Lecture: Inferior Oblique Surgery

The objectives of this lecture are:
• To distinguish the different types of DVD and pick the correct surgical approach
• To determine the correct amount of surgery to perform for IV nerve palsy

Lecture Location: on-board the Orbis Flying Eye Hospital, Accra, Ghana
Lecturer: Dr. Harry O’Halloran, Rady Children’s Hospital, San Diego, USA


One of the things that pediatric ophthalmologists see more than regular ophthalmologists is vertical deviations, and one of the things that I was asked to speak about was inferior oblique surgery. When should you do it? And maybe when should you not do it? And there are some really big textbooks out there, written on this topic. You open those strabismus books, and there’s three or four chapters on inferior oblique surgery. When to do it and when not to do it. And you can read them all, but it basically boils down to a few common sense things, and a certain amount of experience. Right? So the objective here is just to distinguish different types of dissociated vertical deviation, and pick the correct surgical option for you, and then to determine how much surgery will you do for a fourth nerve palsy, or will you operate on a fourth nerve palsy? We talked about this earlier. You know, a lot of children are not normally aligned for the first couple of months. If it’s a really obvious permanent deviation, then they probably have strabismus. If it’s intermittent, vertical or horizontal, for the first three or four months of life, you can say they’ll probably get better and not worry about it. Don’t operate unless you have to. So it’s one of these things. If waiting is not a problem, then just wait a little bit of time and see what happens. For infantile esotropias, we talked about it earlier, but what’s in red is that if they have an infantile esotropia, 60% of those kids have some degree of inferior oblique overaction. A lot of times, if you operate on them early enough and fix the horizontal, the vertical inferior oblique overaction will just fix itself. Or if you operate on their horizontal and they look so much better than they did before, the parents will be happy, and you can do some patching and some glasses and whatever else you need, and just wait your time. The other thing, though, is a lot of times no matter what you do, 40% of those patients will develop dissociated vertical deviation, or we can say it’s part of dissociated strabismus complex. And they get latent nystagmus. For these kids, you want to operate. For general ETs, you want to operate. If you can wait ’til six months, great. Because they’re a little bit bigger. They’re a little bit better able to tolerate anesthesia. But you want to operate between 6 months and 1 year. The longer you wait after that, even the longer you wait in that 6 month to 1 year period, the more likely they are to have inferior oblique overaction that needs surgery, and/or dissociated vertical deviation that may or may not need surgery. Okay. Is it inferior oblique overaction, or is it dissociated vertical deviation? Because they’re different problems, and they are different surgical approaches. So you’ve got to grade it, and it’s your choice. So I’m saying: You develop your own system, if you do enough of it. So you can say DVD, +1, +2, +3 DVD. Mild, moderate, severe, really bad, looks awful. You can have your own system. Distinguish between DVD caused by the inferior obliques and DVD caused by the superior rectus muscles. Because if it’s inferior oblique, then you’re gonna do inferior oblique surgery. If you’re gonna do — if it’s caused by the superior rectus muscles, you’re gonna do superior rectus surgery. If you do the wrong surgery, they look no better afterwards, and you’ve got to come back and do something else again. Now, sometimes it’s a little bit of both. Right? Some patients have inferior oblique DVD. You fix that, and then six months later, they come back and then they’ve got superior rectus DVD. That’s just how it is. I always tell my patients that DVD is always by nature — it’s bilateral. Because you cannot dissociate unless you’re separating two things. That’s what dissociate means. Associate means put two things together. So dissociated vertical deviation is bilateral. It’s frequently asymmetric. And the reason this is important is you have to make a choice. If you’ve got somebody who’s got bad inferior oblique DVD on one side, and a little bit on the other side, I say to may patients — look. I can operate on that one eye. And I guarantee you that within six months, you’re gonna be back complaining about the other side. So even though one is way worse than the other, we’re gonna do them both now. It’s the same with superior rectus surgery. Let