Lecture: Pediatric Ophthalmology and Strabismus Question & Answer Session (2024)

DR. NEELY: Well, greetings, Cybersight friends. It’s a pleasure to be back here with another question and answer session. I particularly like these because we get to address what your specific concerns are and it gives me a chance to see where everyone’s coming from. The topics we’ll cover today are gonna be quite broad in terms of skill level. And so, there will be some questions. It may seem rather basic, but there are some that are a little more advanced. And you can be quite certain that if one person has that question, probably a hundred people have that question. So, let me begin my screen share. It’s a beautiful day in Central Indiana which is where I’m located which is in the central portion of the United States. And let’s dig right into our question and answer webinar. First of all, we had great turnout. We had over a thousand people that pre-registered from 130 different countries with us today. And of those pre-registrations, I will probably prioritize the questions that were submitted in advance. So, there were about 93 different questions. Most of them seem to be strabismus-related. But there are some other topics as well. And we’ll go through all of those. And I think I’m able to cover most of those in the 45 minutes or so that we have together. I’ll also be monitoring the chat. So, if you have questions, you can enter those into the live chat and I will try to answer some of those as well. Just a little bit about me. So, I am in the United States. I’m in the central, heartland portion of the United States, Indianapolis. I’m a comprehensive pediatric ophthalmologist and do a lot of adult strabismus. I have been doing this for 27 years and more than 10,000 surgeries. And I have been an Orbis volunteer for most of that time. For the past 12 years, some of you know me as the Orbis volunteer for Cybersight. As a volunteer, I’ve had the chance to operate in more than 20 different countries around the world. I have a general feel for what general skill-sets are and what general resources are in most of the places that we work. All right. Like I said, try to cover everything and give prior to those of you that sent questions in advance. Because most of this is strabismus-related, I thought I would start off with a couple of non-strabismus-related questions that we had. But first, I want to direct you towards this. There — going over the questions, it appears to me that there might be a need for being aware that this pediatric ophthalmology course that we have on Cybersight. Now, if you go to the library and specifically go to courses, you can find that there is a very comprehensive fundamentals of pediatric ophthalmology and strabismus course. It’s broken down into five or six modules. One is basic strabismus, another on advanced strabismus. But also has modules on pediatric cataract and glaucoma, including how to do the procedures step by step, and a previous one on retinal blastoma. It’s lengthy, but once you take the pre-test, you can go through and look at different sections. If there’s anything you want to follow up with after this seminar, take a look there because most of this is included there. I created that module. And it’s — at least most of it. All right. We’ll dig right into our first question. This is an interesting question, I thought. And the question was: When to operate for pupillary membranes? And people often get worked up about these. I find that most of the time, the vast majority of the time, these do not require surgery. How do you know whether or not to intervene? Because there certainly are some risk when is you intervene. You could create a cataract. So, when you’re looking at these kids, of course, if they’re old enough to be able to do some fixation behavior and tracking, you want to cover the other eye and see how they react and how they’re able to track with this eye. Can you see the red reflex? All right. Now, the pupil can be small, but not too small. And you might still lose the red reflex. But it’s reassuring if you can see it. When the pupil is dilated, can you refract through it? When the pupil is not dilated, can you refract through it? Some of that’s going to guide you. And then can you see the fundus? You know, at any point in time — and it doesn’t really matter if — like in this case, the pupil’s being de-centered a little bit. The centration of the pupil doesn’t matter. What matters is that pupillary opening large enough? And generally, you know, a pinhole test is about I think 1.5 millimeters on an occluder. So, generally, if you have a pupil size that’s 1.5 millimeters or larger, you’re going to be okay. But otherwise, if you feel like you’re not able to meet these criteria, then stripping that pupillary membrane out of there carefully may be indicated. Another question came about scleral fixated lenses. And I have recently stopped doing cataract surgery. But I did pediatric cataract surgery for a long time. And I have experience with both of these. So, the answer is yes. And most commonly, this comes up with Marfan’s syndrome or lens subluxation, familial. I used the left side lens for many years, the Alcon CZ70. It has eyelets in the haptics. You can be certain of your lens centration and rotation. The only down side is that it does involve passing a suture through the sclera. And once you have that suture, you want to be able to bury that. There are published techniques for how to bury the knot. And guidelines on what size suture to use. So, but that lens works quite well. I think I would be more hesitant to try that technique with the lens that didn’t have the holes in the haptics. But I realize that sometimes those are not available. In the more recent years, I’ve switched to the lens that you see on the right side, which is the artisan claw. And I find that to be probably much preferable. And once in a while we’ve had some issues with one of the haptics coming loose, it’s relatively easy to reposition it. And this lens seems to be very well-tolerated and give great results. And I think the long-term safety of it is probably greater since you don’t have that suture going through the sclera. And just remember that a suture, intraocular lens, at some point that nylon or proline suture is going to come loose. The artisan does require a PI. As you can see, it’s done superiorly so you don’t get pupillary block. These are the two lenses that in general would use. And it is safe to do that. Now, of course, I think the big question with sub luxated lenses, when do you intervene? And you don’t want to intervene too early. These are not ideal options. These kind of aphakic lenses. So, for the — as long as possible I try to manage them with careful refraction and correcting their astigmatism and induced myopia. And sometimes you can even treat them as an aphakic patient. If the lens is so subluxated that it starts to get out of the way, you can refract them through the aphakic portion of the eye and maybe even constrict their pupil so that the lens is out of the way. You can treat them with aphakic spectacles as well and there’s certainly nothing wrong with that. All right. And then like I said, you know, most of the questions, well over 90%, were strabismus-related. And so, there’s a gamut of things that we’ll talk about here. And I thought I would just start in an age-based progression here. Talk about congenitally as esotropia. And one of the questions was