Lecture: Strabismus: Managing A and V Patterns

In this live webinar, Dr. Neely will discuss alphabet-pattern strabismus and how to manage it surgically. Case discussion and live questions and answers are encouraged. Cases and questions may also be submitted in advance. Please email us at [email protected] if you would like to submit a patient case to Dr. Neely.

Lecturer: Dr. Daniel Neely, Ophthalmologist, Indiana University School of Medicine, USA


DR NEELY: Well, greetings, and welcome to today’s Cybersight webinar, sponsored by Orbis. Today we’re going to talk about complex strabismus. And specifically A and V pattern strabismus. My name is Daniel Neely. I’m a professor of ophthalmology at the Indiana University, and I’ve been an Orbis volunteer for almost 20 years now. I would like to remind you that this will be recorded and will be available in the Cybersight library. A lot of this material that will be referenced is also available in the courses section of the library. Where, if you look under the fundamentals of pediatric ophthalmology, you’ll find that there is a module four within that, and that is complex strabismus. Of which most of this relates to. We have one case that was submitted in advance, and we’ll talk about that. If there are questions, which I hope there are, please use the chat feature to submit your question to us. And we’ll try to answer those live as much as we can. I’ll go ahead and switch over to screen share here. We’ll begin the presentation. All right. So A and V pattern strabismus. This is all very common. And for the most part, the approach to this is relatively straightforward. But there are some pearls that we need to be aware of. And I’ll try to highlight these key elements during our presentation today. Now, when we talk about A and V pattern strabismus and how we’re going to treat that, so A and V pattern — we have deviations which are greater in one direction, upgaze or downgaze, than they are in the primary position. And as you go about treating these, the whole goal here is to collapse the pattern. So that there is not this big incomitance from upgaze and downgaze. So when we talk about collapsing the pattern, that’s what we’re talking about. So the measurements will be the same in the primary and up and down gaze. Or close to it. As a part of this, we frequently find that there’s dysfunction of the oblique muscles. So part of this presentation will be discussing that. What does that look like. And how do you approach it, when there is oblique muscle dysfunction. Now, this first case was submitted from a physician in Japan. And I thought we would just open this up as an introduction. We won’t complete our discussion of this case until the end of the presentation today. But I thought we should at least take a look at this, because I think there are some good teaching points that will lead us into thinking about what the rest of the webinar is gonna look like. So this is a 27-year-old female. And she relocated to Japan two years ago. Was working there as a teacher. Presented with — desiring treatment for her esotropia. Which apparently had been present since infancy. No history of diplopia or double vision ever. And she has normal vision in both eyes, as most people with congenital esotropia will. So 20/15 in each eye. She also has no stereopsis, which is also quite common with congenital esotropia. And that’s even when a correcting prism is placed in front of her. She just does not have the ability for stereopsis. And therefore that’s probably why she doesn’t have diplopia. And here’s a collage of her gaze positions. It’s noted that she has A pattern esotropia with bilateral superior oblique overaction. So we’ll just focus on the primary position. And you can see her esotropia is not too bad. When I see… When I’m examining patients, I of course look at the primary position. And a lot of times, the first thing I’ll do is kind of go into side gazes right away. And you can see in side gaze here she’s getting a hypertropia in both directions. Now, something to point out here is that she’s actually cross fixating, as she looks in side gaze. So here in right gaze — well, it appears that she’s cross fixating. You don’t actually know, unless you confirm this. But the appearance in these photographs are that she’s cross fixating with the left eye. And that gives the appearance that the right eye is up. And on left gaze, it appears that she is cross fixating and viewing with the right eye, and then that makes the left eye look up. Look like it’s hypertropic. But what we can see when we come into these oblique positions and upgaze and downgaze, what’s really notable here is that from the primary position to upgaze, she becomes significantly more esotropic. And when she goes from the primary position to downgaze, she actually looks exotropic. And down and to the right, you can see that there’s this left superior oblique overaction, overdepression. And here down and to her left, you can see that there is significant right superior oblique overaction. So that’s what we’re presented with. And here are the measurements that accompanied the case submission. So far and distance deviation with and without correction. She has about 30 of esotropia. And then her discrepancy from upgaze to downgaze again is quite significant. 35 in the primary, increasing to 55 in upgaze, and actually reversing to an exophoria or exotropia in downgaze. So we have a significant A pattern with this esotropia. Which, as an aside, with this being a presumed case of congenital esotropia, in someone who has not had surgery before, seeing this A pattern is distinctly less common. What do we normally see with congenital esotropia? Well, we normally see V patterns and inferior oblique overaction. So this is a little bit unusual. But obviously not impossible. All right. And then interestingly, they also submitted some fundus photographs. And these are quite striking, in that there is a fair amount of incyclotorsion. You know, normally when we look at a fundus photograph, the fovea will sit right around — close to the center or towards the edge of the optic nerve cup. This one is a little excyclotorted, here on the left side. You can see that this is significantly excyclotorted. The fovea actually, if you extend a line from the top of the optic nerve, it’s actually above — sorry. It’s actually above the border of the optic nerve. So we have some significant excyclotorsion present in this patient. All right. So the questions that accompanied this I blacked out, because we’ll discuss those at the end. But the physician is planning surgery. And has some questions about… Well, these findings and also what should I do. And there were a couple options presented as surgical intervention, and we’re going to discuss and end up at what I think is the correct decision for this patient. And that leads us into poll question number one. Based on what you just saw, obviously this patient needs a medial rectus recession for the 30 prism diopters of esotropia. But how would you approach this patient’s A pattern? What are you going to do to collapse the A pattern? All right? So are you going to do a medial rectus upshift? Just avoid the obliques altogether? Are you going to do bilateral superior oblique posterior 7/8 tenotomy? So not a complete tenotomy, but just the posterior 7/8 or connecting? Are you going to do a bilateral superior oblique disinsertion? So the complete tendon insertion? Or are you gonna do a tenotomy and cut the tendon, more proximal to the trochlea? Or are you going to do a bilateral superior oblique spacer? So these are our choices. And I’ll give you just a few seconds to complete the results. And at this time, there won’t be a wrong or a right answer. We’re simply going to look at what our results are. All right. And here you can see we have a pretty mixed result of responses. So 26% medial rectus upshift. 26% superior oblique 7/8 tenotomy. 19% superior oblique disinsertion. 23% tenotomy, and then a smaller 6% spacer. So we have quite a diversity of opinions. And that’s fine. Because I think any of those, I think, would actually work, to some degree. Some may be better than others. And as long as you can justify your choice, I actually don’t think any of those were wrong answers. But let’s talk about what leads us or would lead me to pick one over the others. So A and B patterns again — this is a discrepancy between upgaze and downgaze. In A patterns, we tolerate a little less discrepancy between upgaze and downgaze. So the difference to qualify for an A pattern is a 10 prism diopter difference between upgaze and downgaze. So you have more esotropia in upgaze, or you have less exotropia on upgaze. With V patterns, you know, normally there’s some convergence on downgaze. Because when you’re looking at something, a book or a phone, you need to converge your eyes. So there is some normal convergence that has to occur, typically, for us, in downgaze. So we’re a little more generous in what we start to describe as an A or V pattern. So for V pattern, the difference needs to be about 15 prism diopters between upgaze and downgaze, before it is technically a V pattern. And I’m just… Here’s a comment. Oh, yes. On the first case, there’s a correction here. Apparently I said excyclotropia on those fundus photographs. But clearly there’s incyclotropia, as a matter of fact. So thank you for that correction, doctor. Let me close this out. And I’m actually gonna scroll backwards, so that we have that clarified. Because that’s a good catch, if I said that. I’m sure I probably did. Go backwards here. Let’s look at that photograph one more time. Incyclotorsion, both eyes. Right? So we have incyclotorsion from the superior oblique. All right. I’ll advance back to where we were. All right. So here’s our example of an A pattern. Right? So the deviation, the measurements are going to mimic the shape of an English letter A. And so in this case, we have an esotropia in the primary position. Somewhere in the ballpark of 30 prism diopters, likely. And we have increased esotropia on upgaze, and we have less esotropia on downgaze, just like the case that was submitted from Japan. All right? So A pattern esotropia. And similar to the other case, you can