Lecture: Special Forms of Strabismus

Objectives of this presentation are:

  • Overview of congenital and acquired restrictive strabismus
  • Surgical options for diplopia after blow out fracture
  • Surgical management of diplopia in thyroid eye disease
  • Surgical management of persistent diplopia after retinal detachment surgery

Lecturer: Dr. Gillian Adams, Moorfields Eye Hospital, London


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DR ADAMS: So this is on special forms of strabismus. So I’m going to look at some of the congenital and acquired restrictive strabismus options. I’m going to look at how, as a surgeon, you can manage the strabismus occurring after a blowout fracture of the orbit. I’m going to talk about managing strabismus and thyroid eye disease, and how to manage diplopia after retinal detachment surgery. So the questions I’m going to ask now — and then I want you to think about answering later — are: Should Brown syndrome have surgery after the age of 3? Or before the age of 3? Yes or no? And then: Does removing the retinal detachment buckle make diplopia better? And then the third one: Torsion is a problem in thyroid eye disease? Yes or no? On the congenital side, I’m going to look at Brown syndrome, Duane syndrome, Mobius, fibrosis syndrome, and strabismus fixus, and on the acquired side, I’m going to look at blowout fractures of the orbit, thyroid eye disease, and diplopia after retinal detachment surgery. Okay. So you know the classic Brown syndrome. They can’t elevate in adduction, but they can elevate in abduction. There’s no overaction of the superior oblique, although they may have a little downshoot. They can have a chin up head posture. They can have an A pattern or a V pattern. And 85% of them will improve by the age of about 8. So for that reason, very few of them actually need surgery. And if there’s a click that you can actually feel up in the supratrochlear area, then most of them will get better. So the reasons for operating are: Neck problems from chin-up head posture. If they’ve got a significant squint in primary position. So if they’re hypotropic in primary. So when you start the operation, the first thing to do is a forced duction test, and to make sure that it’s tight on elevation in adduction and not tight all the way across, or that it’s loose. If you’ve got a restrictive problem, so if you’ve got a tight inferior rectus, they won’t be able to lift up. And the other thing you can mistake it for is a monocular elevation deficiency or a double elevator palsy. Because they don’t elevate in abduction or adduction. But the Browns don’t elevate in adduction. So you’ve got to be careful not to mix up a superior rectus underaction, a monocular elevation deficiency, a tight inferior rectus, or a Brown. So those are the differential. So after you’ve done your forced duction test and confirmed that you’ve got a Brown syndrome, you’ve got about three or four choice operations that you can do. So that’s the superior rectus, and that’s the superior oblique. That’s superior oblique and that’s superior rectus. So you can just cut it. You can put a tendon expander in. You can cut it on either side to expand it. Like a Z tenotomy. Z tenotomy — you know, you cut on either side, one side and then the other, and it stretches it. Thins it out. Or you can do what’s called a chicken wire suture, in which instead of putting the band in, you just put some 6-0 suture in, and the idea is that if you think you’ve overcorrected it, you can pull it back up together again. So if we move on — I’ll answer questions specifically about any of those if you want me to, later. I’m just going to do a broad cover at the moment. So Duane syndrome is where you’ve got abnormal innervation of the lateral rectus. And I can assure you, having stuck needles into it, it really does fire on adduction, as opposed to abduction. Because it’s abnormally innervated from the third nerve. Okay? So you may find it associated with retraction or indrawing of the globe. And then you’ve got the classic fissure changes, narrowing on adduction, widening on abduction. And it’s important to not mistake it for a 6th nerve, because resecting a Duane syndrome doesn’t help. Because it doesn’t help the abnormally innervated lateral rectus. Now, most of them don’t need surgery. We are a very surgical institution where I am, and we only operate on 25% of them, because you can’t make them normal. You can’t get rid of the fissure changes. You’re never going to make them normal. You can improve some things, but you can’t make them normal. So these are the three types. So this is type 1, with reduced abduction. So you can see that this gentleman is only abduction type 1. So you can see that adduction is normal, but abduction is down. So the only reasons for operating are if there’s a deviation in primary position or there’s a head posture. So your options are bimedial recessions, often with transpositions for an A or a V pattern. Don’t resect the lateral, because it’s abnormally innervated, and that won’t work. If you have got retraction, the thing to do is to loosen off both medial and lateral and let the eyeball come forwards. So recess both medial and