 So, shifting gears, we're going to talk about another kind of interesting aspect of Strabismus that is I think rewarding to think about keeping in mind that when we deal with patients with Strabismus, understanding why you have a head tilt, face turn, chin up, chin down position is important and trying to obtain equal vision, normal binocularity, normal head position is important. So understanding patterns for business is also a big deal and you all know that place. I gave this talk at a meeting in Jaiper, India about six weeks ago. I have no financial interest. My wife wishes I had more but there we are. We're going to talk about first the pattern, a pattern, the common patterns that we see. Also touch on y patterns, x patterns and lambda patterns which some of you may not be aware of, also worth knowing about. Now the incidence, if you look at horizontal Strabismus across the board, about 15 to 20% will have an A or a V pattern. They're certainly the most common players. What do we know about etiology? Turns out that oblique muscle dysfunction is the most common cause. Inferior bleak overaction is associated with V patterns, superior bleak overaction with A patterns. Definitely worth remembering. It helps you tie things together. It turns out if you have orbital dystopia seen with mid-facial hypoplasia like Crouson's disease, V patterns are much more common. Why? They have an abnormal pulley system. It turns out that there's an orbital pulley system that involves locating the muscles, gives them a lever arm. Joe Deemer in Los Angeles has written about this extensively, has done extensive things with MRI imaging including Cine MRI imaging, looking at these pulleys in action. They are real and probably in the future will involve collaboration between Strabismus surgeons and orbital surgeons to get the best possible results in muscle surgery. Horizontal muscle restriction, like what you see in Dwayne syndrome, can involve slippage of the muscle, lateral rectus muscle usually over the surface of the globe. That's what causes up shoots and down shoots in Dwayne syndrome. It turns out in X patterns Strabismus, which we're going to talk about, that also is, has been shown to be an etiology. Now for terminology, there's been a chain suggested because what looks like inferior bleak over action, superior bleak over action, may in fact not be due to those things. Instead of inferior bleak over action, the suggested terminology is over elevation in adduction, superior bleak over action replaced with over depression and adduction. If you've been doing this for a lot of years, and that would probably include me, it's difficult to shift gears, but it is something you'll see in print. Now definitions, A and V patterns, the most common scenario, if you measure the horizontal Strabismus 25 degrees up by putting the chin down, 25 degrees down by lifting the chin up, and you have a 15 diopter disparity, V pattern, you have to have that much disparity to diagnose a V pattern, and an A pattern, 10 diopters of disparity, so a little bit less, that is just what's used by convention, there's no magic to that. Now V patterns are the most common type of pattern seen, most commonly associated with infantile isotropia. You remember infantile isotropia, there are three things that go along with that. One of them is a V pattern with inferior bleak over action. The other is latent, the stagmus, and the other is dissociated vertical deviation. So again, the term over elevation and adduction is used. You also can see V patterns, as Griffin mentioned, with bilateral superior bleak policies. When you see a unilateral superior bleak policy, if you see a large V pattern, you should look very carefully for subtle overaction of the contralateral inferior bleak, under action of the superior bleak, and if not, warn the family before you do unilateral surgery that they're likely going to be back in the future for additional surgery. Now this patient has V pattern, isotropia. What we see here is large angle isotropian down gaze. The patient is ortho in up gaze, smaller angle isotropian primary position, and in both left gaze and right gaze, you start to see this over elevation of the adducting left eye, the right eye here, and it's much more dramatic in the oblique positions up and right and up and left. This patient also has V pattern, isotropia, large angle isotropia, and down gaze. There's much more than a 15 diopter disparity. There's probably about 35 or 40 prism diopters of disparity between up gaze and down gaze. So is this a V pattern? Yes. You see the over elevation and adduction or inferior bleak over action, and so that is V pattern, isotropia. You also can see V patterns with exotropia. In this patient who has large angle isotropia and up gaze is essentially ortho and down gaze, and again you see this over elevation start to show up in straight, right and left gaze, and it's much more pronounced in the oblique gazes. Now the pattern you see in this patient, this patient has cruzons disease, and in this patient what looks like inferior bleak over action, you can say it is inferior bleak over action, you can operate on that patient, recess both inferior bleak muscles, and the patient would look just the same postoperatively. The issue here is not that you've got inferior bleak over action. The issue is malposition of the orbital pulleys, and so what you need to do instead in this patient is to reposition the lateral rectus muscles. And so what we do in this patient with cruzons disease, and we'll touch on this again, is instead of recessing the inferior bleaks, even though it looks like inferior bleak over action, the appropriate thing to do is vertical transposition of the lateral rectus muscles to account for the V pattern, that would involve recessing them if or resecting them either way, and shifting those muscles superiorly. Now treatment of V patterns, if you have over elevation and adduction, weaken the inferior bleaks with a caveat that you do