 It doesn't really need an introduction, roll tide. So I'm presenting on blindness following retro bull bar block. So this is kind of a topic that Dr. Patel gave to me. So when I was on plastic rotation at the beginning of the year, he said, feast, go block this eye. And then he told me that if I perf the globe, he'd make sure I was kicked out of the residency program. So I was able to do the block successfully. But like Dr. Warner always reminds me when I staff neuro patients with her, I'm a worrier. So I was always really worried about what I was actually doing with that block and what it's actually happening because you always hear about the complications that come up with these. So most of the surgeries performed now are done under topical anesthesia. But there's still a lot that we have to do with either a retro bull bar, peri bull bar, or subtenons blocks. And we don't do a lot of these as residents. I mean, I've done hundreds of intervitorial injections, but then can count on one hand the number of retro bull bar blocks that I've done at this point. And so in talking with Dr. Patel, kind of the goal was to hopefully come up with some ideas to have safer retro bull bar, peri bull bar, or subtenons blocks. So just kind of the most basic aspect of this is what do these blocks do? So lidocaine, it binds to voltage-gated sodium channels and prevents the influx of sodium ions. So this prevents the propagation of action potentials down the neuron and prevents the transmission of signals, in this case, pain. The sensory fibers from the eye travel post-yearly, either the ciliary ganglion is a short ciliary nerves or directly to the nasal ciliary nerve is the long ones. And then these enter the ophthalmic nerve, which is a branch of V1. So kind of the goal with these blocks, so this illustration was done by Lane Binion, one of the medical illustrators. It's done a lot with Dr. Patel. And he gave us a really nice picture. So we're kind of shooting for the ciliary ganglion here. So it's a tiny structure of about 3 millimeters in size. It's 3 millimeters lateral to the nerve, 10 millimeters nasal to the lateral rectus, and 15 millimeters posterior to the globe. So with this picture, it looks like it's a relatively straightforward shot. But then when you look at some of the other images, there's actually a lot more going on back there than you'd think. So with the retro bullbar block, the needles introduced through the eyelid skin, the junction, typically of the medial 2-thirds and lateral 3rd of the eyelid along the inferior orbital rim. It's parallel to the orbital floor post-yearly and then redirected superiorly and medially to enter the muscle cone at the posterior border of the globe. And the aim with this is to instill an aesthetic solution into the intraconal space. This is kind of contrasted with the peribullar block. So it's, again, either given percutaneous or can be given through the conjunctival reflection. So the aim here is not to access the muscle cone, but just instill an aesthetic into the retro bullbar space but stay extra conal. So this is theoretically less dangerous to the optic nerve and those vital structures behind the eye than would be with the retro bullbar block, but hasn't really panned out in some of the complication studies. And then one of the other ones that we see a lot of are subtenons blocks. So everybody does this differently in ophthalmology, but kind of the classic descriptions of the papers were to access the infernasal quadrant, you take down and make a snip in tenons in conjunctiva and then introduce a blunt curved cannula to deliver an aesthetic posteriorly. So there's been lots of different reported complications. So with subtenons blocks, there is one kind of case report series identified five complications. So they had two hyphemas, one central retinal artery occlusion, one suspected globe perforation, one episode of CNS depression, and then there's also been others that identified retro bullbar hemorrhage as a complication from subtenons block. Retro bullbar and peri bullbar blocks are often classically associated with retro bullbar hemorrhages, central retinal artery occlusions, and then globe perforations. This one study I found reported on 16,000 consecutive peri bullbar blocks. And so they had 12 cases of orbital hemorrhage, so just under 1% of cases. They had one open globe, two expulsive hemorrhages, one grain mall seizure, and then no cases of cardiac or respiratory depression or death. So kind of my first question when I was asked to do that first block was where exactly is my needle? And that's not something that's easy to identify. We're used to an ophthalmology being able to visualize what we're doing, either a cataract surgery or doing a vitrectomy, we can see our instruments. And with this, we're going through eyelid skin and going behind the eye, so we don't know where we are. So this study was actually, I believe, out of Brazil. So they examined the needle path dispersion