lateral. If the globe is pulling backwards. And you can do transposition surgery, where you take the superior and inferior rectus around to the lateral rectus, with a very small medial rectus, if you’ve got a head posture. So the options that you’ve got if you’re doing a transposition are to do the two vertical muscles sideways. Either in a child you can do it with the medial rectus, but not with an adult. You can just take around the superior rectus, which is called a Crouch procedure. And if it’s — you can add in a medial rectus recession to that. Now, the things you’ve got to be very careful about are not to give the patient a hypotropia, which is the big risk if you take around just the superior rectus, and there’s still a risk if you take round the two muscles. Although it’s slightly less. So it’s surgery that you have to have a big think about, before you start. So this is a Duane 2, with limited adduction and normal abduction, and you can try a lateral rectus recession for that, because these are usually divergent. And then for the type 3, most surgery is not very helpful. You can consider Faden sutures on the contralateral medial and lateral, to limit the adduction and abduction on the contralateral eye to match the deficit, but most patients don’t want that. And one of the other things that you may see in Duane is the upshoot, where the eye shoots upward, and probably the best thing for that is to loosen the lateral rectus and do what we call a Y split, where you split it down the length of it, and take one arm up to the top and one arm down to the bottom. But you need to split it along about 15 millimeters. Split it in the middle. Split it for about 15 millimeters. But you nearly always need to recess it as well. You’ve got to recess and split. Now, Mobius syndrome is where they have abnormalities of the 6th and 7th and sometimes the 5th. So they’ve got this very flat, featureless face. So you treat them like bilateral 6th nerve palsies. So they may need medial rectus recessions. Very occasionally they need transpositions. Fibrosis syndromes often run in families, so you will see it coming down the family line. So if a parent has got it, the children often have it. And the commonest muscle involved is the inferior rectus. It’s usually bilateral, but it occasionally can be unilateral. And these patients get a big chin-up head posture, because they can’t elevate. And the other problem is they’re not very good at shutting their eyes. So we treat them with bilateral or unilateral inferior rectus recessions, but remember, they tend to fibrose again, and you often have to do augmented, or significantly more than you would like to do, in the way of a recession. Loosen off the inferior recti. Now, if you move on to blowout fractures of the orbit, these can be traumatic… And that’s how it usually… It’s usually traumatic. Now, we usually, as strabismus surgeons, get involved in late management. Because early management is conservative for adults, unless there’s significant enophthalmos, significant handicapping diplopia, and if there’s fractures of the face, which the faciomaxillary surgeons manage. So strabismus usually comes at a later date. And in the UK, it is far more young men who suffer this than anyone else, and the problem is that virtually none of them get back to a diplopia-free environment. They always have some double vision in upgaze or in downgaze or in side gaze. Now, that may limit their chances of working again, depending on where their double vision is. And enophthalmos, where the eye goes backwards because of loss of orbital volume, may aesthetically look very poor, particularly in a woman, and in some of the men, if it’s very marked, they can be very concerned about that. Now, the problem about putting a plate in is that it can damage the inferior rectus and make your motility worse. So this is a list of operations that can be considered. And when you see that large a number, you know that none of them are perfect. This is just a list of them. So if you just want to read out that list for them… What I’ll do… I’ll just go down through where you might want to go in different situations. So if you’ve got reduced upgaze but good downgaze, I think an inferior rectus recession is a good move. But you’ve got to be careful that it doesn’t slip. So if you’ve got reduced up, you’ve got to be careful the inferior rectus muscle doesn’t slip backwards. So for the other one, if you’ve got reduced upgaze and downgaze, is to think about an inverse Knapp, where you take the horizontal muscles downward, or you can work on the other eye’s superior rectus muscle, do a combined recession/resection, which is the Scott procedure, or do a Faden. Or you can do an inferior and superior rectus recession to expand the field. So after retinal detachment, motility disturbance is reported in up to 75% of patients for about 4 weeks after repair. Now, very few of these patients — only about 5% — will get persistent problems, long term. And whilst it’s commoner after external explants, such as buckles, it can occur after encirclement or vitrectomy. And the problems can be sensory and non-sensory. So it may not be just diplopia. It may be distortion as