not do that with again craniofacial syndromes with wild abandoned, think about what's going on. If there is no over elevation and adduction, vertical transposition of the horizontal recti, we're going to talk about which way to do that, and then the other issue is this is going to deal either of these with the disparity between up and down gaze. You still need to deal with the primary position deviation, so you do horizontal surgery on either medial or lateral rectus muscles for the primary position deviation. If there is DVD present, you may want to anteriorly transpose the inferior bleak in addition to weakening it. Now, this works, and this is one of those things as a resident when you take O-caps, you just need to memorize, and it is also useful to think through why it works, but in essence for an A pattern or a V pattern, if you shift the medial rectus muscles towards the apex, the lateral rectus muscles towards the open end, notice it works, whether it's A or V, whether you're doing a recession or a resection, this will work. It turns out that when we shift the medial rectus muscles down in a V pattern, when you inferiorly transpose those muscles, you get more effect from a certain amount of recession in down gaze. You correct that larger amount of esotropion down gaze. That's why that works. The same thing happens in the V pattern. If we're going to resect the lateral rectus muscles, when you shift them up, you will get more effect in up gaze with that resected lateral rectus muscle. This tends to collapse the disparity between up and down gaze. You're still left with doing something for the primary position deviation, but this is one of those things that we'll look at again here because that's important to remember. Let me back up there. Now, A patterns. A patterns are more commonly seen with exotropia than esotropia. They're also more common than D patterns in down syndrome and spina bifida. Spina bifida, particularly spina bifida with shunted hydrocephalus, it is very common to see an A pattern. This patient has A pattern esotropia, large angle esotropian up gaze, smaller esotropian primary, the patient is essentially ortho and down gaze. The patient with A pattern exotropia. What we see here is a patient who has large angle exotropian down gaze, smaller exotropian primary, and is essentially ortho and up gaze, in contrast to the over elevation we saw with the V patterns. With this patient, you start to see this right eye head down towards the floor and left gaze, the same thing with this eye, and it's much more pronounced. This eye has gone right down, almost out of sight, the left eye and then the right eye and gaze down and right, gaze down and left. So this is an A pattern. Now, treatment of A pattern. What do we do to treat A patterns? If you've got over depression and adduction, superior bleak overaction, we weaken the superior bleak. You can do that in any of a number of fashions. Typically surgeons will do what they're comfortable with, what they know works best in their hands. You also may want to think about what will have more or less of an effect on the different functions that the oblique muscles have. With the superior bleak and the resonance, what are three things that the superior bleak muscle does for us? Dr. Jardine talked about this a bit, but first of all, it is cyclorotorimuscle, correct? So you're talking about an encyclorotorifunction. Secondary effect will be the vertical function, depression. The tertiary effect is going to be abduction. And depending on what you want to do and what you're trying to accomplish and what you're trying to not accomplish, you may want to think about which of these procedures to do. But typically a posterior seven-eighths tonotomy will try to take care of the vertical function of the superior bleak with minimal effect on the cyclorotorifibers. And then you've got recession, spacers, full tonotomies. If there is no over depression in adduction, vertical transposition of the horizontal muscles are more appropriate. And what about the horizontal surgery for primary position? If you do this at the same time, there are two ways to approach. A couple of ways to approach this. One is to say, you know, the end of the torpedo is straight ahead, and I'm going to do the full amount of horizontal surgery in primary position. But most surgeons will decrease the amount of horizontal surgery because you will see less exodeviation if you weaken both superior bleaks. Remember, it is an abductor. It does have an effect mainly in down gaze, but also in primary position. And other surgeons will simply weaken the superior bleaks and come back and deal with the horizontal muscles in a second surgery. That's something that you'll figure out with experience in terms of what works best in your hands if you're going to do this sort of thing. Now, why patterns for business? This is a really cool entity because it really, again, this is where things look like you have inferior bleak overaction, but it isn't inferior bleak overaction at all. It turns out that there's aberrant innervation of the lateral rectus muscle just in up gaze. So this patient will look perfectly straight in primary, perfectly straight when they look down. So developmentally, everything they need to do where it's most important is working just fine. But when they look up, their eyes go way out to the side, and we can see what that looks like here in this patient who is perfectly straight in primary, perfectly straight in down gaze, and has large angloxatropia. This is what gets the parent's attention. It turns out most parents are taller than their children, at least when the children are very young. So when they looked up at mom and dad, the eyes go way out, or grandma notices it, and then you've got a problem. So part of our job at times is to educate parents about what really matters for the child, and as the child gets taller, this won't be as obvious to them. Their eyes will still be straight in primary