of contrast media that was mixed in with anesthetic, and then the quality of anesthesia in patients who wonder when either a retro bullbar block or peri-bullbar block at the time of cataract surgery. So they selected 20 patients for retro bullbar injections. Needle was intraconal in only 50% of these cases based on the CT scan. It penetrated the intraconal space and then passed extraconally onto the other side in about 25% of cases. It remained exclusively extraconal in 10% of cases, and they couldn't identify the needle path in another 15%. This is kind of contrasted with peri-bullbar injections. So the needle was exclusively extraconal, which was the aim with this, in 65% of their cases. So they had a more accurate with this, but they still penetrated the intraconal space and passed extraconally in about 20% of the cases, and again, weren't able to determine the location of the needle in another 15. So that was kind of concerning for me. They mixed radio-pay contrast media with the injectate at the time of the surgery and kind of looked at that with another scan kind of after the injection. So the contrast material in cases where they penetrated the cone, it remained intraconal in those cases. It remained strictly extraconal in their hands when they were either doing a peri-bullbar block or a retro-bullbar that did not make it into the muscle cone. And then they reported that the quality of the blocks determined by extracular motility measurements was significantly better in the retro-bullbar group. So their findings with this were basically, if you want to instill an aesthetic into the intraconal space, it needs to be through a retro-bullbar injection that peri-bullbar injection was not sufficient to access the intraconal space. This has been contrasted with a couple of other papers that were kind of done in a similar fashion. So Ropo et al, which was an earlier paper, kind of performed a similar study but not on a large subset of patients. So they took about 10 patients for each retro-bullbar and 10 for peri-bullbar and CT scan, two of those. So in both cases of the retro-bullbar injections, the needle tip was found to be intraconal. And in both cases of the peri-bullbar, it was found to be extraconal. But they mixed the iodinated contrast material in the same fashion. They used a little bit higher concentration and they were able to identify diffusion of the contrast material into the intraconal space in all cases of the injection. So all 10 retro-bullbar and all 10 peri-bullbar injections. There's kind of another study that performed latex injections on disembodied cadaver head. So one eye would be blocked with a retro-bullbar and then the other eye was a peri-bullbar. And then they examined the diffusion of the latex material after the heads have been fully sectioned. And they identified latex material in the intraconal space in all 10 of the peri-bullbar heads. And unfortunately, they actually identified it in the cavernous sinus in one of the peri-bullbar injections too. And they weren't sure how to explain that because they weren't able to identify any needle tracks into any of the vessels. So that was also, I worried about that one, Dr. Warners. So, you know, there's lots of different reasons that people can lose vision after a retro-bullbar block but not all of them are kind of these catastrophic retro-bullbar hemorrhages or definite central retinal artery occlusion. So there's a lot of different things that go on. So we started looking at what happens to different structures in the eye when you do these anesthetic blocks. So in terms of that effect on the ocular blood flow, there's an ultrasound study that reported decreased caroidal and central retinal artery blood flow following a peri-bullbar injection of lidocaine, bupivocaine, and hyaluronidase without epinephrine. So they didn't do kind of long-term studies but they did found that the effect lasted for greater than five minutes in spite of a normal intracular pressure. There was no change in the ophthalmic artery blood flow during this time. And so because of these findings, they suspected that this was due to vasoconstriction of the central retinal artery as a result of the anesthetic material, even though they were not using epinephrine in the study. Bible and Geiten reported on some complications following subtenons blocks and they postulated that a loculated cyst of the anesthetic material may form in the subtenons capsule that potentially caused compression of the central retinal artery and cause an artery occlusion in that manner. And then Myer et al in an IOVS study from the 90s reported on local anesthetics by themselves reducing endothelial relaxation in response to bradykinin. So the bradykinin pathway is upstream of the nitric oxide pathway. So when you block response to bradykinin, you block production of nitric oxide and you block dilation of the blood vessels. So that kind of creates a pro-vaso-spastic environment for the blood vessels