see again: Any time you see an A pattern, first thing I’m gonna look for is superior oblique overaction. And that’s exactly what we have again in this case. Superior oblique overaction here. Superior oblique overaction here. Not too bad in side gaze. Here you can see a little bit of maybe what looks like inferior oblique underaction. And inferior oblique underaction. Okay? So we have this imbalance between the obliques and we have an A pattern. V patterns are definitely more common, just as you go throughout your clinical patient visits. You see V patterns just all the time, very, very common. Both esotropia and exotropia. And so again, here V pattern — that means if you have an esotropic patient — and this patient here in the primary position, they’re relatively straight. There’s a small esotropia in the primary position. But it becomes significantly more in downgaze. And they’re a little exo on upgaze. And any time I see a V pattern, what am I looking for? I’m looking inferior oblique overaction. So that’s why I like to look in side gaze right away, both ways. And here you see it quite easily. The patient has significant inferior oblique overaction. But a lot of times in the +1, +2 inferior oblique overactions, you don’t really see it until you take them up and to the side, as we are here, and up and to the side here on the left. So I like to look straight into the side gazes, and then I’ll go up into those oblique positions. And in this case, you can also see the accompanying little bit of superior oblique underaction. And superior oblique underaction down here. So again, it’s the balance between the two oblique muscles. One of them is either overexerting or — when I say one of them, I mean the inferior obliques or the superior obliques — one is either underacting or one is overacting. So the balances are just not quite equal there. All right. So we have our A patterns and V patterns. That’s all pretty clear. Poll question number two. So when shifting horizontal rectus muscles, because that’s the easiest thing you can do when you’re trying to collapse an A pattern or a V pattern — may not be the most effective, necessarily, but it’s the easiest thing to do. So it does apply to a lot of us, and to a lot of our patients. But you need to know which way to shift them. So this is gonna lead into that. So poll question number two is: When shifting horizontal rectus muscles to collapse a V pattern, in this case — I’m choosing V pattern, because that’s the most common — which of the following is true? All right? When you’re shifting… This is a V pattern. So you can shift the laterals or the medials. Right? Doesn’t matter. And first response question choice — shift the lateral rectus muscles down for the V pattern. Or two, shift the lateral rectus muscles up. For the V pattern. Or three, shift the medial rectus muscles up for the V pattern. Or are none of these correct? All right? And these muscle shifts… We’ll go ahead and wait for your responses. But these muscle — rectus offsets — I do them all the time. And I’ll preface that by saying that usually I’ll do this in cases where there is either no oblique dysfunction or maybe there is just mild oblique dysfunction. All right? And so our responses here… So when shifting horizontal rectus muscles so collapse a V pattern, 25% say shift the lateral rectus muscles down. 46%, shift the lateral rectus muscles up. Which happens to be the correct answer. Or 19% saying shift the rectus muscles up. And then 9% were none of the above. So let’s look at that. All right. So… How do we know which way to shift these muscles? Not necessarily intuitive, as you think about it. You might be able to rationalize this or that. And think about the mechanics. But we can make it easier than that. You just don’t necessarily even have to understand the dynamics here. And how do we do that? Well, there’s this mnemonic, MALE. M-A-L-E. And what does this mean? This stands for: Shift the medials to the apex of the pattern and shift the laterals to the empty space of the pattern. So MALE. So here we have an A pattern. And this applies to esotropia and exotropia. It doesn’t matter. But if you have an A pattern exotropia, and you’re recessing the laterals, you can shift them downward towards the empty space of the A. If you had an A pattern esotropia and you’re recessing the medials, then you’re gonna shift the medials towards the apex, towards the point of the triangle, or the top of the A. So medials to the apex. Laterals to the empty space. And it doesn’t matter if your procedure is a recession or resection. This shifting pattern applies. So that’s an A pattern. The same rule applies to V patterns. If you’re working on the medials, whether it’s a recession or a resection, you’re going to shift the medials towards the point or apex of the V triangle. Apex is the point. If you happen to be working on the laterals, recessing them for an exotropia, or resecting them for an esotropia, you’re going to shift the laterals towards the empty space, where the pattern is open. Where the letter is open. Okay? So MALE. This is how we can recall that. So that you don’t have to… Under the heat of doing surgery, you don’t have to think about all the orbital dynamics that go into this. Okay? Medials to the apex. Laterals to the empty space. That’s the rule of thumb that will get you through 90% of this stuff. I see a question in the queue. First question is: Should we suspect superior oblique palsy in a patient with inferior oblique overaction? So a patient with inferior oblique overaction… Should we suspect a superior oblique palsy? Well, let me just back up to the inferior oblique overaction collage here. All right. So a patient like this… The question is: Should we suspect superior oblique palsy in a patient with inferior oblique overaction? The answer is yes, but I don’t really like the term superior oblique palsy. Why do I not like it? Because these really aren’t, most of the time, like a nerve palsy. What’s going on most of the time probably has more to do with orbital anatomy and orbital dynamics, mechanics. You know, the superior oblique tendon could be too short. If it’s too short, you can get superior oblique — an A pattern. Right? The superior oblique tendon is too long, you can get superior oblique palsy. Where now the muscle is pulling normally, but the tendon is so long that it’s not getting the same effect. Right? That can give you V patterns. So that’s the reason I don’t really like the term “palsy”. Should you look for it? Whether you should look for it depends on other things. In a kid like this, you’re probably not gonna start necessarily chasing down looking for a true bilateral superior oblique palsy. Someone would have this appearance and it would be a true superior oblique palsy, like from a nerve injury — again, you’re talking about people with head traumas, who are comatose or knocked out. You’re talking about motor vehicle accidents, falls from ladders, things like that. And that’s a whole nother lecture, how you determine that. But it boils down to measuring torsion. Right? I’ll just leave it at that. You need to know what the torsion is. Because bilateral superior oblique palsies are gonna have a lot of torsion. Unilateral palsies are gonna have less. Congenital palsies… What just look like inferior oblique overaction, they’re also gonna have a lot less. So I’ll just leave that at that for now. All right. There’s another couple questions in the chat, but I’ll come back to them in a second. Just keep moving forward a little bit and then I’ll get to those. Less finish our discussion of the medial rectus and lateral rectus shifts. So shifting in this illustration, it’s a medial rectus A pattern shift. So… Again, shifting the medials towards the apex, top of the A pattern. So they’ve been recessed. They’ve been upshifted in this particular case, almost a full tendon width. Maybe 3/4 of a tendon width. How much do I usually shift them? Well, when I’m doing rectus muscle shifts for A and V patterns, it’s usually anywhere from half a tendon width to maybe 3/4 like this. A full tendon width… That’s more… I mean, that gets to be a transposition, at that point. So a half to 3/4 for me would be pretty standard. And you just have to pay attention to your measurements. Because obviously this one, where you’re still behind the muscle insertion site, that’s pretty easy to measure. But then you’ve got to measure this one. So I’ll do a few things here. I’ll do things like measure not just from the insertion, but I’ll measure from this suture to the limbus. And then kind of duplicate that a little bit, while at the same time kind of accounting for the spiral of Tillaux, where you don’t want to be advancing this, because the spiral of Tillaux tends to get further away. So I’ll be a little lower on my measurement than this one was, by half or 1 millimeter. So just pay attention to your suturing and marking as you’re doing this more distal insertion. So that’s what an A pattern medial rectus shift would look like. And that will correct up to about 15 prism diopters. So you can see it has some utility. 