Lecture: Strabismus Questions & Answers: Part IV

During this highly-interactive live webinar, the full hour will be dedicated to answering your questions about strabismus. All questions are welcome.

Questions submitted in advance as part of the webinar registration will be given priority. Additional live questions are also welcome.

Lecturer: Dr. Daniel Neely, Pediatric Ophthalmologist and Professor of Ophthalmology | Indiana University School of Medicine, Indianapolis, USA


DR NEELY: Well, greetings, everybody. I am Daniel Neely, pediatric ophthalmologist, and consultant to Cybersight. It’s a lovely rainy day here in Indianapolis, at the Cybersight studios. I appreciate you joining us. Today we’re going to go through strabismus questions and answers. I have a list of questions that have previously been submitted that we’ll use as the base here at the beginning, but I also encourage you to submit questions live via the chat function, and as questions come in, I’ll review those and intermix those with the questions that have previously been submitted. For starters here, let me kick off into the PowerPoint. One thing that I’d like to point out is that a lot of these questions that we’re discussing today are really excellent questions. And a lot of them are intermediate to advanced level. I want to remind everybody that we do have strabismus courses available on Cybersight. If you go to the log in, log in to Cybersight, and then once you go to your homepage, as you can see down here, where it says catalog, this will be a listing of all the courses that are available. And here in particular you’ll find the pediatric-related topics. Once you start courses that you’re registered for, they’ll appear over here where it says my courses. So it’s a nice entry portal here. Once you then enter, once you go into the catalog, you can search by pediatric ophthalmology, in this case, we have the nursing, neuro-ophthalmology, glaucoma, cataract, soon diabetic retinopathy. But once you go into that pediatric ophthalmology section, you’ll see the listing of courses available related to pediatric ophthalmology, and the one I wanted to point out to you is this one in the blue, where it says fundamentals of pediatric ophthalmology and strabismus, full course. Now, this is not just strabismus. Once you’ve launched that, you can see there are a lot of modules there. There are about six modules total. And similar ones that are going to pertain to our discussion today would be this basic evaluation, module one, but then more importantly, module two, basic strabismus. This is going to be horizontal muscles, A and B patterns, those kinds of things. And then down here, module four, which is advanced strabismus. This is where you get into things like Duane syndrome, superior oblique palsies, other things that some of you are interested in. So I urge you to take advantage of that resource, which you can do at your convenience. I would also like to remind everyone that this will be recorded today and will be available on Cybersight, under the library resources tab. There were a lot of great questions submitted. I’ve kind of lumped them together. Here you can see we had three different people asking something similar about the age of strabismus surgery. So best age for strabismus surgery, what is the recommended age for correction of strabismus for children born with it and why, and how do you manage a patient with congenital exotropia? Let lump the first two together first. It’s a great question, because it’s something that people have been looking at for a long time. And I think that yes, there are some advantages to the timing of the surgery. But ultimately, it’s going to depend on probably some more local factors. Because this is not going to be earth shattering, like pediatric cataracts, where you have to have that child have surgery and be optically corrected by six to eight weeks of age, or the outcome is not good. We have a lot more leeway, and the results are a lot softer when it comes to strabismus. So you have to take into account anesthesia abilities, you don’t want to be taking kids too early if it’s not safe in your facility. You want to take into account being able to measure the strabismus. Accurately. And not just… Totally ballparking it. And then you want to see what that’s doing over time, and you want to be able to treat amblyopia. So there are a number of factors here, and it’s not going to be just an absolute answer. But there are a couple really kind of hallmark studies that I would like to point out. When you talk about congenital esotropia, which is when we’re talking about timing with congenital strabismus most frequently, this article back in the ’80s looked at pediatric ophthalmologists in several countries, and looking over time, what they found was that there was not a lot of difference, whether you had these children aligned by six months versus twelve months versus 24 months. So this last sentence here: Results of sensory testing showed those adequately aligned by six months versus twelve months versus 24 months were