in proximity to lidocaine even in the absence of any epinephrine. So what happens to the actual vision? So there's been a few papers that reported on visual evoked potentials following the use of these anesthetics. So Levinsky performed a VEP on 16 patients who underwent cataract surgery with either a peri-bulb or a retro-bulb or block. This was, they performed these patients pre-op and then one month post-op. So nothing in the immediate perioperative period. But fortunately they didn't identify any long-lasting VEP effects in any of their patients and all of those patients did achieve 2020 best corrected vision. Ropo et al reported that peri-bulb bar blocks had either a slight to no effect on the VEP or retro-bulb bar block induced a non-recordable VEP in 28% of eyes and decreased amplitudes in another 28% of eyes. This was performed during the perioperative period. And then Pruitt took a page out of Dr. Creel's book and bought a bunch of cats and experimented on them. So they reported in 1967 that retro-bulb or injection of lidocaine consistently blocked the lidovoked potential in cats. So you've got blood vessels and then you have the optic nerve. And so unfortunately brainstem anesthesia has been also reported following these cases. So they identified the latex in the cavernous sinus and in some of these studies, so Covet et al reported the identification of lidocaine in the cerebrospinal fluid of a patient who had respiratory depression following a retro-bulb bar block. It's presumed to be due to a direct penetration of the optic nerve sheath and that allows it to travel posteriorly but that's again makes me worry. So the question is really what should we expect after a block? So most of the time when I'm in the OR with the surgeons or the attendings, you always hear the patients talk about, oh, I see the light, I see the instruments moving and everybody's like, okay, hold still. And so it's not really quite clear what you're supposed to expect after these blocks. So I mean, Dr. Zog, when you do a PK, what do you expect in terms of the vision during the, in the OR? It's kind of variable, but some people say they can't see anything. It's just kind of like, usually they're able to see the least light. Dr. Vanhoes, when was the last time you did a retro-bulb bar block? You know, since I only use them now for kerigia, I don't really ask the people what they're seeing. So, because we actually cover the corneas, I don't know, it's been a while, but yeah, when it was when we were blocking every patient for cataract surgery, it was variable. We had some patients who could see the light fully and see the instruments. And again, we had others who were just black, black-style, you know? So, how did it go? Since I wasn't the one that was doing those blocks in those cases, I didn't worry as much about those, but I could see why people would. So, this paper, 11 and all reported a positive APD and about 31% of patients who underwent a retro-bulb bar block. So, during the period, that was during the period operative period. So, 19% had a visual acuity better than six over 200, and 73% of their patients were able to describe movements of instruments during the surgery. Talks et al reported on peri-bulb bar blocks. So, they found a positive APD and about 85% of patients. And they found that all of their patients had decreased visual acuity with 35% recovering immediately post-operatively. During the surgery, about 25% were no light perception and then 65% were count fingers or worse. Shen et al reported no light perception vision in about 93.3% of patients who underwent a subtenance block for combined cataract and vitrectomy. And then, in a more recent study on the effects of topical anesthesia, Rengaraj et al reported that no patients undergoing topical anesthesia for cataract surgery experienced no light perception vision. And that was compared with about 10% of patients who had a retro-bulb bar block during that time. So, I looked up a bunch of different complications so that I would lose even more sleep. And they, I found about 20 cases of post-operative vision loss. So, 20% of these were in patients who had a retro-bulb bar block, 20% with that peri-bulb bar block, and 55% with a subtenance block. And Dr. Patel, there was also one patient who was undergoing a blepharoplasty and had upper eyelid injection, medial fat pad injection, who also lost vision. Yeah, it does. So, over the span of these cases, lidocaine was used in about 13%, so just over half of them. It was used alone in nine of the cases. It was used with bupivocaine in four of the cases. And otherwise, the authors used bupivocaine alone or with mixtures in the bupivocaine or epivocaine. Hyaluronidase was only used in about nine cases, so about 45%. Vision loss was reported to be due to central retinal artery occlusion in the majority of cases, so 55%. So, two of these came from a peri-bulb bar block, four came from a retro-bulb bar block, and then the remaining five