Objectives of this lecture are:
• To learn to diagnose vertical strabismus
• To differentiate “A” from “V” patterns
• To recognize and manage Dissociated Vertical Deviations – DVD
• To learn the surgical anatomy of the inferior oblique muscle

Lecture Location: on-board the Orbis Flying Eye Hospital in Bridgetown, Barbados
Lecturer: Dr. Rudolph Wagner, Rutgers – New Jersey Medical  School, Newark,  NJ  USA

Transcript

(To translate please select your language to the right of this page)

DR WAGNER: And welcome to all the Cybersight participants throughout the world. Thanks for watching this, and we’ll try to make it worth your while. We’re gonna talk a little bit about what I call advanced surgical techniques for vertical strabismus. And some of that will be diagnosing these conditions, and then also how we surgically manage them. But as we do always here, we start with prequestions. And we have in our audience — we’re asking people to respond. We have these devices where they can answer them. So we’ll try to answer these questions in the lecture, and we’ll then repeat it at the end, postquestions. So let’s start with the first question. Surgical correction of A and V patterns always requires surgery on the oblique muscles. In other words, do you always have to weaken the superior obliques and inferior obliques, if you have an A pattern? And we’re asking people to respond to that question. And when we get the responses, we’ll see what everyone said. That looks pretty good. So the answer is: 14% said yes, and 86% no. Thinking about… You don’t always — you know, the question is: Can you have A or V patterns either without oblique overaction or if they have it, can you approach it another way? And we’ll answer that question. In a 14-millimeter recession of the inferior oblique tendon — the inferior oblique tendon is attached where? Just anterior to the inferior temporal vortex vein, A. B, at the lateral insertion of the inferior rectus muscle, B. Or C, at the lateral rectus muscle insertion. We’ll ask people to answer that question, this 14-millimeter recession. Where do we usually reattach the inferior oblique tendon. So most people feel we do it just anterior to the inferior temporal vortex vein. Some of them heard me yesterday speaking on this a little bit. Or at the lateral insertion of the inferior rectus muscle. We’ll answer that question, and we’ll show you where it’s placed in the lecture. Now, to correct a V pattern esotropia — and by V pattern, we mean that the strabismus is more divergent in upgaze. Either you could have an increased exotropia in upgaze, or less esotropia in upgaze than you do in downgaze. And that causes the V pattern. So to correct a V pattern esotropia, the medial rectus muscles may be moved more posteriorly, A, B, downward toward the apex of the V, C, superiorly toward the open V, or D, not moved at all. So how can you approach a V pattern esotropia, when you also have a vertical component, and you’d like to correct it in a different position of gaze? So if we look at the responses that we have, we have 50% say that you can move it downward toward the apex of the V. Some believe you can move it superiorly toward the open V. I can tell you just briefly — we’ll get into it, but as a general rule, it’s medial towards the apex, lateral towards the base, if you’re gonna correct a V or an A pattern. So we usually do move them down, because you get more effect of the recession that you do of the medial rectus muscles in the area where you have placed them. So if you have a greater degree of esotropia in downgaze and you move the muscles down, you’re gonna correct more of it in that position than you would in the primary gaze position. So that’s one of the approaches to a V pattern. But we’ll talk about that. So our objectives in this lecture are to learn to diagnose vertical strabismus, to differentiate A from V patterns, to recognize and manage dissociated vertical deviations, what’s commonly known as DVD or dissociated alternating hyperphorias or hypertropias, and to learn the surgical anatomy of the inferior oblique muscle, because that’s gonna be involved in most of these conditions that we talk about. So: Vertical deviations. First of all, you can have either comitant or non-comitant or incomitant deviations. Comitant means basically that the deviation is the same in all positions of gaze, or very close in all positions of gaze. Where non-comitant means it could be different in upgaze or downgaze. Hence these V or A patterns which can occur. So vertical deviations are often incomitant. And they can be due to either dysfunctional overaction or underaction of the superior or inferior oblique muscles. Could be paresis or contracture of one of the cyclo-vertical muscles, or it could be due to mechanical restriction, as we’ve seen in thyroid or in trauma, to the muscles. So many things can cause this incomitance, meaning that the deviation is different depending on where you’re looking or