not statistically different. So whether you had them had a perfect surgery at six months or you had a perfect surgery at 18 months, it didn’t make any difference, at least in terms of their sensory outcome. Now, where they did find some dropoff was after 24 months, so after two years of age, they did start to have a significantly lower percentage, with evidence for binocularity. Doesn’t mean it had bad outcomes, but in terms of high grade or some grade of stereopsis, they didn’t do as well. So you should say: Okay, what should my target be when I have a child borne with esotropia or exotropia. We’ll extrapolate this a little bit. And I would say having that surgery completed by age two years is pretty reasonable. That gives you enough time to see them more than once, get accurate measurements, make sure it’s not changing, make sure you’ve treated any amblyopia, and from an anesthesia standpoint, most facilities can handle children in this age group, between one and two years of age. So I think that’s a pretty good target. Now, there historically has at times been a push for ultraearly surgery, And as a matter of fact, when I was a fellow, twenty-some years ago, I looked at this with my mentor, Dr. Ellison, and I had the job of going out and examining people in their homes, 10 to 20 years after their surgery, ten patients, but they had all had surgery at about 10 months of age for congenital esotropia. And on average there was not a remarkable outcome. In terms of the sensory outcomes, still nine of ten had DVD, four of ten had latent nystagmus, and four did have measurable stereo acuity, but we’re talking about generally usually 3,000 arc seconds. A couple were better than that. One had 140 seconds. So you’re looking at the possibility that early alignment gives better stereopsis, but I don’t think that’s earth shattering enough to force early surgery on these kids. How do I manage exotropia? Pretty much the same as esotropia, congenital. First thing I do is try and get some estimate of the angle, of course. And if there’s a fixation preference, I may do some patching. If you’re seeing these children really young, say they’re four months, three months, I usually will see them a couple months later, and repeat their measurements. And as soon as I feel that they have relatively equal vision, with amblyopia treatment if needed, and as soon as I feel that the measurements are stable, and that I’m relatively confident in the amount that I’m anticipating to do surgery for, then for me, that’s the time to do surgery. So it’s more along those lines than it is saying: Okay, I’m gonna do surgery at six months, or I’m gonna do surgery at twelve months. I think you have to be adaptable, and base your target on those other factors. In my institution, anesthesia is not a concern, but if it is at your institution, then I think that’s probably the biggest factor. Because the advantages of early surgery are so soft, the last thing you want to do is do an unsafe surgery, if you have anesthesia concerns. Okay? Okay? So I think that’s where I would leave that. Next question… This is always a good question. In cases of consecutive strabismus, what is the best management plan? So what’s the most common situation here? The most common situation is you do surgery for esotropia, and they are either slightly exotropic right away, or they become exotropic over time. So how do you decide? In terms of a corrective surgery, for me, it really depends on what their motility looks like. I’m gonna go to the white board here. So if I’m seeing someone on follow-up… And they had a BMR of 6 for congenital ET, and they come back post-op, and now… A few months or a few years later, they now have XT, 15, what are we gonna do? Let’s look at their motility. So motility grid. Again, two ways you can look at motility. I use these Hs. Other people use an asterisk kind of shape. So if you look at their motility, and they’ve had medial rectus recessed 6, you want to know: Is there adduction? This is what we’re interested in. What is their adduction? If I see someone and they can’t bury the sclera, they have -1 adduction, then for me it becomes a very simple… That’s the same as this, right? These two methods. For me, that tells me: If I’m going to fix this, I need to go back and look at these medial rectus muscles, and I need to figure out: Why is this happening? Because they’ve probably slipped, they’ve definitely overcorrected. They shouldn’t be crippled if they have 6 millimeter recession. Motility should be full. So that means I need to go back and advance them, and if there’s an area of empty scar tissue, I need to resect that. People don’t like doing that, because it’s a little bit harder to plan: How much am I going to do? But that’s the only way you can fix these people. However, what if this is not the case? What if they come, they have this consecutive 15XT, but you look at their motility, and it’s normal. Okay? So we say it’s full. Their motility is full. Well, now what do I do? Now I can do whatever I want. So why would I want to do something difficult