me back it up a little bit. If you’re gonna do inferior oblique transpositions for dissociated vertical deviation, it’s the same procedure. If they have asymmetric superior rectus DVD, you can modify the amount you do. More on the worse side, and less on the less affected side. So if they have straightforward inferior oblique overaction, after esotropia — the development of esotropia — do you do their inferior obliques, or do you transpose the medial rectus? Or if you’re doing lateral surgery, do you transpose the lateral rectus surgery? We talked about this before. If you’re gonna transpose the medials, you transpose them to the point. So if it’s a V for Victor pattern, you transpose the medials down. You move the laterals up. If it’s an A, it’s the opposite. Right? Laterals go down. Medials — so the medials always go to the point. To the sharp point. Then you have to decide: How big is the pattern? Because this is how you make your choice. You look at them in primary position, and they have 15 diopter deviation. They look upwards, they have a zero diopter deviation. They look downwards, they have a 30 diopter deviation. So the pattern goes from zero to 15 to 30. Right? So that’s not a huge pattern. Some patients go from 25 to 75. 25 to 75. And they’re big deviations. And the reason that is really important is that just by recession alone, you’re gonna get a certain correction. So a horizontal recession — you’ll get a certain correction of a V pattern. And, you know, maybe 10 prism diopters. So let’s say 8 to 12. Right? So if it’s a pattern of 30, 8 to 12 — that might be enough of a correction for you. So you’re gonna recess anyway. So recess them and transpose them, and that’s all you have to do. If it’s a bigger pattern, you’ll get an extra 15 to 20 prism diopters, if you do a tendon transfer. So you can say: Okay. Recession got me 8 to 12. If I transpose them up half a tendon width or a full tendon width, or down half or a full, that gets me another 15 to 20. That’ll get rid of most people’s pattern right there. So you don’t have to touch the obliques. It’s only for the ones — let’s say you have an esotropia, or let’s say you have an exotropia of 20 in primary, 0 when they look down, and 7 when they look upwards. And they have inferior oblique overaction. You can recess and you can transpose, and you’ll still leave them with a pattern of 30 or 40. So those ones are the ones that get inferior oblique surgery. And that’s why, again, you’ve got to be cautious. Because it’s so much better to do a certain amount and have to come back and do more than do way too much and have to come back and undo what you did. And there are surgeons who will come up here and tell you: I can reverse my inferior oblique surgery perfectly. I can’t do that. If I operate and transpose your inferior oblique, I cannot go back. If I made a mistake, and I have to undo what I did, I personally cannot go back and make that muscle work the way it used to. I just can’t. And I’m sort of thinking if anybody stands up here and says that they can, maybe they’re being a little bit less than truthful. So maybe the thing to do, if you’re on the fence, is do the recession. You know you’re gonna get a certain improvement. Do the transposition, and you know you’re gonna get more of an improvement. And then wait and see, and say to the parents: We might have to come back and transpose the obliques at a later point. For oblique surgery, it’s always better to weaken than to strengthen. And I mean… So we prefer to recess than resect. Right? If you try and tuck an oblique muscle, in my experience, it really doesn’t work very well. So you want to just — if at all possible, number one, leave it alone, if you can. Number two, weaken it, if you can. And number three, if you really have to tuck it, then tuck it. Because that’s just more complicated and more likely to not work. It and then can we fix this whole thing by transposition? So in transposition, you take… So your inferior oblique muscle is an elevator. Right? So for my right eye, I look to the right. If my inferior oblique is overacting, it elevates my eye. And if that’s happening in DVD, I want to take that muscle off. I want to move it. And I want to make it a depressor. So you’re changing 100% the function of that muscle. Sounds complicated. But it’s not. You find that muscle, you put a suture through it, close to its insertion, at the lateral rectus, cut it off, and you just move it down, and you resuture it to the very lateral border of that inferior rectus muscle. It’s not a difficult surgery to do. But it’s almost impossible to undo it. That’s why you want to make sure that it really is the thing to do. So you go through your checklist in your