well as the diplopia. So the sensory changes are: If you’ve had a macula-off detachment, your vision may be reduced, you may have distortion, you may have torsion, you can have aniseikonia, image size difference, if you make someone aphakic, you can get a larger image, and if they become myopic — so if you’ve got a problem at your fovea, you won’t be able to bifoveally fix the images. To see and fuse, you need two functioning foveas. And the scarring ones may be adhesions, and the mechanical effects of explants, and muscle damage. Now, removing the buckles doesn’t help. So if you can get them to fuse and get rid of their double vision with a Fresnel prism or botulinum toxin, they should do well from surgery. So we would advise adjustable sutures. And it may be very scarred. Much as I love my retinal surgeons, there is no doubt that this is quite a challenge to a motility surgeon. The general rule is that taking away the buckle will not alter the motility. And when you take the buckle away, if you do, you’re going to find — you may well find scleromalacia, so a very black, very thin sclera underneath, and you may well have extreme difficulty in managing that situation. So the usual rule is: Don’t take the buckle away. Operate around the buckle. And in the old days, muscles were damaged by cryotherapy, and the orbital fat may be traumatized. So you may well have really quite a scarred eye to operate on. Now, we’re going to move on to thyroid eye disease. Motility problem — do you have a lot of thyroid? Yeah. Well, as you know, motility is a very serious problem in thyroid eye disease. And it’s a very challenging time to operate. The first thing is: Wait until it’s stable. Don’t operate before it’s stable, or else you’re going to get a bad result. Now, if you’ve got a very tight orbit, then you need to have the orbit decompressed, and our rule is that if there’s more than 23 millimeters of exophthalmos, we decompress first. If your orbital surgeons decompress medially, so the medial wall and the floor, you’re going to get a hypertropia with an esotropia. So our orbital surgeons now try to take the floor temporally, and the temporal wall. But we still have a lot of orbital — despite the orbital surgery — we still have a lot of motility to deal with. Now, these patients usually need two or three procedures. And they’ve got a very high failure rate. And a couple of things that are really important are that if you recess the inferior recti too much, you’re going to get an A pattern, so they’re going to get diplopic on downgaze. And you can also induce torsion. And you’ve got to be aware that if you put the inferior rectus muscles on adjustable stitches, which is quite common for some people, you’ve got a 30% risk of slippage. But the first thing is to start by telling the patients you can’t get them back to where they were when they were 21. The aim has got to be to restore single vision in primary position and in downgaze, because that’s where most people read their phones, look at their computers, eat, go downstairs. In an adult, if you operate on three muscles, you’ve got a risk of anterior segment ischemia, particularly if it’s thyroid, particularly if they’re smokers, so don’t do it. Now, these muscles are very tight. So when you put them up on hooks, they can snap. And that’s one of the reasons I started using that 240 band. Because if you slide it under a tight thyroid muscle, you don’t have to pull it up onto squint hooks. You can leave it running flat, and it reduces your damage rate. And beware: If they’ve had a decompression, they will look normal, but the muscles will still be very tight. So as a sort of general running rule, if they’ve got more than 20 prism diopters of vertical deviation, they will need to have two muscles operated on. So usually an inferior rectus on one side and a superior on the other. So if you look at this gentleman, who can’t elevate, this eye can elevate, but this one can’t — that’s a very big deviation. So you may have to loosen the right inferior rectus and the left superior, to get them balanced in primary position. Now, if you do an adjustable on the inferior rectus on a thyroid, you have to be very careful, because the slippage rate — in other words, an overcorrection — is about 30%. On the other hand, if you do it as a fixed, you’re likely to undercorrect it. So what we often do in something like this is do a maximal inferior rectus, which for me is about 6 or 6.5, if I have my arm twisted, and then I’ll do the rest on this superior rectus muscle. And remember, as I was saying, not only will you get the risk of an A pattern if you overrecess the inferior rectus muscles, but the lower lid gets pulled down, and the patient gets unhappy with the appearance. So if you’ve got the horizontal problem, the very tight muscles, and this is one of our patients — you can see he’s got vertical and horizontal problems — so look at the abduction. So he can’t abduct either eye. He can’t elevate. So look for an A pattern, which you often find after a decompression. This is the gentleman after decompression. If you’ve got very tight horizontal muscles, you actually have to release the inferior as well, because they act