15 prism diopters of A pattern. But it’s not gonna collapse 40 prism diopters of A pattern. That’s a significant A pattern. But small A patterns, when you don’t want to mess with the obliques, this is kind of a good go-to. And what does a V pattern shift look like, again? The example here is medial rectus recession. And I’ll just point out that when you recess the medial rectus, just straight back, you’re collapsing some V pattern just in the process of doing that. So recession alone might collapse up to 10 prism diopters of V pattern. So then when you do a downshift, in medials to the apex, you’re gonna maybe get another 15 prism diopters of V pattern collapse. So that’s a total of 25. So it’s fairly powerful for A and V patterns, with no significant oblique muscle dysfunction. And then there’s no… I don’t have illustrations here of the laterals, but it’s the same thing. Just in the other direction. But while we’re talking about shifts, I will point out this one little pearl. And that is: When you’re doing maybe like a recess/resect procedure, and a lot of times you’ll see patients have a small hypertropia in that eye, either because they just have poor fusion or they have sensory strabismus, so a patient like this, they’ve got a decent angle exotropia, but they’ve also got this little hypertropia in the exotropic eye… You can try to bring that eye down by doing a vertical displacement of the recessed and resected muscles. So here you can see the resected muscle has been downshifted, and the recessed muscle has also been downshifted. And so rule of thumb for this is: If you move the muscles down by about 4 millimeters, that’ll give you about 6 prism diopters of vertical correction. And again, the maximum is about 15 prism diopters, if you’re doing close to… Closer to 3/4 or full tendon widths. All right? Now, the muscle insertion here is usually about 10 millimeters wide. So 4 millimeters is about half a tendon width. And a full tendon width is gonna be about 10 millimeter downshift. And what direction do you move in? You move the muscles in the direction you want the eye to go. So our example here: We have a hypertropic eye. And you’re gonna move the muscles down. Now, sometimes it seems like people overthink this. And they’re like… Well, if I move them up, they’re tighter. It’s gonna pull down more. But you actually want to shift the muscles where you want the eye to go. So analogous to doing transpositions for 6th nerve palsy. You’re gonna take the superior and inferior rectus, and shift them temporal, because that’s where you want the eye to go. Same thing applies here. Inferior oblique overaction. So, so common with A and V patterns. I’m gonna pop up to our Q and As here. And this question is: Does bilateral medial rectus recession alone also correct a similar amount of A pattern? Or does that only work for V pattern? And what might the reason be? It’s a good question. And I actually don’t know the answer to that one. I’ll have to get back to you on that. I’m unsure. Although… Again, it’s certainly a less common thing to even do. Seems like most of the times when I’m collapsing A patterns, usually the A patterns are pretty significant, and I’m working on the obliques. It’s just the primaries, and I’m just not sure what those results will be. This question is… Is A-V pattern considered as comitant, because angle of deviation changes in different gazes? Well, if you have an A-V pattern, I think automatically that is incomitant. Right? Comitant would mean the deviation is the same in all directions. But if you have an A or V pattern, your deviation is not the same. In upgaze and downgaze. So I personally would call that incomitant. Particularly once it gets above kind of those expected normal deviations or variations, where there might be 10 prism diopter difference for an A pattern or 15 prism diopter difference for a V pattern. Once you exceed that, I would call that strabismus incomitant. This next question is about transposition or slanting procedure. Which one is more effective. We’ll talk about slant procedures towards the end. But I don’t think there’s any question in my mind which is probably more effective, and it’s going to be transpositions. Transpositions are going to be the most powerful procedures you can do for moving an eye. And collapsing incomitant — if you have A or V patterns, or nerve palsies. Which is why it’s what we do for 6th nerve palsies. Transpose muscles. All right. So we’ll go back to our lecture here. So I mentioned that — we see this all the time, right? We see V pattern esotropia. We see V pattern exotropia. Super, super common. Now, first of all, what do I do for that? Well, usually it depends on how I am quantifying the amount of inferior oblique overaction. So mild inferior oblique overaction, +1. Moderate inferior oblique overaction, +2 or 3. And severe inferior oblique overaction is a +3 or 4. That’s all very subjective. We don’t typically find that measurements are helpful for this. You just grade it and try to be consistent in how you grade it. +1 through +4. And we’re going back to this example. This one is pretty significant. I would call this a +3 inferior oblique overaction. And it doesn’t mean everyone is gonna call it +3. But that’s what I would call it. So once I’ve quantified this, what do I do with it? Now I have to pick a procedure to correct that. All right. If I have real mild inferior oblique overaction, to me, I will do recessions. If I have moderate to severe inferior oblique overaction, whether it’s a patient like this, with congenital ET or XT, or it’s a patient with a superior oblique palsy, then I’ll start moving into these myectomies. And we’ll talk about myectomy versus large recessions. And then there’s the anterior transposition. Right? When do we do anterior transpositions? Well, as we’ll talk about, we only do this when we think the patient either already has DVD, dissociated vertical deviation, or they’re at significant risk to develop DVD. Who is that? That’s the congenital esotropia patients. Because when you follow those congenital ET patients over time, at least in our population that we’ve studied, at Indiana University, 90% of them have developed DVD by the age of 10. So super, super common. And that might sway you between one of the first two procedures versus an anterior transposition. Even if they don’t have DVD yet. Right? Because a lot of times those don’t develop until several years have gone by. And then the other way to diminish inferior oblique overaction, which is probably the least commonly chosen approach, is the superior oblique tuck. And again, I’ll reiterate this again later on: The only time I would ever tuck a superior oblique is when it is lax. It’s redundant. It’s loose. And you can confirm that by traction testing. And also, the deviation has to be quite large. I don’t do this ever in mild cases. These are people that definitely have +4 inferior oblique overaction. And you do their traction test and you feel almost nothing, and you almost wonder if they even have a tendon insertion. And occasionally, you’ll find people who don’t have a superior oblique tendon insertion. It’s not common, but you’ll find it. All right. So… Inferior oblique recession. I don’t do these a lot, because I’m a big inferior oblique myectomy person. But in cases where you’re concerned about overcorrection or the inferior oblique overaction or the deviation, the vertical deviation in unilateral cases is quite small, then I think this is a very reasonable approach. Keep in mind: So we’re looking here on the screen left. The course of the inferior oblique. Right? Runs beneath, inferior to the inferior rectus. And then it inserts underneath the lateral rectus. All right? So that distance behind the insertion to where the inferior oblique muscle border is, is 8 millimeters. And we’ve got to keep that in mind. When we’re working on the lateral rectus. Because a lot of times, I see novice surgeons put hooks in. And they sweep way back, way back, further than they need to, to hit the insertion. And what are they doing? Well, they’re getting into the inferior oblique, and then they’re pulling it forward, into the more anterior insertion. And then if they’re doing resections in particular, they’re creating inferior oblique inclusion syndrome. So be aware that there’s an 8 millimeter space to pass your hooks. And try and stay in that space. Now, when we’re doing a recession, what are we doing? Well, we’re just simply doing what we do with all recessions. We’re disinserting the muscle from here, underneath the lateral rectus, and then we’re following its course, its normal course, and then we’re reattaching it back here somewhere. And that somewhere — typical inferior oblique recession — is 10 millimeters. Well, we don’t measure with calipers from the insertion, like we do with other recessions. It’s just difficult to do that measuring. So how do we estimate where to sew this inferior oblique back on? Well, it’s this guideline of 3 and 2. So from the inferior rectus, which you can see hooked here, inferior rectus is hooked, from that corner, set your calipers, measure straight back 3 millimeters. And then you move it temporal 2 millimeters. So down 3. Over 2. Right? So that’s gonna put you right there on this other illustration. And that’s where your suture that’s closest to the cornea is going to go. And then the second suture is just gonna be spaced out proximately in that same zone without bunching up the tendon or changing its width. So 3 and 2. That’s how we estimate a 10 millimeter standard inferior oblique recession. Now, you can do largely inferior oblique recessions. And the larger recession is a 14 millimeter recession. What is that? Well, 14 millimeter recession is gonna be pretty much putting it here at the border of the inferior rectus. And right around in this area, right where my arrow is right now, that’s where the vortex vein is sitting. And in a 14 millimeter recession, you estimate that by pretty much placing your sutures on either side of the vortex vein. And that’s the main reason that I don’t personally like 14 millimeter recessions. I would just as soon stay away from the vortex vein. Once you sew it there, it’s not easy to reoperate on it, because you’re going to destroy the vortex vein and have a bloody mess, as you go back and try to change it. So you’ll see that’s about the same spot where a myectomy is probably going to end up sitting. And so I don’t feel like there’s any advantage to a 14 millimeter recession versus a myectomy. And I think the results are similar in the amount of correction you get. There are several questions building up in the Q and A. And once I finish talking about inferior obliques, I’ll go into those. Then I’ll hit superior obliques. All right. So inferior oblique myectomy. This is my preferred thing to do. You know, these are fast. They’re very forgiving. Once you get the muscle disinserted, they’re relatively easy to do. They don’t require any sutures. So it’s kind of what you might say… Self-correcting. Right? You don’t really have to measure these. That muscle… So here you can see: What are we doing? Well, we’re clipping out an 8 to 10 millimeter section of inferior oblique. And then we’re just letting it go. We don’t sew it back on. And to me, that gives maximal weakening for large V patterns. So up to 40 prism diopters of correction. If