Lecture: Management of Complex Forms of Strabismus

Complex strabismus syndromes, in which eye movement in at least one direction is limited or paralyzed result from mutations in genes, are referred to as the “congenital cranial dysinnervation disorders.” Management of these complex disorders will be discussed in this webinar.

Patients with craniosynostosis have an increased incidence of refractive error and strabismus. Pre-surgical planning includes: imaging of the orbit and extraocular muscles and improvement of surgical technique outcomes.

Ocular motility dysfunction in children with cerebral visual impairment, and strategies in management of these such cases, will also be discussed.

Lecturers: Dr. Andrea Molinari, Dr. Fiona Dean & Dr. Suma Ganesh

Transcript

DR GANESH: Good evening. Good morning. Good afternoon. Wherever everybody is. Welcome to our Cybersight webinar. The topic is management of complex forms of strabismus. We have two faculty. And the third is me. Dr. Andrea Molinari, Dr. Fiona Dean, and myself. We shall begin. The topics with Dr. Andrea Molinari. She is the director of the fellowship program in pediatric ophthalmology and strabismus from Hospital Metropolitano, Quito, Ecuador. And the past president of the Latin-American Society of Pediatric Ophthalmology, the Vice President of the International Strabismological Association, and our dear Orbis volunteer. Complex strabismus syndromes, in which eye movement in at least one direction is limited or paralyzed resulting from mutations in genes, which are referred to as the congenital cranial dysinnervation disorders, is the topic she will be speaking to, as well as management. Dr. Fiona Dean is a consultant in pediatric ophthalmology and strabismus. She has a fellowship in Great Ormond Street Hospital in London, and has been touring the world with many Orbis programs. She spent ten years working in the multidisciplinary regional craniofacial team at Birmingham Children’s Hospital and gained a wealth of experience in the motility of these patients. And she’ll be talking on this subject: Patients with craniosynostosis, which have an increased incidence of refractive error and strabismus. She’ll teach us how to do presurgical planning and improvement of surgical techniques. The last is me. I’m from Delhi, from Dr. Shroff’s Charity Eye Hospital, I did my fellowship in pediatric ophthalmology and strabismus at Manhattan Eye and Ear Hospital, I too am an Orbis volunteer faculty, my mentor is Dr. Andrea Molinari herself, I’ve been very fortunate, and I’ve done HBP programs at Nepal and Indonesia. I will be talking on strabismus with cerebral visual impairment. Now I’ll hand over the webinar to start with Dr. Andrea Molinari. I’m stopping my share.