as a leash. They stop the eye moving. So you’re going to have to release, in this case, both inferior rectus muscles. Probably asymmetrically. And then release both medial rectus muscles. And they’re very tight. And it’s quite difficult to do. Do the inferior first. Why? Because if it’s going to give you a lot of bleeding, it doesn’t bleed into the surgical field of the medial. If you do the medial first, it’s going to bleed and obscure your view of the inferior rectus surgery. Now, the other thing to look at in very severe thyroids is that the superior oblique muscle is also enlarged. And if the superior oblique muscle is enlarged, that will be the cause of torsion. Now, what you may find is that the patient doesn’t complain of torsion until you release the inferior and until you release the medial, and they can actually move. Because if it’s very tight, they don’t appreciate the torsion. So you need to warn patients, when you look at the scans — because if we go back… There’s a superior oblique enlarged on both sides. Now, what we found is that they are 2 to 3 times larger than normal in severe thyroid, needing surgery. So you need to be aware of that. Because if you’re not aware of that, you’ll think, A, you’ve done something wrong — or the patient will think you’ve done something wrong. So you need to tell the patient right up at the beginning: I’m going to release the horizontals. I’m going to release the verticals. And then you’ll start to see the twist. And when that happens, you’ll need to be able to deal with that, and the way to deal with that is to do posterior-superior oblique tenotomies. Now, you may need to do 70%, 80%, or 90% posterior tenotomies. Don’t go for the anterior part. Because if you do, you’ll give them torsion. So the surgical technique is to remember that, first of all, expect it to be difficult. Because the muscles will be very tight. Use a grooved squint hook. Or the 240 band. As a way of making sure that you can get into the muscle. But if they are really tight, you won’t get a grooved hook underneath that muscle. But you will get a 240 band under. And do recessions. Yes, you can do resections, but only as a sort of fourth procedure. You must never do them as a primary procedure. You’ve got to release the tight muscles first. Remember the risk of muscles snapping. It’s called PIT. Pulled in two syndrome. And it’s where the muscle shears around about 5 millimeters back from the insertion. And you put them up on hooks and they just tear apart. If you do more than two rectus muscles, you’re at risk of anterior segment ischemia. And if you fix the vertical muscles, you’re likely to be undercorrected. If you put them on the adjustable, you’re likely to be overcorrected. So if you’re doing adjustable, aim to undercorrect them by 8 prism diopters, because it will stretch over the next 6 weeks. And there’s an increased risk of necrotizing scleritis, postoperatively, so whatever you do, don’t send the patient off with a huge big bottle of steroid and no follow-up, or they’ll come back with this huge big black area. So be very careful. So the restrictive syndromes are — both the acquired and the congenital are not common, but they’re quite interesting squints. Most of them do not require surgery. Particularly the congenital ones. And there is no rush to go and do an intervention. In the restrictive cases, wait until it’s stable, or else you’re going to get a bad result. And you’ve got to be very realistic about what can be achieved. You cannot get them back to normal. So Brown syndrome should have the surgery before 3 or after 3? After 3? After 3. And removing the retinal detachment buckle will improve double vision? No. And torsion is a problem in thyroid eye disease? Yes. Excellent. Now, questions? If you’re going to do a Faden suture, how do you do it? I use 5-0 prolene. It comes on a beautiful evil needle. It’s very sharp. Very, very sharp. And it goes through sclera magnificently. But you have to be quite careful about it. And if I’m doing a Faden, I’ll put it around about 5, 6 millimeters back from the insertion, roughly. On the superior rectus. If I’m doing it on the medial, I’ll try and get it at about 12 to 13 millimeters back from the insertion. Okay? From the limbus. So they’re quite far back. So you need really good visualization. Indications for Faden sutures? You need them if you have limitation of abduction on one side, and you put them on the contralateral medial rectus. If you’ve got limitation of elevation in one eye, you can put them on the contralateral superior, and you can fadenize the inferior to stop one inferior rectus fully depressing, if the eye doesn’t go down fully on the other side. So those indications are usually… The vertical ones are often thyroid or… Restrictive, more than blowout in particular. You can also use them — some people use them in accommodative esotropia. When they’ve done bimedial recessions. And you’ve still got convergence for near. What I tend to do then is to set them back supramaximally, rather than do the faden. But you’ll find that some people use a faden for that.

June 6, 2017

Last Updated: October 31, 2022

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