like advancing medial rectus muscles if the motility is full? If the motility is full, I’ll simply do a lateral rectus recession on one or both sides for 15 prism diopters. I would treat them just like I would treat someone who never had surgery before. That’s my approach to it. Now, there’s another situation here… If we erase this… You have people that… Oh, let’s say they were ET. So they started off ET. And they have a BMR. But they’re still ET. So now they have a second surgery. Second surgery. They’re going to have bilateral lateral rectus resection or plication. And then this is when they become XT. So they’ve had two surgeries for ET, and now they’re XT. What do we think is the culprit here? Do I think that they have slipped medial rectus muscles? No. So because the most recent surgery was this one, the lateral rectus resections, even if the motility might be a little bit limited, I might just assume that this is too tight. Okay? So if they went XT after the resections, this is where I’m gonna focus my attention. And I’m gonna go back and I’m going to explore the laterals. And I’m going to recess them. So that’s how I’m gonna deal with the consecutive strabismus, in this particular case. So motility and presence of motility deficits is your number one guiding force. And you’ll see this a lot of times, particularly you’ll see this in adult patients, so they had surgery as a child, and then they come back, a few decades later, and now they’re exotropic. And frequently you see people who had surgery as a child have these consecutive exo deviations. All right. Let me look at the live questions. See what we have here. All right. Here’s a question related to the first topic we were talking about. Regarding congenital exotropia. Would you suggest a neurologic exam, brain imaging, or any other systemic investigation other than ophthalmic concerns? Yeah, that’s a good question. This has come up because congenital exotropia is less common. There at times have been suggestions that these children are more likely to have neurologic impairments, and that you should do maybe more of a workup than you would for a child with congenital esotropia. And I don’t do that. I think that the reports on that are mixed. There are reports that say that there’s no higher incidence of neurologic abnormalities. But of course, with both of these, you can see children with and without neurologic abnormalities, whether it’s congenital ET or congenital XT. Right? But keep in mind that the true definition of congenital esotropia is that that’s their only problem. They don’t have any other neurologic issues. And so I think by default, the true definition of congenital exotropia is going to be the same thing. If you have infantile exotropia, and that’s your diagnosis, they should have no other neurologic issues. Any time you see these kids, whether it’s ET or XT as infants, as long as they seem neurologically normal, and their growth and development are normal, and there don’t seem to be any other concerns from a physical or neurologic standpoint, I don’t automatically do neuroimaging. I don’t think it’s necessary, okay? So I think you have to take all of these as a case by case basis. It’s just like — say you see a five-year-old with an acquired ET that’s non-refractive. I don’t automatically image all those kids. I think you have to look at them, talk to them, and see if there’s anything else that’s a red flag that makes you want to put them through an MRI or a CT scan or some other expensive evaluation. We’ll touch on this one too. Second question: Nystagmus with strabismus. The question is: Just correct the strabismus? Or not? So when you see nystagmus with strabismus, I don’t think there’s gonna be a straightforward answer here. Because it can be a host of things. Kids with congenital esotropia frequently have — usually have — latent nystagmus. And they may have manifest latent nystagmus. Well, in these children, we’re not doing anything other than just treating their esotropia. Now, that’s going to be different from someone who has maybe albinism or optic nerve hypoplasia, and they’ve got nystagmus and sensory strabismus. In those cases, you may choose to combine the two surgeries. So say someone has — let’s go with albinism. Let’s say they have a exotropia, and nystagmus. You’re going to fix the nystagmus by doing lateral rectus recessions. Maybe you want to also try to dampen their nystagmus by doing four muscle recessions or tenotomy, and this gets more complicated when you’re talking about people who have head postures, and you’re doing a Kestenbaum-Anderson for the head postures, but you’re also treating the strabismus, and you want to straighten the head turn but you also want to correct the strabismus. Again, there’s no formula for that, but you want to start looking at the numbers and shaving off or adding appropriate numbers to compensate for the strabismus as well as the head turn. I’m gonna go back to the previously submitted questions here. All right. And… Get some of these windows out of my way. So that was the consecutive. The role