DR MOLINARI: Thank you, Dr. Suma, for the introduction. It’s a pleasure for me to share this webinar again with you, a friend for so many years. And this is also with Dr. Fiona Dean. Well, hello to all participants of this webinar. Welcome, and today I’m going to talk on the surgical management in patients with congenital fibrosis of the extraocular muscles. Which is probably one of the most challenging entities among strabismus syndromes. And this is mainly due to the profound anatomical changes that you will encounter in patients with this problem. Notice here a histological structure of lateral muscle of one of my patients here on the left. Compared with the structure, anatomical structure, of a normal extraocular muscle, on your right. You will see on the left only scars, muscle fibers, which correspond to these small pink structures here, immersed in this blue tissue, which corresponds to fibrosis. Formed by fibroblasts and collagen fibers. On top of these important anatomical changes, in many of the patients you will find rare innervational anomalies, like synergistic divergence here on your left. And convergence at elevation. You will see here on your left the girl when she tries to look to the right — the left eye not only does not adduct, but it does abduct. And the patients who show convergence at elevation — you will see that the patient, when trying to look up, both eyes converge. So all these anomalies, the anatomical anomalies, and the innervational anomalies, make the surgical planning of these patients so difficult. And this will mean that the results are so variable and unpredictable. The huge variability in the surgical results of these patients have been reported in several papers. And this is one of these papers. Where 9 patients were all treated with the same surgical technique, which was a free myectomy. And you will notice that in some patients, like case 6 to case 9, the effectiveness of this procedure was much larger than with the first cases. And this huge variability in the results of these patients has also been my experience. And I’m going to demonstrate this by showing two cases. My best case and my worst case. This was by far my best case. This was an 11-year-old boy that consulted due to this significant anomalous head posture. The chin up posture. Together with a severe ptosis and a very large exotropia. The patient could not elevate the eyes and also could not adduct the eyes. So during surgery, the forced duction test demonstrated a very significant restriction to elevation and adduction. In this patient, we elected to do bilateral 8 millimeters inferior rectus recession, and bilateral 10 millimeters recession of the lateral recti. With a decent result, as you can see here. After this procedure, we performed a frontalis suspension, and the patient got rid of his anomalous head posture, and the eyes were pretty much aligned in primary position. It is important to note that when you are going to perform frontalis suspension in these patients, that do not have good elevation, you have to be very conservative. You should try to place the lid not as usual, at the limbus level, but on top of the pupil. Because these patients do not have Bell’s phenomenon. And the concern of exposure keratitis is really big. And here you can see the patient before the surgery and after only one strabismus surgery and one ptosis surgery. Showing a pretty good result. Unfortunately, not all cases will respond in the same way. And let me show you my worst case. I saw this girl when she was one year old. With a clinical scenario that was pretty similar to the previous one. She had a large exotropia. Also a ptosis. Not as severe as the previous case. And a very significant exotropia also with restriction to elevation and to adduction. In this patient, we chose to perform a bilateral inferior rectus recession of 8 millimeters, and bilateral recession of… Well, of lateral recti of 7 millimeters. And as you can see here, the postoperative picture, although the chin-up posture improved a little bit, the strabismus remained pretty much the same. So a couple of years later, we recessed both lateral recti, 20 millimeters from the insertion with the hangback suture. And you can see that the eye position did not improve very much. Finally, we performed a third procedure, by resecting her left medial rectus 6 millimeters. Which didn’t do practically anything. So what to do next? When you have a patient where you already did three procedures, and the result is not good? And this might answer Dr. Al Nasir from Saudi Arabia’s questions, that he sent: What do you do when you do maximal recessions of the muscles, and you still don’t get the result that you want? So I didn’t give up with this patient. And a couple of years later, well, you can see here… After following this patient nine years, and three years after, her chin-up posture was better, but the eye position was pretty much the same. So I didn’t give up with her, and we performed a fourth surgery. And in this surgery, we found the left lateral rectus that was 80 millimeters from the limbus. Not from the insertion. Which meant that the previous recession that we performed with the hangback sutures did not work as desired. The muscle pulled back. And we also performed a re-resection of the left medial rectus, fixating the globe to the medial periosteum, with a Mersilene suture. And this is how the patient looked five years after the last surgery. The eyes were pretty much aligned in primary position. But she didn’t get much movement in other positions of gaze. Surprisingly, even after fixing the lateral rectus to the periosteum, she could abduct the eye a little bit. So the other thing to notice here is that we didn’t need to do a ptosis surgery in this case. So which are the surgical techniques that we have in our armamentarium, in order to treat patients with congenital fibrosis of the extraocular muscles? Some of them are more useful than others, in my opinion. We can perform a free tenotomy, a free myectomy, large recessions of the extraocular muscles. Preferably with scleral fixation, not with hangback sutures, since the muscle might crawl back. We’re going to discuss the role of resections in these patients. And finally, we can use periosteal fixation in very severe cases. Periosteal fixation of the lateral rectus is especially useful in those patients that show synergistic divergence. Because in these cases, you really have to inactivate the force of the lateral rectus. And the best way to inactivate these muscles is through a periosteal fixation. So what about resections? Do they work? As you can see here, this is the medial rectus of the last patients that I showed you. And you can recognize that the muscle is very thin. Notice how it is transparent to the hook, to the muscle hook, when you place the hook underneath it. So resections on these types of muscles, which are the antagonists of the fibrotic muscles, really don’t work very well. Let me show you a surgery of one of these patients. This surgery is really difficult. It shouldn’t be left in the hands of inexperienced surgeons. In most of the cases, you have to work very far back into the orbit, because the muscle is so inelastic and fibrotic. And it’s not only the muscle that is fibrotic. You can see that the tissues surrounding the muscles, the ligaments, the intramuscular membrane, they are also very thick and fibrotic. And contribute to this lack of movement that these patients refer to having. Another characteristic that you can see here is how the vessels over the muscle are really enlarged. Which makes… And this is something you have to see. To take into account. Using grooved hooked muscles like this one is very useful in these cases, in order to place the sutures safely or to cut the muscle, at in this case. One other useful tip when doing a free tenotomy, like I’m going to do in this muscle, is when you have these large vessels, to cauterize the vessels first. Because if you don’t cauterize the vessels, they will keep bleeding. And you’ll see here now that the muscle retracts far in the back of the orbit. And if they keep bleeding, it can produce a retrobulbar hemorrhage that will be very difficult to control. Another typical finding in these patients is the anomaly of the insertion. Here you can see now after the tenotomy how the duction gets free. But look at the diagonal insertion of the muscle. One pull, one border of the muscle is closer than the other one. This is also a very typical finding in these cases. So in the surgical treatment of congenital fibrosis of extraocular muscles, our goals should be to improve the anomalous head posture, and to improve the ocular alignment. At least in primary position. You probably will not get much more in these cases. But even with such a fair result, you should try to help these patients. Because even getting this result makes a huge difference for them. So to conclude, be prepared for unpredictable results in these cases. You have to explain to the patient that you might need more than one procedure, in order to get a better result, and explain to them that they will never have a normal ocular motility. Large recessions, especially with fixed sutures, free tenotomies, and periosteal fixation in the most severe cases, are in my opinion the most useful techniques to use in these types of strabismus. Always perform strabismus surgery first, and then ptosis surgery only if required. Remember that these patients do not have Bell’s phenomenon, and exposure keratitis is always a concern. Well, thank you very much for your kind attention today. And I will be very happy to entertain any questions. Let me stop sharing my screen. And I guess we have some minutes for questions, if they are available. Right?

DR GANESH: I think the questions will keep coming in. At present, there is one question. What do you mean by hangback? Is it adjustable? That’s the question you’re asked. Does hangback sutures mean adjustable sutures?

DR MOLINARI: Well, when you perform a hangback suture, the technique is very similar to an adjustable suture. The only difference is that you are going to adjust if the patient is cooperative. And most of these patients are children, so they are not very cooperative. So I usually do not perform adjustables. But I really stopped doing hangback in these cases. Because I saw that the muscles really pull back.

DR GANESH: I have a question. Since the questions are coming in. Would you prefer a straight — for a lateral periosteal fixation — for tenotomy? What is your experience? I have never done a tenotomy.

DR MOLINARI: I do free tenotomies in cases like I showed during my presentation where the muscle is really, really tight, really tight, and it’s very difficult to pass sutures, and especially even more difficult to place the sutures very far back. It is where you have to put them, in order to get an effect, or the effect you want. And what I have seen, which was shown in the video that I demonstrated, is that when you cut these muscles, they retract very far back in the orbit. And what you need here is just to free the ductions. And you get this by doing free tenotomies in these very, very fibrotic muscles. If I can, I prefer to recess the muscle by placing fixed sutures. But if this is dangerous, because of the situation, I then perform just a free tenotomy.

DR GANESH: So the one question by Dr. Mohamed — hemihangback is preferable to hangback. It means you take small bites on the sclera. Where you have fixed it. So the muscle does not creep in. So that’s another question is… Yes.