you do this particularly. This is my go-to for unilateral superior oblique palsies. So if I have someone who’s got inferior oblique overaction, looks like a superior oblique palsy, and they’ve got up to 10 or 15 prism diopters of hypertropia, inferior oblique myectomy would fix them 90% of the time. Now, if you have more than 15 prism diopters of hypertropia, you have to start adding muscles. But again, that’s superior oblique palsy. So doing this myectomy, taking out an 8 to 10 millimeter section, the power of that is very similar to a 14 millimeter recession. As I said in the previous slide. So… I had videos of this, and they weren’t running. So I’ve deleted the videos. But I’ll try to get some good oblique muscle videos up on the Cybersight library. Reviewing that this past week, I see that we don’t have a great selection right now. So I’ll get some of my videos up there, and I’ll narrate them, so that we have some good examples of superior or inferior oblique surgery. But in this still photograph, this hemostat was placed across the insertion. Of the inferior oblique, right at the lateral rectus. So it’s been disinserted from the globe. And what you’re looking at is where the inferior oblique disappears through posterior Tenon’s capsule. And right around the lateral rectus border and the vortex vein. Okay? So what are we gonna remove? We’re gonna pretty much remove everything down here to just where it exits posterior Tenon’s capsule. So I clip it, clamp it, take a second hemostat, go right across here, and try to get everything right up to the posterior Tenon’s capsule. So here’s the second hemostat on. First one is at the top. Second hemostat is at the bottom. You can just cut this with scissors and then do cautery. Because this bleeds. You’re cutting across a very thick vascular muscle. So you have to be a little judicious about hemostasis. The clamp will help some by crushing. If you cut with scissors, cauterize with bipolar or a flame heated open cautery, I use these battery powered disposable cauteries a lot. You can see what we’ve done is: My assistant is holding a wet cotton tip. So we’ve soaked it, and it’s pushing the eye back. And I’m pushing the slide forward. It’s pushing the eye back away from the cautery. So I can just — this cautery will cut and cauterize at the same time as I come across. And then just get rid of that segment. So that’s my technique to do the inferior oblique myectomy. And then we open the hemostat and release it. And where does it go? It doesn’t go anywhere. So it’s sitting right there at the exit through posterior Tenon’s capsule. And that’s why you don’t have to suture these. So some muscles, you can lose the posterior Tenon’s and never see it again. This is a great example of that. But other muscles — inferior oblique, superior oblique, lateral rectus, you know, they have a lot of attachments to other structures. So they don’t tend to really just disappear like those medial rectus muscles can. So this muscle — you can shove it back through Tenon’s. And you can close Tenon’s in front of it. So it doesn’t adhere. But generally we’re just letting it sit there and it reattaches right there. And again, that’s probably in about the exact same place that the inferior oblique recession would be. If you’re doing a 14 millimeter vortex placement recession. So that’s why I think the results are frequently quite similar. And it doesn’t necessarily stay right there. A lot of times, it kind of creeps back up a little bit. And if you ever have residual inferior oblique overaction, you can always repeat the traction test and see if you still feel that inferior oblique band. Go back and repeat the myectomy, if it seems to be not complete. All right. Let me finish inferior oblique anterior transposition discussion. And then we’ll get to those questions. So anterior transposition, I mentioned that… This will weaken the inferior oblique. And it will also collapse the V pattern. But it can have some negatives. You can create some restriction or some antielevation syndrome. So I will typically only do an anterior transposition if I have a patient who has DVD, dissociated vertical deviation. Or I think that they’re at significant risk for developing it as they get older. So a one-year-old or two-year-old with congenital esotropia and inferior oblique overaction, rather than doing — and they probably haven’t developed DVD yet, because they’re too young — but rather than doing a myectomy or recession of inferior oblique, I might just go ahead and do the anterior transposition, knowing that they’re at risk for DVD down the road. All right? And again, just an example of what does DVD look like? So there’s that eye, after it’s occluded. What do we not see? So here we see a left hypertropia. If you do alternate cover testing, you will never see a right hypotropia in patients with DVD. They just have this dissociated upward movement. But there is never a corresponding downward refixation or hypotropia in the other eye. That’s a hallmark of DVD. Anterior transposition. Look, it’s the same thing as doing a recession. You’re just sticking it back on in a different spot. The technique is the same, though. Where do you put it back on? Pretty much next to the corner of the inferior rectus. So here’s the inferior rectus. Here you can see this inferior oblique has been sewn on about 1 millimeter in front. Does it have to be 1 millimeter in front? No. And I don’t mean in front. I mean adjacent to… Inferior oblique, inferior rectus, adjacent to each other. And then maybe shift it just forward a little bit. Can be anywhere from 2 millimeters anterior to the inferior rectus insertion. 1 millimeter, like this example. 0 millimeters right next to it. And sometimes I’ll even do negative. -1 or -2. So some people call that a pseudoanterior transposition. But somewhere between a recession and an anterior transposition. All right? So… Again, diminishes DVD. Diminishes inferior oblique overaction pretty substantially. Collapses V patterns. Might have some negatives, when you start talking about antielevation. What is antielevation? This muscle now is so far anterior that the eye doesn’t elevate very well. One thing that I don’t do — and in this illustration, the inferior oblique is spread out wide — most people will bunch up and make the insertion narrower. The concept there is that it supposedly reduces the incidence of antielevation syndrome. So I tend to have the insertional sutures relatively narrow. All right. So before we go on to the last section, superior obliques, let’s go back to the questions here. We’ll open it up and see what we have cooking. First question, basic one: Why should we operate on an A or V pattern? Well, you don’t have to. If it’s not causing problems. But particularly the downgaze position. You know, upgaze, who cares? Unless you’re an airplane spotter or an electrician, where you’re working overhead, upgaze is our least important position. I almost never make decisions based on upgaze. But we all the time are making decisions based on anomalous downgaze positions. If you have a big V pattern, then your eyes are crossing while you’re reading or working on a computer or looking at a phone. If you have a big A pattern, then in downgaze, same thing. Your eyes are divergent while you’re trying to read or use a mobile device. So that’s why. But it all depends on other things too. We’re not usually doing these for cosmetic reasons. We’re usually doing these for functional reasons, particularly in downgaze. Close that one out. This question is management of X pattern, resulting after V pattern correction. Well… Again, it’s a bit difficult to answer that. Because it depends on how much and is it problematic or not. And I think… I don’t find that I have to go back and revise surgeries, based on someone developing an X pattern after I’ve surgically treated a V pattern. But I do think this goes to patient selection and choosing the right surgery to do. You don’t want to be overly aggressive about treating V patterns. Or A patterns. You know, if you have an X pattern — so now you’ve got divergence in downgaze, after you did something for V pattern. You need to reverse what you did. I don’t think it’s any more complicated than that. If you did a myectomy, it’s gonna be harder to reverse. That’s for sure. Compared to a recession or an anterior transposition. Yeah. I mean, mostly you have to reverse it. If you can’t reverse it, well, you can try to compensate by doing horizontal rectus muscle shifting. Right? So say you did an inferior oblique myectomy for a V pattern, and now you have an X pattern. You have A pattern, basically, in downgaze. Shift to the mediolateral. Try to collapse that downgaze position. All right. This question is: Do you shift horizontal muscles in one eye for V pattern? Like moving one MR down and one LR up? I don’t. But it can be done. I do have that graphic, and I use it in some of my other lectures. But because I don’t do it, I don’t talk too much about it. But it’s a fair point. If you have… If you’re doing monocular surgery for an A or V pattern, you can… So sensory exotropia or sensory esotropia… You can shift the medial and the lateral while you do the recess/resect. You’re shifting them in opposite directions. All right? But you can do that and try and collapse the A or V pattern with monocular surgery. You follow the same MALE, medials to the apex, laterals to the empty space, direction for your shift. It’s a good question. How to position the muscle along the spiral of Tillaux? Angulate the end stump a little bit to follow it. Yeah. So the spiral of Tillaux — the rectus muscles are not all inserted the same distance. We know what the averages are for superior rectus, medial rectus, lateral rectus, inferior rectus. You know what those averages are. So you have to compensate for that a little bit. An example is… When we do shifting of the superior or inferior rectus for 6th nerve palsy, and you’re shifting them temporal, most people will recess the superior rectus a little bit, because normally the superior rectus sits the furthest away from the limbus of all four rectus muscles. So if you just measure — if you just shift it and you’re putting it next to the lateral rectus, you’re