posed: Can we identify strabismus in a newborn? Well, you can. But in some ways, you don’t really care too much about it because it’s going to change. So, I don’t get too — I think screening for red reflex in a newborn is great. I think screening for strabismus is probably not a big deal. Now, this has been looked at. People have gone around to NICUs, one of my senior partners did this project 30 years ago. They went and examined babies in the NICU. And the most common alignment was exotropia. And that was resolved. And all of us are sent kids that are a few months old, intermittent esotropia. Even if they have a manifest esotropia, if they’re 3 or 4 months old, not going to do a lot. In general, refer patients to us if their alignment has not normalized by 4 to 6 months of age. And then we’re generally going to be monitoring them for a while. They don’t usually have fixation preferences in amblyopia. First year of life, managing that is the main priority. Now another question, how to differentiate whether strabismus is congenital or acquired when the patients come at a later date. Well, there are some hallmarks of congenital esotropia. Lots of different names. Sometimes we call this con Gen Al esotropia. The more preferred name recently is essential infantile esotropia. Characteristics, it’s usually a large angle like you see in the photograph here. By definition, needs to be present by 6 months of age. They typically are going to have pretty mild, minimal hyperopia. So, to be a peer essential infantile tropia, it’s 3 diopters. Full motility. No evidence it’s a six nerve palsy or a Duane syndrome. And some of the patients later, presence of latent nystagmus, or OKNs any — asymmetry. And the inferior oblique overaction, as well as DVD. These don’t guarantee when you see a 6-year-old that it was a congenital condition. But these are the things that are generally suggestive of congenital strabismus. Now, the question is: How do you manage infantile esotropia, what is the optimal timing of surgery? In general, not a refractive problem. But if you have 1-year-old, plus 4, plus 5, it’s worth trying them in the refraction to see if that has any impact. Most of the times, we try that and in infants, it doesn’t make any difference. But you’re obligated to see what if any component is refracted. Part-time occlusion, a fixation preference or suspected amblyopia. And then perform part-time patching to try to equalize that. Because these patients usually have very minimal hyperopia, not candidates. You don’t get that much blur-induced when someone is a plus 2 or plus 250. The good news is usually patients this young, they don’t have a great pincer reflex. It’s hard to remove the patch. They’re usually pretty easy to patch. A related question here was: Is there an age when you would rather not perform strabismus surgery in children or adults? Well, first of all for adults, no, I don’t really have an age for adult surgeries. I will operate on people that are 90 plus years old if that’s what they need. And as long as someone’s healthy, you know, the general anesthetics are safe. And these procedures are pretty short. Older adults can also easily be done under local anesthetic if need be. They seem to have much lower pain. Amounts of pain from strabismus surgery than younger people do. But in terms of this population, this infantile esotropia population, there’s just not a big hurry to operate on these kids. A few decades ago, there was a push to do very early surgery. And I know in our institution, we were operating on kids as young as 6 months for this. And then we followed up on them for the next 10 years. And it just turned out that doing the surgery at 6 months of age was technically more difficult. You know, things are very small. It’s a small space. The surgeries are very difficult in these really young kids. And it turns out, there’s probably not a huge advantage to that in terms of obtaining stable alignment, stereopsis, fusion, maintaining alignment. It’s mild helpful. In general, wait until the kid sare a little bit older. Target around a year of age or a little bit after. But certainly many places, Europe or other places, where it’s more traditional to operate on these kids at 2 or 3 years of age. I’m aware of a paper that did show some benefits to operating before 2 years of age versus after 2 years of age. But again, the benefits are on the small side. And I don’t think you have to have an absolute. I do think that the critical thing here, especially if you’re in a limited resource setting, is when is the anesthesia safe? You know? If your anesthesia service cannot safely put a 1-year-old to sleep for surgery, then you wait. It’s just not that big of a deal. Another advantage that comes up maybe in terms of later surgery is that if you’re operating when they’re 2 or 3 years of age, you know, a lot of times by then the DVD has started to develop. So, if you start to see that, if they’ve got DVD and inferior oblique action, then at this point you can do both the ET surgery and the DVD surgery at the same time. Versus if you operate at a year of age, you’re fixing the ET usually. And then several years later, you have to have a second surgery to fix the DVD. So, some pluses and minuses to both. The bottom line, do what’s safe because the visual benefits are gonna be limited. Questions came up, several questions came up about glasses and strabismus. One, can squint be corrected by spectacles? How to prescribe glasses for squint patients. How to manage isotope ya with hyperopia? Hypermetropic correction? Is surgical correction more convenient than prescribing glasses? What are the crossed eyes than can be cured with glasses? Address them, the second to the bottom one. Is surgical correction more convenient than prescribing glasses? Maybe. There are a lot of times when people don’t want glasses. They don’t want their kids in glasses. They have trouble getting glasses and keeping them repaired. But the bottom line is, especially if you’re talking about refractive esotropia, you got to put them in glasses. That’s the treatment. If you operate to refine so they don’t need glasses, then you end up with a consecutive exotropia over time. We need to correct the hyperopia when that is a factor. There’s just no way around it. Before I move on, another question came up about prism. And in kids, I will almost never use any prism correction. Because they’re very good at suppressing. They generally don’t need it. And generally their angles of strabismus are quite large. You know, from a practical standpoint, how much prism can you put in glasses and have people tolerate? Well, that number is around 8 to 10 prism diopters. I see people with more than that, they can’t see well, there’s distortion. They don’t like it. It’s heavy. Practical standpoint, prism in glasses is limited to smaller numbers. 