DR MOLINARI: I agree with that, and I have done hemihangback, but you have to try to go as far back as possible. To place the suture. And the other question was: When I do the periosteal fixation? Well, I don’t do the periosteal fixation as a first procedure. I do that when the other procedures failed. Like in the second case I showed. And I do them in all the cases where I have synergistic divergence. Because in these patients, you have to inactivate the lateral rectus.

DR GANESH: So how much lateral rectus would you recess? The maximum you think we should recess? In such cases? You just go as far back as possible?

DR MOLINARI: Yeah. Probably… As far back as possible, or as far back where the ductions get freed. When you see that the duction is negative.

DR GANESH: Okay. Because there’s another question they’ve asked. Dr. Andrea, how to determine the length of the recession for inferior and lateral rectus in these cases?

DR MOLINARI: That’s the answer. When you see that the forced duction test is free. So what you can do is place it on a hangback suture, see when it’s free, and then place a fixed suture, where the muscle lies.

DR GANESH: So there’s another question. How do you do the periosteal fixation? I think…

DR MOLINARI: Yeah. You know what? This morning I was thinking, since I had a couple of minutes left, I should have added a video on how I do the periosteal fixation. Because actually, for strabismus surgeons, it’s not an easy procedure to do. So I find it very… Maybe if we have time, I will try to find it in my computer, and at the end, maybe I can show the technique. What I use is a baby right ptosis needle. And I do a small cut at the periosteum over the skin here. And I disinsert the muscle. And I pass this ptosis needle… And I take it out through the skin suture. And I passed the needle, which is very strong, the needle, through the periosteum, at the orbital rim. And then you make the knot outside the skin. It’s a very small wound in the skin. Just 2, 3 millimeters. So it doesn’t get noticed afterwards. And this is the easiest way I find to do a periosteal fixation. Of the lateral rectus, of course.

DR GANESH: There are more questions coming. We’ll just take one more. Hi, Dr. Andrea. It’s from Dr. Wei Yuang. I hope I pronounced it properly. I’m so sorry. How would you decide which procedure to choose when the patient is initially seen in the clinic? Or the decision is made interoperably?

DR MOLINARI: How I decide. If I have a patient that has a large exotropia, a large hypertropia, positive forced duction test and recession — if I can do large recessions with fixed sutures, that’s my first procedure of choice. And I do them until the forced duction test is free. If I see that there is synergistic divergence, I perform for a first procedure a lateral rectus periosteal fixation. I don’t perform any more resections of the muscles.

DR GANESH: So you never do a resection of the muscle in the first setting?

DR MOLINARI: Not now. I used to do it. But you saw the picture. The muscles, the antagonist muscles are so thin, that they will not give you much.

DR GANESH: Okay. A few more questions. Dr. Andrea, could you answer them in the chat box? Because I think we now request Dr. Fiona Dean to share her presentation, please.