came from a subtenance block. Cellular retinal artery occlusion occurred in one case following a subtenance block. Globe perforation, which I didn't perform thankfully, was in one case following a subtenance block, which they found a little unusual, because they had used a blunt cannula and didn't try to pass the needle vigorously, but the eye filled with blood, and they sent them to a retinal specialist to perform a vitrectomy and found a needle track. So if the retina specialist looked at it and found a needle track, you know they're right, because they've never been wrong, so. And then there is directing a seizure to the optic nerve or brain in two cases following subtenance block. And then the cause of vision loss was not postulated in the others. So of these 20 cases, about 12 of them had visual acuity improvement to 20, 60 or better, and most of those actually recovered to 2020. Three cases recovered to 2200 or worse, and then in five of them the visual recovery was not reported. So this is, you know, I had hoped to kind of come up with some tips for, you know, how to avoid complications during this, but there's a lot of potential reasons why somebody could lose vision following this, and you know, a lot of, we do a lot of different blocks, and fortunately the incidence is low, but it still happens, and you know, I think with the numbers that we'd have to look at, we're getting into big data, so I'm gonna have to turn this over to Dr. Stag when he goes to Michigan. But I was hoping just to get some input from everybody here who's had way more experience than I have, but you know, not all the vision loss that we see with the block is abnormal, so when should we start worrying about it? You know, obviously when somebody develops a tense orbit, that's a sign to worry, but you know, if you're doing a PK and somebody says they can't see light during the case, you don't necessarily get alarmed, but when should you? You know? I don't know if anybody has any thoughts on that. This thing, you'd actually say that, because they had a case once, I mean we do retro, but the blocks almost routine me for our camera still, because we don't have preserve that we like, and many patients, we can tell them, I mean, the vision, we don't know, whether you're at a level off of immediate COVID surgery, and had a patient who went home after the block, he's accepting that his vision is not so, came out two days later with us to the original occlusion, so it was probably the activation, it didn't happen after the block. Yeah, so you know, I was hoping to have an answer, say, you know, if the block doesn't wear off by 45 minutes, then that's something to worry about, but I couldn't find anything in the literature about when the vision is expected to be recovered by. So, Dr. Roscoe? So just, I mean, you said when to worry, but with respiratory suppression, first-hand experience, is that, you know, immediate? Yeah. Dr. Penny? Yeah, so a lot of times we're patching these patients because they can't take their coronary, so they're not necessarily taking a patch on the next day, so I don't really have a great answer. I think essentially every regular block I've done, whether it's doing outreach gather and surgery over here, we patched just over the next day. In retina surgery, obviously, you know, patients, lots of them have no light perception, but many of them can describe the instruments exactly. And when we didn't use, there was a time when we couldn't get high-euteronidase, and you could really tell, lots more patients could see exactly what was going on. Some like it and some don't. Yeah. There's a couple of comments. I collected years ago, there was a prominent local cataract surgeon that had a nurse in essence giving all these blocks, and I collected a whole series of eyes that went blind, were blinded immediately. And a couple of comments. If you're using high-euteronidase, you're gonna get a better block. And if you're compressing the eye after the block, you get fewer complications. As Boopy will tell you, there was a time in plastic surgery when the leading legal case, successful legal case against plastic surgeons was loss of vision after blepharoplasty in the United States. And I've seen many of those cases where they got very aggressive with removing orbital fat. And even if they did inject, they patched those patients or clipped those patients or ice-packed those patients and they ended up losing vision to one extent or another. So I think that practically being a corneal surgeon and giving a lot of blocks over 35 years compression after a block, I think, cuts down on the complications and the use of high-euteronidase. And my experience is that Terry Bulbar blocks are just as successful and a lot safer in ophthalmologist hands, but especially in non-empty hands. I think people that are doing blocks, anesthesiologists and nursing anesthetists who are doing the blocks with each and a half needles are going to get into trouble. So the