In this live webinar, we will discuss the appropriate clinical evaluation of vertical strabismus, most commonly associated with superior oblique palsy, including strabismus measurements, assessment of torsion and the Three-Step Test. We will also discuss selection of an appropriate surgical plan based on examination findings.
Lecturer: Dr. Daniel Neely, Pediatric Ophthalmologist & Professor of Ophthalmology, Indiana University School of Medicine, USA
Dr. Daniel Neely: Greetings, everyone. Welcome to the final Cybersight webinar for the year 2020. And boy, what a year it’s been. I think we all are happy to see this one come up in the rearview mirror. And I hope that all of you are staying healthy and that your families are staying healthy. Personally, I did come down with COVID a couple months ago and I can tell you, it really sucked. I’ve had dengue fever before and this was like dengue fever times five. As soon as you can get access to a vaccination, please do go ahead and get it.
Some light at the end of the tunnel here, my colleagues here in the U.S. are just this past week getting their first doses of the COVID vaccine. So hopefully, at least in the U.S., within the next six months we’ll have a significant vaccination program completed. And I hope that all of you equally have access to that in the very near future. And today’s presentation is superior oblique, but we are largely restricting it to superior oblique palsy. So if you had questions that were Brown syndrome or otherwise, I will get to those in our next presentation.
Evaluation and management of superior oblique palsy. This is really a favorite topic of mine and I find it’s of interest to people. This is not going to be just a lecture. We have a few videos here, we have your questions, and we’ll have some case discussion. and that’s also something I’d like to do more of in the future.
This brings us to our very first poll question. What is the most common cause for vertical diplopia? And it probably doesn’t matter if it’s adults or children. But you can see what our options are here: DVD, dissociated vertical deviation, double elevator palsy, skew deviation, superior oblique palsy, third nerve palsy, thyroid ophthalmopathy. Obviously the title of today’s lecture is going to be a dead giveaway.
And there we go. I appreciate that you are paying attention. Good job! And it’s true. The reason these are important, really anytime someone walks into my office and they say they see two things up and down or they see double vision, which is diagonal or oblique like these two E’s on the screen. Then that is, to me, a superior oblique palsy until proven otherwise. It’s just going to be that.
Now of course, you need to exclude the other things that we’ll talk about, but this is super common. So we need to be familiar with it. We need to be comfortable with it, because frequently we’re not comfortable with this. Once you get out just a horizontal esotropia, exotropia, a lot of us are now out of our comfort zones.
The first audience question is related to differentiating this. How do you tell the difference between a skew deviation and a superior oblique palsy? And this is from one of our participants in Egypt. Usually the difference is that superior oblique palsies are going to have incomitance. They’re going to be different in right gaze versus left gaze. Now it’s true that superior oblique palsies can become more comitant over time, but in general there is some significant incomitance. Interesting thing, skew deviations, we don’t frequently think of them as having torsion. They do, in fact, frequently have torsion with them. And really to tell these apart is a diagnosis of exclusion. It can be difficult. But skew deviations, we’re looking at a very particular population, we’re looking at usually the elderly, or those that are at risk for strokes or have had strokes. Because usually this is, or demyelination I suppose. This is usually brain stem related and prenuclear vestibular input. So very difficult to image that. Some of these characteristics, the comitance or incomitance, I would say is the number one way to differentiate this.
And, like I said, a lot of times these are out of our comfort zone. We have someone come walk in, like this gentleman on the right, he’s got a big head tilt, he’s got this oblique diplopia, and now we’re like, “Oh my gosh, we have to measure every position of gaze to figure this out.”
Well, that’s not quite true and one of the things I want to do today is show you just a very simple way to approach these patients. This shouldn’t be complicated. Takes a little more time than horizontal strabismus, but it shouldn’t take a lot more time. We’re talking a five minute evaluation or less.
Some more audience questions. From the Philippines, “What are the possible causes and diagnostic considerations?” “What causes superior oblique palsy?” from Nigeria. Well, the vast majority of what we call superior oblique palsies are congenital. They present either in childhood with a head tilt or they present in adulthood as something that has decompensated.
These congenital palsies, and I’m saying “palsy” with quotations for a very good reason. These are usually due to the superior oblique tendon being too long, sometimes what we call too lax, too loose, too long. Just think of this as the opposite of a Brown syndrome. Brown syndrome the tendon is too short, too tight. And in a congenital superior oblique patient, it’s usually that the tendon is too long, too loose. It’s not that the nerve is palsied. I think that’s a bit of a misnomer term that we should keep in mind. It’s not like there is typically damage to the trochlear nerve. This is usually a result of that complex structure of the superior oblique tendon.
The other 25%, one quarter, are the acquired palsies. And I think, easily in my practice, most common ones are trauma. And we frequently think about these as being bilateral, but they can be bilateral, asymmetric, or they could even unilateral. And we’re not talking about trauma like, “Oh, I fell down, tripped on the carpet.” We’re talking about trauma where someone fell off a ladder, someone fell off a building, someone was in a car accident, and they hit their head severely, and maybe they were in a coma for three days, or they were in ICU for a week. These are significant traumas usually, these are not just bumping your head during your daily routine.
Vascular, of course aneurysms, inflammatory conditions can cause damage to the trochlear nerve, neoplastic tumors, of course, can press on the trochlear nerve. People can have surgical causes for trochlear nerve palsies. Any kind of intracranial surgery. When we see an adult, one of the things we’re trying to figure out is this decompensated congenital or is this acquired? Because what we do with that patient and the workup we do in terms of further investigations, is going to be dependent on that. And I’ll try to give you some tips of how do you sort that out. Because every adult that I see with a fourth nerve palsy, I just don’t go image all of them. I image a very distinct minority and I’ll show you how that works.
First, we should look at the superior oblique anatomy. Because, like we said, it is unique. It’s morning, I’m getting my coffee here. Primary function of the superior oblique, because it comes in and this big reflection through the trochlear complex, and then inserts starting behind the equator, inserting behind the equator, back here. Because it comes in obliquely, it’s inducing incyclotorsion. So intorsion is its primary function. So when it’s damaged and not doing its job, the eye gets excyclotorsion. So that’s a major hallmark and it’s something that’s under-evaluated when people see patients. Because it’s behind the equator, it’s a depressor as a secondary function. It’s pulling the back end of the eye up, pushing the cornea down. And then finally, because of the fact that it’s positioned here, posteriorly, especially those posterior fibers, when they contract they’re going to produce some abduction of the eye. Those are the tertiary functions.
Another set of audience questions. First one from Bangladesh, “Easy way to measure superior oblique palsy?” Second question from Tanzania, “Systematic examination for palsy in brief?” This sums up what I want to pass onto you. Let’s make this easy, let’s make it brief, let’s not make this be a big headache, you can make this really complicated if you want to. It doesn’t need to be.