DR DEAN: Hello. And thank you for inviting me to speak to everyone out there around the world. It’s a fantastic thing to be able to do. And I really enjoy sharing the knowledge that I’ve gained through looking after this group of patients. So I think we can learn something together with it. So this is a strategic approach to squint surgery on craniofacial patients. Whom I looked after for about ten years or so. So first of all, as an introduction, I need to tell you what the craniofacial disorders are. They’re a group of patients who have a premature fusion of one or more of the calvarial sutures. And they might just be a single suture. Which is about 1 in 1700 to 2500 live births, or there’s the syndromic forms. These are hereditary. And they have extracranial malformations. And this is about 1 in 25,000 patients. So what is the actual effect? Well, when the suture fuses prematurely, then you get abnormalities in the calvarial shape. And this is due to restriction of growth which is perpendicular to the fused suture. Oh, the pictures should be coming up. Sorry, these are all coming up separately. So if we take, for instance, this one here, this is a sagittal suture synostosis, where the suture going from the anterior to the posterior direction has fused too early. And the skull shape becomes long and boat-like. So you do not get the lateral spread here. Particularly in the frontal area, on this particular patient, that you should. This next patient, the metopic suture has fused. And this gives a triangular shape to the skull. And in this patient, we have bicoronal suture fusion. And that gives a brachycephaly. And then we have unicoronal. So we’ve got one suture fused along here. And this gives a flattening of the forehead on this side. And a normal-ish rim on the other side. So this creates interesting ocular features. So there are many different syndromes now recognized. And I’m not able in this short time to go into details about all of them. I’m gonna concentrate on the first three of them, primarily. Because they have some interesting ocular features that we can talk about, particularly with reference to their squints. A lot of these genes have been identified. Sometimes the appearance of one may be very similar to the appearance of the other. And it’s only when you do the genetics that you actually get a true understanding of what the underlying syndrome is. Those ones are called syndromics, and then if they don’t have a particular pattern, then they would be called non-syndromics. Particularly if they’re not genetic. So these children have multiple problems. They have problems with their speech and development. This is particularly due to the fact that they get delay in brain development, because the calvarium is not big enough. But it also might be because they have abnormal maxillae and abnormal mandibles. The base of the skull, effectively, participates in the derangement of shape that they get. They undergo multiple surgeries. Of many, many different types. They have episodes of raised intracranial pressure, which in itself causes problems. So as the ophthalmologist, we might be called in quite late, because the patient has all these other pressures, life threatening pressures, pressures on their general development. And the best way to approach them is to be part of a multidisciplinary team, where each member of the team understands the role of the other. And that helps in the timing of the intervention, where it’s really important for us to preserve the development of the vision. The squint can often be addressed later. But we have to help the team to understand that. (audio drop) Allowed to operate on the squint at a certain time, because something else is going on with the child. And the vision may be compromised by many, many things. This is a huge list I’m not going to go through all the details of. But some of these things are treatable and some of them are not. So preventable visual loss can certainly be like any other child. The need of glasses, because they have a refractive error or anisometropia. These children are often at particular risk of corneal exposure, because they have shallowing of the orbits. And they get amblyopia. But in addition, they might have ocular dermoids, due to fusions of the sutures and areas where the embryonic planes come together. They might have exophthalmos, hypertelorism, the muscles might be missing. They can have optic atrophy because of raised intracranial pressure, ptosis, and of course strabismus, which is going to eventually be the focus of this talk. So we have a couple of things that we really have to, as pediatric ophthalmologists, concentrate on, in these children. And the first is optic nerve swelling from the raised intracranial pressure. Because the sutures fuse early and the brain is still trying to grow, there’s no room in the calvarium, for the growing brain, and as a consequence, the intraocular pressure rises, giving of course the typical signs of papilledema, and if this is left, then these children wind up with optic atrophy, as well as many other developmental issues. The other problem for acute sight threatening disease is the fact that they have shallow orbits and they get corneal exposure. Quite often, their eyelids won’t close completely, or even sometimes the eyelid gets caught behind the globe, which is so proptosed that there’s no room in the orbit for the globe itself. So we have a preventable visual loss. And if we were to look at those groups that I was explaining earlier on, Apert’s, Pfeiffer’s, Crouzon’s… You can see… Oops, sorry. And unicoronals. With half having Aperts, 45%, Pfeiffer’s, 24% Crouzon’s, and 18% unicoronals. So it’s important to get them into glasses. But they often have an abnormal head shape and need hearing aids as well. Pediatric ophthalmologists are aware of the difficulty of getting children to wear glasses when they have hearing aids at the same time. But when they have an abnormal head shape, trying to get glasses with astigmatic correction in, at the right angle, on an abnormal shaped face is extremely challenging. So we can finally move on to strabismus in these patients. Again, looking at these three groups, you can see that practically all of the patients in Apert’s will have a squint. Very small percentage, 5%, in this group, that didn’t. Some of them can be eso in one direction and exo in another. 6, 14%, is not insignificant. Those are particularly tricky to sort out. It’s much easier if you have got one eso or one exo. We have a similar kind of pattern with Crouzon’s, and a similar type of pattern with the Pfeiffer’s. 20% of those patients didn’t have a squint at all. So it’s a significant need of input from a strabismologist for these patients. But not all the children who present will actually need squint surgery. Some of them may be binocular in the primary position, as this child is. But they might have eyes that are not aligned in all other directions of gaze. And we need to remember that keeping the primary position as the most important area, that and downgaze, has to be our remit. And although the parents might be quite concerned about the appearance of the eyes in lateral and up and downgaze, we need to sometimes emphasize to them that primary position and downgaze are the most important. And that perhaps the child might get this disrupted if we do a squint repair on them. So we have to have a strategy for approaching these patients. We have to understand the reason why they might squint, as this guides our management. And we have to be prepared with investigations before the surgery. Because this prevents some nasty surprises, which unfortunately I have had in the past. We have to understand the syndromic abnormalities. They each have their nuances, in to how each suture (audio drop) shape of the orbit. We have to treat the underlying visual problems with the rest of the team, to investigate the orbits and muscles. And this would involve CT scanning and MRI scanning. So many of these children will have already had a CT scan, because they want to look to see whether there’s suture synostosis. But an MRI scan may not have happened. Or may not have incorporated the orbits. And we need to see where these muscles are, and indeed, we need to see if the muscles are present at all. Because some of these patients will be missing muscles. We also need to consider squint surgery during the general aesthetic as another procedure that the child is undergoing, and it’s our job to help the multidisciplinary team to understand the importance of binocularity, and the fact that we might need to operate on some of the squints early, in order to either attain that, or retain it. So these muscles themselves may be abnormal. And the orbits may be abnormal. They do not subtend the globe at normal angles, and they give a wide variation of pattern. A pattern, V pattern, X pattern. As I said before, the muscles themselves might be missing. And you need to know whether they’re missing. Otherwise you start your surgery expecting to transpose a lateral rectus, and find — guess what? The lateral rectus isn’t there. And the orbits may be