of the macula as well as the peripapillary area. The image analysis is done with a custom MATLAB algorithm and also some nice consultation with our biostatisticians. So this is Ricky Wong's algorithm that the data I'm gonna show you is built upon. Essentially we can measure six different measurements per each three by three superficial plexus image both for the macula and the optic disk. So let me show you an example. So control is on the left, that's number one. And then there are four eyes, all left eye of patients with optic disk drusin from someone with no visual field defect to very little to more and more. So the second row is basically the olive for instance, imaging you can see more drusins as the severity increases in the superficial area. And then you could see the OCT and geography raw images on the bottom. So we did some further analysis and basically the analysis is I think then a necessary portion to remove the large blood vessels cause they're not so relevant and they dominate that optic disk picture. So we remove the large blood vessels and then we could calculate the six different measurements I mentioned. So this is just a heat map of the vessel area density which is the most commonly measured commercially available number for OCT and geography currently. And then the bottom one is the vessel complexity index which is related to the tortuosity of the blood vessels. So basically what you could see is that in the drusin with severe vision loss on the right that there is a dropout. So a reduced heat map, reduced vessel area density. And there's also a reduction in the vessel complexity index. Just for comparison, these are eyes from diabetic retinopathy as well as anterior scheming optic neuropathy. So those of you who are really interested in diabetes I would encourage you to consider studying the optic nerve because a lot probably happens there that we're unable to measure until now. So in diabetic retinopathy, which is the second row, in patient, so this is a patient with A1C greater than eight and 10 years of diabetes. There's actually a fullness and an increased vessel and increased tortuosity of the superficial vessels on the optic disk. And then in acute AION, there's some dropout, superiorly, same eye, chronically, you could see that there's a significant loss of the vessel area density. So just looking at these easy measurements that you could obtain clinically could tell us a lot about the blood vessel state. And you have to keep in mind that OCT and geography is kind of a functional measurement. It's not perfect, but there is a flow component. And as we go from the current sub-source, sorry, from the current spectrodomain OCT to like a 200 kilohertz sub-source OCT, we're gonna get better and better at being able to look at flow and look at these measurements. So I'm gonna summarize our findings in a few slides. So the take-home message is that in optic disk drusen and in other optic neuropathies, even though we measure six different OCT and geography measurements, many of them are highly correlated. So actually, if you just look at the optic disk vessel area density, that's actually pretty good. So all the lines are right in the middle, those are extremely highly correlated. And same thing for the macula. And so the commercial software actually does a decent job. If we were to look at a correlation matrix, just comparing the different values, what we see is that visual field loss in optic disk drusen is positively correlated with changes in the OCT, so nerve fiber layer loss, ganglion cell complex, and the optic disk vessel area density. So that's the red. So in the first row, that's probably the easiest place to look. Everything that's kind of reddish orange is positively correlated. And then it's interestingly negatively correlated with macular measurements. So the macular vessel diameter increases in optic disk drusen, and the flux, which is a measurement of flow, increases with optic disk drusen. So very, very striking. So if you look at principal component analysis, looking at just these five measurements, you could see that you could segregate the controls, which are in the black circles, away from the patients with optic disk drusen really well. And so let me show it to you in a different way. This is a hierarchical cluster analysis where we basically objectively cluster measurements. So that's the horizontal dendrogram. And we simplified it, so it's only these five key measurements versus the patient measurement. So the vertical dendrogram in the y-axis is every single eye that's included in the database. So it's kind of a complicated data set, but the beauty is you could see all the data. And so the reviewers can't complain that you're hiding something, right? So the take home story is actually really interesting, which is there are three clusters. So the middle cluster are the controls and optic disk drusen with no vision loss. And so they have normal OCT measurements, nerve fiber layer ganglion cell complex, normal optic disk vessel area density, and relatively lower macular vessel diameter and flux. So group two, that's on the bottom. So these are the patients that have some vision loss, but relatively mild. And what's really striking is that the, let's see if I can point, yeah, right here. So these two columns, those are the macular measurements. They turn red. So it seems that mild vision loss, the first thing that's associated with is a change in the macular microvascular chart. So they still have relatively normal nerve fiber layer and ganglion cell measurements, but the macular measurements has changed. And then the third group are the patients with more severe vision loss. So in this group, what you see is that the macular measurements are still increased, but the nerve fiber layer, the ganglion cell complex and the disk vessel area density has decreased. So this seems to be sort of the irreversible component of vision loss and optic disk drusen. So let me just summarize this in a slightly different way. So basically the questions that I posed before, which OCT and OCTA measurement are most important for vision loss and optic disk drusen? So these are the five. So there are two OCT measurements, nerve fiber layer and ganglion cell complex. They actually do a decent job, but the optic disk vessel area density, the decrease specifically is important for visual field loss. And the macular vessel diameter and flux increases. And so that's actually the most striking and kind of, I guess I was surprised at the time, but maybe I shouldn't have been, you know, so these five measurements. So it'd be interesting to look at that in other diseases, you know, papillodema, maybe glaucoma, like what's the history of progression of these changes certainly for AION and drusen. So does OCT add value beyond, OCT add value beyond OCT? Yes. And then we think, and this is just a hypothesis because we have no data, no long-term perspective data. We'd love to know if you can have some data so that my vision loss and optic disk drusen is associated with the very first thing which is probably related to auto regulation, just an increase in the blood flow overall, almost as a compensatory measure response to a decrease in perfusion at the optic disk. So that's actually the macular vessel diameter and flux. And then with visual field loss, you get irreversible thinning of the neurofiber layer, ganglion cell complex and loss of density. So there may be a combination of changes in OCT that potentially pre-see the vision loss as well as changes in OCT that's as a result of the neurodegeneration in optic disk drusen. So I'm happy to report that we were able to through philanthropy raise money and that's necessary for the research. So we were just approved by Stanford to form their very first center for optic disk drusen research. There's a basic science group of faculty as well as a clinical group of faculty. Some of them are imaged here. And so the idea is that we have a pretty ambitious multi-prong approach looking at animal studies as well as human studies. And part of the reason I'm here is this. So I would love to work together to identify the first genes for optic disk drusen which may be also important for other optic neuropathies and retinal diseases. So the goals for the center is to identify important clinical as well as other biomarkers for vision loss. We wanna look at at least 100 patients to start with but hopefully we could go well past that goal. We wanna know what leads to vision loss both in children and adults. Identifying the first genes will go a long way with that which will tell us who may be vulnerable, who which molecules may be the genes to target either through viral deliver constructs to knock down the expression, boost the expression or by other ways. We also have the goal to establish the first small and large animal model for optic disk drusen in mini pigs. That's the rodent and mini pigs. That way we could test potential therapies. There's currently no model for optic disk drusen. And then to understand what happens when you have optic disk drusen and lots of it, what happens that I bring that work. So I'm gonna stop there. Please consider flying just less than an hour and a half away to come to our meeting on May 11th. I've gotten some commitment from the Neuroarthmology group already but really would love to see all of you at this meeting. Thank you.