Here is my basic needs when I see a superior oblique palsy patient. We always do primary position measurements, right here. I like to see up gaze and down gaze to see if we have A-patterns, V-patterns, or limitations to motility. And then I like to see right gaze and left gaze and this is what I’m looking for in those gaze positions. Am I seeing inferior oblique overaction? You don’t always see superior oblique under-action. As a matter of fact, I would go out here and say you usually don’t see super oblique under-action, but you do see this. The inferior oblique overacting is what is easily seen and is our hallmark. So those five positions of gaze will serve me in 90% of the cases. And then add to that the Bielschowsky head tilt test. Tilt to the right, tilt to the left and we’ll discuss why that happens if there’s a difference in head tilt. That’s another important simplified topic. All right, so that’s the data I need.
Before I show you that typical superior oblique palsy, let’s talk about how we document this. Because as I see strabismus consults coming into Cybersight, I frequently see that people are not comfortable with how to document motility or strabismus measurements. When I measure someone’s motility, first thing I do when I sit down to examine a patient is I have my little toy, my Tigger toy, right here with me. So I have a fixation toy and I move this left, right, up, down, maybe I’ll go up to the oblique positions to bring out their inferior oblique overaction. But I want to see their motility and their versions to make sure I’m seeing overactions, under-actions or any kind of restriction.
And then I need to document that. These are two systems on this slide but they are really the same. So one is this star, asterisks system, which is diagrammed for a right eye here. The left side is the one that we use at my institution, it’s more of an H. But despite the shape of the bars, what’s the same is the location of the muscles. Because each of these bars is a position of the primary function of that particular muscle. So medial rectus, abductor, so it’s in on both sides. Opposite is the lateral rectus, out on both sides. Superior rectus takes the eye up and out on both sides, inferior rectus takes the eye down and out on both sides. Superior oblique down and in, inferior oblique up and in, and that’s again, superior oblique palsy, that’s the one we’re looking at.
Real quick, whiteboard exercise here. When I see a patient and they have inferior oblique overaction, probably most people use this system. If I see that right RIO overacting, and this is subjective. It’s +1, it’s +2, it’s +3, it’s +4, so then I’ll put a +2 like that. If, for some reason, because that’s the IO position, this would be the SO. If, for some reason, you did see superior oblique under-action, you could go -1, -2, -3, -4. Just like this could be +1, +2, +3, +4.
That’s the very same thing as doing the H’s like we do at my institution. Right inferior oblique overaction +1 to +4, I will grade it. And I’ll put a number there. If I’m showing under-action of the superior oblique I’ll go -1 or -2. Usually, for what we see with superior oblique palsies, you’re either going to see normal or you’re going to see -1. And yes, this is subjective, there’s no great way to quantify muscle under-action and overaction, but as long as you’re consistent in how you do it, then you know what it means to you. 1 in a little, 2 is a medium, 3 is a medium, 4 is a lot. It’s just that simple. Okay?
Back to my lecture material here. Whiteboard demonstration. Again, in Cybersight, these grids are built in. Here you can see the lines in the background, the asterisks, star. And if you click on the arrows, you can then enter +1, +2, +3, +4. Or -1, -2, -3, -4. I encourage you to use that because when we look at photographs for giving you consultations, this supplements that. A photograph is a moment in time, this is your impression. So use both, please.
And then documenting on your EMR or your paper, whether it’s blank paper or a pre-printed paper like this. I still use paper forms and this is what our strabismus pediatric ophthalmology, adult strabismus form looks like. Let me highlight a couple areas. Again, our versions, our motility with the H system. The strabismus grid, the tic tac toe grid here. Primary position, up gaze, down gaze, right gaze, left gaze, up right, up left, down right, down left. Oops, let me go back.
I also never use these four corners. I have to really see something abnormal on the motility for me to start doing these oblique measurements. Usually we’re playing in this zone right here in the middle. One last circled area, DMR, that stands for double Maddox rod, measuring torsion. This is something that I see is done very infrequently around the world and we’re going to talk about this and I’m going to highlight why it’s critical that you have this ability and do this when you evaluate, especially, superior oblique patients.
All right, same thing carries over to your Cybersight form when you’re submitting a strabismus consult. If you click, the H is for horizontal, the V is for vertical, if you click on those, it opens up numbers so you can put in numbers for the strabismus. These are your prism measurements. It also includes the head tilts for the Bielschowsky head tilt test.
I’m talking about this and taking just a couple minutes to go over this with you because most people don’t use this and I want people to be comfortable with this because it helps whoever’s giving your opinion, your professional consult to you, it helps them to give you accurate information. And so you don’t have to fill out the full form, but you need at least a few of the key areas with prism measurements.
Audience question. This one from Saudi Arabia. “Is inferior oblique overaction,” which we frequently abbreviate at IOOA, “accompanied with superior oblique under-action?” And I’ve talked about this just a little bit. The answer is, maybe. I would say most of the time I can’t see superior oblique under-action, because most of the patients we see are congenital palsies and their superior oblique works, it just doesn’t work super well. So when they force it, they can take it through its full version. So most of the time, no, you don’t see definitely superior oblique under-action. However, when you see acquired palsies, especially severe acquired palsies, you definitely can see superior oblique under-action. -1, -2, I would say that those are common numbers for acquired palsies.
Back to simple, how do we make this simple? Well, I talked about looking at versions. Having the patient track you around. Looking specifically to see that there’s no restriction and looking specifically for inferior oblique overaction and superior oblique under-action. So again, it comes back to the Tigger toy or some other fixation device that the patient will track. Measurements. Three-step test, we’re going to talk about that, we’re going to make it simple.
You really need to have prism in your clinic to do measurement for superior oblique palsy. However, interestingly, a patient like this in the clinic. This is a little baby, child, a lot of times I don’t need prism to make the diagnosis of superior oblique palsy. I don’t need to do measurements in every gaze position. I can just look at this child’s versions, if we had a video, and I could tell you they have a superior oblique palsy. And if that kid has a head tilt, I’m going to go ahead and operate regardless of what the measurements are. And so we’ll chat why that is, why would you be so preemptive on surgery like that without measurements.
Torsion, again, the big one that people don’t do, you’ve got to measure torsion or have some assessment of torsion. There are other ways to assess this and we’ll talk about that. And then the FAT scan, this is how you avoid the CAT scan and I will tell you what that is coming up.
So first of all, let’s talk about equipment and prisms, this is our second poll question. I’ve seen many places that do not have prisms. So answer number one, do you have prisms in your clinic? I don’t care if it’s a loose set of prisms, or vertical and horizontal prism bars, I use both, I think that’s ideal. But do you have that? Or if you don’t have prisms, do you at least? Number two is do you have prisms? And number three is do you have prisms and double Maddox rods for torsion? And number four is do you have really fancy stuff, you’ve got prisms, you’ve got double Maddox rods, and you have Hess screens? So go ahead and answer that.
And I’m asking about Hess screens because I had several questions about Hess screens in superior oblique palsy. I do not have Hess screens, I don’t use Hess screens, and so I’m curious to see how many of you actually have those.
My only surprise here, okay, so some of you don’t have prisms. Not surprised, I see that all the time. Many of you, in the middle zone here, have prisms and double Maddox rods, I’m glad to see that that’s true for double Maddox rods. And then I see a larger percentage than I would have guessed have Hess screens. I’m going to touch on that, but I’m really not going to talk too much about Hess screens because I don’t use them. And I think it’s against what my concept, or my mode here is of keeping things simple.