advancing it, actually. So most people will recess it by 1 millimeter or so, when they do the transposition. Otherwise, you get these verticals. So you just kind of have to have… It doesn’t have to be precise. But you have to have some ballpark knowledge of what the spiral of Tillaux measurements are. And yeah. You’re gonna put one pole slightly further than the other pole. To approximate that. Another question. What is the importance of knowing these two patterns, A and V pattern? Well, the importance is: If they are clinically significant, you probably want to fix them. Now, if they’re not clinically significant, you can ignore them. If they’re not causing a problem or not expected to cause a problem and the patient is not bothered by it, you don’t have to do anything. But if someone has a big V pattern and you’re doing bilateral medial rectus recessions anyway, you might as well try to fix them as well as possible and fix the V pattern as well. So it all comes down to magnitude. Right? I wouldn’t necessarily operate just to make an A pattern or V pattern look better. This question is: I’ve encountered numerous patients who had significant V-person exotropia. So VXT. But no or minimal upshoot in side gaze. But significant upshoots in oblique gazes. Yes, I would agree with that. A lot of times I don’t see it when I go straight to the side, but when I take them up in the oblique positions, now you really see the inferior oblique overaction. What would your recommendation be? Superior or inferior oblique weakening or horizontal transpositions? I still… Even if they don’t develop that hypertropia on side gaze or inferior oblique overaction on side gaze, if you just bring them up a tiny bit and all of a sudden that eye is kicking up, I still count that as oblique muscle dysfunction. And I will usually work on the inferior obliques as a result. In this particular example. But it boils down to the degree to which I’m seeing that happen. Again, small patterns, small oblique muscle overaction. So you can just do horizontal shifts. But when you have significant degrees of oblique muscle overaction, or A pattern, V pattern deviations, you kind of have to work on the obliques, definitely. I’m sure a lot of people aren’t comfortable working on obliques. And that’s the other, I think, point here. I’m gonna back out of the questions for now. If you’re not comfortable working on the superior or inferior oblique, don’t do it. You’re just gonna make things worse. Stick to the rectus muscle shifting. You’re gonna help them. It may not help them as much, but you’re gonna help them, and you’re gonna have a low chance of morbidity with it. So do what you’re qualified to do and are comfortable doing. All right. Let’s chat about superior obliques, before we go back to questions here. We’re coming up on the hour. So we’re gonna keep it moving a little bit. Still have some important points here to get through. Superior obliques can also give you A and V patterns, depending on if there’s too much superior oblique effect. Brown syndrome. Or just generally tight superior obliques. Kind of like the patient we saw in the very first case from Japan. You get A pattern. Because superior oblique is overacting. Or the inferior oblique is underacting. It’s always a balance here. Or if the superior oblique muscle is underacting, superior oblique palsy or just kind of a long tendon kind of situation — then you’re not getting enough superior oblique effect. They’ll have these V patterns. As we’ve been discussing here. Last poll question. All right? If we’re gonna weaken the superior oblique, we need to know what we’re gonna get out of it. The question is: When performing a tenotomy of the superior oblique, which of the following is true? There’s two choices here. Cutting the superior oblique tendon closer to the insertion on the globe produces the most weakening. Or is it true that cutting the superior oblique tendon closer to the trochlea produces the most weakening effect? Just cutting the superior oblique anywhere along its course is not equal. So go ahead and answer these. And then we’ll talk about it. Where you cut that superior oblique is gonna give you different amounts of effect. It’s important that we know that. All right. And we’re kind of divided here. 43% say closer to the globe gives you more effect. And 58% say closer to the trochlea gives you more effect. Closer to the trochlea gives you more effect. If you just disinsert and cut it off at the insertion in the globe, a lot of times that gives you very little effect. It’s underwhelming. If you cut right next to the trochlea, you’re gonna get a total superior oblique palsy. So we almost never cut next to the trochlea right away. Usually when we’re doing a tenotomy, it’s gonna be close to the nasal border of the superior rectus. So closer to the trochlea, more effect. Closer to the muscle, superior rectus, right here, that’s the superior rectus, or at the insertion, less effect. All right? So it’s graded. Here’s another graphic showing that. Here’s a superior oblique. Tendon. Superior oblique isolated in the tendon sheath still. Sheath’s been opened up. Got the superior oblique tendon. On the Stevens hook here. And it’s being cut. So that’s a tenotomy. And closer to the trochlea, more weakening. Closer to the superior rectus, less weakening. This is an example of a spacer being put in for Brown syndrome. Where do I usually cut the superior oblique? Probably 90% of the time if I’m doing a superior oblique tenotomy, I’m doing it right here, along the nasal border of the superior rectus. 90% of the time, I’m right there. 10% of the time, I’ll be doing something out here at the insertion. And that’s what I’m gonna be talking about next. Doing disinsertions or doing 7/8 tenotomies. And why do we do those? So 7/8 tenotomy. I borrowed this graphic from Dr. Krishnan. But it’s a nice illustration of the posterior 7/8 tenotomy. And this is again — when you’re weakening the superior oblique, you’re generally treating an A pattern. So again, this goes back to the patient from Japan with an A pattern. So you can see the insertion. And it’s tough to get this insertion. This is not easy to isolate the insertion of the superior oblique. It’s easier to get the superior oblique here, where the fibers are condensed. But out here at the insertion, it’s easy to miss this. Because it goes back so far, so posterior. And there’s also a vortex vein back here. Just to give you a heads up. You’ve got to be cautious when you’re putting hooks in here. Because right here is a vortex vein. But a 7/8 tenotomy, we’re just cutting, disinserting, the posterior 7/8, and we’re leaving the anterior 1/8 of the superior oblique intact. So if you cut it, this is what it looks like. Now, here it’s been removed. I cut the tendon. A lot of times, what I’ll just do is I’ll just cut here with my scissors. And not actually remove it. I’m just disinserting here at the insertion until I get to there. All right? Now, why would you do this? The reason you do this is because these anterior fibers that we’ve left intact — those are predominantly the torsional fibers. All right? Whereas these more posteriorly have more to do with the vertical effect of the superior oblique. So you can collapse the A pattern by doing the posterior fibers. And you can avoid the torsional changes by leaving the anterior fibers intact. So particularly a patient that you have — that might have an A pattern, but they actually are able to fuse and they could potentially get torsional diplopia — you might want to not mess with their fusional status, and you might want to preserve those fibers. Now, most of the time, honestly, these A pattern exotropes, they’ve got huge XT and don’t have any fusion, so we don’t have to worry about that so much, but there are some patients where you have to be concerned about inducing cyclodiplopia. And this is how you avoid that. And it’s still relatively effective at collapsing the A pattern. V pattern, superior oblique palsies with V patterns. You know, you get these big upshoots. Bilaterally. And a lot of times if you do a traction test, then you say… Oh my gosh. That superior oblique — I can barely feel it, it’s so lax. And here’s an example of comparing a normal tendon, superior oblique tendon, versus a lax superior oblique tendon. So you see this with congenital superior oblique palsies, typically. It can be unilateral or bilateral. But these superior oblique palsies will give you V patterns. And if you have a lax tendon like this, sometimes the pattern is so large that you don’t feel — here’s another picture of what a lax tendon looks like. You don’t feel like you’ll get a sufficient correction of the V pattern just by doing an inferior oblique myectomy. And so you may need to do a tuck of the superior oblique. We won’t talk a lot about this. But we’ll just kind of touch on this. So tucking the superior oblique, which I only do when there is a lax tendon on one or both sides — I’ll just use a non-absorbable or even an absorbable suture — will work. And isolate superior oblique. Gather it up either on hooks or in a tucking clamp. And this is a tucking clamp, which I don’t have. I just use two hooks. And just suture the borders together. And so you’ve taken the slack out of that tendon. And some people will suture it down. I just leave it like this. How do you know how much to tuck? You just… You do that by doing the traction test after you put the sutures in. You want it to feel normal. You don’t want it to feel tight. If it feels tight, or if it feels tighter than the other side, in the unilateral case, you need to take it down, or they’re gonna have a Brown syndrome. Right? You can fix it here on the table while you’re doing it. And that’s why you’re doing the traction testing. But once that scars up, it’s really hard to reverse. So always the endpoint here is: To feel normal at the time of the tuck with your traction test. All right? Again, we’re not gonna spend — that’s a whole nother lecture. Someone had asked about slanted recession. So let’s touch on that, and then I think we’re pretty much just gonna go into question and answer after that. So you can treat A and V patterns with slanted recessions. Where you’re recessing the muscle, but