mind. Is it really DVD? Is it really DVD caused by the inferior oblique muscle? Okay. Can I get away with just — can I fix the pattern with just a recession? Do I have to transpose? Okay. I’ll recess and I’ll transpose. Last case scenario, you recess, you transpose, and then you take off that inferior oblique muscle and do a transposition. What’s the single biggest risk? I talked about it in this cyber-thing. But when you do inferior oblique surgery, what’s the single biggest surgical risk? Pardon me? Correct. So the question is: What’s the single biggest risk with inferior oblique surgery? And the risk is hemorrhage. Because you take off that inferior oblique muscle, and remember, it comes from down here. You’re putting it back. You’re suturing it a little bit behind the inferior rectus. And if you haven’t got good hemostasis, it’s gonna leak, and that blood will track along the inferior oblique muscle, into the back of your eye. The cone of your orbit — there’s not a lot of space in there. There’s not a lot of wiggle room. So if you’ve got a big hemorrhage in there, it puts pressure on your optic nerve, and in no time at all, you’re blind. And the problem is that that blindness gives you ischemic optic neuropathy. So there is no treatment for ischemic optic neuropathy. We used to do high dose steroids. And I mean enough steroids to treat an elephant. It doesn’t work. We used to do optic nerve sheath fenestrations. Doesn’t work. So the only thing that works is prevention. If you cause it, you probably cannot make it go away. And this is just to show how you have to do your positions of gaze. Right? So this kid really only has — he has strabismus left eye. You can look at him and think… Okay. This is a pretty straightforward infantile esotropia. But when he looks to his right, he’s got a little bit of inferior oblique overaction. Now, for those of you — this is for everybody. Does that look like it’s really bad? Does it look severe? When you do his pattern, do you think it’s a huge pattern? No. So you’re gonna do his esotropia surgery. Are you gonna do one or both eyes? You’re gonna operate on both eyes. Are you gonna resect the laterals or recess the medials? You’re gonna recess the medials. You’ll get 8 to 12 diopter improvement, just by recessing the medials. But this is a little bit of inferior oblique overaction. So will he have — and think about this. It’s not a trick question. Will he have a V for Victor pattern? Or will he have an A pattern? What do you think he’s gonna have? So in primary, in primary, he drifts in. His inferior oblique overaction takes over when he looks up. So what’s gonna happen? Will he drift in more or less? Think about it again. In primary position, looking straight in front, he drifts in just a little bit. Right? He looks upwards. But when he looks upwards, his inferior oblique overaction becomes more evident. And the inferior oblique is also an abductor. So he looks upwards, and what happens? His esotropia gets worse or better? It gets better. So he has an A pattern esotropia. Because when you get him in to look downwards, most of the time they drift out worse. My point here is: It’s not a big A pattern. But it’s an A pattern. Right? So are we gonna resect the laterals or recess the medials? What are we gonna do? We’re gonna recess the medials. So it’s an A pattern. It looks like this. Which way are you gonna move those medials? Up or down? You move them to the point. So for this child, a proper examination — you say I’m gonna recess a little bit, and I’m gonna transpose upwards a little bit, and I’m gonna make sure that it’s a recession, not a resection. If you have comitant DVD, and this is a little tricky of a slide, but… So for inferior oblique overaction, you look left, your right eye goes upwards. Okay? But your left eye goes… Okay. You look to the right. Your left eye goes upwards. Your right eye stays in. So it is incomitant, by its nature. Right? It’s totally different in right and left gaze. With DVD caused by the superior rectus, you patch one, one eye will drift up. You patch the other, the other — but they both drift upwards. It’s kind of like they’re going in the right direction. So you can say it’s a comitant type of DVD. So for them, you do superior rectus recessions. We learned this yesterday. What do you have to be really careful about, when you operate on the superior rectus or the inferior rectus? What’s really important? Right. So there are a whole bunch of little connectors that connect your superior rectus and your inferior rectus to your upper and lower eyelids. And you have to remove all of those connectors, because if you don’t, if I recess the superior rectus, and I haven’t separated it from the upper