where your eyes are. So true vertical deviations — I define true as: They’re described according to the directional position of the non-fixating eye. So if you have… You can have right hypertropia with the left eye fixating, or you can have a left hypertropia if the right eye is fixating. But they can really be the same thing. When you have a true deviation, the reason it’s a true vertical is because you have — the two eyes correspond to each other. So if I have a right hypertropia, and I’m looking with my right eye, my right eye is gonna be in the primary gaze, but my left eye will then drop down. Be a hypotropic. If you fixate with the left eye, and I’ll cover my right to make me use the left, my right eye will go up, so in a true vertical deviation, I’ll have a right hypertropia in this case, with the left eye fixating, and a left hypotropia with the right eye fixating. As opposed to a dissociated vertical deviation, where you don’t necessarily have the hypotropia in the opposite eye, and you can have both eyes having hypertropias alternately. And that’s why it’s a dissociated deviation. The eyes are not functioning normally, as they do together, to give you the deviation. So it’s important to keep in mind. And most of the deviations that you see are true verticals, where there is a hypo in the other eye. But we usually define them or we measure them by which eye — by the hypertropic eye, just by convention. You can do it otherwise, but when we do the three-step test for cyclo-vertical deviations, we usually define it by where the eye is higher, or the hypotropia. And I mentioned this in the talk I gave the other day. But just because you have — let’s say you have a right superior oblique palsy, for example. That would normally give you a right hypertropia in the primary gaze. If for some reason that right eye is the preferred eye that the patient wants to use, they may present with a left hypotropia, even though the muscle problem is really occurring in the right eye. Just something to keep in mind. A lot of that depends on why they prefer to use one eye over the other. It could be because of the disparity in the vision. One eye could see very well, and the other not. So it’ll confuse the issue slightly, but you can just figure it out. So let’s talk about primary overaction of the inferior oblique muscle. This is inferior oblique overaction that occurs without any superior oblique muscle paralysis. It develops in perhaps 2 out of 3 patients with congenital esotropia over time, whether they’ve had surgery or not, to correct the congenital esotropia, they may develop this. Sometimes it’s not clinically significant. It doesn’t require intervention. But it can show up if you look for it. And it presents as overelevation of the adducted eye and lateral gaze with the abducting eye fixating. True hypertropia and hypotropia on alternate cover testing will be present. So we’ll see what that kind of looks like. Here’s a guy with no primary deviation. A little boy. Eyes look pretty good alignment. If we then have him look to either side, gaze up and to the left or up and to the right, you can certainly see that there is overelevation of each eye in the adducted position. This is significant overaction of the inferior obliques. You can grade them differently. Some people grade them +1 to +4. A lot of it’s based on your own individual… What you consider to be… To me, this is probably +3, at least, with that much of an elevation. And what you use if you’re not sure, when you get them in the lateral gaze position, is you can compare the inferior limbal height, where it is, in relationship to the lower lid. Now, it’s not exact, but you can certainly see a lot more conjunctiva in the overelevated eye, in both cases. This is pretty easy to diagnose, that there is overaction of the inferior obliques. And management of primary overaction is usually to weaken the inferior oblique in some manner. You can recess it, which is the 14-millimeter recession, or you can do a modified lesser amount of that. You can do a disinsertion of it. Just cut it loose. Or you can take a piece out of it and cut it loose, which is a myectomy. Another option is anteriorization, which is anterior displacement of the inferior oblique to the lateral margin of the inferior rectus muscle insertion. And this can also be very useful in cases of DVD. In fact, many times if we have both inferior oblique overaction and dissociated vertical deviations, we will do an anteriorization, and it can solve both problems. You have to be careful with asymmetric surgery in some of the oblique procedures. Especially an anteriorization. Normally they’re done symmetrically, unless there’s marked inferior oblique overaction, because of a unilateral condition of superior oblique palsy, say. So the inferior oblique muscle, as you can see, originates in the floor of the orbit, the maxillary bone. Comes out around medially to laterally, below the inferior rectus muscle. And