two different shapes and sizes. And that can actually lead to a mechanical advantage imbalance between the two eyes. They may be very shallow. And they may be far apart. Giving the patient hypertelorism, which is more likely to lend to exotropia. So here’s an example of a patient with plagiocephaly. That means that they’ve had a unicoronal synostosis. So the synostosis is here. And the corresponding shortening of the orbit is here. And you can see this is the base of the skull. And the base of the skull is not normal. The orbital shape — this is the right, actually. And this is the left. So the orbital shape here is tilted outwards. And the distance between the front and the back of the orbit, along the nasal wall, is actually shorter on this side than the other. You can see the right side suture synostosis here. So this is a diagrammatic example of a patient with plagiocephaly. Where the orbital wall is shorter on this side. So this is to represent the superior oblique. It’s coming to the trochlea here and turning through the angle. And as you can see on the other side, this subtends a normal angle. B being the superior oblique on this side. And a being the inferior oblique. But when you’ve got the shortened upper wall, your superior oblique subtends a different angle to that subtended by the inferior oblique. So they no longer balance each other out. And in addition to that, by the fact that it’s… Whoops, sorry. By the fact that it’s coming at this angle, it causes more extorsion — sorry, intorsion — than it does depression. So it changes the balance compared to the other side, and also, it’s out of balance, compared to the inferior oblique. So this is an example shown in the paper published in the Journal of Binocular Vision and Ocular Motility. This child is a unicoronal synostosis. And this child is unable to elevate very well with this left eye here. And the superior oblique is also weakened. So they actually treated this patient bilaterally, with bilateral superior oblique tucks, in order to try and strengthen the superior oblique strength bilaterally. And these sort of treatments — you need to take very much on a case by case basis. So bilateral was appropriate in this case. But in the previous patient that I showed you an example of, of me doing a unilateral superior oblique would have been appropriate. So this patient has Apert’s syndrome. And as you can see, the orbits are a very different shape to usual. And what I want to bring your attention to is the fact that this actually is a tilted orbit. So the medial canthus here is much higher than the lateral canthus. And we’ve got the same on the other side. And the normal is that your lateral canthus is a couple of millimeters higher than your medial canthus. And what this indicates is that the whole of the orbit… (audio drop) so if we look at this diagram here, the medial rectus, which is normally pulling in this direction, this is a demonstration of the left eye, the medial rectus is actually an elevator. As well as an adductor here. And the lateral rectus is a depressor as well as moving the eye laterally. So this child will end up with a see-saw movement. Now, this doesn’t just occur in patients with craniosynostosis. I see this quite often in my clinic with patients who would be considered as “normal”. And if you see this see-saw movement from left to right, then this is something you should be considering. And look very closely to see whether the lateral canthus is below the level of the medial canthus. Because the lateral canthus is at the suture of the temporal bone and the maxillary bone. That’s where it engages. And therefore if the orbit is an abnormal shape, the lateral canthus will tell you that. So here is a child who has — this upper one here is perhaps not quite so clear as the lower one — this child has the see-saw movement. You can particularly see it in this one here, where the eye rises upward, and this eye goes downward. So how do you know this is not just inferior oblique overaction? And it is about looking for the lateral rectus, depressing the eye, as the eye moves outwards, as well as seeing the eye moving medially, elevating. And then you get a swapover. And the swapover is much more obvious in this patient here, where it’s elevating here, depressing here, and on this side we’ve got elevation and depression. So in these patients, if you think this is an inferior oblique overaction, I’ll go and do that surgery, you’ll find it won’t work, because it’s not the underlying problem. And therefore you need to consider moving the horizontal recti up or down, depending on whether they have predominantly an A or a V pattern. Normally it would be a V, but not always. So as I mentioned before, you might have patients who have missing muscles. I apologize. These pictures are rather dark. But this young man could not abduct this left eye at all. And that’s because the lateral rectus was missing completely. And therefore if you hadn’t done your MRI scan to look for that muscle, then you’ll go in there and go… Oh! Now what do I do? Much more comfortable if you’ve actually been able to plan this situation well ahead of time, by working out that the muscle is missing, and you may have to transpose the superior or inferior rectus around, with the Foster’s suture together, or move them completely around to the position of the lateral rectus. Or split them. There are many ways of doing that. But without the preparation, then you’re not going to know that that kind of thing is possible or necessary. So other things we may need to consider are the lids. Many of these children, because they have a shallow orbit, will not actually be able to use the lateral gaze, because they’ve had to have a tarsorrhaphy. And therefore if the primary position is not too bad, then the lateral gazes may become less of a cosmetic issue once the tarsorrhaphy is done. And this is a good example. Where this child has an extremely shallow orbit. As you can see, these eyes have actually had a tarsorrhaphy performed laterally. And if that had not occurred, this eyelid would in fact be way up almost behind the equator, or behind the globe. So these patients don’t usually have the proper bony support that you require to keep the globe well protected, and the tarsorrhaphy becomes necessary. You might even have to drop the lid if possible. But they have a skin shortage as well, which makes that even more difficult. So as you can see, although this child is a little bit exotropic, this is not particularly relevant at this time in the child’s life, and looking lateral is not really a problem. Because nobody is going to see the fact that they’re exotropic when they do this. So just to reiterate, the orbits can be shallow. They can be asymmetric. Longer or shorter. They might have a frontal prominence. So the plagiocephaly patients, who have a flattened orbit on one side and a normal orbit on the other side, become astigmatic on the normal side. A bit like ptosis gives you astigmatism. One orbit that’s more proud on the frontal bone than the other can also do the same thing. The orbits can be tilted or extorted, and the patients can have a wide IPD and hypertelorism. It’s important to understand what kind of squint you’ve got. And you have to expect the unexpected, which is very similar to Dr. Molinari’s talk about these patients, where you get the unpredictable results. Make sure that you’re not looking after a case of a missing muscle. Understand the shape of the orbits. And that’s why it’s nice to have the MRI scan and the CT scan. And are you seeing an overaction on one side because there’s a difference in mechanical advantage, due to length and angle? The muscle might subtend to that eye. And just be mindful of the fact that sometimes there may be mimicry of certain muscles looking like they are overactions of others, because of the tilting of the orbits. Timing of surgery — primarily we would like to preserve binocular function, and that would be a reason to operate early. But again, you want to try and consider whether you can piggyback that onto another surgery that this child is undergoing. Because you want to reduce the number of general anesthetic episodes and the number of admissions these children have. The craniofacial surgery, the change in the calvarium, does not affect the squint. We used to think it did, but we know now it doesn’t. And that’s because the key landmarks within the orbit are not changed. The operations don’t change the position, for instance, of the trochlea. And the strabismus surgery, unfortunately, to a strabismus surgeon, has to take a lower place in line of many of the other surgeries, which are key to the development of the child. So just to reshow this slide, because it’s the most important, really, you need to understand the reason for the squint. That will tell you what the management is. Be prepared by doing the appropriate investigations. Understand the nuances of each of these syndromes, so that you know what you’re most likely to come across. And consider as part of a multidisciplinary team timing your anesthetic need with that of another procedure. Thank you!