8 to 10 or less prism diopters. When do I use prism? Well, I will use it in young children who are actually diplopic. That’s when someone gets a consecutive esodeviation after surgery for exotropia. We use a prism for now, but you have to go with a permanent prism if they don’t settle down over time. That’s the one most common time in kids that I use prism. My results for things like converted sufficiency, I think generally kind of disappointing. But once in a while, there’s an application there. For adults, your applications for prism are much greater because they are generally more sensitive to diplopia. Keeping in mind what’s practical. Don’t give someone 20 prism diopters of prism. That’s just not going to work. Those people really need surgery if their deviation is that large. And how do I do prism? Well, I’ll just mention this. What I like to do with adults in particular is let them hold the prism. Give them a prism bar and have them subjectively move it up and down. And that way you can find what is going to be most comfortable and most clear. And I’ll generally look at that and I try to give them the least amount of prism that it takes to resolve their symptoms. So, keep prism to a minimum. Get some subjective input from the patient before you dispense that. All right. But there’s more to talk about here with glasses and strabismus. But as we lead into that, what — the question came up: What are the most common causes of strabismus? Well, that’s — that’s almost impossible to answer because there’s such a huge list of all the other factors that go into it. But I think there’s no question, the number one factor is hereditary. If you see a kid with refractive ET, it’s so common that you see a parent with refractive ET. And same thing with exotropia. That tends to run in families as well. And then we have all these other modifying factors. So, most of the time this stuff is unknown. It’s idiopathic. There’s a familial tendency. But what are the other factors. It’s hard to say. But what are the most common types of strabismus? So, I think that’s what we should talk about. And how do you handle these most common types? Because as you go through your clinic day, the vast bulk of the patients that you see for strabismus, at least in children, are these two category. It’s gonna be the accommodative isotropies and it’s gonna be the intermittent exotropias. And, you know, there’s a lot of variation as you go around the world as to what’s more common. But by and large, these are the two big things that we deal with, with pediatric strabismus. Now, the accommodative or refractive esotropia onset, usually around 2 to 3 years of age. These kids don’t present at 6 months of age. 2 to 3 years is quite common. But they can be younger. You’ll sometimes see a 1-year-old that’s a patient. But true congenital esotropia, that’s a lot less common than we think. And there are various estimates of this. But, you know, it’s just not that common that you see a pure infantile esotropia. Manifest, low hypertropia, large angles, and just not the environment that you see with the accommodative ETs. And basic type exotropia, or a divergence excess where the distance measurement is greater than the near measurement. Again, onset typically in that same age group, 2 to 3 years, but they can be younger. And like congenital esotropia, true congenital XT is less common. You see it, but it’s even less common than congenital XTs. And they are managed, and typically non-refractive. And just like congenital, typically surgical issues rather than refractive issues. Accommodative/refractive ET, all right? This is the bread and butter. You got to know how to handle this. These are kids that have significant hyperopia or they can have a nice my tropia, tipping them over to cross. The key, you got to do a cycloplegic refraction, and in the full plus. And relax them as much as possible and get the eyes straight. I will only reduce the plus if it doesn’t work out. So, if they have esotropia like this child does, they’re getting the full plus. Come back and won’t wear the glasses or having other problems. Or maybe you get an XT in the glasses, then I will reduce it. Now, for straight-eyed kid with hyperopia, we don’t typically put them in the full plus, right? We reduce it by a half a diopter or one or two diopters so the straight-eye kid can do some normal accommodation. But if they have esotropia that’s manifesting like this, put them in the full plus. I’ll give them the full plus and recheck the alignment in a few weeks. Usually see them back month or so later. And at that point in time, decide if they need amblyopia. If they come back and ortho at distance, but ET at near. That’s still not necessarily a surgery patient. Next step is put them in the bifocal. Try to relax their alignment at near and see if you can nurse them along. If they’re not ortho, then if these people have — if these patients have manifest ET at distance, and near, then you’re operating for that leftover amount of deviation, okay? So, we’re measuring for their alignment in the glasses. The — all right. The intermittent XTs. The question came about, it’s just a popular category. The question came about: Do you avoid surgery for intermittent XT? And then there was a question about refractive error management for XT. How to treat exophoria in an emmetropic eye? how to treat XT? Do I avoid surgery in the intermittent XTs? No. But I try to time it. First step with the kids when you see an intermittent XT that’s two or three years old. And the refractive areas, they have significant myopia or significant astigmatism, then they want to correct that. Because if they’re blurred, that’s similar to being occluded.
there’s only a manifest their deviation more frequently. So, when I see these kids, I’ll prescribe the full minus correction and give them the least amount of plus. Now, sometimes these kids are surprising and they are hyperopes, they are so blurred, give up the XT even though they’re a hyperope. In that case, you want to correct most of their hyperopia so they’re doing more normal amounts of accommodation and then see what their alignment is. There’s always the topic of overmining for intermittent XT. I do over-minus some kids. But I’m not a huge fan of it. For me, it’s typically something that’s a temporary move until someone has surgery or until they’re ready for surgery. Or in those cases where the families are trying to avoid surgery. But I don’t find it to be a real reasonable, long-term solution. Obviously, a younger kid can tolerate over-minusing in accommodation. However, as they get older, they’re able to accommodate less well. So, it gets to be diminishing returns as they get older. When you over-minus, you’re finding out whatever their refractive area is. And then you’re giving them another, typically, another minus one minus two diopters of correction. That stimulates accommodation and convergence. So, that’s how you’re trying to just improve their control. Some people will even over-minus by larger amounts, up to four diopters. I tend not to do that. I think that’s a big, accommodative demand at that point. So, this goes back to the other — one of the questions I mentioned earlier. How do you treat an exophoria in an emmetropic eye? What I would do with a patient like this, if we’re just trying to control this exophoria or intermittent exotropia, us putt minus 2, minus 3 in front of them and remeasure them. If stimulating that accommodation by giving them minus lenses instead of no glasses, if that helps to improve their control, then I would feel comfortable dispensing that in glasses and monitoring them. But again, it’s probably gonna be a temporary move here. Yeah. For me, the big question is not do you intervene? XT, but when do you intervene? It’s not so much an age-dependent question. Although there are some common ages. It’s really more dependent on their level of control. You don’t want to do it too early and you don’t want to do it too late. What’s too early? Really on an intermittent XT, if a — you don’t want to operate too early because if