eyelid, you’re gonna have eyelid retraction. Upper and/or lower. You’ve got to come back and fix that. So it takes an extra couple of minutes to just go in, lift up the conjunctival tissue, look for all those connections, and separate them. There’s no real formula for how much you recess the superior rectus muscle. So you have to have your own sort of decision. You have to decide… Is it really bad DVD? You say to the parents… Do you see it all the time? Do you just see it some of the time? Less than 10% of the time? Is it cosmetically obvious, which is a big deal for a teenager, and then it’s a pretty large recession, when you do it. 8 to 12 millimeters of superior rectus recession. And that’s why you really don’t ever want to do one side. Because if you only do one side and you recess it that much, it’s just not gonna look good. So you have to do both. You can make it asymmetric. So if you’re gonna do 12 on one side, you should probably do 7 or 8 at least on the other. And it’s even okay to say… You know what? I’m just gonna do the same amount on both sides. What’s the other thing about DVD? Can you ever cure it? Is it ever gone? So it’s never ever ever gone. You have to say to people: This is not a permanent cure. You’ll always have a little bit, no matter what. No matter how good of a job I do. You also have to make sure they recognize that again, the name — dissociated vertical deviation — just means your eyes are dissociated. Your brain has decided it’s not super important to keep them together. So you may start off with DVD caused by the superior rectus muscles. You fix that, and then they come back six months later, and they’ve got inferior oblique overaction DVD. So you have to tell the parents: You’re very likely to be coming back. So for the DVD surgery, you transpose the muscle anteriorly. You change it from an elevator to a depressor, and you totally change the function, and then for a lot of people, that’s a very uncomfortable feeling, afterwards. And you have to say: It’s gonna take your brain a little bit of time to stop feeling different. And then you realizing that that’s normal. Fourth nerve palsies. So everybody knows the three step test. Does the three step test work if somebody has had eye muscle surgery? Let’s say somebody has esotropia surgery as a baby, and then falls off their motorbike, and comes in it with what looks like a fourth nerve palsy. Does the three step test work? No. It doesn’t. So the three step test only works for people — where they’ve never had anything done. Right? And the three step test is: One eye is higher than the other. So you do cover/uncover, and you tilt your head, and you see how big — is the deviation worse in left gaze or right gaze? Tilt your head left. Tilt your head right. And then decide. If you choose to do inferior oblique surgery, and we did one yesterday — yeah. And I just saw his pictures, and he looks great. So you have usually hypertropia on one side. If you’ve got somebody who’s got a hypertropia in primary position, of any more than 5 prism diopters in primary position, just doing the oblique is probably not gonna fix it. But you have to decide. So with inferior oblique, with fourth nerve palsy surgery, you’re probably gonna operate on the inferior oblique muscle. You have to decide: Am I just gonna do the inferior oblique muscle? Or am I also gonna do a vertical muscle on the same eye, or on the other eye? In primary position, 0 to 5 of a hypertropia, you can probably just do the inferior oblique muscle and wait and see. More than 5… The hypertropia. In primary. Right? So you’re looking at them, and you can see it’s a little hyper. So 0 to 5 — you can probably just do the inferior oblique muscle. More than 5, you have to decide… 5 to 10… Do I do a vertical or not? Greater than 10, you’re probably gonna have to do a vertical. Then the next question is: Do I do it today? When I’m doing the inferior oblique? Or do I tell the parents… Yeah, we’re gonna do this, but we’re probably gonna bring you back, and we’re gonna have to do something else? And you have to decide that. So the three step test is valid only if there hasn’t been previous surgery, or some sort of funky abnormality, like a dermoid that was removed, or whatever. If the deviation is less than 15 diopters in primary position, then you’re only gonna do one. I think 10 to 15, you’re sort of hedging your bets. But the rule is: According to the rulebooks, 15 or less, do one. 15 or greater, do two. Maybe even do three. But this is where it boils down to your own experience. And you remembering… Well, the last time I did it for 15, I overcorrected. Or I undercorrected. So you have to… I keep a logbook of my cases, and especially when I don’t get the