generally inserts just below or right behind the insertion of the lateral rectus muscle. Not usually right up at the insertion, but back maybe 4 or 5 millimeters. That varies when you do a particular case. When you do lateral rectus recession, you usually will see it, if you look for it, if you go back far enough, and you can avoid it. When you do a big resection of the lateral rectus muscle, sometimes you inadvertently bring forward the inferior oblique muscle, and if you go back on a reoperation of someone who’s had a resection of the lateral, many times you’ll find it all the way up at the insertion of the muscle, in that malposition, and it could affect it in some cases. Generally not much of a problem, though. So just important to know the anatomy of where the muscle is. As you know, it’s the only muscle that doesn’t originate in the orbital apex. All the others do. It’s the shortest muscle. The superior oblique, when you include its tendon, is the longest muscle. And the rest of the rectus muscles are about 40 millimeters in length. The nerve enters the rectus muscles about 2/3 of the way back of the 40-millimeter lengths, closer to the apex. But the nerve does enter the inferior oblique at the point where it passes through Tenon’s capsule, and it’s more anteriorly displaced. So you can actually see changes in the pupil, because the pupillomotor fibers are carried in there, when you operate on the inferior oblique. If you hook it, and really pull it tightly, you can actually sometimes see some dilation of the pupil. It’s just because it’s the only muscle, really, that you do get involved with the — being somewhat proximal to the nerve. Where it enters the muscle. Not commonly, but it’s possible. We used to do a procedure, and some people may still do it, called a denervation/extirpation. We actually would try to locate where that neurovascular bundle is, cauterize it, cut the muscle way down here, and tuck it back inside the Tenon’s capsule, to give you the ultimate weakening of the inferior oblique muscle. So if you don’t want to do an inferior oblique recession, let’s say, this is just an illustration of it, where we have a hook — we’ve actually — this is looking… This is looking at a surgeon’s view. You’re looking down at the eye. And this would be the left eye. And you can see that this hook is actually subconjunctivally on the inferior rectus muscle. So we’re looking down at the view that you would get if you’re operating, and that’s the inferior view. You’re sitting over here. And this is the inferior oblique muscle that’s been hooked, and has sutures placed in it. When you have inferior oblique overaction, it generally looks like this. Pretty thick, wide muscle. Whereas if it’s not overacting, it looks much thinner. When you look for it, you’re doing an inferior or lateral rectus, let’s say, it won’t appear to be as bulky. The good thing is, when you find one that looks like this, you know that it needs surgery, because it’s probably the reason for the overaction, and you can differentiate that, when you’ve looked at a lot of different ones. So what you’re doing here — and these slides are trying to show kind of the same thing — this is the hooked inferior rectus muscle. And this is the inferior oblique muscle, and we have sutures attached to it. We’ve already preplaced our double armed suture. And on the other side there, we’re actually reattaching it to the sclera. Now, in this particular case, we’re attaching it just lateral to the inferior rectus insertion. So that’s really more of an anteriorization than it is of a recession. When it’s attached in that particular position. If we want to really recess it, maximally, or put it back to the… Put it farther back, we would attach it back here, along the lateral rectus, inferior rectus muscle, locate the inferior vortex vein, which is pretty far back — maybe about 10 millimeters from the insertion — and place it just anterior of the sutures, just anterior to the vortex vein, where it exits the sclera. And when you do that, that’s technically a 14-millimeter recession. So we never take a caliper and measure 14 millimeters. It’s just been, by convention, determined that that’s the average of where it is, when you put it near the vortex vein. When you reattach it for an anteriorization, as we’re doing here, if you go too far anteriorly, you can actually produce a hypotropia by converting this muscle into a depressor. You do that in all of these cases when you anteriorize it, but you can grade it, if you need to take advantage of that effect. You can also leave it farther back from the insertion, if you don’t want to have that much of a correction for any hypertropia that you have. So asymmetric surgery can be a problem if you do more on one side than the other, and here you can see the muscles attached there, just lateral to the insertion, before we remove the hook from the inferior rectus muscle. So this is… There’s a recession versus anteriorization. The