DR GANESH: Thank you, Dr. Fiona Dean. It was a very nice presentation. And the questions — before I read the questions, I have a few. Most of these children, I find that they have a large V pattern. Most of them come with a large V pattern.

DR DEAN: That’s the most common.

DR GANESH: Like a 40 V. You know. Sometimes even doing an inferior oblique and shifting the medial rectus, the lateral rectus forward — it was exo — I find still some amount of residual — so is there anything specific which we have missed or something?

DR DEAN: No, I think that you’re just… You’re working with an orbit that’s tilted. And this creates the V. So if we think about the slide I showed you where the medial rectus was working upwards, the superior rectus is working upwards and outwards. So the superior rectus is also creating the V. And the inferior rectus is working downwards and inwards. And is also… So everything is pushing towards a V pattern. So if you were to treat your inferior obliques, and move your lateral recti up, and your medial recti down, and you still had a very big V, then the next thing you would have to consider would be to move your verticals across. In order to decrease the V further. Now, in my experience, that’s never been really necessary. Usually doing all those other things is enough. And I think you can get to a point where you could keep going forever with them, really. And that may not be appropriate. Just because we can doesn’t mean we should.

DR GANESH: So I think the importance is doing the imaging. I think the imaging is very important.

DR DEAN: Yes, it is.

DR GANESH: Has to be done in most of these cases, because there could be surprises. Any questions, Dr. Andrea, you have, before I take questions from the audience?

DR MOLINARI: Go ahead with the questions of the audience, which are more important.

DR GANESH: There’s a question from Dr. Claudia, who is asking: Is the fundus torsion useful in these patients, for inferior oblique hyperfunction?

DR DEAN: I think it’s just part of a puzzle. I don’t think you can ever take things in isolation. But it is helpful to know that the fundus is also tilted. But it’s not always there. So sometimes you might think… Oh, this patient ought to have a fundus that’s tilted. And guess what? It isn’t. So not everything necessarily follows what you think it should. And sometimes I’ve seen fundi tilted, extorted, and the extraocular movement pattern hasn’t fitted with that.

DR GANESH: Have you had that you have done the procedure, and there has been some problems for the corneas? There has been increased exposure? You see in inferior oblique, anterior transposition should not be done. Have you seen… Recession, you should do, mainly an inferior oblique recession, and not anterior transposition — I don’t know if it mentioned in one of the books. So I just thought that —

DR DEAN: I haven’t actually seen that as a particular problem, mainly because the corneal exposure is just such a significant issue that they’re better off having the frontal face brought forward. That’s really what they need. They need the orbits deepening, rather than us doing something with the eyes. They need the orbits deepening. That is going to sort the problem out. The problem is that you do not want to advance the maxillae until the secondary teeth are through. And this is why the timing is so important. However, you can’t leave the globe exposed until they’re 16. So you have to sometimes do the maxillary surgery earlier than would be the ideal timing for the teeth.

DR GANESH: A question: There is a case of postoperative diplopia, if the patient is not accepting monocular occlusion or fogging — what to do next?

DR DEAN: Not particularly relevant to this talk.

DR GANESH: Normally do get fusion in these patients. If they are operated early.

DR DEAN: Yes. You can do. And if they don’t, then you’ve got to consider whether or not they go for occlusion or whether you might be able to give them a contact lens. Worst case scenario, you might have to give them occlusive intraocular lens. But usually they’re small enough children that they’ve adapted and they end up suppressing in the areas where they’re not going to be seeing with the eyes aligned.

DR GANESH: I think we’ll take the next questions… Dr. Fiona, if you can answer the questions, I would go ahead with the presentation and you can answer them in the chat box. Could you stop the share, please? Because a few other questions are addressed to you personally, Dr. Dean.

DR DEAN: Am I still sharing?

DR MOLINARI: There you go.

DR GANESH: I hope I’m visible. Okay.

DR MOLINARI: You are, you are.