maybe you’re not recessing all of it, or maybe you’re recessing all of it, but you’re suturing it back on at an angle. And I have not done a lot of this. I know there’s a fair amount to this that have come to some of my friends in South Korea. I personally don’t have a lot of experience with it. So that’s why I’m not gonna claim to be an expert on it. But I think that there’s an interesting caveat to this. When I’ve looked at this in the past, the two papers that I’ve looked at, the top one here is the technique by Simonsz and Von Graefe. And the bottom one is a paper from Bietti. And you can see they’re slanted in different, opposite directions. But these were both being done for V pattern esotropia. So I don’t know. I struggle with that a little bit. That those two things would have the same effect. But if anyone out there does this on a regular basis, share your comments with us. I’d love to share with our group. But again, this is not something I do a lot of. I’ll just kind of do the other things that I’ve talked about. But I think it’s an interesting concept, and it’s worth all of us being aware of. So summary. Let’s summarize this. Let’s go back to our case in Japan, and then we’ll go through our questions. Summary. So small patterns without oblique muscle dysfunction or if you’re not comfortable operating on the obliques, just simply shift the horizontal rectus muscles up or down, following that MALE mnemonic. Medials to the apex, laterals to the empty space. If you have significant oblique muscle dysfunction, inferior oblique overaction, superior oblique overaction, superior oblique underaction, those are the three common ones, then you probably really to get it under control — you’re gonna have to operate on the obliques. And then we have this third option of the slanting strabismus surgery recessions for A and V patterns. Which again… I don’t know. All right. So back to our original case. Now that we’ve gone through this, what do we think about this? So we’ve got a congenital esotropia. No fusion. Never had diplopia. Doesn’t have stereopsis, even when you give them correcting prisms. So we don’t feel like this person has a lot of fusion potential here at age 27. And then we’ve got this big A pattern. And superior oblique overaction. Right? This is just going straight down, straight down. Big deviation in downgaze. Big ET on upgaze. All right. So we’ve got this big A pattern. And we have esotropia. 30 ET. We’ve got incyclotorsion. So we’ve got too much superior oblique effect. Including torsion. Now, we don’t have a measurement on the torsion. But it’s pretty significant from this photograph. So we’ve got esotropia, superior oblique overaction, superior oblique incyclotorsion that’s too much. And probably no fusional potential. So the surgery being discussed was of course bilateral medial rectus recession. To treat the esotropia. But then what to do — the question was: What to do for the superior oblique? Do I do tenotomy? Or do I do a posterior tenotomy? The posterior 7/8 tenotomy? And as we just talked about, if I was worried that this patient was gonna have postoperative cyclotropia, cyclodiplopia, I would do the 7/8 tenotomy. But since they probably are not really at risk for that, and they’ve already got too much incyclotorsion, then that’s probably steering me towards doing superior oblique tenotomies right along with superior rectus border. Personally, that’s what I would probably do. So that’s what I would choose. And that it brings us to the end. Now, I mentioned: If you want to look at this stuff in more detail and look at the videos that we have, and go through the teaching points, you go to the Cybersight library. And you can search the strabismus videos. You go to the Cybersight library, and you can go to the courses section, and in the courses section is fundamentals of pediatric ophthalmology and strabismus. Now, that’s everything. That’s pediatric glaucoma, cataracts, strabismus. But module 4 of that fundamentals series is advanced strabismus, of which this material is a part of. I’ll just remind you: As you start into that 6 module series, you have to take the pretest first. It’s just 10 questions. But you have to do the pretest to unlock the modules. You can’t just go in and start doing a module. So just take the pretest. It doesn’t matter what your score is. But take the pretest. And you can unlock the modules. All right. So with that, I’m gonna stop the share. And I’m gonna go to our questions. And I’ll take as many of these as we can here. First question: How do we do an exact calculation decision for the correct — to correct the A and V pattern? You don’t. People hate those answers when we talk about strabismus surgery. They want to know exactly how much to do. Well, it doesn’t quite work like that. This stuff is like DVD. It’s small, medium, large. There’s not a formula for this stuff. But you know… If you have small patterns, you do something that has small effect. Like shifting the horizontal rectus muscles. Or an inferior oblique recession. If you have large patterns, or I’ll throw in there superior oblique disinsertion, or 7/8… You have large patterns, you have to do something more powerful. Talking inferior oblique myectomies. You’re talking superior oblique tenotomies. All right? So you just have to be comfortable that it’s not exact. You have to have a feel for how much. And you do small, medium, large kind of stuff. Next question. Do you have a preferred way to cauterize the nasal side of the inferior oblique muscle to facilitate the muscle to go back to the orbit? So yeah. I did show that. I like to use a little battery — the high temp cautery. To cut and cauterize at the same time. Now, keep in mind, if you’re using — there’s a low temp cautery and a high temp cautery. The low temp battery cauteries are the ones that you’ll be doing like during muscle surgery, to cauterize a bleeder on the sclera, where the anterior ciliaries leak a little bit. A high temp cautery is too hot to use on the sclera. So we’re just cutting the muscle with it. And as soon as you cut the muscle, the cautery cools down. You’ve got to cut a little bit. Come off. Let it heat up again. Do a little bit more. And you need to make sure that not just the wire tip, but also the brass sleeve — none of that touches the skin. So you’ve got to be careful how you hold it. And you also have to be careful that you’re keeping the underlying globe away from the cautery. So you don’t burn the eye. If you don’t have those cauteries, it’s no big deal. You just cut it and you can cauterize with bipolar cautery. Or if you have the — you know, the muscle hook that you stick in the Bunsen burner, and you can do that. It all works the same. I think it’s fine. But the key point is: No matter how you do the cautery, pay attention to that inferior oblique. Because if you’re not careful about making sure it’s not leaking, these people will get big lower orbital ecchymosis. It’s probably not gonna hurt anything, but it’s gonna look bad for a while. Next one. What age of child should we do these surgeries? Well, you know, like anything we do, I don’t know that there’s a magic answer. When do we do surgery for congenital esotropia? There’s a lot of controversy about that. We’ve tried early surgeries. Doing surgeries by six months of age. We’ve tried late surgeries. I can’t say that there’s a huge discrepancy as to when — what the results are based on when you do it. You do it when it’s a problem. Now, from a point of practicality, a lot of times we’re treating A patterns and V patterns before kids go to school. Because that’s when downgaze and learning become so critical. So that’s a common age. But you know… If you’ve been following someone all along, you do the surgery when they need it. If you’re going in to do something for an esotropia or exotropia, and they have a pattern, you do it then. You just do it all at the same time. But if you had someone that purely had a V pattern, which you’ll see… You’ll see someone — they don’t have esotropia or exotropia. They just have a V pattern, an inferior oblique overaction. You either don’t have to do anything, or you do something when they’re school aged, if people think it’s a problem with their learning or their education or their ability to learn to read. Okay? This is a good question that we didn’t talk about. This is: How to avoid injury to the parasympathetic nerve during inferior oblique surgery? What are we talking about here? We’re talking about the pupillomotor fibers travel for a short distance, adjacent to the inferior oblique. Or within the inferior oblique. Adjacent to the inferior oblique, basically. And so if you have the inferior oblique in a clamp, a hemostat, and you’re doing a myectomy, and you pull on the inferior oblique too much, you will stretch that pupillomotor nerve fiber, and you’ll blow their pupil. And it may or may not recover. So how do you avoid it? You don’t pull too much. Okay? You don’t have to do — you don’t have to be a baby about it. But you’re just gonna put enough tension to do what you need to do. And you don’t stretch it out or let it hang there in a hemostat, unsupported. You just handle it carefully. And if you do that, you won’t have any problems. But you sit there and jerk on it or let the hemostat hang off the side of the face… You’re gonna blow the pupil. Thank you for the presentation. You’re welcome. How do you avoid the vortex vein when performing inferior oblique myectomy? Good question. Because you don’t want to hit the vortex vein when you’re doing a myectomy of the inferior oblique or working on the superior oblique. It’s not gonna hurt anything. But it is a bloody mess, and because it’s bleeding from — it’s like bleeding coming from the bottom of a hole. You can never really see it, to cauterize it and stop it. It is really tough to stop this stuff. So how do you avoid that? If you go to… You can see my inferior oblique muscle surgery videos on the advanced strabismus module. But basically when you are exposing the inferior oblique insertion, you want to see — you’ll see the sclera. You’ll see where the inferior oblique border, posterior border, tents up. And then… So then a third side of the triangle that you’re looking at is the