juicer that I'm coming out to the guidelines for post-prankure and best, that's one of the colleagues. The legal cause of the surgeons losing the cases before the case starts because they've patched those patients to the other one. And the other one that we did talk to you years ago, you're trying to establish that you do a blepharoplasty. Do not put a patch on the patient for long. You have to check the vision and leave the patch off. If you feel you're bleeding and you put a patch on, you keep the patient in your clinic. We'll solve that area until you are happy. You know, sometimes there's problems upstairs, nurses all over your home. Because we leave our patients with an eye. At times we're not saying, sorry, we just see, we're away from the middle patient overnight. That's $12,000 cost to the middle of the night. Because it takes two to three hours to wash them. So sometimes it will change the way we practice. I have to say to you, if I was a computer surgeon like Fist, I took him through a toaster and found the patient for one night, maybe. The other hour he's entered, so there was no balance. I said to him at the end, I'm happy. Now, he says, no, I'm worried. So what are you worried about now? He said the lift can be too high or it can be too low. You know, one night first. So I said to him, every night is good for the person. But he's still worried. He wants to see the patient next day or the day after. The other comment is just learning from Moopy and other oculoplasticity and look at the literature. If you do a block and you patch, the majority of those people will end up with ptosis. And we see it all the time in cornea where we've done a cornea transplant. The patient comes back and you think, well, that eyelid's lower just because of inflammation or something. But you look at them a year or two or five years later and that lid stays down. So a pressure patch keeps the oculoplastic people busy. So looking at all this stuff, if you're going to do a surgery reason you need an akinetic anesthetized eye, did you decide which block you'd like to do? I don't know. I think the ones that found that the diffusion material like didn't get into the intraconal space was a minority. And just, I think from the clinical experience that peri-bulbar block seemed to be sufficient. So I would probably vote for that. I mean, it was kind of one of those pictures towards the back that if it were just me having it, I would probably want the peri-bulbar block because there's just a lot of other stuff back there too. So. One of the first pictures that I think we showed on the needle going back. Yes. If I get the diagram right, usually you try to put the bevel on four dots, well, thankfully we had pictures. It's still a work in progress. This one, so this picture we actually got about nine o'clock last night. Just a comment with Dr. Miller said, are you, is the feeling that anybody who's had a block and a patch, whether or not they've had lube surgery, so assuming they have not had any eyelid surgery, are you saying that if you do a block and a patch that that will predispose to ptosis in that patient? Right. If you look at the studies, if you look at it, you get disinsertion, I'm not on a plot, you get disinsertion, especially if you use pressure patch beyond what you have anesthesia. Because the patient will try to stretch that eyelid open and you get a disinsertion of the levator. And you look at them, and if I look at my cornea patients, I mean I can block in, I can, five years after they've had a transplant, if I, at the time I was blocking the amnesia center, I do most of mine under general for that reason now, and I don't put, I don't, you gotta be careful the same way with general pressure patch. I don't patch as much, and if I give a regular block on a mature cataract, I use, I don't pressure patch, I just use a wing. Cardiac is from the plastics, on that? Yes, so, it's something like 12% of cataract patients, just after standard, modern cataract surgery will have measurable ptosis within three months or so. And what that tells you is, use the lid specular, and pulling it in opposite way is enough just to take a rarified apneurosis and leave it, it's going to be more. So, taking it the opposite way, you're absolutely right, the pressure patch will stretch rarified attachments that will give you a distance search of whether it's associated with the factor. And the block wears off, there's a secondary contractual to the weight muscle. People will tell you on a patch, I can feel my eyelid opening, and they'll try and close it further, and there's this constant test, you're likely not to have a hematoma or apneurosis, you can be guaranteed there's going to be distance search on the elevator. Do you know, I have patients coming to me, probably monthly, saying, I want to talk to a cataract surgeon, my ptosis surgeon, and say, I'm sorry, we did my cataract surgery, they gave me ptosis, and I said, no, no, that's not how it's done. You