DR GANESH: Okay. I’ll be talking on another topic, which is actually very dear to me also, which is cerebral visual impairment and strabismus in children with cerebral visual impairment. So any child with subnormal vision — you need to do a detailed ophthalmic examination. You need to check whether it is ocular disease or an abnormal anterior visual pathway. That it is not CVI. You get a normal examination and disproportionately subnormal vision, we need to suspect it is a CVI. We need to ask for a proper birth history, neurological evaluation, and neuroimaging is important. So we should suspect CVI in all children with unexplained bilaterally decreased vision. So what exactly is CVI? It is basically a deficiency in the function of vision. Something is wrong with the visual pathways or processing sectors in the brain. Specifically those posterior to the lateral geniculate body. So the eyes work fine, but the brain does not consistently understand or interpret what the eyes see. So basically we know that now vision is a neural association. We have the dorsal stream and the ventral stream. The dorsal stream connects the occipital area with the posterior parietal cortex, and that tells us it is where. And the ventral stream connects the occipital temporal lobe and tells us what. These are the many ocular manifestations we see in these children. You can see here that the child is not fixing or following a light. It’s not appropriate for the particular age. So there is no eye contact. So the parents say the child is squinting. It is wandering eye movements, no eye contact, and they say it is squint. It’s not squint. Basically they’re not even fixing and following the light. If there is any decreased contrast sensitivity, if you find in these children — most of these children have decreased contrast, that’s the important test to check whether we need to do some more rehabilitation. We also need to check their fields. Because some of them have inferior field defects. And these are simple tests where we can do the field and find out if there are any field defects, and that could help us in our management. Now, this is a child where we find that there is very poor visual latency. The visual latency is very poor. He’s not reaching out to objects. So the cataract has been done. But still the child has delayed milestones, and is not really looking at any objects. Small esotropia. But the child is not — is feeling confused. Or you can have like this, where there is a gaze preference. And the child does not look towards the left side. Only towards the right side. So these are children we need to pick up in the clinic. Because these are children who may come to you with small forms of strabismus. And parents say they are slow learners. And then we find the simple test — we have made it with the help of a carpenter — where we can see that the children have visual conceptual skills are absent. And these children need to be taken care of, so now sometimes the therapist or the psychologist may refer to that these children are under therapy, but please help us. Maybe there is also associated strabismus, and you need to take care of this too. And of course, the strabismus surgery also helps in this regard. So the other test which you could do is a LEA Mailbox. You can see that this child… It clearly tells you where the orientation of the slot is. You ask them where the orientation is. And the child puts the card into the particular correct slot. But see this child with CVI, small amount of esotropia with brain damage, and not able to do… There’s a severe eye-hand coordination problem. And this child could be helped with therapy and maybe even your strabismus surgery. So there could be — so the other things we have to look for is optic nerve. Whether there is optic nerve hypoplasia, or issues with the disc. The strabismus is seen as high as 75% of patients with CVI. It may range in cerebral palsy from 19% to 50%. Esotropia is most common. Then exotropia and specific traits, and we find there is angle variability and shifting patterns. An important cause of ocular motility dysfunction is periventricular leukomalacia. It’s important to ask if there are any birth history or missed milestones. Vertical deviation, any of the squints which may be present. In our article we found that exotropia was seen more commonly than esotropia and nystagmus was present. And we had a large number of children with exotropia and esotropia, and the range was very large. And it was also present with DVD. Another paper which we published in Journal of Pediatric Ophthalmology and Strabismus revealed that we had 67.04% of children with strabismus. All of which had variable angles, which were seen in a few patients. And some of them were intermittent. And we could only measure them around a few number of children. Most of the time, the children are very uncooperative. This child came to us at five years of age, with concerns like poor vision, squinting both eyes, maintaining head posture, very poor performance in school. It was a preterm baby, did not cry at birth, MRI done diagnosed HIE stage 2. Referred to ophthalmologist and said that to wait for some time. The child fell down from the stairs because of the problems. And suffered another right hemiplegia and facial palsy. We planned squint surgery at 6 years with vision of 6/24. Why are we scared about operating with these children? They’re not very cooperative for measurements, do they have good outcomes, or do they achieve binocular fusion? This was a paper published that you need to observe the children with poor visual behavior and unstable deviation or shifting pattern. But if they develop a constant angle, we should go ahead and operate. At least take four stable measurements. Of course, only 16% showed spontaneous resolution. This child, who we had esotropia, a premature baby with delayed milestones, but stable angular presentation, 45 days out, and he was operated for strabismus. It is important not only to do the strabismus surgery, but also to continue with the therapies postsurgery. This is what the parents tell us. Before the surgery, the child was not able to write a line. The handwriting was not very good. And after the surgery, the handwriting improved. It was within the line. And this is what the therapist tells us. At least we’ll do the surgery, because we do find an improvement in the hand-eye coordination. So what are the long-term results in these children? The paper said that they have less predictable surgical results, overcorrections, and some of them say there are satisfactory results with additional procedures. We did a study, comparing with normal children. Of course, our data was very small. We just had 26 children in our data. And we found that most of them had birth asphyxia and cerebral palsy, they presented with vision problems, and had 63.31% success rate. There’s another paper published from Swaminathan that said they had good outcome in 60% of patients. And we found residual esotropia, since we were undercorrecting them. Some wound up with residual esotropia, so we had to add another surgery. But after another surgery, they did do well. And we found that a few patients developed consecutive exotropia. But there was a paper published in IOVS that said that binocular alignment and fusion is a realistic goal. I find we should operate, because we don’t get the amount of stereopsis that we would like, but there is a reduction in vision problems. We have to be careful of them ending up with consecutive exotropias, and there are a few other papers published — because of exaggerated effect of bilateral medial recession, we need to do 30% undercorrection. But sometimes when we leave behind 30% undercorrection, they have some amount of esotropia left, so we need to continue with patching. Maybe add a little bit of hypermetropic glasses, and treat them. When you have consecutive exotropia, you need to do medial rectus advancement and lateral rectus resection. This was referred by a psychologist, saying this child was not improving fixating. The child was not able to write properly. There was an attention disorder. And they were suspecting autism. He said there is an exotropia. Why don’t you do the surgery? I said will there be a good result after the surgery? I operated. There was motor stability. And what he did was… The psychologist… He said that before surgery and after surgery, he found a few parameters improving. Like a social portion, he found that communication, socializing, then he found that even the borderline developmental delay test, which was done, improved with cognitive and other communication skills improving. And also the other attention problems were also improving. So he has convinced me that we need to go and operate them much earlier. In cases with sometimes presenting with dissociative vertical deviations, along with esotropia and being slow learners and not performing well in school, it’s important to get MRI and we find these are children who have been missed as HIE. And when the squint has progressed, they have foundational fusion, the parents are noticing the squint is more visible and we have to do the surgery. This is simple exotropia surgery with superior rectus recession surgery — was done for the exotropia with DVD. Another boy with a 14-year-old — he was saying that he could not draw his geometric figures. He couldn’t do any squares or circles. So much problems because he had developmental delay. Therapists were working on perceptual skills, they did modificational writing. But always one eye used to go up. There was exodeviation. And they convinced me that please go ahead with the surgery. After doing the surgery, I found that the child had — the boy says himself, says that now I can do the geometry. He is so happy, saying… For the first time, I can do the geometrical figures. In this child, after I operated, I found there was still residual dissociated vertical deviation. I thought the left eye DVD was more than the right eye, but found in the surgery now there was residual DVD in the right eye. I did a right eye IR plication, and this is what I want to discuss. I found the right eye was slightly smaller and there was limitation in elevation. So I wanted to ask: Is this seen routinely? Because I don’t do too much of plications. But because I wanted to prevent an anterior segment ischemia, I did plication on the superior rectus. But the third week of surgery, the limitation of upgaze was there. There are mixed deviations in these cases. We need to look at all types of squints. They’re there. This is a child with esotropia, superior oblique palsy, head tilt, he could not walk. We are helping the child by doing the surgery and the child can get — the child’s parents say they do better. Therefore it represents a spectrum of disability, and we should — and they get significant benefit from specific intervention for ophthalmological anomalies. But of course we need multidisciplinary services. Thank you.