And here are these audience questions I eluded to. “Any simple way to remember superior oblique palsy in a Hess chart?” This is from India. And then from Nigeria, “Evaluating unilateral superior oblique palsy with a Hess chart?” Hess charts, this is what they look like. I stole this from this person on the internet that you see at the bottom. Hess chart of a congenital right fourth nerve palsy. So this is right eye here. This is a congenital right fourth nerve palsy, or superior oblique weakness. And that’s what it looks like.
To me, this is not simple. It’s a nice diagram. It’s like having someone that can do a nice Goldmann visual field for you. But if I were to do this in the office, either I would have to do it and it’s going to take a lot of time. Or I have to have a very trained person who is capable of doing this and it’s going to take them a lot of time. Or the patient’s going to have to come back on another visit to get it done at another time. While maybe this can be helpful in a smaller percentage of patients, I think that probably 99% of the time you don’t need this. This is making things too complicated, this is like using synotophores for routine strabismus. If you’re interested in this, great! Knock yourself out. But since most of us don’t have this available, I’m going to skip it and I’m going to stick to keeping it simple.
Step one, when I see a patient that has vertical oblique diplopia, I want to look at their motility, I want to look at their versions. And what am I looking for? Right, she’s got the head tilt, I measure her vertical in the primary position and I’m like, all right, I’m going to look for superior oblique overaction. It’s there until I prove it’s not. This is not a great gaze picture on her right gaze here, but there is no superior oblique overaction, so she’s got a right tilt, make a note of that. So you’ve got right inferior oblique overaction. Boom. Right now I’ve just narrowed down my diagnostic considerations to superior oblique palsy and just a few other little things. Observation.
Now, I want to supplement that with measurements. You’ve got to get out the prisms. You’ve got to get out the vertical prism bar. There’s frequently a horizontal component to this. It’s usually not significant, so if you want to keep it simple, just measure the vertical and then maybe in the primary position measure the vertical and the horizontal together. But in each of these positions, I want to get the vertical measurement and then the head tilts.
I just got a message that my headphones are going to die in a little bit. So at some point I’m going to switch audio, so just be prepared. It’s going to be amazing.
So, up gaze, down gaze, side gaze, head tilts. We need this. This is the minimum you need to do your diagnosis and evaluation. And torsion, right? So down here at the bottom, I’ve got measure torsion. Double Maddox rod. This is the holy grail right here of evaluating superior oblique palsy.
Make sure I didn’t skip, okay, we’re good.
All right, next question from Lebanon. “Any pearls to differentiate between inferior oblique overaction and dissociated vertical deviation?” Yes, this can look the same, right? So you take someone who has DVD, you take them into side gaze over here and their eye goes up. It’s going up because vision’s being blocked by the nose, so it’s like having an occluder over this eye. How do you tell whether that’s DVD or true hypertropia? You do alternate cover testing in side gaze. When you alternate cover test this person in side gaze, if this is a DVD, you will only see this, you will only see the abducting eye go up. You will never see the corresponding hypotropia over here. This is hyper, this should become hypo when you do alternate cover testing. That’s how you differentiate.
Next audience question from Canada, “Please describe in simple terms the Bielschowsky head tilt test.” Right, so you’ve got to understand this to understand the three-step test. How does this work?
Well the Bielschowsky head tilt test is that when you tilt the head to the side of the superior oblique palsy, the eye goes up. So this lady has a right superior oblique palsy, she’s in her right head tilt position, her right eye elevates. She develops a worsening of her right hypertropia. Which is why she adopts a left head tilt, generally, when you just leave her alone because she’s fusing now, there is no hypertropia, it’s all under control.
Well, why does this happen over here? This happens because the superior oblique, when she tilts her head this eye has to incyclotort. This eye over here has to excyclotort. So because the superior oblique is weak and this eye is not effectively incyclotorting, the backup muscle, the superior rectus, the superior rectus while it’s primarily an elevator, one of its secondary actions is to provide incyclotorsion. And that’s because it’s positioned like this on the globe. It’s not straight, front to back, it’s at an angle. So the superior rectus is an incyclotorter. The superior oblique is not doing its job. Superior rectus tries to help out. But superior rectus is a much better elevator than it is an incyclotorter. Yes, it produces a little bit of incyclotorsion but it’s also producing a lot of elevation. And that’s where this head tilt positivity comes in from the Bielschowsky head tilt test.
Three-step test. This is confusing. It’s great if you understand it, it’s fine if you can just do it. I’ll be happy if you can just do it. So how do we just do it? Well, when I see a patient that I think has a cyclovertical muscle problem, I use a piece of paper, an exam note, I just flip it over and I write on the backside. And this is what I write down: SR, IR, IO, SO and I do that for both eyes. And then as I look at my strabismus measurements, I start circling groups of these. Flip your paper over or get a scrap piece of paper, write down these four muscles. Why these four? Because these are all vertical and they also have some torsional impact, I mentioned the superior rectus is incyclotorter, as a secondary function, as is the inferior rectus because it’s also at an angle. It’s an excyclotorter as a secondary function. Those, when we have oblique strabismus, these are the four muscles of interest.
And our lady in this example, measure her in a primary position, she has 15 prism diopters of right hypertropia. A right hyper is the same as a left hypo. One’s up, one’s down. How it looks just depends on which eye they fixate with. If they fixate with the right eye, they’ve got a left hypo, if they fixate with the left eye, well, now they’ve got a right hyper. Same thing.
So if she has a right hyper, that could be a weakness of the depressors on that eye, the bottom set here, so I circle those. If she has a right hyper, that’s the same as a left hypo, so it could be a weakness of the elevators of this eye. So we’re circling the elevators on the left side. Step one, we have right versus left, elevators versus depressors.
Step two, is the strabismus, the hypertropia, is it worse in right gaze or left gaze? Well, we’ve already seen she is way worse in left gaze because she gets this big right inferior oblique overaction. Our lady, let me backup one slide. Our lady, she clearly is worse to the left side. Right inferior oblique overaction, her deviation, strabismus, is worse to the left. So now we’re circling cyclovertical muscle pairs that work in left gaze. So in left gaze it’s either the right inferior oblique and right superior oblique right here. Or, it’s the two here, the left superior rectus and left inferior rectus. So I’m going to circle both of those muscle sets. These are the elevators working in left gaze for each eye.
So now, two steps down, that’s right, one to go.
Third step, comes back to that Bielschowsky head tilt test. Is the patient worse with right head tilt versus left head tilt? This lady is worse with right head tilt. And I’ve put this little green line there because we’re going to be looking at diagonal circles now. We’re going to this way or this way. So you can just think about this circle I’ve drawn here imitating her head posture. This is the way to remember this last one. Her head is tilted to the right when her strabismus is worse, so I’m making two circles tilted to the right here and there. Just duplicate her bad strabismus head posture.
So that’s why I’m saying, yes, if you understand the Bielschowsky head tilt test, you can come up with this on your own. But if you don’t remember that, just duplicate her head posture and that will get you through drawing the circles. Because once you’ve drawn the three circles, you’re looking for this. Where do they intersect? Or where do they not intersect?