had weakening coming off already, and so, I'm not saying they're all from cataract, they see it, but they wouldn't blame the cataract surgeon that he gave me the ptosis, what they forget is, ptosis isn't coming off, this is a vital insight, if you like, and so, you just need 200 microns of fruit because of this, positively, if you like. So that could just be from the lidspec, you could be topical in a seizure with a lidspec, possibly, that's very interesting. Did you find any, we in neuropomology get to plopia after a reservoir bar on periodal war blocks because of direct action on the muscles? Yeah, so I mean, I saw stuff like that, but I was, I kind of limited it to just the actual vision loss. This is a little bit of my own toxicity, but those are well-described, my own toxicity after retrovolving blocks, and that means a percentage of, like, two percent, but how many of those, after retrovolving blocks? So, we were concentrating on retrovolving blocks, and see there's a better retrovolve than he would be designed. The history of Moran is very interesting, we went through a period of about 20, 2006 to 2010, when several of the, I said, called me to give a retrovolve block to people that could do the case. I was sort of the retrovolver guru, because, you know, they've all become topical jobs, they've all become topical retrovolves. You'd be surprised how often you get a small detail about that. They've got this needle floating about. I found that comment very interesting, who said, bevel up, bevel down, don't forget. Your needle penetrates not from bevel up or bevel down, it's the tip that penetrates your eye hole. I think sometimes we fool ourselves into being scientists, but it's the tip that we'll hope, and if you say it's bevel up, the tip is further away, it's only further away by about 200 microns. So, you've got to be careful where the tip is going. I don't know, any of us have claimed to be brilliant retrovolver ejectors, I'll just tell you a story, which we'll start through here, I had a fellow resident who was both resident through the extra caps and catapults, and we were doing them, we really get really fast, and we were extra captured about 15 minutes. We're having lunch, and Stevie Kay, again, is complaining to me, ah, life is boring, I need to do something else, this catapult, I can do a hundred a day, you know, we're just having this resident power. He calls me the next day, and he says, you've got to come over, you've got to come over. He had had two retrovolver averages sequentially in such two cases, both of them developed a huge average, and both of them went, no light perception. The lesson is, it doesn't matter how good you think you are, complications will occur, and sometimes they do. And he was using a blunt needle, so instead of that needle, which had a sharp tip, they make retrovolver blunt needles, he got two retrovolver averages, both went to the end of the feet, one after the other, so not to make you want to give up to a certain piece, that would worry you, that's a little bit. That's what I was going to ask you, in your study, then, were there complications with those needles, retrovolver needles, or were they sharp? I don't remember, actually for most of them, I have to go back and look, so yeah. Well, the one that worried me the most was the subtenons, the globe perforation, too, so. I mean, the thing is, there's a reporting box, right? I mean, you're not going to report complications from a retrovolver block, because it's already been reported. Yeah. From the subtenons, people say, I, you know, this is supposed to be safe. This is newsworthy, so they're definitely going to react. I know. They're going to bury one of these, it's not much volume, where are you putting it back here? It didn't work from four MLs to eight MLs. I've been with the surgeon who did re-regulate what parts of the row, because he was getting out of man this season, probably put 18 MLs, right? So, I'm sure that the amount of volume matters, so it's going to potentially inject to a closed space, with a major complex space, so. And one thing is, you know, I often see residents sitting back on the plunger, you know, they really just pull back to, so they make sure they're not getting in the vessel. But really, if you're in a vessel and you just pull back a little bit, you'll know. You don't have to pull back so much that you're actually air coming back, that was like, you're just sucking into the tip. I didn't have a couple of cases to launch for a, just to bury a volver block, I'd give it like a Michael, Michael, I'd name it in the anterior chamber. It didn't seem to bother the surgeon, it didn't bother you that there was some volume in the anterior chamber, did they talk about anything like that? Just some kind of more grossly visible hythemes following subtenance blocks, and I think maybe one of those is in a, I don't think there are cataract cases, I think they're like maybe tritium or something else, so. All right.