of Botox in strabismus management. That’s a good question, and again, you’re going to find a lot of individual and regional variability to this answer. In the UK, John Lee, who passed away a few years ago, he was really, really a big Botox user. And he would use Botox for congenital esotropia, and other acquired esotropias, by the thousands. And that was his go-to. I think that was kind of unique. I don’t think most people do that, but he was quite happy with his results, doing that. I would say for me personally, and the people I work with, we mostly use Botox in the setting of say acquired 6th nerve palsy. That’s probably definitely gonna be the most common thing. So you see someone who has an acquired 6th nerve palsy… And let’s say they’re about six weeks out from their onset of their palsy. So what’s that look like? You have someone who has a new 6th nerve palsy, and as a result, they’ve got this ET of 40, and this has been there for six weeks. They have such limited motility here. What we don’t want to have happen is we don’t want this medial rectus, this antagonist, we don’t want this antagonist medial rectus muscle to contract. All right? We want it to stay loose, so that it’s not interfering with later correction, as hopefully this recovers, or as you decide to do surgery for this. So in these cases, in an acute 6th nerve palsy, I will do Botox to the medial rectus. Whether you do that in the office, or whether you do that in the operating room, I think, doesn’t matter. That’s just gonna be personal preference. I personally like to take people to the operating room, and give them a little bit of propofol, and then I’ll use a fixation forceps, and I’ll abduct the eye to get my needle started, and then I’ll pull the eye back into the primary position, and try and put my needle as close as I can to the medial rectus before I inject. And I’ll put about 5 units of Botox into the vicinity of the medial rectus. And in general you try to have them elevated, at the head of the bed, or have them sit up, so that you don’t get too much spread of the Botox purely towards the levator. I think it does help. The other use for it sometimes is chronic palsies. You know, a lot of times… So I think the best use is what we just discussed here. These acute palsies. But what if it was six months ago? And now you’re seeing them, and they didn’t recover. And they’ve got this total 6th nerve palsy. And they’ve got that same kind of 45 ET. So someone like that is gonna need a full tendon transposition. They’ve got no lateral rectus function at all. So I like to take the superior and inferior rectus muscles and I like to transpose those temporal. You can do that with a Foster augmentation suture or by itself, but it’s nice if you can relax this medial again first. So ideally you would do Botox to that medial, a few weeks before you do the surgery. And try and get that medial to loosen up. Now, we don’t always have that luxury, and I’ll admit, most of the time I don’t end up doing that. I’ll either do it at the time of surgery, or I don’t do it at all. But that would be the other big use. Okay, so that’s my prime use for it, which is these 6th nerve palsies. When else do I use it? I’ve had some kids with infantile esotropia, or acquired non-refractive esotropias, and I thought maybe… Well, maybe they’re going to recover. All right? Or maybe their neurologic status is questionable enough that we think that they’re going to improve, or maybe this is a postviral thing. There’s a host of scenarios where you’re not sure if you should intervene surgically with something. Reversible but semi-permanent. And in those cases, I will use Botox, rather than surgical adjustment of the muscles. And I’ve had relatively good luck with that. Now, do I think it keeps you from doing surgery? I think in most of those cases, I’ve ended up still needing to do their surgery. Do their medial rectus recessions. But that’s the other time where I will sometimes just kind of buy time. And there certainly are enough reports in infantile cases of people having good results by just simply getting good sensory fusion early on that I think it’s not out of the question. But I think again, for most of us it boils down to the cost. Botox is about $400 a vial, and you’re only gonna probably be able to use it on one patient. You’re not gonna have a bunch of kids running around with esotropia that you can use it on. So expense is another one. And let me go to the live questions here. How about the recurrence rate after correction of sensory strabismus? How much effective control can be seen when prescription overminuses in intermittent exotropia? Those are two different questions. I’ll come back to those, because we have one previously submitted. But let’s just chat about the recurrence rate. Yeah, the recurrence rate is higher. That’s why they develop the sensory exotropia to begin with. That doesn’t keep you from doing the surgery. It just means you explain it to the patient. For me, most people, when I talk to them about strabismus surgery, I’ll say you’ve got about 