vortex vein. So you’ve got… You’re generally going in with something blindly, like a Von Graefe hook and elevating the inferior oblique away. But then you have to isolate the inferior oblique itself. And you want to see the vortex vein that’s kind of stretched out, and you want to see the posterior border of the inferior oblique, and you want to put your Stevens hook in, just underneath the muscle. So the first hook that goes in is a blind hook. But you’re just elevating enough that you can identify that triangle of the vortex vein, posterior border of the inferior oblique, and the sclera. And then you direct — under direct visualization, now you finish hooking the inferior oblique, and that’s how you avoid the vortex vein. This question. How to differentiate DVD from inferior oblique overaction? Most commonly, they occur at the same time. But you can have people with DVD and no inferior oblique overaction. And you can have inferior oblique overaction with no DVD. The way to identify DVD is just an occluder. Right? You don’t have to worry about having them look left or right. You’re occluding the eye. The eye behind the occluder goes up. All right? So you know that they have a vertical there. Now when you do alternate occlusion, if it’s DVD, all you’re ever going to see is the one eye going up. Or if they have bilateral DVD, you see both eyes going up behind the occluder. But you never see this hypotropia. Right? You never see this. Both eyes shifting vertically. That’s a hypertropia. Somebody has inferior oblique overaction and a true hypertropia, this is what their eyes are doing when you do alternate cover. If someone has DVD, when you do alternate cover, you just see this, for a unilateral DVD. If they have bilateral DVD, they do this and that. And that. And that. But it’s not this. You don’t get that down and back up to the midline. So that’s ultimately how you tell. Yeah. Another good question: What do you do in cases with recurrence of inferior oblique overaction when you’ve already done a myectomy? Okay? So someone had inferior oblique overaction, I do a myectomy, and after they’ve healed up, they still have inferior oblique overaction. Whether it’s unilateral or bilateral. So even though you did a myectomy, they still have inferior oblique overaction. What do I do? After they’ve healed up, I go back, and I do traction testing of the inferior oblique. Okay? So we do that a lot less commonly than we do the other muscles. But just like you do traction testing on the superior oblique, you can feel the inferior oblique if you practice traction testing it. And if I go back and I can feel it, I can feel the eye bump up and over that inferior oblique stump residual, because it goes back to the globe, it sticks back on, if I can feel it, I will probably definitely explore it, find it, clamp it, and take out more of it. Okay? Now, you can’t usually get a lot more, but you can get usually a hemostat’s width and take that off, and then what I’ll do in those cases… I’ll take an 8-0 vicryl and I’ll sew posterior Tenon’s closed in front of it, so it doesn’t stick back on to the sclera. All right? Now, if I don’t feel it, I may or may not explore it, or I may just go on to something else. But it’s usually worth exploring if you have some residual inferior oblique overaction. Your advice on the J-shaped deformity in inferior oblique anterior transposition? Well, you want to create that J-shaped deformity. That’s what gives us the effect of the anterior transposition. The only thing you don’t… So it’s natural that you have that J shape, as you pull that inferior oblique anterior. What you don’t want is you don’t want antielevation. So that means we don’t advance it too far in front of the inferior rectus. That also means we keep the muscle… The inferior oblique bunched up as we sew it back on. And those are the ways you prevent antielevation. All right. Thank you very much. Again, you’re welcome. Two more thank you very much. And then we have… Best surgical technique for inferior oblique overaction? Well… The best… For me, personally, if I have inferior oblique overaction, my preferred technique is to do an inferior oblique myectomy and take out 8 to 10 millimeters of the muscle. But people will have different opinions on that. Some people will prefer recessions. Now that the exact technique that I use for inferior oblique myectomy we will save for another day, so I can have a nice video for you. And we’ll devote that just to the inferior oblique topic. But you can expose it with hooks under the lateral and inferior rectus. I like to put a 4-0 silk suture under the lateral rectus. So that I can position the eye to access the inferior oblique, even if I don’t have an assistant with me. Question. This is a good one. How do you manage A or V patterns without any primary position deviation? So they just have… What I see with this one is I see kids with inferior oblique overaction and V pattern. But no strabismus in the primary position. You don’t have to do anything. Yeah. If they’re doing fine, and it’s just something you see on your exam, you don’t have to do anything. If, however, they really have a huge V pattern, and the patient or the patient’s family or the patient’s teacher is concerned about the impact of that on education and downgaze at school, then you can treat that. But you do the same thing. So either weakening the inferior oblique, if there’s inferior oblique overaction, or you can shift the medial rectus muscles or lateral rectus muscles without doing recession/resection. So they keep them right along the spiral of Tillaux, and you just do the shift to A or V pattern. I don’t find that I do that very often, but I do occasionally do inferior oblique myectomies alone for this situation. Or recessions. This question is: Do A and V pattern measurements need to be done at near fixation or far distance fixation? I only do them personally at distance fixation. The only time I might look at near fixation in downgaze is when I’m using bifocals, because you want them looking through their bifocal to see if the bifocal is helping for high AC/A ratios. So typically in a normal patient with A or V pattern, I do a measurement at near in the primary position. All the other measurements are done at distance fixation. Unless there’s a bifocal. Or evidence of a high AC/A ratio. All right. What could we do with a V pattern in a patient with bilateral… Sorry. It says MD recessed? Maybe… This is someone who’s got a V pattern and they’ve already had the medial rectus recessed? I’m gonna assume that that’s what it is. If they’ve already had — if they still have a V pattern, they’ve already had the medial rectus recessed, and their esotropia is fine, but they have the V pattern, you can still downshift them and just not change the amount of recession that’s already there. Now, that’s messy. And I wouldn’t be in a big hurry to do that. But you could also go to the unoperated muscle. Go to the lateral rectus. Shift them upward without recession. That would be another option. All right? So we’re about… 1 hour and 20 minutes. I’ll keep going here. And see how many we can get through. This is about the slanting recessions, particularly the one described by Bietti. Bietti slanting would not change the final target horizontal alignment. Because the muscle is not being actually recessed, if you don’t take off both poles, my thought would be that no. The actual horizontal deviation wouldn’t change. But you can do the slanting recessions and an actual recession. So I would assume that if you don’t disinsert the whole muscle, that the primary position doesn’t change a whole lot. Here’s a comment from my good friend Yoshimi, thanking me. And Yoshimi, you’re very welcome. Good seeing you. Thank you, thank you. Best Cybersight course ever? Thank you very much, Dr. Neely. I will forward that to the people at Orbis and I will ask for a big raise. You are welcome. This is about… When you’re doing inferior oblique myectomies. Do we have to push the end of the inferior oblique into the sleeve of the posterior Tenon’s for fear of anterior reattachment? No. So some people choose to do it on every case. I don’t do it typically. So I cut the inferior oblique. It’s been cauterized. I can see it sitting there. Kind of through the funnel where it goes through posterior Tenon’s. And I just leave it there. Unless I get a recurrence. Now I have seen people — Gene Helveston was one of my mentors, and I think I can recall him sometimes, if there was a very large V pattern, really, really heavy inferior oblique overaction, and he wanted to make sure that that V pattern got collapsed and didn’t come back, he would push the cut, cauterized inferior oblique into posterior Tenon’s. And he would take an 8-0 vicryl and put a stitch across that. So yeah. You can do that. I think for most of our patients, you don’t have to do that. But you might consider that for large V pattern. Or in someone where you’ve done a myectomy and it’s recurred. I think that’s a good question. I think that would be a reasonable approach. This question… Bilateral inferior oblique overaction with bilateral inferior rectus underaction with X pattern. Can we do bilateral inferior oblique recession and bilateral lateral rectus transposition downward as a single surgery? All right. A lot of stuff going on there. A lot of moving parts. So if I had inferior oblique overaction and an X pattern… Which I don’t think I see very often at all… What would I do? Well… If you do an inferior oblique… It’s hard to even imagine that would happen. Having an inferior oblique overaction in an X pattern still. To get to your point, though, can you do all this as a single surgery, if you wanted to do this? Can I do an inferior oblique myectomy and can I do a bilateral inferior rectus recession at the same time? If you felt you had a clinical situation that needed that, the answer is yes. I think you could do those at the same time. Relative to the topic of anterior segment ischemia. Now, generally we don’t put a lot of importance on the inferior oblique in terms of anterior segment ischemia. But we definitely put a lot of importance on the inferior rectus and superior rectus. When you operate on those muscles, you can see how vascular