When they intersect, it maps out to her right superior oblique, which is exactly what we expected to see. Now, if you get something other than that, don’t be surprised, you just need to recheck your measurements or consider other diagnoses. It’s nice when it maps out perfectly, but it’s not always going to map out perfectly, especially if someone had spread of comitance or other reasons. My piece of paper that I’ve been circling, this is what it looks like when I’m done. Again, I’m happy to see that it’s consistent with what I thought the diagnosis was.
Now, that’s what makes the three-step test so great. It can really reinforce your diagnosis and give you confidence when you’re planning your surgical interventions and making your diagnosis.
Audience question from India, “How accurate is the three-step test in long-standing cases?” Well, it’s a good question. Because long-standing superior oblique cases you can see a spread of comitance, where the measurements become more equal in the different positions. They’re not always totally equal, like a skew deviation would be, but you see that the numbers are less and less and it’s six hyper here and eight hyper there. They’re not that different. And then you start to say, “Did I measure it right?” So you can see a spread of comitance. This is one of what they call perversions of the three-step test. And by perversions, it just means, what are some of the anomalies when it’s not accurate?
If you have vertical rectus contracture. Let’s say like this lady. This lady maybe has had a long-standing, severe right superior oblique palsy. Her eye’s been hypertropic all the time. If that right superior rectus becomes contracted, all the sudden her strabismus is going to be a different pattern than if that right superior rectus wasn’t contracted. So any kind of vertical rectus contracture, whether it’s from thyroid, or injury, or inflammatory, can throw the three-step test off.
And again that comes to number two here, restrictive disease. Restriction doesn’t play well with the three-step test. If you have paresis of more than one muscle, third nerve palsy. Three-step test, again, is not going to be very accurate. Skew deviation is another one. Previous surgery. Previous surgery can throw off the measurements and the accuracy of the three-step test. Things have been changed. Myasthenia gravis, because it acts in funny patterns, and can be variable, will throw off a three-step test, and then dissociated vertical deviation. When we talk about differential with cyclovertical muscle strabismus and oblique diplopia, these are the things that are on the differential that if our evaluation doesn’t clearly map out to an isolated superior oblique palsy, these are the other things that we now need to consider and evaluate the patient for. Three-step test is an awesome tool but it’s not always perfect.
Next audience question. “How to differentiate inferior oblique overaction from mild superior oblique paresis?” This is from Pakistan. And again, another good question just like the one about skew deviation and differentiating that. They can look very similar. And I would say, in general, if I was to differentiate between inferior oblique overaction and superior oblique paresis, I’m probably looking for torsion as my primary thing. Torsion, incomitance, but probably largely torsion.
And then of course, well, I won’t talk about traction testing at this point, it may not apply. But I think torsion’s going to be the main thing. Bottom line is, these can look the same. But your treatment’s probably going to be the same even though they’re different conditions, perhaps.
Torsion, this is the big one. I want the world, all of you, to have more love for double Maddox rod testing of measurement. This is such a critical element for superior oblique palsy, which is a common condition. What do you need? You need double Maddox rods. What do we mean by that? Well, these are Maddox rods. It’s better if you have a red one and a white one, because then you get this image here. Where the patient can see a red one and white one and it’s a little bit easier to tell which is which. But you can do it with two of the same color.
The trial frame is nice because then you can quantify how much torsion. And what we do is, we put pencil marks on the frame of the lens, and then when they rotate them to line them up, so we put the glasses on, this is what the patient sees. They see not two parallel lines but they see one’s at an angle and one’s not. And then we have them reach up and adjust, doesn’t matter which one they adjust, as long as they make them parallel. Adjust one of the sides, the knobs on the trial frame, until they line them up. You can say parallel, but I usually say railroad tracks, a lot of people don’t know what parallel means. But everyone knows what railroad tracks are supposed to look like. So we have them line them up like railroad tracks. And then, using that mark, you can read how much excyclotorsion they have.
So double Maddox rods are going up and down, the image they make, the image the patient sees is going side to side, like that. And then this patient has five degrees of excyclotorsion. In this case, on the right eye. You just have to be careful, the lenses, the glass part, can rotate inside the frame and you just need to make sure that the Maddox rod stays lined up with your pencil mark. But this is what we do to really quantify torsion.
If you don’t have that, but you just want some other objective measure, especially in young kids. Babies with head tilts, you can pick this up on their fundus exam. Or adults, you can take fundus photographs and you can get some assessment of torsion that way. This is a normal fundus photograph, this is the fovea, this is a line going to the optic nerve. The normal fovea sits right at the middle of the optic nerve or maybe just below the center of the optic nerve. Now this is in a photograph, keep in mind in an indirect ophthalmoscopy it’s going to be rotated, it’s going to be opposite.
Here’s a fundus exam, so let me go back. Normal, let’s go forward, on indirect ophthalmoscopy this is reversed. So here’s not the exact center of the optic nerve, but maybe a one-third demarcation. And the fovea should be right around that area, lined up with that.
Now if there’s torsion from a superior oblique palsy, and again, this is the inverted view from an indirect ophthalmoscope, this is a right eye. Normal right eye, fovea’s going to line up or be a little above that midline point. But if there’s significant torsion, now the fovea is up significantly. The fovea is above the upper edge of the optic nerve.
So this is what we’re looking for. This is usually obvious enough. And here’s a fundus photograph showing that. These are bilateral fundus photographs with bilateral superior oblique palsy. And see here’s the line coming from the top of the optic nerve to where the fovea is. That line from the fovea is actually above the top of the optic nerve. Fovea above the top of the optic nerve. This is the kind of significant torsion you can pick up on examination to confirm your double Maddox rod testing or in place of if you don’t have that available to you.
Torsion pearls. These are important. Congenital palsies may really not have much torsion. And again, that’s because the superior oblique is functional, it’s not truly palsied, it’s just got a long tendon. So it can crank it out, it just can’t maintain it. So they may have little or no torsion. But I would say that they usually have some. Most older kids or adults that I see with congenital palsies, they’ll have two, three degrees of excyclotorsion.
Acquired palsies essentially always have torsion. And it’ll be more, it’ll be four to five degrees of torsion. Bilateral palsies, this is the big one. Because you can have an asymmetric bilateral palsy and it looks like a unilateral palsy until you operate on it and then you unmask the other side. If you measure torsion, and they have more than 10 degrees of torsion, you need to be thinking, “Is this a bilateral palsy?” Because they will, they’ll have 10 degrees, 15 degrees. Down gaze they might have 25 degrees of torsion. This is where it’s very important to have this torsion measurement. It helps sort out congenital, acquired, bilateral.
Next audience question from India. “Investigations for determining the etiology of superior oblique palsy?” From the U.K., we have, “How to distinguish between congenital and acquired? And when to scan for acquired?” So I think this is the big question. When you see someone, A. you need to sort out, is this congenital or acquired? If you’re confident that it’s congenital, I never image those. Okay, that’s just a tendon problem.
If you are confident that it’s acquired, you need to be able to explain why it’s acquired. If you know they had brain surgery or they had a massive trauma and were in a coma for a week, okay. I’m okay with that, they’ve probably already had imaging anyway. But if you see someone with an acquired palsy and you can’t explain why. Well, now maybe you do want to get an MRI on that person. Or whatever other investigations that might be appropriate. Acquired palsies, if it’s clearly acquired, I image those.