80% chance, regardless of what surgery you’re doing, that you just do one surgery and you’re probably done. You have about a 20% chance that you’re undercorrected or overcorrected, and it’s gonna change over time and you’re gonna need a touchup. I think those are reasonable numbers for straightforward strabismus. If someone has sensory strabismus, or some complicated situation, where you’re not sure they can maintain their long-term alignment, you just simply say — look, you only have a 70% chance you’re gonna maintain this. You have a 30% chance you’ll need another surgery. They don’t care. They just want their eye straight, to look good, and if it needs a touchup down the road, they’re fine with that. You just need to counsel people appropriately. Let’s go back to the previously submitted questions. This is an interesting one. What’s the ideal way of managing small angle esotropia? Or let’s just say small angle strabismus in general. And the example here is 16 prism diopters of non-refractive, non-accommodative esotropia. This situation I think is pretty easy. For me, 16 prism diopters is a single muscle recession. So if you look at surgery tables for 16 of ET, you can probably do something like bilateral medial rectus recessions of 3 or 3.5 millimeters. Or you can do 1 medial rectus recession of 6, 6.5 millimeters. Okay? Now, some people don’t like doing single muscle, large recession. Because they are worried about incomitance, or crippling the muscle. But as long as you stay somewhat within our normal physiologic recession and resection ranges, you’re not going to cripple the muscle. So I’m perfectly comfortable doing a single muscle for 14, 15, 16 prism diopters of esotropia. The ones that I think are tough are: What do you do when you have something even less than that? You know? What do you do if you have 7, 8, 9? Those are tough. Because you can’t do smaller amounts of recession. So… iTunes is just killing me here. Okay. Let’s just say we have a patient, and they’ve got 9 ET. So maybe… Or they’ve got, say, 5 left hypotropia. So these are two different patients. This one needs a medial rectus recession, and this one would need an inferior rectus recession. Well, what do you do for these kinds of numbers? 5? 9? I’ve only done this a few times, but Ken Wright has described what’s called a mini-tenotomy. This is your muscle, and you just snip the middle part. So you take your scissors, and you’re just cutting right there. So you’re leaving the corners up. But now you created kind of a sag to the muscle here. And he even describes doing this in the office, under topical anesthesia. The times I’ve done it, I’ve done it in the operating theater. So a mini-tenotomy like that, maybe it can give you 3, 4, 5, something like that. So if you have really small angle strabismus, and someone who can’t wear prism or won’t wear prism, because they don’t wear glasses, that’s an option. I would just have some realistic guarded expectations with that. But by all means, if you have someone who’s got 14, 15, 16, whether it’s ET or XT, you can do recessions or resections for these smaller amounts, quite fine. All right, we’ll do another live question here. And let me open up your questions. Sorry. All right. Here it is. They opened off the screen. I just didn’t see them. Okay. There was a question about overminus for intermittent exotropia. Let’s do that one. Let me find that in our list here. So overminusing for exotropia — here we go. This is the next question anyway, so that’s perfect. So the question was: What about overminusing for exotropia? These other questions are related. Intermittent exotropia, when do you decide to do surgery, what non-surgical management do you recommend if amblyopia is not present. Other question: What are your considerations before operating on a child with intermittent exotropia. So let’s just talk about intermittent exotropia in general. So you see a new patient with intermittent exotropia. What you’re going to do probably depends on a few factors. It’s going to depend on their age. If you have a one-year-old or two-year-old with intermittent exotropia, and you only see it when they’re tired, you don’t do anything. However, if it’s a 30-year-old, and they have intermittent exotropia that’s happening while they’re trying to talk to people at work, and they’re really struggling from this, being self-conscious about it, it’s not hurting them, obviously. They might have a little bit of transient diplopia, or awareness of the deviation. But you’re gonna be way more quick to offer surgery to that 30-year-old than you are to the one-year-old or two-year-old that have the same problem with intermittent exotropia. When I see a one-year-old or two-year-old with intermittent exotropia, as long as they can pull it back in, and it’s present less than half the time, I just see them every six months, until they get a little bit older, and I try to save these corrections for this kind of preschool age, as you get between 3, 4, 5. When you start — as long as people maintain their near control, this kind of arm’s length