you get someone who is over-corrected after their surgery, and it’s a 2-year-old or a 3-year-old, well, now you’ve convert adenine intermittent exotropia that just looks different, you’ve converted that to a constant exotropic deviation that stimulates suppression. Now you’re dealing with an amblyopic eye that you have to patch. And if you operate too early, less confident in the deviations and measurements. It seems like a lot of these measurements build up over time. They might be prism diopters at age 1 or 2, but then by 4, that deviation more like 30 or 35. So, by waiting a little bit, it helps you avoid the risk of amblyopia with the consecutive esodeviation. And also allows you to monitor them and do a surgery for a maximum deviation trying to minimize reoperation. We know intermittent XT has a high rate of correction and high rate of re-operation. Surgeries for residual XT can be as frequent as greater than 50%. Now, there’s a difference between these kind of intermittent XTs that start at 2 or 3 years of age versus those that are infantile congenital. These kids that are XT from birth and they’re never straight, and I pretty much handle those like congenital ETs. And so, I will not do the surgery immediately. But once it’s safe from an anesthetic standpoint and seems that the measurements are predictable, I’m usually operating around a year of a age. There are some reports that congenital XTs have a higher rate of neurologic abnormalities. But I would not automatically do an MRI in this age group unless there was a sign that something was wrong. For me, usually monitoring these kids a couple times a year or more. And then we’re typically planning surgery as they get ready for school age. So, around 4 or 5 years of age. I think that’s enough time to get vision development. Decrease the risk of amblyopia if you have an over-correction. And from a social standpoint, these kids aren’t usually having problems with other children until around age 5 or so. And that’s when you start to see that becomes a factor. You want to operate before the near control is lost. You don’t want these kids to be manifest all the time. Some people will lose stereopsis permanently once they lose that intermittency. That’s a little bit too late. But letting them decompensate a little bit is ideal. Me, when I talk to parents and try to get them to wait a little bit. Kind of describing this as you have a piece of fruit that’s ripening. And you don’t want to do — you don’t want to eat that fruit too early or it’s not gonna be good. And you don’t want to do it too late or it’s not gonna be good. We try to time it just right to get the best result. And in the safest manner possible relative to the anesthesia and the amblyopia. All right. Surgical approach. Question came about surgical target for intermittent exotropia. Well, the surgical target is typically going to be the larger deviation on alternate cover testing. And that larger deviation is typically going to be the distance deviation. This is where strabismus surgeries have 20-foot, 6-meter lanes because we want to get that distance fixation and that distance measurement. So, we’re operating for the maximum distance deviation, typically. Now, what is the procedure of choice? Do you do a bilateral/lateral rectus recession? Or do you do a unilateral recess resect? Probably doesn’t matter. I think a lot of this is going to be surgery and patient preference. There was a study about 5 years ago, PEDIG, and there were some small advantages to R + R on one eye versus the BL recess. At the end of the day, it was not significant. I think you can pick and choose what you like. I will use both of them and I have some preference for one or another. If, for instance, if there’s a really large disparity between the near and distance deviation, such as the example I have here where they’re 40 XT at distance and 20 XT at near, I’ll probably be inclined to do lateral rectus recessions for that. And then also if you have the need to do an upshift or down shift or pattern, the resections allow you to do that easily. However, when the distance of near deviations are pretty similar or when you have a large deviation, 40 and 50 prism diopters, I find that a unilateral recess resect procedure allows me to get that larger amount of correction more easily without having to do a large amount to cripple the lateral rectus function. Question about what tables are best for squint outcomes? Well, I don’t know that any one table has been proven to be superior. There are many versions out there from very well-respected people. Most of them are quite similar. I think where I tend to see that the — there’s a difference in a different table is when you get into the larger deviations which are less predictable. Some of the tables don’t cover those quite as well. The measurements that I — the surgery dose table they tend to use is this one, which is based on Marshall Parks recommendations and it’s been modified over the years. But again, it doesn’t really address very large deviations. So, the big thing is it’s very easy to look these tables up. And you are typically, when looking at the deviations and picking out numbers, you’re trying to do the maximum deviation. In general. And you want to try and avoid estimation techniques. And we had some questions about how do you measure deviations? All right. Now, that seems like a pretty basic question. And that’s the kind of stuff that’s covered in the strabismus module. But how do you measure the deviation? What — you really need to be able to do a prism and cover test. So, that means you need a fixation target for both up close and in the distance. And you need to be able to do alternate cover testing. So, when you do alternate cover testing, the prism is in front of the eye and the occluder is going back and forth. And that is going to uncover the maximum deviation. All right? So, that’s the tropia plus the for a component. That’s most of what you want to use for most of our strabismus surgeries. There’s always some exceptions. If you’re not comfortable doing prism and cover test, there’s a simulator that’s available. It’s just that the American Academy of Ophthalmology website, there’s a pediatric ophthalmology center. And the stimulater allows you to simulate, practice doing cover testing. And it also allows you to measure vertical deviations and it allows you to practice with simultaneous prism and cover. So, for a very basic introduction, that’s a nice thing to experiment with. Question came up, the difference between Krimsky and the modified Krimsky, which is better? Probably not a whole lot of difference. The differences are on the left side, the Krimsky test, as originally described, originally was putting the prism over the deviated eye. Looking at the corneal light reflex, holding the torch or the muscle light, and center that reflex and then the prism deviation. That was modified to the modified Krimsky where you’re putting the prism over the straight eye, the normal eye. And you change the prism until the deviated eye appears to center. Probably the only major advantage over that is that cosmetically you can see the deviated eye and get an assessment of where it looks good. And then also if the deviated eye has any kind of corneal irregularities, it’s a little easier to judge the centration with the modified technique. But ultimately, they’re both estimation techniques. There’s probably not a big difference. They are not preferred. And