outcome I thought I would, I’ll write it down, and I look back and see… Oh, what should I do next time? And I go back and I reference that, when I have somebody who comes in with the same thing. I’m like… Ooh, I’ve done 15 of these. Let me see what I did and how they turned out. So let’s assume — bear with me here. It’s my right eye. It’s just the easiest one for me to point to, because I’m holding the microphone. It’s my right eye. I have inferior oblique overaction. In primary position, I have a 20 diopter vertical deviation. So I have a hypertropia of 20. And you’re gonna do a myectomy here anyway, on my inferior oblique. Right? So you’re operating on my right eye. I still need more vertical correction. This eye is still gonna be too high. What are you gonna do? So you have really two choices. Because we’re not going to resect. Correct? We’re not gonna resect the inferior and pull it down. That’s out. That option is gone. So my choices are: Bring my right eye down to meet my left eye. Or bring my left eye up to meet my right eye. It’s not a difficult choice. Right? If you get rid of the resection, so resection is off the table, done, now go back to the other rule. I much prefer to do what? Recess, but I prefer to do both eyes. Because this one’s gonna look a little bit different. I’ve done surgery. I’ve made an incision. It’ll be a teeny bit more red. So if you give me a choice, I’ll do the inferior oblique on this side. And then I’ll do the inferior rectus on this side. So you do the inferior oblique. It pulls this eye down a certain amount. You do the inferior rectus here, it lets this eye come up a little bit. So you can use the same principles for every eye muscle surgery. Try and not… You know, make sure you know what you’re doing. Try and do as little as possible. Always say… Maybe it’s better to come back and do another surgery. Let’s wait and see how this goes. But if you have to keep going, always do a recession. Not a resection. Always try and do both eyes from a cosmetic perspective. Now, patients don’t like to hear you say cosmetic, but I say: You get a nicer result. But cosmetically, it will look better. And if you’re operating on an 8-year-old, that kid will care how they look when they’re 13 or 14 or whatever age they start chasing boys or girls. Right? So the question is: Since you haven’t operated on the inferior rectus on this eye, but you’re gonna operate on the inferior rectus on the other eye, is there gonna be a problem with downgaze? I mean, yes. There will be a problem with downgaze. But they’re kids, and they will adapt very quickly, because one of the things that children do all the time is look down. They’re constantly looking down to play with toys or eat their food or whatever. And they will adjust pretty quickly. So children will develop fusion much quicker than adults. And adults may never develop fusion. The issue is — and it’s a very good question — if you do a really big recession, then you’re gonna have problems. Right? But if you’ve got a 25 prism diopter vertical, and you fix the inferior oblique on one side, that fixes a lot of it anyway. Let’s say you get 10 to 15 corrected, and you’ve got 8 or 9 on the other side. You do 2 or 3 millimeters on the other side, and worst case scenario, you could come back later and do a little bit of recession on the superior, on this side. So as long as you do recessions, you have multiple options. Because you can come back again and again and again and again. Because you’ve never removed any tissue. And if you do a nice careful surgical approach, you’re not gonna get a lot of scar tissue. What’s really nice about that Q-Tip dissection is, if you push all that tissue back with a Q-Tip, it’s all intact. You haven’t made a whole bunch of tiny little cuts that have little bleeding points that cause scar tissue formation. You push it out of the way. It’s really easy. And those kids, bizarrely, don’t tend to scar that much. So you can come back and do a little bit more surgery very easily, if you have to. And you can always undo your recession. So if you recess this eye, the inferior rectus, and they complain of a little bit of double vision, you can come back. You can advance the previously recessed muscle a little bit. And then you can do a little bit of a recession on this side. On the superior rectus. So you have multiple options, as long as you plan perfectly initially. So the question is: For unilateral fourth nerve palsy, do I operate on the superior oblique? And the question is good, but it’s a trick question. Because she asked me this question yesterday. I don’t like to do superior oblique tucks, because I find that I just have to come back and undo them. And maybe other people can do them