Nelson: Our topic today is surgical management of nystagmus. I'm going to present several cases. The first case is a 4-year-old girl with 20/80 best corrected visual acuity (BCVA), horizontal pendular nystagmus, and a 25-degree chin-down position with no strabismus. How do you measure degrees of chin-down position?
Miller: Even though I work in Washington, DC, which is Marshall Parks territory, I trained at Johns Hopkins and my preferred method is to put prisms in front of each eye. If the eyes are up, I am going to put base-down prism and equal prism in front of each eye to see if I can move the null point more centrally. Then, based on the amount of prism diopters (PD), if I measured it to be similar at distance and near, I would consider doing vertical strabismus surgery to correct that amount of prism diopters.
Strominger: My approach is the same as Dr. Miller's. I don't have a compass to measure the degrees off the center, but I want to know why the child has a chin-down position. Is it a chin-down position because the null point is there or because the child is able to force enough convergence or focusing in that area to dampen the nystagmus and improve the acuity? It is especially important to try and figure out in this case of horizontal nystagmus. She also might turn her head to the right or left in a convergence movement to dampen the nystagmus. I'll then put yoked prisms to determine what the treatment options are. If it's a horizontal nystagmus, like in this case, I'm not convinced that doing vertical strabismus surgery is going to be helpful.Sometimes I'll just keep the child in the prism, if I can keep it to a 6 or smaller amount of prism. But in a 4-year-old child whose visual acuity is 20/80, I might see if I can somehow improve the acuity by dampening the nystagmus by doing horizontal rectus muscle tenotomy and reattachment, and then determine whether improving the acuity may help with the chin-down position in that case.
Dotan: When you see a child with any vertical or abnormal head position, you have to make sure the nystagmus is the reason for this and rule out any other possibilities such as pattern strabismus, ptosis, or astigmatism. To determine the amount of deviation of the head, with horizontal movements to the left or the right, it's easier to measure with a goniometer. Vertical deviation is more difficult to measure and it's usually more of an assessment as to whether it's a mild, moderate, or severe head elevation or depression.
Nelson: If you're going to do surgery for the chin-down position, is there an age requirement?
Strominger: I don't think there's necessarily any age differentiation. These chin positions are frequently picked up when the child is young because in preschool everyone sits on the floor and looks up at the teacher. Having a chin-down or chin-up position makes it difficult for the child to participate. But as the child gets older and is on eye level with the environment, it doesn't make as much difference. If the head posture is not causing problems with the neck musculature, walking, or other motor development, sometimes I will put the child in prism glasses and observe. The head posture will often resolve itself as the child gets older.
Miller: I don't have an age requirement, but if they've come to me early and it's a consistent head posture that is present at distance and near, it becomes difficult to do a lot of activities while keeping your head in that posture.
Dotan: I find that children usually adopt a head position when they try to fixate or make an effort to maximize their vision. So usually it's not evident at a young age, but when they're starting to look at the board and try to make out what's written on there, then you start noticing the head posture. Age is not a criterion for me, but I do find that abnormal head position is more evident in older children.
Nelson: If you decide to do surgery, what procedure would you do for a chin-down position?
Dotan: I would do superior rectus recession and inferior rectus resection.
Nelson: Would you do all four muscles?
Dotan: Yes, both the recessions and resections would be performed 5 mm.
Strominger: I am concerned about doing too much initial surgery for chin-up or chin-down positions because the child may end up developing some other horizontal strabismus that will require surgery later. In this case, I would recess the superior rectus muscles, and I might do almost 8 mm at that point just to get the eye down more and save the inferior rectus muscles and the rest of the horizontal muscles for another time. I'm still thinking that I might want to do the horizontal muscles to try to improve the acuity and dampen nystagmus if there's a horizontal component to it.
Miller: I would also start with the superior rectus in this setting. You could also pull the eye down by recessing and anteriorizing the inferior obliques to hold the eye down so that you wouldn't necessarily have to do surgery on tendons that would affect the vessel supply.
Nelson: The second case is a 6-year-old boy who has 20/60 BCVA, horizontal pendular nystagmus, 25-degree right face turn, and no strabismus. How would you treat this patient with that large of a right face turn?
Dotan: My preferred surgery for this child would be the Kestenbaum-Anderson procedure. I would adjust the numbers according to the angle of head turn, resecting the right lateral rectus and left medial recti muscles, and recessing the right medial and left lateral recti muscles.
Nelson: So you have specific numbers that you use for that amount of face turn.
Miller: I agree with this approach, but I need more information. Is the head posture the same at distance and near? Is it affecting life? Is it variable? For small head postures, you can sometimes get by with an Anderson procedure and just recessing. The right eye is essentially an esotropic eye and the left eye is essentially an exotropic eye. You can recess the medial on the right and recess the lateral on the left. In this case for a 25 degree turn, I agree that, if it is stable, I would do a recession of the right medial and resection of the right lateral, and for the left eye a recession of the lateral and resection of the medial, which is a standard Kestenbaum procedure. I base the amount on the prisms that I hold in front of the eyes to straighten the head.