about the only time I will use these is when I am operating on an eye that doesn’t see well and you just don’t have any way to do fixation and alternate cover. You really want to be able to do cover testing to get an accurate measurement. And here’s the example of the table screenshot that I showed you earlier. And this is — you know, like I said, these are just rough guidelines. You always have to modify this. One of the questions came up about what do you do for residual strabismus? And if someone has ET surgery and then they’re still ET and I’m going to the laterals, I will just say that I will back off on the resection component for the second surgery. So, when you’re resecting against a muscle that’s already been weakened with a recession, I think you want to be a little cautious and back off by a half or one millimeter and do a little bit less surgery than what’s actually on the tables. The question came up, do you ever do single muscle surgery? And answer is yes. Here you can see the very first column on the left side. For small deviations. So, 15 prism diopters. It’s probably equivalent whether you 2, 3 millimeter recessions or a single 6 millimeter recession. For me, doing 2, 3 millimeter, bilateral recession just kind of seems odd and I will usually do the single muscle recession in this case. And you’ll notice that there’s really not a table for single muscle resections. A lot of people have looked at this. You will find tables or guidelines out there. I’ve looked at this in my own practice. And I’ve found that the single muscle resections were pretty variable. And so, while I will use that as a follow-up surgery for some people, for a primary surgery, for a horizontal deviation, I would not say that I do that very often. And then here’s the same table for XT measurements. And so, I know you can screenshot these. But again, if you go to the strabismus course that I mentioned, these tables are all there. And I believe that actually the one that I showed you that was a document, I think that is downloadable as a PDF from that course. And again, you can see same question about single muscle surgery for small angle XTs. 15 to 17 prism diopters. Then you can do a single large lateral rectus recession. All right? For vertical deviations, guidelines are a little more straightforward. In general, resecting or recessing 1 millimeter per 3 prism diopters is typically what we do. Keep in mind restrictive cases like thyroid, you’ll tend to get a higher change per unit of recession. So, you might get more of a 4 diopter correction per millimeter. Is it better to operate on one or both eyes? It probably doesn’t make much difference, you know? We spent a lot of time talking to people about the surgery can be on the left side or the right side? Or is it gonna be bilateral? And ultimately, it probably doesn’t make any difference. And so, I always listen to the family input and see what their feelings are. I’m pretty flexible on this. In some ways we prefer unilateral surgery. For large deviations, a unilateral recess/resect, I think you can get more correction. Secondly, if you do a unilateral recess/resect and don’t get enough correction, then it feels cleaner to got to the other eye and it seems more predictable. When I’ve done medial rectus or lateral rectus recessions and then I end up with a large resection, and looking at bilateral rectus recessions or plications. You just too commonly you end up with a little bit of restriction or over-correction with that. I just kind of try to avoid that when I can. A question came up about what are the risks of squint surgery? We kind of take it for granted that there aren’t really any risks. In general, that’s true, you know? Can you get infection, bleed something yeah, you can. But those things are pretty uncommon. Need for additional surgery. Now, that’s a big one. I routinely tell people, inwith the most straightforward case, that there’s a 20% chance that they need a re-operation. But we know with some of the conditions, re-operation rate’s gonna be much higher, like 50%. So, you do need to make sure that people are aware that have. Loss of vision, fortunately, is quite rare. Various estimates for endophthalmitis, 19,000 to 250,000, and anterior segment ischemia. In 27 years, two cases of endophthalmitis and one case of anterior segment ischemia. Both did not do well, but they are rare. How to get endophthalmitis from strabismus surgery? Typically starts off as conjunctivitis and then you get some abscess formation around the suture. And it’s able to erode into that scleral tunnel and then erode to the scleral wall. The two times that I’ve seen it, I think that is what’s happened. And it just didn’t get caught early enough. Diplopia. People make a big deal about diplopia and counseling people not to have strabismus surgery, particularly adults. And I got to tell you that most of these adults have diplopia to start with. So, they’re generally just interested in getting their diplopia reduced or their eyes cosmetically aligned. And I have — I don’t think I’ve ever had to reverse someone’s surgery because of diplopia after surgery. You know? So, I just don’t take that into — I like to assess for it and counsel people. But I think from a practical standpoint, it’s actually uncommon that you create diplopia that people didn’t have. And related question came up in strabismus surgery, how you predict diplopia? Well, with kids, I don’t worry about it too much. Most of them adapt. As long as you get accurate measurements, most of them will be okay. It’s very rare that they have persistent post operative diplopia that’s a problem. And if they do, sometimes prism is need odd revising surgery. In adults, I try to see subjectively if they can fuse with the correcting prism. It’s not make or break for me. I feel more assured and can feel more confident in talking to them if they’re able to fuse. But there are definitely times when I can’t get them to fuse and, you know, we proceed with the surgery. And they usually do fine anyway. But you want to be cautious about that. Angle kappa? Take that into effect, the angle and cosmetic axis don’t align. When you have a significant angle Kappa, you have to be aware of it. And you have to decide, are you going for functional result or do you want the optical axis to line up? Which is usually what you for kids in particular. Or looking for a cosmetic result. I see this in adults. I don’t know, they have a dragged phobia from childhood ROP or something. Really what they want is they want their eyes to cosmetically be aligned more than they want the optical axis to be aligned. So, talking to the patient, figuring out what the goals are, and then you decide if the angle Kappa is a factor. Question about — a couple questions about Duane syndrome and doing consults on Cybersight for a long time, almost 2,000 of them, I will tell you that Duane syndrome is one of the number one topics for consultation. So, it is a big deal. This first question was about Duane syndrome type 1, how to operate for it. Usually, why are you doing surgery for Duane syndrome? Usually a head turn from the eye being restricted. Esotropic, or manifest esotropia in the position. And you can safely and predictably do a moderate recession on the Duane’s side medial rectus. It’s tight. But 5 millimeter corrects the head posture and aligns the eye. The other way to do this is to do a bilateral medial rectus recession, but do it somewhat asymmetrically. While