better than I can. But when you read the strabismus literature, nobody has 100% success with them. So it really becomes… You know, you’ve got to go by what the books say. You have to go by hopefully what the most recent research says. But you are still the individual doing the surgery, and some people are better than others at certain things. So if you’re just not a really good superior oblique tucker, then don’t do it. And that’s why it’s good to keep your own log, and see… Okay. Well, I tucked that one. But six months later, I had to undo it. Or I did two muscles there, when I really wasn’t sure. So if you keep your own log, after a while, you see a pattern, and it tells you… You’re either overly aggressive, or you’re underaggressive, or in my case, it shows me that I’m just awesome. So we’ve answered this a few times, but the biggest risk from inferior oblique surgery is retroorbital bleeding. I can’t emphasize it enough. So take a little bit of extra time. Put in a couple more throws in the muscle. If it’s even weeping just a little bit, just put in another suture and tie it off, so that you know it’s not gonna bleed. What percentage of infantile esotropia patients have DVD? 40%. And think about that. 60% have inferior oblique overaction. 40% have DVD. So they don’t all go on. All those 60% of inferior obliques, a lot of them can just get better when you fix the horizontal deviation. And then… So tricky question. Third nerve or fourth nerve palsy, and the deviation in primary is 12. Are you gonna do one or two muscles? One. Because you’re right on the fence. Right? And it may work. Sometimes it works. And sometimes it doesn’t. But if it’s my kid, I’ll take the sometimes it might work, and then that’s when less is more. You know, the less you do for them, the better the result you get. So the more effective the result you get. So the question is: If you do an inferior oblique myectomy, and you’re looking at a post-op, and you don’t have the world’s best results, how long do you wait before you do another surgery? So some people say that experience — it’s like a residency program. Right? In residency, you go year one, year two, year three. And with experience, you get some experience, a bit more experience, a bit more experience. Other people will say that residency is just like experience. It’s learning to make the exact same mistakes with increasing confidence. So that’s why keeping your own log is a really good thing. You keep a log, you see how you do, and then with experience, you say to yourself: Well, okay. The last 10 of these that I did… I only did one muscle, and none of them needed a second surgery. This kid does not look great today. But it doesn’t look awful. Let’s wait and see. And remember, it takes about two weeks, in my experience — everybody is different — but in my experience, for my patients to be at about 95% of where they’re gonna be. Now, that extra 5% you can play around with. Prism and stuff. Prism doesn’t work in cranial nerve palsies, because they’re incomitant strabismus. Prism only works for comitant strabismus. Same deviation, every position of gaze. So I wait, and a lot of times, I’ll just do some patching, and then I’ll even tell the parents to just do some extra exercises. Have the kid exercise the eye that you need to move in a certain direction. And a lot of times, you can get a few more prism diopters of correction, as long as you pay attention. So I’m a believer that for small deviations you can exercise that small deviation away, and it’s worth your while waiting. If I’m on the fence, and I really can’t decide, I wait a minimum of three months. I just wait three months. And that way, I feel like I have waited long enough. And also, you want the eye to fully heal. You want all the incisions you made — not alone to heal, but also to scar and scar down. You want all those blood vessels to be sealed off. So you don’t see anything unexpected. And these are just things that I’ve learned over time. But when patients say to me: Will there be a scar? Every incision leaves a scar. And that is what I say. Oh, every incision leaves a scar. The question is: Will you be able to see it? And I say: Well, you’re the parent. You will find that scar. It doesn’t matter how good a job I do. I know that you are gonna find that scar. We’ve all done those eyebrow repairs, where you fix the eyebrow, and they look great, but if you get right up there and take a look, you can see the scar. So I say to them: But there won’t be a visible scar, as long as you use the eye drops that I give you to use after the surgery. Any other questions? Cool. Thank you.

November 21, 2019

Last Updated: October 31, 2022

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