conversation — as long as they can keep it straight there, they’re safe. They are not going to lose stereopsis. So what’s the worst thing you can say about their strabismus? It looks funny. Maybe their depth perception is off when it drifts. But they’re generally not too troubled by it, other than things like light sensitivity or squinting. All right? So you can really be really conservative about when you correct this or if you correct it. Some people don’t even want it corrected. But if people start to lose their near control, that’s usually definitely a trigger for me. Especially when you’re talking about children who are school age, and sensitive to losing stereopsis. We don’t want people to get where they’re exotropic all the time. We know when people have manifest exotropia, the longer they go with their manifest exotropia, the less likely they are to have normal stereopsis when you realign them, even if you have a perfect outcome. So we want to not get to that point, but there’s a lot of leeway between when it starts and when you decide to do surgery. If you have amblyopia, which you usually don’t — intermittent exotropia, they usually don’t have amblyopia, but if they do, you would of course treat that. If they have a refractive error, which is interfering with their vision, we of course treat that. So particularly myopes. If someone is a -1.50, -2 myope, they’re blurred, and it would be more likely to manage their strabismus. If someone is a hyperope, I want to point out: You don’t want to be giving them their full plus. You want to reduce their plus for sure, you want to take at least a couple diopters off their refraction, at least for children, because you don’t want to relax them and have them go out. That’s what we do with esotropes. We try to relax them so they uncross. What about overminusing? I will do it temporarily, but it’s just that. It’s a temporary kind of thing. I’m not a huge fan of overminusing. What are we talking about? We’re talking about overminusing. Let’s just do a little scenario here. You have someone who has distance XT, near XT. Let’s just say it’s intermittent. And that deviation is… Well, that might be kind of generous. Let’s go less. Make it more realistic. 20 and 15. They don’t have horrible exotropia, but they have intermittent deviation that’s visible. And let’s say their refraction is plano. So for them, you might overminus Rx them, give them -2, -1.50, maybe -1. Most kids can tolerate anything like that. Now, an adult probably wouldn’t tolerate that. But what are you doing here? You’re giving them minus correction, but their refraction is plano. What does that do? It stimulates… If I can spell… Stimulates accommodation. Right? They have to accommodate, and when they accommodate, they converge. Another example. Let’s go to the hyperopic example. What if they weren’t plano? What if they were +2? Well, that’s gonna be kind of hard to deal with. You don’t want to give them +2. They’ll be more XT. So don’t do that. If you give them plano, well, that’s what they’re walking around with anyway. So that’s no net change. Someone like that, you would have to give them something like -1. So now they’re accommodating 3 diopters. That could help you, potentially. And then the final thing is… What if they’re myopic? Let’s just blank it out. If they’re -2. What are you gonna give them? Maybe +3 or +4. Extra accommodative effort to keep them straight. I do that occasionally. It’s just a temporizing measure. You’re not fixing anything, and eventually they’re not gonna be able to do that. A kid can do that, but other people can’t. As you get older, they’re going to be… Get uncomfortable from that. Right? They’re gonna get uncomfortable, because while a six-year-old can accommodate that much, a 20-year-old can’t do that. And certainly a 30-year-old can’t. Sorry, I see what’s happening. My iPad is trying to sync, while we’re doing our webinar, which is fun. All right, so overminusing — not a big fan. Basically once they start to lose their control, and they’re noticing it a lot, I do their surgery. Now, why do we not do early surgery on a two-year-old or three-year-old for intermittent exotropia? It’s because intermittent exotropia is a safe deviation. You don’t get amblyopia. You don’t get much in the way of symptoms from it. But what if you do their surgery and they get overcorrected? Which is not uncommon, especially early on after surgery. We usually have these early overcorrections. So now you have a two-year-old who’s overcorrected by 2 prism diopters of ET after surgery for exotropia. Now you have an amblyogenic condition. Now you have to treat for esotropia. I treat this like a piece of fruit that’s ripening. We know they’re gonna end up needing surgery 90% of the time. In children, we’re trying to time it where there’s a balance between being too young and at risk for overcorrection and the downsides and being too old where kids are teasing them and they’re having trouble in school. So that normal range for me is between 3 and 5, ideally. It’s a totally different kettle of fish when you’re