position, still be straight in down gaze, right gaze, left gaze, and so part of our job is at times not to operate on patients. If you get your arm twisted and they want to have the eyes fixed, the thing that you do in this circumstance is to do a superior transposition of the lateral rectus muscle, keeping in mind that this is not true in fear of bleak overaction. If you weaken that child's in fear of bleak muscles, you will not be happy with the result. If you superiorly displace the lateral rectus muscles, and you may not have to recess them at all if there's no primary position deviation, you will collapse that wide pattern. Axe pattern strabismus is another entity that you may or may not ever see in practice, but it is really cool. What happens here is you see both over elevation and over depression when you get a little bit above or below the primary position going in the lateral gaze. The reason you see this is that you've got slippage of the tight lateral rectus over the surface of the globe. So this is similar to up-shoot and down-shoot that we see, particularly in type one dwinds when they try to add up their eye with a tight lateral rectus. And the treatment is similar. And if we look at this drawing, what we see here is a patient who's ortho and primary, large angle exo and up gaze, large angle exo and down gaze, and hear what looks like inferior bleak overaction and superior bleak overaction when in fact that isn't the culprit, important to recognize again, because weakening both superior and inferior bleaks probably will not fix this. You can either recess the lateral rectus muscles, particularly if they're very tight, but keeping in mind if they're ortho and primary, if you recess the lateral, you're likely to create an esotropy, aren't you? So the appropriate thing may in fact be to do a Y-splitting procedure where we split the lateral rectus muscle lengthwise, spread the ends out, what's called a sagalization procedure to diminish the up-shoot and down-shoot without changing the primary position deviation, an elegant solution, and again, one where you need to think about it ahead of time to do the right thing for the patient. Now, lambda patterns, this is actually just a variant of a pattern exotropia. It is really superior bleak overaction and they typically will have ortho and primary position, up gaze, large angle exotropia and down gaze and the appropriate course of action is to weaken the superior bleaks. Now, summary to kind of put this together. A and V patterns. You want to weaken the offending oblique muscle if there's over-elevation and adduction or over-depression, oblique dysfunction. One big caveat here. Let's say I showed up in the neuro-optimology clinic having been seen over the weekend in the emergency room. Someone at home suddenly noticed that my eyes were doing funny things when I looked down. And they noticed in neuro-optimology that I had large angle, A pattern exotropia and superior bleak overaction at my age. The question would then be what do we do to fix this because I want it fixed because somebody at home thinks I look funny. I've been doing fine all of my life and so we decide to go ahead and weaken both of my superior bleak muscles, recess both of my lateral rectus muscles and my large A pattern exotropia. And I come back a week after surgery telling you, doctor, everything looks tilted. I can't even walk. I can't drive. I can't function. What went wrong? What we didn't do was think about the effect of weakening the superior bleak when somebody A has fusion potential and they're an adult. So this issue of weakening the superior bleaks is a great idea in small children where we're most often confronted with this but sometimes in an adult who's got fusion potential, when you weaken the superior bleaks, remember the superior bleak is an encyclorotorimuscle, you weaken it, you're gonna get an x-cyclorotation and in an adult they may not be able to compensate for that. And as a result, they're gonna have torsional deplopia. They're not gonna like things. So even though for that A pattern exotropia, the right thing would be to weaken the superior bleaks, you may wanna say, you know, I just don't think that's the right thing for you. And instead, we just downshift both lateral rectus muscles. Very important point and I have seen a number of patients who've had that happen. What happens when they come to see me after somebody has weakened their superior bleaks is then you have to offset either vertical rectus or horizontal rectus muscles, which you also can do to try to compensate for the torsion where they need to help the most, to try to help them get things in a range where they confuse the deviation. So if there's no oblique dysfunction, do vertical transposition of the horizontal recti and you can do either unilateral or bilateral surgery. You can shift for a V pattern, a medial rectus down and a lateral rectus up if you're doing unilateral surgery as opposed to bilateral surgery. And let's look again at this diagram. This is worth looking at one more time. This again is an A pattern. This is a V pattern. And with this, we've got the lateral rectus being shifted towards the open end of the pattern, medial rectus towards the closed end. That you do need to just remember if you're gonna be trying to sort this out. And for the residents, I can guarantee you on OCAPS there will be some sort of question that relates to having remembered this. And we'll talk more about this. I think I'm gonna also be speaking to the residents on Friday morning, so we'll talk about this then. And as far as references, again, if you look here, the basic science course section, pediatric ophthalmology is for business has a section on patterns for business. The preferred practice plan, it's noticeably absent. It should be in the next update included, but it wasn't in the last update in 2012. The images came both from the academy website and from clinical key. And here we go. Questions? Otherwise, have a nice day.