It’s not always clearly acquired though. And a lot of these can be decompensated congenital palsies. And there are other ways to sort that out. What are some other tips to sort this out? Degree of torsion, we mentioned, with the double Maddox rod. If it’s acquired, they’re more likely to have significant, measurable torsion.
Vertical fusional amplitudes. If you have a congenital palsy, they are used to fusing up and down for a long, long time. And if you, once you get the prism that they can fuse with, you can keep adding more and more vertical prism and they’ll keep fusing it together and it builds up. Most of us that don’t have superior oblique palsies, we become diplopic if you put more than one or two prism diopters in front of our vertical, in front of our eye. But people with congenital palsies can build up and they’ll tolerate three, four, six, ten? They can fuse a lot of prism.
People with acquired palsies are more like us, they can’t tolerate prism beyond what it takes them to fuse, they become diplopic. Acquired palsies usually have small vertical fusional amplitudes, congenital palsies usually have larger fusional amplitudes.
FAT scan, I mentioned this before. FAT scan, not CAT scan. FAT scan stands for Family (photo) Album Tomography. Look at old pictures. If you look at someone’s picture, they’re 40 years old, and you look at their picture from school and they’ve got a head tilt. Well, that’s probably a congenital palsy that decompensated, right? But if you’ve got a 40-year-old patient and they’ve got a head tilt and you look at their old pictures, or their ID card, their driver’s license, and their head is perfectly straight? Whoops. That probably is acquired, they don’t have an old evidence of a head tilt.
Facial asymmetry and head tilts is what we’re looking for here. Facial asymmetry is another one. Facial asymmetry is not specific for superior oblique palsy, it just simply reflects that someone has had a chronic head tilt. And what you get is a compression of the downhill side of the face and you get expansion of the uphill side of the face, if you will. So you can see a torticolis of any sort.
And here’s a diagram of that. We’ve got a line going through the lips and we’ve got a line going through the head. And because they’ve got this chronic tilt, this side of the face is compressed, this side is widened. You’ll see asymmetry of their nasolabial folds. Facial asymmetry is a sign of a long-standing, chronic head tilt. And this is soft tissue changes and bony changes. It’s not just soft tissue changes.
And here’s that flashing back to the FAT scan. If I showed up in your office tomorrow and I have a big head tilt. You say, “Pull out your ID card, Dr. Neely.” It’s from 2018 and my head is straight. So now we’re like, “Yeah, this is probably acquired, he doesn’t have a head tilt in his driver’s license.”
But if you see that someone’s got this long-standing head tilt in their old photographs, now they probably don’t need imaging, they don’t need a CAT scan, they don’t need an MRI. We can see that it’s probably congenital.
More audience questions. From Nepal, “When to not treat a superior oblique palsy?” Well, that’s a good question. Just because someone has inferior oblique overaction, or DVD, or whatever they have, doesn’t mean we have to operate on everyone. So yeah, if someone doesn’t have symptoms, or someone doesn’t have a big head tilt causing problems. They don’t need surgery, they just need monitoring.
From India, “Mild superior oblique palsy, does it need to be treated even without diplopia?” Again, same as the first answer. No, like anything it depends on are they symptomatic, is it hurting them in some other way? Are they getting facial asymmetry? Are they haven’t double vision? Mild palsies can be observed, they can be treated with prism, they don’t necessarily need surgery.
“What are the indications for surgery in children?” This question from Sri Lanka. Yeah, different ballpark here. Because these are the kids who we see come in and they’re one or two years old and they’re like this. Their head is turned, slanted over, and they’ve got what looks like a superior oblique palsy. To me, that’s an indication for surgery.
Because this child, if this child is big head tilt like this all the time now, they’re going to get the facial asymmetry, and that’s going to be permanent.
If I can identify that in an infant, I’ll go ahead and do a superior oblique myectomy. I may not be super aggressive with things, but at least I’ll get that and try and get them back straightened up.
From the United Kingdom, “How soon should we operate after diagnosis?” Well, in an infant, as soon as I’m confident that I have enough information from versions, maybe prism diopter measurements, maybe fundus torsion on ophthalmoscopy. Boom, I will go ahead and operate. The adults, how soon you operate depends again on how symptomatic they are.
Again and here’s that kid, the kid with the big head tilt. I don’t want this kid to get facial asymmetry, so as soon as I pin down this diagnosis I’ll go ahead. I’m not going to wait until they’re school-age, I’m not going to wait until I can get accurate gaze positions and measurement in every direction, and they can do double Maddox rod testing. If I see this and they have big time superior oblique overaction, maybe some torsion. Good to go, inferior oblique myectomy.
Another set of questions. These were similar from Argentina and India. “How do we help the patient with dissociative diplopia or if it’s affecting their occupation or schoolwork?” Well, it depends, right? It always depends how significant is their problem? If it’s mild, no symptoms, no significant head tilt, we observe. If it’s mild. They have mild diplopia, or if it’s intermittent, we can try prism correction. We can grind prism into the glasses, or we can do a stick on Fresnel prism. Not a big prism person, but they do have a role.
However, if someone has a larger deviation, they’re bothered by it all day long, they’re having trouble with their job, or with their school, or it doesn’t look good, or they don’t wear glasses and they don’t want to wear glasses, they don’t want prism. Okay. Now we talk about surgery. So it’s a lot of the things we do with strabismus.
Similar question from Peru and Columbia. “What is the limit for treatment with prisms?” And then from India, “In superior oblique palsy with diplopia while reading, in particular, how much prism can we give and how?” All right, so what I do is I will do my measurements. And I do alternate cover, so that’s the maximum prism measurement, alternate cover. But the patient may need only part of that to fuse. So I will give them a vertical prism bar and let them slide it up and down in front of their eye until trying to find the minimum amount of prism that brings the image together, and that they think the image looks clear and is comfortable. And if I’m going to do prism, that’s the amount that I give them.
For ground-in prism in the glass? The limit is practically, it’s like six, eight, maybe ten. But as you get up in eight and ten, there’s a lot of thickness and distortion and optical center issues. Most people don’t really tolerate when you get 10 and above. Fresnel stick-on prisms, you can give someone a 20 prism diopter, a 40 prism diopter Fresnel, but there’s so much distortion that it’s practically just occlusion. From a practical limit, it’s smaller amounts of vertical prism.
For the second question here with reading, how much do we give? Well, you have to see how much prism they need in a reading position, looking down, and then you have to see if they still tolerate that in the primary position looking straight ahead. If they do, then you can just give prism in the whole thing. But if they don’t, then you have to have either two pair of glasses. Or what’s called an executive bi-focal where you have two pieces of glasses, this has one amount of prism, this has another amount and it’s fused together. I have a very difficult time finding optical shops that can make that kind of different prisms in the top half and bottom. So that’s a possibility but it’s difficult. Expensive too.