anteriorization at the insertion, the recession back 14 millimeters, or a moderate recession could be 2 millimeters over and 3 millimeters back from the insertion of the inferior rectus muscle. And there are different reasons why you would do it, depending on how much you graded the overaction to be. So there’s the inferior oblique isolated again. This is trying to show you the… Oh yeah. This is looking at the view. Inferior rectus is down here. Under the conjunctiva. Here’s the inferior rectus as it runs back. There’s the vortex vein, exiting the sclera, and those are the two sutures, straddling the vortex vein, just anterior to it. And that’s one way of attaching the inferior oblique to the — near the vortex vein. And once again, we talked about the potential for the hypertropia, if you anteriorize it too much. One of the things that’s also an issue is you really… Whenever you reattach the inferior oblique, you want to keep it relatively close to the insertion, the lateral margin of the insertion. You don’t want to displace it too laterally from there. Otherwise it can give you other effects of actually not functioning as well as an elevator and producing more of a depressor, and it can sort of negate some of the effect that you’re looking for, when do you that. So we generally attach it pretty close to the lateral margin of the inferior rectus. Some people really prefer to almost bunch it up a little bit at that point, rather than risk having… There’s something called an antielevation syndrome, which means you’ve sort of weakened it too much, and you can prevent… You can actually prevent elevation in the eye, in that position. In adduction or lateral gaze to the other side. And it can be a bit of a problem. So dissociated vertical deviation means that neither eye refixates with an upward movement, whether abducted, adducted, or in primary gaze position. So you never get a real hypotropia in the opposite eye when you do your cover/uncover testing. All you do is, when you cover in front of the eye, you’ll get a hyper in the eye, overelevating. It sort of sometimes extorts a little bit too. You can measure it with a prism and alternate cover test, but you’re only really looking at the eye that you’re measuring. So if I have a vertical right — dissociated vertical deviation, I’m gonna hold a base-down prism in front of the right eye, and I’m gonna keep alternate covering, but I’m gonna only watch what happens — I’m gonna keep increasing the prism, until I no longer see a dropdown of that hypertropic eye. And when it stops moving, that’s the number of the vertical deviation. Not even looking at the other eye. It’s simplest to do it that way. And then you come up with how much the vertical deviation is. And you can do the same for the opposite eye, because many times you’ll have a vertical in that eye when you go back and forth. So that’s opposed to a true deviation, when you’ll obviously see a hypo in the opposite eye. And usually we correct it by anteriorization of the inferior oblique or by superior rectus recession. If you need to do it in both eyes, we usually prefer the anteriorization. If you only need to do one eye, we often do the superior rectus recessions. That’s because you can create a vertical, if you do one anteriorization not in the other. And there are cases, for example, where a person has a superior rectus — has a dissociated vertical deviation with a right hypertropia where they have a strong fixation preference in their other eye, because maybe this eye doesn’t see as well. In those cases, you can get away with just treating the superior rectus, maybe recession on that eye that deviates up. That’s how I approach it in those asymmetric cases. So what does a DVD look like? Well, this is a guy who’s straight, little boy who’s straight in primary gaze. If you go back and forth, it may spontaneously or because of your alternate cover, overelevate the left eye. So I think you can see it’s not super high there. But it certainly is different from here, where both eyes are in alignment, and there the left eye is up, in a left dissociated vertical deviation. Now, you can also have the combination of the two, as I mentioned earlier. And this is a patient that — he’s ortho in the primary position. He’s got a right DVD, and I say that because he has an overelevation of his left eye, even in the abducted position or in the primary position. Whereas the inferior obliques overaction generally only occurs in the adducted position. So if you do your alternate cover and you see this eye going up, probably that’s the DVD in this case. But he’s got more than that. If we have him look to either side, he certainly also has overaction of each inferior oblique muscle. As you can see, in the adducted position, there is also elevation, and in the right — in the right eye and the left eye, as he goes to lateral gaze.

Download Recording

High Quality

Standard Quality

May 25, 2018

Thoughts? Please leave a comment...