the Duane side might get resect 5 millimeters where the muscle is tight, on the normal, contralateral eye, you can do a large recession of that medial rectus. And by large, I mean, 7 millimeters or so. What does that do? Well, if I have Duane’s syndrome and my left eye won’t go out, if I do a big recession on the contralateral medial rectus, now that eye doesn’t go in quite as easily or quite as well. And so, you can get a little better matching of their diplopia-free field. The second advantage is if I’ve done a big weakening on the non-Duane’s medial rectus, now that’s gonna drive a lot of input to the Duane side medial rectus. If there’s any adductus, you can drive that to be better. Those are my two typical approaches to Duane syndrome, type 1. The question came up about Duane syndrome type 2, or XT Duanes, and specifically with upshoots. Sometimes you can have a type 2 that’s not exotropic at all. It’s mostly the upshoot that’s the problem. Other times, the XT plus the upshoot. These, if there’s exotropia, you want to recess the lateral rectus. If there’s in exotropia, but there’s an upshoot, or an XT plus an upshoot, then splitting that lateral rectus is helpful. You know, these eyes look like they’ll kind of look like inferior oblique — when you have the Duane upshoots. But that’s not it. It’s the fact that the lateral rectus is tight. And as the eye tries to adduct in towards the nose with the equator of the globe is coming right up against that tight lateral rectus. It’s either gonna roll above it or it’s gonna roll below it. So, you can get upshoots and down shoots. Because of that contact with the tight lateral rectus at the equator. If you split it, now you’ve spread out the width of the lateral rectus and it diminishing that upshoot/down shoot. So, splitting the lateral rectus, possibly combining that with recession is what I will do in these cases. How do you split it? Well, before you dis-insert the muscle, before you put a suture in the muscle, just take a Steven’s hook and slide it along the length of the muscle fibers. Kind of as far back as you can go with the small hook. The Stevens hook. And put the double sutures, one in each half that have muscle and then spread it out when you reattach it so it’s roughly the width of the original insertion. That’s how you do a wide split. That’s covered in the strabismus modules that are in the Cybersight portion section of the library. All right. This is an interesting question. This came up: What do you do with a new onset, non-refractive esotropia in a 5-year-old? We see this not infrequently and it’s always disturbing for people. Kid is normal. No family history of strabismus. One day the kid just has esotropia. And I see these kids. They get sent for MRIs, lumbar punctures and all this stuff done and finally get sent to us. And, you know, 99% of the time these kids are just normal. And we don’t know why it starts. Is it post-viral? You never really quite fully know. Now, how do I handle these? Well, it kind of depends on the timeline. If it’s been there — if it came on acute and it’s been there 2 year asks they have no refractive error? Then that’s different than someone where it’s just come on about 2 months. If it’s been there 2 years, then you know just from time that it’s probably not a tumor or something dramatic like that. All right? It would have changed. So, what I — now, if it’s new, though, if it’s — if they were normal two months ago and now they’re not, then that’s probably gonna raise your concern level a little bit and you’re gonna be more likely to do neural imaging. And preferably an MRI. Limit the radiation exposure in these cases. When I see these kids, I want to make sure that their motility is normal. There’s no evidence of a six nerve palsy, right? If you have evidence of a six nerve palsy in a kid what about it buys neural imaging in my book. And screening of the other crane ideal nerves, make sure nothing is out of the ordinary. And do a dilated exam to make sure they don’t have papilledema. Then the nerve imaging becomes optional. You kind of have to listen to the family’s concerns and kind of have to see how much time has phone by and make a decision as to what you’re comfortable with. In 27 years, I don’t think I’ve ever seen a 100% healthy normal kid with acute onset ET that I found anything in the imaging. You want to be careful, but usually the workup is going to be negative, fortunately. Getting close to the end here, I think I have a couple more slides perhaps. One of the questions that came in was about Faden suture and when do you use the Faden suture or thread suture as it was referred to? Well, what is a Faden? If you look at the image over here on the left side of the screen, you’ve got a normal — let’s just say this is a medial rectus in frame A. in frame B here in the middle, you can see a suture has been placed. And that suture is not the entire width of the muscle. But basically, it’s a non-absorbable suture that is placed through the borders of the muscle. So, the one-third muscle width to either side of the muscle. And then you tack that to the sclera using a partial thickness scleral bite. Now you’ve fixated the muscle to the sclera. Usually it’s at the equator or slightly behind the equator. So, maybe in the ballpark of 8 millimeters back or so. Or 10 millimeters back. You kind of got to see where in practice, you’re trying to do it more or less as far back as you can get it. And then what happens is, if distance fixation, doesn’t really change the function of the muscle. But now when someone tries to converge and look at something up near, the new, effective insertion of the muscle is where that Faden suture is. So, it allows you to get weakening of function only in the field of action of that muscle. So, in a esotropic patient with a high ACA, pretty straight at the distance, but then a huge ET at near. A Faden suture can be useful to decrease that near deviation. Now, you don’t want to do this in a 5-year-old, a 6-year-old. You want to — if you’re gonna need a Faden suture for a high AC/A ratio, let that kid’s normal hyperopia and accommodated convergent response run its natural course. So, I find this to be useful either in adults or older teenagers who have not outgrown the need for a bifocal for a high AC/A ratio. Not in a hurry to do this. Difficult to reverse it once you it. But there is a way to get people out of bifocal it is they don’t improve over time. The other time that I’ll use this is the orbital floor fractures. People get the orbital floor fracture, and the inferior rectus gets damaged or tracked. And maybe doesn’t work even if it’s repaired. And now the eye doesn’t go down the way it should. But the other eye is going down normally. And they get these big, hypertropias in down gaze. Well, if you do a Faden on the normal eye and limit the inferior rectus on that side, now both eyes don’t go down as well. And you’ll get a greater range of diplopia-free balancing. It’s not perfect, but it helps a little bit. And then the final top sick how do you do a modified Nishida Procedure? So, transpositions. Six nerve palsies, monocular elevation deficiencies, third nerve palsies, sometimes Duane’s syndrome. All these instances when they’re doing transposition procedures. There are lots of different transposition procedures. I’ve had a long-time preference for doing full tendon with transpositions. Frequently adding a foster augmentation suture, which is almost like a