Next audience question is what about, and we’re almost getting to a couple videos here, so hang in there, I know we’re rolling up on one hour here. “Can it be treated with Botox?” This is from Columbia. Well, superior oblique palsy is not an ideal candidate for Botox because you would have to put in the antagonist muscle, the inferior oblique to weaken it. And I would say there’s a pretty good chance you’re going to contaminate the lateral rectus or the inferior rectus. And now you’re going to get other vertical deviations. Plus it’s temporary, you’re going to have to repeat it. Personally, I don’t see a big role for Botox here and it’s such an easy surgery. I can do an inferior oblique myectomy in about less than 10 minutes, for sure. Probably takes you three minutes to do Botox. I don’t see a big difference here.
Okay, now we’re getting to the surgical questions. How do we fix this? If we’re going to do surgery, what do we do? We need to talk about surgery, and we need to talk about bilateral palsies still.
From Egypt, “Efficient surgical management of superior oblique palsy?” And that’s what we want, we want efficient, simple, systematic. Ecuador question, “Which surgical technique do you prefer to treat superior oblique palsy?” Right of the bat, I’ll tell you that 90% of the time I’m doing an inferior oblique myectomy. Or recession, maybe, but 90% of the time we’re talking about inferior oblique myectomy. Because you just got to get these people back in the ballpark. If you just get them close, they’re happy, they’re good.
From India, “Management approach for unilateral superior oblique palsy?” Let’s look at unilaterals here first.
When I’m planning my surgery, number one, I want to know what’s the primary position? Because if the primary position is less than 15 prism diopters, I’m probably just doing one muscle, that’s all I’m going to need. One muscle, less than 15 prism diopters. And then I’m looking at the versions, I’m looking at the inferior oblique overaction. If someone has 10 to 15 prism diopters of deviation in the primary position and they’ve got visible inferior oblique overaction, I’m going to weaken that inferior oblique. I’m going to do a myectomy or I’m going to do a recession, that’s it. That’s going to get me there.
Torsion. I’m looking at torsion because I want to make sure I don’t have asymmetric bilateral superior oblique palsy. Because you’ll see, the surgery approach to a superior oblique palsy is much, much different. And you can have small deviations in the primary position and yet you’ve got a bilateral superior oblique palsy that needs surgery on both eyes. Torsion comes into the equation, even though steps number one and two are the most important, that’s also important.
Superior rectus contracture. If I see evidence that the eye does not depress because the superior rectus is contracted, I need to recess that. And then traction testing. At the time of surgery I do traction testing. So that I know what the superior oblique tendon feels like. These are all part of my plan.
Superior rectus contraction. I mentioned that, why does that happen? In this patient, in this photograph, this patient has a long-standing left superior oblique palsy. The left eye has been hypertropic, it’s been elevated, manifest for a long time. The superior rectus here has contracted. And now when they look down and to that same side, it’s restricted, it’s not going down all the way. So what happens, is the contralateral superior oblique now overacts. This is Hering’s law of motor correspondence. The eye’s trying to go down and out over here, but this is restricted. So it’s getting extra, extra input to the inferior rectus. And then it gets an equal amount of extra input to the inferior rectus’s yoke muscle, the superior oblique on the other eye, and so you get over-depression. We’re looking for this when we talk about superior rectus contracture.
And also this is when you might be doing those oblique position measurements because this is going to be their area of greatest deviation down here. That’s about the only time I start going off into the corners of the strabismus grid.
Traction testing, we want to be able to tell if that tendon feels too long, laxs, loose. And this just gets graded again, subjectively, a one to four. Little bit of laxity, medium laxity, is the tendon even there? I don’t know, I don’t feel it. So how do we do this? This is a surgeon’s view from the top of the bed, left eye left screen, right eye right screen. And I grab, almost like a V pattern, grabbing obliquely. And then I’m going to push the eye up and in and rotate it.
You also are retropulsing the eye. You are pushing it into the orbit and that’s different than when you’re testing rectus muscles. Rectus muscles you test restrictions by pulling the eye out and then moving it around. Here, we’re pushing into the orbit and we’re rotating side to side across that tendon, the superior oblique tendon is right here. We’re going to roll back and forth, back and forth across that tendon. And if it’s there and it’s normal, you feel like bumping over a log, it’s like rolling a ball over a log. You feel it. If it just rolls like it’s a flat floor, you’re not feeling the tendon and it’s probably too long, it’s lax, it’s loose.
Here, you can just see when we’ve just pushed the eye up and in. This is a normal view on the left, you can see a little bit of cornea still. Look how the right cornea just disappears, totally buried here. And then when you do surgery and you look at the tendon, here’s the left superior oblique tendon normal laxity. But look at this one on the right where the cornea just disappeared. You see how much extra tendon there is, it’s very lax. And that confirms your diagnosis.
Here’s video, we’re going to look at this. Pushing the eye up and in, this is a Brown syndrome. It’s really tight. So that’s not a normal tendon, that’s a Brown syndrome. Let’s look at that one more time. Brown syndrome tendon, tight, oh! That’s super tight, that’s a +3, +4.
Now I’m showing you that because now we’re going to do a tenotomy on that Brown syndrome so that we can create a superior oblique palsy. So here’s the superior oblique tendon and we’re cutting it. We now have a total superior oblique palsy from the tendon. So let’s look at what the traction test is like now. It should be very lax and loose, right? Grab the eye, push it up and in and it just disappears. There’s no cornea at all there, it just disappears. So that’s what a laxed tendon looks like.
Now, you can’t just do this one time, you need to do this when it’s a normal eye. You want to feel normals so you know what abnormal feels like. So just don’t just do it on your superior oblique patients, do it on some others.
Laxity pearls, superior oblique laxity pearls. It’s variable, but in general, superior oblique laxity is exclusive to congenital palsies where the tendon is too long. Again, opposite of Brown syndrome. There are cases of acquired palsies that have tendon laxity, but most of them don’t. Keep that in mind, you can find it if someone really has a totally dead superior oblique and it’s been there for awhile. You’ll find some tendon laxity on traction test. Inferior oblique overaction is usually significant when a tendon is lax.
And that guides us to maybe then we want to tuck it. So be looking for superior oblique overaction, always compare the relative laxity between the two eyes. Because a lot of times if we’re looking for asymmetry. Asymmetry’s what leads to these vertical deviations. So we’re looking for asymmetry and that’s what we want to fix. Again, practice on normal eyes so that you know what normal is before you have to decide what’s abnormal.
Now what do we do? What are going to operate on? Well, I mentioned inferior oblique already. But the basic premise to strabismus surgery, in general, you’re always trying to match the deviations to the muscles. So you’re picking muscles that have their affect and the direction of the greatest deviation. And that’s the concept of the Knapp classifications. So there’s Knapp one through seven. And the grids in the Knapp classification show where the diplopia is greatest. And then that leads to suggesting which muscle that you weaken or operate on, is going to give you the greatest effect in that position. And so you don’t have to go by the Knapp classifications, but that’s the concept of what you’re going to do when you operate.
You’re finding your area of greatest deviation and then you’re going to modify that based on the magnitude. Do you need one or two muscles? Based on the superior oblique tendon laxity, maybe you want to tuck if it’s lax. And based on superior rectus contracture on exam or on traction. Because if it’s tight, you probably want to recess it, just like any restriction. So we have these modifications.
Again, deviations less than 15 prism diopters. Single muscle surgery, usually. If there is inferior oblique overaction, weaken it. I don’t care if you do a recession or a myectomy, but weaken it. That’ll fix that patient 90 plus percent of the time and it’s easy and safe.