talking about older kids or adults. For them, you just do it if it bothers them. The bottom line. Let’s go back to our live questions here. Question: What is the suggested approach for dealing with intermittent esotropia in a child? Well, intermittent esotropia — it really depends on if they have a refractive error or not. If they have a hyperopic refractive error, you give them their hyperopic correction. If they don’t have a hyperopic refractive error, sometimes you can give bifocals. Plano up top, a little bit of plus in the bottom, and that will buy you time, because they’re probably more symptomatic when things are up close. But you can test that with trial lenses. If someone has a 30 prism diopter intermittent esotropia, and no significant refractive error, it’s not a super common situation. And I would go slow with making a decision about any surgery. You can try prisms. You can operate on them. But I would be conservative about that, and I would make sure you follow them for a bit, before doing that. There are people with cyclic esotropia, and they eventually become more manifest over time. And even if they’re cyclic, they tend to respond just as they normally would to surgery, even though they’re straight part of the time. So they can have surgery if needed. Another question relative to ET. This is another live question. ET with accommodative spasmus, 8 diopters, which you don’t see with total refraction on glasses. So people who have — this is similar. They’re having intermittent esotropia, and you’re not finding a refractive error. Kind of the same thing. If people have intermittent esotropia or spastic esotropia or accommodative esotropia without any significant refractive error and it’s variable, I’ve had some luck — if they have intermittent esotropia with certain activities, they’re blurred walking around with -2, you can put them on atropine for a while, you might have to put them on bifocals for a while, but you can break the accommodative spasm for a while by giving them atropine for a bit. I’m gonna go back to the previously submitted questions. Next question here. All right. This is a question about dissociated horizontal deviation. So this is actually the same question. What do you do in cases of dissociated horizontal deviation? So we definitely see dissociated horizontal deviation less commonly than we do dissociated vertical deviation. But the concept of the treatment is somewhat the same. Let me go to the white board for this discussion. Because the management is a little bit different. All right. So someone has DVD. And we’re seeing one eye, and the other go up. These are really weird eyes that I’m drawing, but you get the idea here. So we’re seeing one eye or the other just go up. What do we normally do? We’re normally recessing the superior rectus on both sides, even if it’s asymmetric. We might do more on one side than the other. Occasionally you see a patient where they only have DVD on one eye. And we just do a single superior rectus recession. Now we’re talking about in the absence of inferior oblique overaction. That’s different. That’s when we do anterior transpositions. So you can see unilateral DVD. And that’s most commonly what you see with DHD. So what does that look like? You have someone… Let’s just say intermittently, one eye goes out. But the other eye never goes out. It is purely one eye goes out when it’s occluded. It comes back in when it’s straight. Cover it. Goes out. Uncover it, goes back in. It is dissociated from the other eye. So what do we do with this kind of situation? You recess this lateral. All right? Let me clean this up a bit. If I have someone with DVD, and it’s most of the time horizontal, or DHD, I’m sorry, if I have someone with DHD, it is most of the time an XT DHD. That is what you see most commonly. And you can get somewhat of a prism diopter measurement on this. Right? You can try to measure with prisms. But it’s really hard to do. A lot of times… Let’s just say it’s going to be about a 20 deviation. Not uncommon. What would I do for this? I am simply going to recess this lateral rectus. And I’m gonna do a really large recession, just like I would do a really large recession for superior rectus for DVD. So I’m gonna recess that 8 or 9. And we can maybe even do more. Can probably do 10. But I want to do enough to cut down on that. So that’s pretty straightforward. You can do resections. For both DVD and DHD. I guess I use those less commonly. My go-to is usually the recession for these. All right? And let’s go back to another live question. Oh, iTunes is still trying to sync. Let me click that again. Okay. This was a question about congenital XT in neurologic exams. I think we already touched on that. I’m in the already answered ones. Okay, here’s the open ones. What is your approach for large angle exotropia, roughly 65 prism diopters? So large angle strabismus… Let’s go back to the white board. And just so you guys know, we have less than ten minutes left in our session today. Then we’re gonna wrap it up, okay? All right. So we have a large angle XT. 