foster — or almost like a Faden future in how it’s applied. You can do partial thickness transpositions, you can do Jensens, Hummelsheims, all these things. The Nishida is just another version of that where it was originally described to split say for a six nerve palsy, splitting the superior and inferior rectus, and transposing the half the with just the suture bite through them, transposing them down through the lateral rectus. And over time, the modified Nishida was described, like here. What happens is you have a non-absorbable suture, nylon or mersilene or proline, and taking a bite through the border of the superior and inferior rectus. Maybe getting about a third of the muscle width. And then you are in this quadrant. And that goes about 9 or 10 millimeters back from the insertion. And then in the quadrant between the muscles, in the direction you’re trying to augment the lateral rectus function say for a six nerve palsy, in that quadrant, you’re measuring back about 12 millimeters and you’re just partial thickness by scleral there. And then you tie that. And rolled out of my share here for a second. Let me go back. Yep. So, then you tie that and it drags the superior rectus and the inferior rectus there temporally. So, that you’re getting some lateral force. Why do we do this rather than some of the other techniques? It’s vessel sparing. So, essentially if you have some concerns about anterior segments ischemia, this is one way to limit vascular disruption. I’ve only recently started doing these so I don’t have a great feel yet how to compares to my results for full tendon transposition. You expect it to be a little less powerful. But we’ll see. But it’s a nice option and that’s how you do a modified Nishida Procedure. All right. So, we’ve made it through the bulk of the previously-submitted questions. And so, I would just — let me just go to our chat here for a minute. Let me go through a few of these. Here’s a question, regarding patients with restrictive strabismus, especially chronic sixth nerve palsy. Even after large resections with transposition, still have residual ET with positive traction testing. What should I to? This is tough. Describing someone with a sixth nerve, and superior and inferior and the resection, and they’re still restricted. And they have a positive force duction test. Well, only so many things you can do here. Transposition is kind of an all or none. The only things you have remaining are to loosen that remedial rectus. If it’s been recessed, you can re-recess it, you can Botox the medial rectus. And you can go to the contour lateral medial rectus and recess it and try to get some effect. But practically, sometimes, you just can’t get all the function that you need. But if there’s a restriction, thyroid or this case, if there’s restriction, the answer is alleviate the restriction, if possible. So, more recession of the medial. Question about your approach to DVD surgery. So, DVD, like I said, 90% of kids with congenital ET get DVD. You have options of if there’s inferior oblique over-action with the DVD. I will do anterior transposition of the inferior oblique, all right if that’s probably my preferred procedure. If there is not inferior oblique objection with DVD, I will do large recessions of the superior rectus. So, if it’s bilateral, we’re talking 8 millimeters. If it’s unilateral or asymmetric, we’re talking 5 to 8 millimeters superior rectus recessions. The third option, which is probably the least commonly performed, is you can treat DVD with inferior rectus resections or plications. And at various times in history, that’s been more and less popular. But it’s definitely the procedure that I do the least often. So, preferably inferior oblique anterior transpositions. All right? Next question regarding children with a large angle ET. 60 prism diopters or more. I usually perform three muscle surgery to address the whole deviation. Sounds like there’s in these — so, large angle ET doing three muscle surgery in one or two cases. The patient turned out to be exotropic at distance. What should I do when they’re inattentive? Well, typically, if someone gets an over-correction from — whether it’s from this or just regular esotropia surgery, how do you approach overcorrections from esotropia surgery? I think that’s a good question. If there’s any evidence that the motility is not normal, that could be evidence that the resection is too tight. They’re restricted. Or it’s evidence that the medial rectus is too weak. That it slipped. And so, if I see that there’s an AD duction deficit, I will traction test the lateral rectus to see if I think it feels tight. If it is, I’ll recess it. If there’s no restriction, though, but there’s an a deduction deficit, then you need to explore the medial rectus and advance it and resect it. You’ll usually find that it slipped and there’s gonna be a section of anywhere from 3 or 7 or 10 millimeters of attenuated muscle where it’s slipped back within the muscle capsule. It’s not state-sutured. In those cases, you just need to resect that attenuated section and decide if you just put it back in the same spot or you’re gonna advance it some. Question regarding pediatric uveitis with cataract. How is it managed? This is always a difficult thing because you don’t want to do cataract surgery in a hot eye. So, if you have active uveitis, or you’ve had active uveitis, you don’t want to do anything right away. You want that eye to be quiet for at least 6 months. And so, whatever has to be done in terms of steroid-sparing medications like methotrexate, some of the other agents, steroids, you want that eye to be quiet before you do cataract surgery. Particularly if you’re doing a lens implant. If you put a lens implant in a hot eye, you are asking for a disaster. If you really have to do cataract surgery in a patient with recent or active uveitis, I would leave them aphakic and I would do a secondary lens once the eye is settled down. All right? Question about how the interocular pressure changes in children. What’s the normal level for neonates/infants/toddlers/teens? And whether do you consider the IOP is raised for a particular rage group. This is a question that really has no answer. We don’t want to fixate too much on intraocular pressure even though there are some normals. Again, you go to the pediatric ophthalmology course, there’s a whole section on pediatric glaucoma. But it’s usually lower — low to mid-teens. You can have a kid with congenital glaucoma that clearly has changes to the structure the eye, and the pressure might be 20. But they still need surgery. Whereas in an older child or a teenager, you know, the pressure is gonna be more what we think of in adults where normal is more like 15 to 22. So, don’t fixate on the pressure so much as comparing the right and left eye. If there’s a difference. That’s a sign that the pressure is too high. Or if there’s structural changes in the eye. Those are things that you really need to pay attention to. Next question which — yeah, I’m surprised we didn’t talk about this. But the question is about Botox. Indications for botulinum toxin injection in strabismus. Some people use Botox for a lot of things and in place of surgery. For me, the role for Botox is typically going to be acute sixth nerve palsies. If I have someone who has a large sixth nerve palsy and it’s been there for a couple months and we’re gonna wait 6 months or to see if it resolves before surgery, I will use Botox to