My personal technique for this is if it’s very mild inferior oblique overaction, +1, I’ll do a recession. If it’s +2 or more, I’ll do a myectomy. When I say recession, I’m talking about a 10 millimeter recession, which is measuring three millimeters down from the inferior rectus insertion and two millimeters over. A myectomy is probably equivalent to a 14 millimeter recession which is placing inferior oblique over the vortex vein, so that’s a different lecture.
If there’s no inferior oblique overaction, or excyclotorsion, they just have the vertical deviation, then maybe I’ll go to just a vertical acting muscle like the contralateral inferior rectus. Because that’ll help with my incomitance and gaze to the opposite side. Or if the superior rectus on the same side is restricted, then recessing the ipsilateral superior rectus for the hypertropia. Those are definitely less common for me. Easily, 90 plus percent of the time this is what I’m doing up here. These others are more supplemental in my practice.
Audience question from Pakistan. “I have a question about inferior oblique muscle surgery. Tips on how to grasp the inferior oblique during surgical manipulation.” This brings us to a video, because this is where it’s at. Inferior oblique surgery is simple, it’s easy, it’s fast, but yet it’s really difficult. What’s difficult? Difficult is getting it in position so you can do it. Once you get the eye in position, it’s easy. But there are tips, so let’s look at a video, and let’s talk about these tips.
This patient has something done to the medial rectus, probably medial rectus recessions. I think this is a congenital ET patient. So fornix incision, going through the inferotemporal quadrant, conjunctival incision, tent up the tenons, open tenons, and spread down in that quadrant. Now we’re hooking the lateral rectus here, this is the lateral rectus. And putting a 4-0 silk suture under the lateral rectus. And I’m going to use this to position the eye. Now I’m pulling it in and I’m going to pause right there for a second. Because this position is critical. The 4-0 silk is going across the bridge of the nose and then it’s clamped over to the drapes on the far side of the head. This light, this is a gauze, I’m placing that under the suture so that the sucture doesn’t bite into the patient’s face.
When you bring this eye in towards the nose, you want the cornea to be up, up and in, like the position of the inferior oblique overaction. The cornea needs to be above the suture when you clamp this with the hemostat. This is what you want to see to put the inferior oblique in the easiest position to grab down here. What I’m going to do now is open up this space and so this is a Stephens hook. And it’s just opening the space up. What’s going to grab the inferior oblique is this long hook. This is a Von Graefe hook. A Von Graefe hook has no knob, let me backup a little bit, maybe.
This is the Von Graefe hook right here. It has no knob, it’s like a giant Stephens hook. And this is going to go in, hugging the sclera, staying as close to the eye as possible. And it’s going to blindly come up underneath the inferior oblique to get it up so I can see the posterior border. So let’s watch that. It goes in, I can’t see the inferior oblique but now, ah. Now I just went back to the beginning. Okay.
All right, so here we are. Scroll back just a tiny bit more. The Von Graefe hook has gone in and it’s elevating everything down here, it’s lifting up the inferior oblique, it’s lifting up the fat, it’s lifting up the periorbita, it’s getting it all the way from the sclera. Because I want to see three structures. I want to see a triangle that is inferior oblique, and I’m going to a new share here.
I’m going to be looking for a triangle down here. And this is what we’re looking at. Our incision is opened up here. That’s the lateral rectus, the lateral rectus has a suture going under it. That Von Graefe hook is in there and that little Stephens hook is right there.
What am I looking for? Well, I am looking for… This has picked up the inferior oblique, the oblique is right there coming up to the lateral rectus. I’m also looking for a vortex vein. Now it will stretch, but I don’t want to break it or cut it. Vortex vein. And then the final thing we’re looking for, this is going to be a little bit odd, but the border of the sclera. So we have this triangle which gets formed. Vortex vein, posterior border, the inferior oblique, sclera. And this is going to be white. And this is how I’m going to isolate the inferior oblique.
This is going to be an inferior oblique. Let’s watch this in action now. This is the posterior border of the inferior oblique. Little bit tough to see but we’re going in with a Stephens hook. I’m going to go just past that border and we’re going to hook it. Just past the border, hook it, vortex vein, ah, damn it. Killing me, Smalls.
Hook the inferior oblique, you can see the little triangle back there real quick. So now we have the inferior oblique, plus other stuff, and we try and unload everything so that the tip of the hook is right up against the muscle, and then we pierce underneath it. We don’t want all the fat, we just want the muscle. And now we’re placing larger hooks to open up that space underneath the muscle. And this last Green hook here gets reversed to elevate everything away so that we can see the insertion down here. And then we’re just cleaning off the insertion. And now we’re putting a hemostat across the insertion of the inferior oblique, and then we’re going to disinsert it from sclera. And again, keep in mind this is right along the inferior border of the lateral rectus.
Now, once you have the inferior oblique disinserted, you can do anything you want to it. Put a suture in it like this, so that you can do an anterior transposition or a recession. Or, you can put another hemostat across it right here and remove this whole section. This is what I usually do. I’ll cross-clamp right here with another hemostat and I’ll take off the distal 10 millimeters of inferior oblique and then I’ll just let it go. I don’t suture it back on. So that’s what I’ll do. Either a recession with the sutures being put in or a myectomy. And I’m going to stop that.
All right, so that’s how I find the inferior oblique. Now there are other ways to do it. You can put in hooks underneath the muscles, you can elevate with a retractor. But this is a real nice way to do it.
This question comes from Spain, I’m going to try and wrap this up, we’re closing in on 90 minutes here soon. “If the angle is greater than 15 prism diopters, do I need to touch operate on 2 muscles?” Answer is yes, generally yes. How do you pick the second muscle? I will almost always weaken the inferior oblique as my primary muscle. And then I’ll add a second muscle, depending on what else I see. If the superior oblique does not feel super lax, it just feels okay or just a little bit lax, I will recess the contralateral inferior rectus. Again, that’s for the incomitance off to the opposite side and again, I will recess it. I’ll assume that the inferior oblique is going to give me close to 15 prism diopters and then I’ll base how much more I need at a dosage of three prism diopters per millimeter of inferior rectus recession.
If the ipsilateral same side superior rectus is contracted, I will recess that instead. That’s uncommon. If the superior oblique tendon is super lax, redundant, I will tuck that. I will usually pick one of those three things.
And let’s talk about tucking, it’s our final poll question. When performing a tuck, how much do you tuck? Do we always do A? Four to six millimeters, just do a small, medium conservative? Or number two, do you tuck enough so that it feels tighter than the normal contralateral side? Or three, do you tuck enough so that both eyes feel normal on traction testing? And again, you get into this, it’s all about similarities. We have a problem that’s because the two eyes are dissimilar. We need to equalize that. So how do we do that if we’re going to do a tuck? What’s our end point?
About half of you said yeah, tuck them so they are similar. And that’s right. Now, sometimes that tuck may be four to six millimeters. You don’t want to tuck extra, you will create a Brown syndrome. This is where superior oblique tucks sometimes get a bad rap and people avoid them. Because if you tuck it too tight, you’re going to get a Brown syndrome and it’s really tough to fix that once you get it. On the table, once you have sutures in, your end point is tucking it so that the traction test feels equal.