65 prism diopters. What are we gonna do for that? Well, they’ll usually tend to manifest on one eye, right? So they see… The patient sees… Right eye. XT. All right. And let’s just say motility is full. Might be trace amounts, but it should be pretty full. All right, so… What do we need to do here? We need two eyes… Right? This one’s got a big XT. This one is kept on target. My approach to this… Big recession over here. So we’re gonna do a big R and R. And resect or plicate — we’ll talk about that for a second, because I really like this — resect or plicate. And I’ll do large amounts. How large is large? Usually for me, I might do… If I want to get about 45, I’ll do about 8, 8.5 recession, and I’ll do 6 to 7 plication. All right? That’ll give me in this ballpark. 45 to 50. What do we have left over? That leaves about 15 left over. So I’ll go over to that lateral rectus, and I’ll do a large recession. 8 millimeters there. That would be my approach to 65 XT. They come back, and they’re undercorrected still. They’re unlikely to be overcorrected by that. They come back and they’re undercorrected, I’ll go back and I’ll resect that, or plicate that other muscle. You can have, of course, larger deviations. And if someone came in, and they didn’t have 65, they had 80 or 90 XT, I would do all four. I would do one, two, three, four, all at the same time. So it really just kind of depends on doing it that way. Doing large amounts. And I’m gonna go back to… Back to our previously submitted questions here. How to operate on A and V patterns? All right. This is always a good question, I think. I think I’m going to make this our last question. We’ll come in right at an hour. This is gonna take a couple minutes to discuss. Let’s go to the white board here. All right. So we’re talking about A and Vs. Now, what you do for those is going to depend on if you have oblique muscle dysfunction. So A patterns — you tend to see with superior oblique overaction. V patterns you tend to see with inferior oblique overaction. In general. So if you have an A or V pattern with oblique muscle dysfunction, you ideally really need to operate on the obliques. So in this case, it’s pretty easy. I just do inferior oblique recession or myectomy. And that’s how I collapse the V pattern. This case… A little more complicated, because you’re talking about the superior oblique, and the possible induction of torsion. If you do tenotomies. Now, a lot of these times, you see these A pattern, it’s gonna be like an A pattern XT, and they don’t have any fusion. They have these large manifest deviations. If they don’t have any fusion, you don’t have to worry so much about postoperative torsion. So in that case, they just do SO tenotomies. If you have someone who’s fusing, or you’re worried about torsion, then you can do posterior tenotomies. Now, why is that? Because the anterior fibers… Are the torsional ones. So if you leave the front portion of the superior oblique tendon attached, then we can not induce any torsional changes. Now, the downside of that is it doesn’t weaken the superior oblique quite as much as if you did a full disinsertion or a full tenotomy, but the upside is it protects you from torsion. So that’s my approach in the presence of oblique muscle dysfunction. Now, what if you don’t? What if you have, let’s just say, a V pattern XT? So they’re like 40 XT, 30 XT, 15 XT? So we’ve got this V pattern. But the motility looks normal. Looks full. What do you do with them? Well, there’s no oblique muscle dysfunction. -L So in this case, we’re going to look at this number right here, the 30 XT. So that’s a bilateral lateral rectus recession for me of about 7 millimeters. And we’re going to shift that. Right? So we talked about this mnemonic, MALE. Right? Medials to the apex, laterals to the empty space. If you’re shifting the laterals for the V pattern, this is your V, you’re shifting the laterals upward. So that’s gonna be with, let’s say, a half tendon width upshift. And if you had a V pattern esotropia, and you’re working on the medials, then the medials would be shifted down. They would be shifted towards the apex. That’s the where the A is. So that’s the approach to A and V patterns. With pattern strabismus. All right. So we are at about an hour here. I think we will wrap it up. And we will continue these discussions in our next month or two, as we continue going through these. I appreciate all the people who submitted really great questions in advance, and I appreciate those of you who have submitted some on the fly, and I hope it’s okay that we kind of mixed those two up. I like kind of going both ways with this a little bit. It’s interesting to see what people come up with. But it is very helpful to have them in advance, because I think that helps guide our discussion, and can have some limited amount of material prepared in advance. All right. Thank you all. And we will join you again next time. Okay.

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July 22, 2019

Last Updated: October 31, 2022

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