keep that medial rectus from getting restricted. And I’ll usually be doing these injections 2 to 3 months into the palsy. Don’t do them right away, because so many of these are gone by 6 weeks. But if it’s persisting in 2 or 3 months, that’s a good role for Botox. Put 5, sometimes 10 units in the medial rectus. And you could do that in the office or you can do it with sedation in the operating room. I’ve kind of developed a preference through doing it in the operating room. But whatever you’re comfortable with. Rarely do I use it in long-lasting strabismus. Although one could make an argument for doing a medial rectus injection in chronic sixth nerve palsy to try and loosen that muscle before doing transposition or other procedure. But I think from a practical standpoint, I usually just go straight to surgery if it’s been chronic. Question about how do you measure angle for surgery in a partially accommodative esotropia. We touched on this, but if you have a partially accommodated esotropia and you are measuring for surgery, then I treat these like a fully accommodated esotropia. I’m measuring their deviation with the glasses on. And I’m operating for the residual deviation. I would not try to correct what they look like without the glasses. All right? Because a 5-year-old with hyperopia is gonna start to lose that hyperopia after 8 years of page and you’ll create the consecutive exodeviation, all right? So, operate for what they look like in the glasses. Case — here’s another question. In case of consecutive esotropia in patients with hypertropia. For example, + 4, should we prescribe glasses before surgery even though the esotropia increases with correction? Well, if you’ve done surgery and they’ve developed a consecutive exodeviation, you don’t want to necessarily give them the full plus. And here’s where you can play with decreasing the plus. So, this is similar to over-minusing, right? So, you give less plus or give someone more minus. If someone’s a plus 4 and they’ve got a consecutive exodeviation after surgery, put trial lenses in front of them, see what that look like with a minus one or two or three. If they look better, then reduce the hyperonic correction and play games with that accommodative convergence response. And some people tolerate that, some won’t. And sometimes you just got to go back to surgery. A lot of times you can get away with reducing the plus. Next question: 6-year-old child with 6/6 vision in both eyes. Normal vision. Cycloplegic refraction is + 1.75. But they have a manifest exotropia of about 30 prism diopters. In a 6-year-old, 1.75, I would say that’s normal and not a factor. I would not put them in glasses. And if they had a manifest 30 XT, I would operate for 30 manifest XT and the optical question is just not a factor. What is your preferred incision location for strabismus surgery? Well, there’s not a set answer here. What do I prefer? In — I think, you know, so there’s a fornix incision and a limbal incision. The fornix incision I think has the advantage of it heals with less scarring, it heals more predictably. I think patients are more comfortable. Sometimes it doesn’t require a suture. But you need to have healthy conjunctiva to have a foreign incision. For me, it’s usually kids and young adults up to middle age for primary surgery. For a primary surgery, or a repeat surgery in a older adult, the conjunctiva is very thin. You can’t stretch it like that, you’ll just tear it. For adults that are middle age and older, I’m usually doing limbal incisions I. I also do limbal incisions for re-operations on children. Especially if I didn’t do the previous surgery. Having that exposure is helpful. Limbal incision, because it has better exposure, it’s easier to do and easier to see what’s going on. For less-experienced surgeons or if I’m teaching, sometimes that’s preferable. I think they both have a role. I don’t think one is better than the other. Other than I have the preference for the younger kids with fornix incisions. MRI, do you do an MR initiation superior oblique palsy? Not normally. But the question, are there questions whether it’s an intracranial process, is it new or not? Most of the patients with superior oblique palsies, they are decompensates congenital palsies. And you can look at the patients, they have facial asymmetry, look at the driver’s license and old photographs and they have a head tilt from years ago. And measure the torsion, 5 degrees or less, those patients probably don’t need neural imaging, they have decompensated congenital palsies. But if they don’t have facial asymmetry, there’s no history of trauma and they’ve got small vertical fusion amplitudes and a lot of torsion, well, in that case, yeah, now you’ve got something that looks like it’s an acquired palsy. You want to be able to explain why that is. That’s when I might do an MRI. This question is about bifocals for accommodative esotropia which are ortho, with distance glasses, but near esotropia. So, a patient has refractive esotropia. They’re ortho at distance, but residual ET at near in question says some reports say there’s no significant benefit to bifocals versus no bifocals over time. What I have seen is that if you have a patient, let’s say they’re 5 years old and you have a high ACA ratio and distance is ortho. And then I put them in bifocals and I can kind of control their near deviation. A lot of those patients successfully outgrow the strabismus and don’t need surgery. So, you know, is there a statistical significance to it? I don’t know. I guess I haven’t seen those studies. But from a practical standpoint, yeah, there are many patients that you can nurse along during that young age with bifocals and then as their hyperopia and their accommodative convergence naturally decrease after age 8, get them out of the bifocals and they avoid surgery. So, I tried them. And when they work, they seem to work quite well. If they don’t work, then we go on to surgery. When do you use a microscope during strabismus surgery? Never. I find that it’s in the way. Obviously you have great magnification. But you have a small field of view and now you have something that’s in the way when you’re passing instruments back and forth. I really dislike the microscope for strabismus surgery. I think you’re much better off having surgical loops. And there are inexpensive loops out there. You know, $400, you can get a pair of loops. What are you looking for in loops? You’re looking for about a 2.5x magnification. That’s a good compromise of magnification and field of view. And you’re looking for a long working distance. So, 16, 18 inches. I think that’s preferable. Question about patching for intermittent strabismus to improve control. I have tried this over the years for intermittent exotropia, it doesn’t make a difference. Other people have other opinions. To me, this is something people do to buy time and doesn’t really impact the outcome of the strabismus. Not a big fan of part-time occlusion for exotropia in the absence of amblyopia. Well, we’re an hour and 15 minutes into things. I think I’m gonna bring this to a close. As always, it’s a pleasure. I’m always enjoy the question and answer sessions. Thank you to the 93 people who sent in questions, that was appreciated. And, of course, this will be recorded and in the Cybersight library. Also look for us on YouTube. And we are streaming live. So, thank you. And good luck out there. Let us know if you have any questions. Thank you.