Always err on the side of under-correction because these patients have large vertical fusional amplitudes frequently and they can keep doing it. But if you make them go the opposite way, they have never done that, they don’t do it well, and they are miserable. Shoot for under-correcting them in general. Also in general, I say in general, maybe not always, but in general, probably shouldn’t tuck a tendon that’s not lax on traction testing. Now, there are times when it’s helpful or necessary, but it’s a smaller percentage for sure. Be careful about tucking non-lax tendons.
How do you do a tuck? Well, you can use a tendon tucker like this, just designed to lift the tendon and keep it smashed together, that’s helpful. But you don’t have to do that, you can just have a muscle hook under there. And then you’re putting in a suture at the borders, front and back, to make this fold. And you can use a non-absorbable suture like mersilene, braided polyester. Or you can just use vicryl. Some people then tack that fold down, I don’t do that, I just leave it up and tuck it all back in. But that’s basically how you do a tuck. And what you do, is you put those sutures in, then do your traction testing, see how it feels. If it doesn’t feel symmetric, cut those out, do more, do less, whatever you have to do until the traction test feels equal.
Now, let’s talk about bilateral palsies, as we close out on things here. Scary patients. What do we see here? This guy’s coming in with a chin-down, this is a hallmark of a bilateral superior oblique palsy. Why do they do that? That’s what we’re going to talk about.
Audience questions from India. “Diagnosing and managing bilateral palsy?” Yes, we’ll talk on that. “What subjective complaints does the patient with torsional diplopia have and how do we measure that?” Well, we talked about double Maddox rod testing and we talked about the fact that they usually have more than 10 degrees of excyclotorsion. Our doctor from Turkey. Let’s talk about torsional diplopia.
They generally have large degrees of excyclotorsion, more than 10 degrees. Measure it with double Maddox rod, and they have complaints that things are tilted. The classic thing to ask them about is door frames. Door frames should look straight up and down. But they’ll tell you that the door frame looks tilted. That’s torsional diplopia. That’s the subjective complaint.
Chin-down head posture, why do they have that? Because they usually have a V-pattern esotropia. So they have diplopia on down gaze and eyes diverge and the diplopia goes away on up gaze. So, to take advantage of that, they drop their chin. Now they’re in up gaze and their eyes are no longer V-pattern esotropia, they’re ortho. But it does mean that they have diplopia in the reading position. It’s a common complaint.
Because both superior obliques are usually relatively equally affected, the primary position deviation, while they may have esotropia, they don’t have much vertical. It’s either the same or there’s a little bit of difference. That’s another thing. They do have alternating hypertropias. So right hypertropia, left hypertropia. Look this way, right hypertropia. Look that way, left hypertropia. They get these alternating hypertropias which is why we need the side gaze measurement and we need the head tilt measurements. We’re looking for this condition.
This is from India, “How do you manage bilateral superior oblique palsies differently than unilateral?” Other question from India, “Best way to manage the esotropia in down gaze with extortion?” So that’s a problem, how do we do these things that are unique to the bilateral?
Your approach to this is different than bilateral superior oblique palsies. And they all have the same goal there, all the muscle options. You need to collapse that V-pattern and reduce the chin-down posture, and diplopia in the reading position. You need to nullify any primary position vertical deviation, and you need to reduce the torsion. Simply doing bilateral inferior oblique myectomies usually doesn’t work very well. It can help some, but it doesn’t really drive home these problems. So usually this algorithm over here is what I’m choosing from. Inferior rectus recessions for the alternating hypertropia in the V-pattern esotropia. MR downshift for down gaze diplopia, V-pattern. Harada-Ito for torsion, inferior rectus naso transposition for torsion, or superior oblique tucking for hypertropia and torsion.
You can see it’s a little more complicated when you get into these. And again, bilateral IO weakening is usually not quite going to cut it. We look at the yoke muscles to the inferior oblique, I’m sorry, the superior oblique. And so we’re looking at bilateral recessions of the inferior rectus muscles, five to six millimeters as a really good approach, collapses that V-pattern. You can do it asymmetrically to compensate for any primary position deviation. So again, three prism diopters per millimeter difference on your recession if you need to neutralize that primary position.
Audience question, “When do you use Harada-Ito procedure?” This is from India. Harada-Ito is for torsion. We typically perform super oblique Harada-Ito when you have bilateral superior oblique palsies with larger symptomatic degrees of torsion. 10 to 15 degrees or more. How does this work? Harada-Ito, you’re working with the anterior fibers of the superior oblique. The anterior fibers of the insertion of the superior oblique are primarily torsional. They don’t have a lot of vertical impact. If you advance, if you split that tendon insertion and advance the anterior half or third of the superior oblique insertion, you can produce torsional changes without inducing vertical changes to any significant degree.
Now the original Harada-Ito looked like this. Split the tendon, drag a loop of it towards the lateral rectus. Now over time, people have switched more commonly to this Fells modification, at least people that I know. Split the tendon, put a suture in that anterior third to one-half, and then advance that along it’s arc toward the lateral rectus. And measuring back eight millimeters from the insertion and just a millimeter or two above the lateral rectus, you suture those torsional fibers right there. You now are inducing more incyclotorsion. Put it here, more incyclotorsion gets induced without inducing up and down.
I’m going to skip through this. How much does that give you? Let’s get to that. How much effect does that give you? In this study that I was a participant in, we compared bilateral and unilateral Harada-Ito procedures. And on average, unilateral Harada-Ito gave you eight degrees of incyclotorsion correction. And a bilateral gave you 12. So it wasn’t really proportionate, double. So a lot of times you’re going to have a little bit of torsion left over. But that still gets you in this ballpark.
One of the final audience questions, “When there is a hypertropia more than torsion in a traumatic palsy, is it better to do a tuck than a Harada-Ito?” And I would say yes, if you do a tuck, you’re going to get more hyper-correction as well as a torsion correction. The Harada-Ito is primarily a torsional procedure. There should be, in this particular question, some advantage to a tuck.
I don’t have a video of a tuck that I’m going to show you right now for time reasons. But, this is my plug for Cybersight. If you go to the library, and look under videos and strabismus, you’ll find a very nice video of a superior oblique tendon tuck. Fully narrated and this was done on the Flying Eye Hospital. And you will find other strabismus surgical videos on Cybersight. And again, these are all great because they’re narrated, they’re done by skilled professionals that are best in the business. So take a look at the video offerings in the Cybersight library.
There were many questions about inferior oblique overaction and superior oblique, Brown syndrome, basically, A-patterns. I did not include those because. as you can see, this was a long presentation as it was. I did not take many questions from the chat because we had all the people that had submitted questions in advance that filled out the lecture. I’ll take a look at the questions that are in the chat and if I can provide some answers to those, I will.
The next time, let’s talk about tight superior oblique tendons, let’s talk about Brown syndrome, and A-patterns. And a lot of those questions we can funnel in there as well. Thank you for your attendance. I hope this was useful. Goodbye 2020, bring it on, 2021! Let’s get the vaccine out there, let’s all stay healthy and do well. Take care and I’ll end this now. Thank you.