they are. And so when you get multiple rectus muscles and particularly multiple vertical rectus muscles, you do have to be a little bit careful. So while I don’t recall dealing with this clinical situation, the answer is yes. I think you could do it if you felt that was applicable to you. Thank you for your presentation. You’re welcome, Margarita. You’re welcome. Nice to hear from all my friends. What are some tips to isolate the inferior oblique and superior oblique easily? Inferior oblique, as I mentioned before, looking for that triangle, and the other thing, besides identifying the triangle of the sclera, the vortex vein, posterior border of the inferior oblique… The other thing that’s key, key, key to the inferior oblique is getting the eye in the right position. So I like… If I’m operating on the right eye, I either use a suture or hooks to position it so the cornea is in. The eye is adducted, and I want the cornea up. So if I have a suture going across the nose, it’s below the cornea. So the eye needs to be in and up. And that puts the inferior oblique insertion in the area where you can expose down there and find it. For the superior oblique, look, superior obliques are tough. It is… It’s a definite learning curve. And even for people that do a lot of strabismus surgery, you know, it’s messy up there. And so… I like to isolate the superior oblique along the nasal border of the superior rectus. Because that’s where the tendon is most condensed, and it’s usually 8 millimeters back from the nasal pole of the superior rectus. So I know about where it should be. And I can find that condensation. And I can usually hook it pretty easy. And I typically approach from a temporal fornix incision. But doing a limbal incision is gonna give you a lot more exposure, and particularly if I’m wanting to do something around the tendinous insertion, it gets so wide out there, and it’s so posterior that it can be very difficult to isolate the superior oblique from that side. If you’re having trouble, some people — and I’ll do this too — will isolate it on the nasal side, put a silk suture around, loop it underneath the identified tendon, and then you drag it underneath the superior rectus to the temporal side, and it gathers up the whole tendon out there. And so that’s a good technique to make sure you have the whole superior oblique tendon insertion. But yes. It’s difficult even under the best of circumstances. Thank you again. You’re welcome. Bilateral tropia. Right eye hypo, and left XT. How to manage if the patient doesn’t want surgery. I’m gonna defer that question. I’m not sure I understand it well enough to give you an appropriate answer. So I’m just gonna… Save that. And maybe I’ll give that some thought and come back to you. Another thank you. You’re welcome. Thank you. Very informative. I have a V pattern XT. So V pattern XT — frequently that’s gonna be inferior oblique overaction. With minimal overaction the other day. I was wondering if horizontal shift would be more appropriate or inferior oblique myectomy. Absolutely. If you have a V pattern XT, and relatively minimal inferior oblique overaction, I think it is 100% reasonable just to shift those lateral rectus muscles. Again, upward. To the open space. And that’s quite appropriate. Rather than doing inferior oblique myectomy or recession. Not a problem. Go for it. This question is for seemingly unilateral inferior oblique overaction, should I do a unilateral or bilateral myectomy? Okay. So we see this a lot with what we call congenital superior oblique palsies. Unilateral inferior oblique overaction. If I’m convinced that it looks to me to be 100% unilateral, I would do a unilateral inferior oblique myectomy. Okay? You will occasionally get burned on this. And you’ll do one side and they heal up, and you have unmasked, uncovered inferior oblique overaction on the other side now. So look at them real carefully and decide if it’s a unilateral or bilateral. I will sometimes do bilateral asymmetric. So I might do a myectomy on one side and a recession of inferior oblique on the other. So I think it’s that preoperative determination — is it truly unilateral, is it asymmetric, or is it bilateral? Thank you. You’re welcome. And thank you. How can I fix strabismus at home? Is there any way to do treatment? Well… Despite some of the parody videos I have made, I do not recommend the do it at home strabismus kit. How do you manage the patient who had bilateral medial rectus recession and bilateral lateral rectus recessions? So they’ve had medial rectus recession, bilateral lateral rectus recession for congenital esotropia initially without DVD but now postoperatively has bilateral DVD and right hypertropia? One concern I would have… If someone has had medial rectus surgery and then lateral rectus surgery, and now has a postoperative vertical deviation, my concern would be the inferior oblique inclusion syndrome. So I would probably explore the inferior oblique on one or both sides and see if it has somehow been incorporated into the lateral rectus surgery. And if it is, try and free it up. Otherwise, I would probably just deal with your DVD. If you have inferior oblique overaction, you can do a unilateral… Sorry. In this case, it’s bilateral DVD. Bilateral DVD and bilateral inferior oblique overaction… Doing anterior transpositions — if they have bilateral DVD but no inferior oblique overaction, I would probably do superior rectus recessions. And here you’re saying they also have a right hypertropia, so you can do superior rectus recessions asymmetrically to accommodate the right hypertropia. It’s a longwinded answer for a complicated question. But yeah. You can do… If you’re doing superior rectus recessions, for DVD, we frequently do them asymmetrically. And you can do that in this case to accommodate — if you appear to have a right hypertropia or an asymmetric DVD. Just checking on my time. If the child has a slight V pattern at 4 months, should extraocular muscle exercises be used, and for how long? If a child at 4 months of age has strabismus, I’m not aware that there is any exercise that you can do that has been proven to be helpful. I don’t think I would do anything at 4 months of age, other than see them back in another 4 months of age. What are the cases of vertical diplopia? Should thyroid be considered? Yes. You know, this is a long list, obviously, of what can cause vertical diplopia. But if someone has vertical diplopia… You mentioned thyroid. Those should be pretty obvious. Because they’re gonna have thyroid ophthalmopathy-looking eyes, typically, or there’s gonna be restriction. But just to comment to this… If someone has vertical diplopia, 90% of the time that person is going to have a unilateral superior oblique weakness. Superior oblique palsy. And I would look real carefully at that. I would measure torsion. I would do head tilts and side gaze. And I’ve bet they’ve got a superior oblique palsy and need inferior oblique weakening. Thank you from Saudi Arabia. You’re welcome. It’s always nice that we have people from all around the world. And I appreciate our audience. Bilateral… Oh, that’s the one I couldn’t understand before. Thank you. You’re welcome. Thank you. Thank you from Malaysia. You’re welcome, Malaysia. Glad everyone is doing well. Stay safe. All right. One last question. Here it is. Which school of thought describes the pattern deviation correctly? Horizontal, vertical, or the oblique? The pattern deviation correctly? Horizontal, vertical, or oblique? Which school of thought describes the pattern deviation correctly? Horizontal, vertical, or the oblique? I’m sorry. I’m not quite sure what the question is. You know, you can have A and V patterns with just rectus muscle dysfunction. And you can have oblique muscle dysfunction. So it can be both. Thank you from Nigeria. You’re welcome, Nigeria. You guys have quite a medical system there. Good job. Keep it up. How early do you operate on congenital ET and what guidelines do you rely on? Congenital ET… You know, we had a big push at my institution to do early surgery. We were operating before 6 months of age. I can’t tell you that the results were any better than they are if you wait until children are a year of age. And I think the sweet spot is probably between 1 and 2 years of age. There is some published literature that says results are better before 2 years of age. And certainly anesthesia is safer after one year of age. And your measurements are better. And surgery is easier. So that’s kind of my sweet spot. Is around age 1 year. And hopefully before age 2. Ultimately… I suspect it probably doesn’t make a lot of difference. But some people would certainly argue for early surgery with better stereopsis. But we did not find that to be the case. Thank you from Sri Lanka. Thank you, orthoptist member. From Nigeria. You’re welcome, Nigeria. 15 degrees hypotropia and 15 degrees exotropia, how is the management if the patient doesn’t want surgery? Not much you can do if they don’t want surgery. I don’t know of any way to correct… Prisms would be the only thing. But even then, I find a lot of people don’t like prism or can’t fuse or they don’t have diplopia to begin with. So if you have a hypo and an XT, your options are kind of limited. Because you really can’t improve vertical deviations very much with any kind of exercise type activity. Thank you from Pakistan. You’re welcome. All right. That’s it. I’m gonna call that a wrap. Looks like we went through 55 questions. There were two or three that I couldn’t come up with… Or didn’t quite understand well enough. Sorry. To give you an appropriate answer. But thank you for everyone’s attention. All of this is recorded. All of this will be present in the Cybersight library. And we will see you for the next webinar. Good day.

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September 20, 2021

Last Updated: September 12, 2022

3 thoughts on “Lecture: Strabismus: Managing A and V Patterns”

  1. Excelente! Soy asiduo asistente de todos los webinars pero lomfelicito especialmente Dr. Daniel Neely, espero los vídeos que faltaban en la presentación. Atte. Muy agradecido. Dr. Lucas Horacio Otal desde Argentina


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