DR MOLINARI: That was a very nice presentation, Dr. Suma. I was wondering… Because I have seen the same observation of improvement in all other psychomotor areas. After operating on the strabismus. And we also have done a paper on this. Or an investigation. We didn’t publish it. But the problem is that sometimes I have seen cases — and you probably have too — of patients that the angle of strabismus is so variable that they start with an esotropia, and you keep observing them, and then in the end, they end up being exotropic.

DR GANESH: Yeah.

DR MOLINARI: Without having done anything. So I think you have to put in a balance. If the angle is very variable, maybe it’s better to observe, in some cases. To see in the end what happens. The other question I had is: You said that you usually undercorrect these patients. So you use other numbers for recessions. And you mainly do recessions. Not resections or plications. General.

DR GANESH: No. Yes.

DR MOLINARI: What I do when I have esotropic patients with very, very variable angle, what I have been using in the last decades, is a small recession, together with a Faden procedure. And I have seen that by doing this, I have had less incidence of consecutive exotropia.

DR GANESH: Yes. I wanted to ask what the plication… So will this improve over a period of time? It’s just three weeks postoperatively…

DR MOLINARI: Yes. It’s like… It’s like a Brown syndrome. It’s like a iatrogenic Brown. When you do a plication of the — a tucking of the superior oblique tendon, you have a Brown syndrome at the beginning. And this gets better. The same thing I have seen it with plication of inferior recti. Although you have to be careful when you plicate the muscle. After doing the plication, try the forced duction test, and you have to notice that the forced duction is not so positive.

DR GANESH: Okay. Thanks. Dr. Fiona, any comments? And are there any questions?

DR DEAN: I certainly have an experience with these patients who have cerebral palsy, going from eso to exo or exo to eso. They are quite unpredictable. For many years now, I’ve treated what appears to be congenital esotropia, with botulinum toxin, the earliest I possibly can. From 6 or 7 months, up to a year old. And some of them we don’t know have cerebral palsy at that point. But when I did audit these, we found that the ones that were having less predictable outcomes with Botox were also those with CVI or cerebral palsy. As far as Andrea was talking about — delaying or perhaps just observing some of these patients… If we have tried to intervene to get binocularity early on, then that’s great. But if they then converge or diverge again, and have a consecutive (audio drop)… I say to the parent: Let’s wait until it’s really important to the child. Because this child is on a lifetime pathway of needing multiple surgeries. Because the eye goes in, it goes out, it goes in, it goes out. Let’s do it when it’s really needed. And that then decreases the number of surgeries. But say they are starting to… They want a job. And they’re going to go for an interview. That’s the kind of time they need it. They’re going to get married, or they’re looking… You know, for a relationship or something like that. These are key times in someone’s life, where their eyes might really matter to them. And that’s probably a better time to operate on those than just jump in and do it because it’s there. When you’re gonna end up doing many surgeries down the line on the same child.

DR MOLINARI: I totally agree with Fiona. And there is a question in the chat box… In the Q and A box… For you, Dr. Suma. On how do you explore visual fields in CVI?

DR GANESH: I showed the video, how you can use a white board. Because in these children, it’s very difficult to put them onto any machine. You take a white board and you show toys. I showed the video where you can pop off toys in the upper field, the lower field, on the side. A gross confrontation test. Whenever you pop up… Otherwise you have the LEA Wand. LEA has come up with the field test where you have… You can use it as a LEA Wand is there. But it’s pretty expensive. So — and it’s not — you can come to know in these patients — most of them have inferior field defects. So we just have to tell the therapist that… You know, they need to be… Rehabilitated. Because sometimes they keep falling down. And the parents say they’re bumping into objects. You could do a simple test where… I just showed the video with the white board and just pop up all the objects on all sides like a confrontation test and see where the child does not look at the object.

DR MOLINARI: This is also why the behavior of these children improves, or one of the reasons why the behavior of these children improves after surgery in esotropic patients. Because the visual field is larger.

DR GANESH: Becomes better.

DR MOLINARI: Yeah. They can be more receptive to stimulus, external stimulus.

DR GANESH: Yeah. I think there are more questions. How do we address contrast sensitivity in these patients? We use the contrast high-D. The high-D test. They are not really going to be cooperative for the Pelli-Robson chart. I showed the video particularly of how we do the contrast test with the LEA. There is the contrast high-D test that is available. And it is from 5%, 10%, 25%, 50%, it tells you how much is the loss. We all have around 5% — that’s normal. But in children, sometimes they have 25%. In these children, they’ll have a 25%. So you need to tell the parents or you need to tell therapists that they do not have much contrast sensitivity. And then the therapists, what they do is they tell the parents that maybe they need to make… Put dark lipstick or something, to increase the contrast of their faces. So that’s why the contrast sensitivity is very important to do in these children. Okay. I think that’s the end of the webinar. I think it was very nice. Thank you, Dr. Andrea and Dr. Fiona. It has always been a pleasure to discuss cases. And having Dr. Fiona Dean also in the grand rounds, and Dr. Andrea also. I hope we continue to teach more. And I also learn in the process. Thank you so much.

DR MOLINARI: Thank you so much for the invitation. It was a pleasure. Again.

DR DEAN: Thank you so much.

DR GANESH: I would like to thank you Orbis, Cybersight, the team, Lawrence, and all the — I think Lawrence is a big help. And he always is there on time and helps us with the meetings. And ensuring that our presentations are on time. When we send it to him. Thank you so much, Lawrence and the team from Cybersight. Thank you!

>> Thank you, everyone.

DR MOLINARI: Bye, everyone! Thank you for attending! Bye!

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August 5, 2021

Last Updated: September 12, 2022

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