Strominger: That's also my approach, determining the angle by the amount of prism. I use free Fresnel prisms and put the child in trial frames or, if they wear glasses, tape the prism. In this case I put a yoked base-out prism on the right and a yoked base-in prism on the left, and keep building it up until I get the head straight. I might have the child wear it around the office for a while or send him home because I want the parents to be confident that what we're doing is going to be helpful. Then I base my numbers on that prism. A base-out on the right is consistent with esotropia so I will do a recess-resect for the esotropia. A base-in prism on the left is consistent with exotropia, so I will do a recess-resect for the exotropia. That seems to work well because the Kestenbaum numbers over the years have been modified by different authors and it confuses me.
Nelson: The third case is a 5-year-old child with 20/100 BCVA in the right eye, 20/40 BCVA in the left eye, horizontal pendular nystagmus, and 25-degree left face turn with a right esotropia of 45 PD. How would you manage the patient?
Miller: I would do a patch test to determine which eye is in charge in terms of the head posture. Assuming that both eyes are important to it, we have a left face turn and we have a right esotropia, so this is more interesting.
Nelson: Essentially this is a patient who prefers his left eye and has a poorer seeing right eye.
Miller: Then I would put base-out prism in front of the preferred left eye, which is driving the left face turn until the head straightens and then I would do a recess-resect for that amount on that eye. I would also do a reconstructive procedure for the right eye with recession for the residual strabismus in the head straight position.
Strominger: If the child has a face turn to the left, the left eye is toward the nose. I put a base-out prism as much as I need to get the left eye straight because the child is not really fixating with the right eye. Then I would have to put a base-in prism on the right eye to balance as a yoke. But the patient is also esotropic, so you actually have to account for that base-in prism. For example, if I have to put a 25 PD base-out prism on the right, and the child has 30 PD of esotropia, once the head is straight you have to determine the amount of surgery on the right eye based on the total prism over that eye. Thus, if the total prism for the right eye is 25 base-in for the head turn, plus an additional 30 base-out for the esotropia, the angle to operate on would only be a 15 base-out prism or monocular recess-resect for 15 PD of right esotropia.
Nelson: If you operate on the right eye, is it going to improve the face turn?
Strominger: If you only operate on the right eye, it will probably not improve the face turn because it is determined by the left eye.
Dotan: It's important to remember that nystagmus surgery requires careful planning and also making sure that you are performing the surgery that you had planned before. We have a board and we write down what is planned before surgery begins so everyone in the room knows what is expected. In the case you describe, my approach would be to do a Kestenbaum procedure. The combination of nystagmus and esotropia is easier to manage than nystagmus and exotropia, because the surgical dose you perform on the deviating eye is less, not more, than usual. In the fixating left eye, I would perform a left lateral rectus resection and a left medial rectus recession according to the angle of head turn as usual. In the esotropic right eye, I would reduce the amount of right medial rectus resection and left lateral rectus recession according to the angle of esotropia.
Nelson: The next case is the same patient, except with 45 PD of exotropia.
Dotan: In that case, I would use a similar approach, adjusting the amount of surgery performed in the exotropic right eye, increasing the amount of right medial rectus resection and lateral rectus recession performed according to angle of exotropia.
Strominger: I would go back to my original prism adaptation trials to see what I can get away with and try to put the head straight with the primary fixating eye and then look at the residual deviation. You're going to end up doing more surgery for the exotropic eye than if that eye was esotropic to get the head turn straight. Of course, then you get into large numbers because if you're at 80 PD of exotropia, then you're doing maximal recess-resect on the non-fixating eye. But if you have to do that to get the head straight and fix the exotropia, then that's what you do.
Miller: That's exactly how I would approach it.
Nelson: The next case is a 7-year-old boy with congenital nystagmus, 20/70 BCVA, no strabismus, and no anomalous head position. The parents ask if there's any treatment to possibly reduce the nystagmus intensity and improve the vision.
Miller: This is classic congenital nystagmus where we're confident with the diagnosis. You can try some base-out prism, which may induce accommodative convergence and a little better vision by dampening the nystagmus. You may have to change the refraction for some added myopia. Although I had a case of albinism where I did surgery for esotropia and had an unexpected improvement in vision, I'm not generally a proponent of surgery for nystagmus in the absence of strabismus or head posture.
Strominger: I'm doing more tenotomy and reattachment surgery. That probably is based on twin brothers who were 16 years old and wanted to be able to pass a driver's license test. They had a visual acuity of 20/50, and 20/40 in our state is the minimum for an unrestricted license. I did the surgery and their visual acuity improved to 20/40, approximately one line, and they were ecstatic. Of course, it doesn't change the way we see the nystagmus. The waveform might change when we measure it, but they still have nystagmus.I sit down with parents and say, in my experience, I've seen improvement in acuity of approximately one line with tenotomy and reattachment. If you are in that amblyogenic age range of younger than 8 years, you might improve more. I don't know. Maybe if we slow down the waveform when the child is 2 or 3 years old, that might actually improve visual development. I'll sit down with the parents and I'll discuss all of the articles that I know of and my experience, and they can decide if they want to have it done or not.Overall, tenotomy and reattachment improves vision approximately one line. I've also seen some improvement that has been dramatic. A lot depends on the etiology of the nystagmus because sometimes it's hard to know if a child has truly idiopathic infantile nystagmus versus maybe a little albinoidism or something like that. I think in those cases it probably doesn't improve or only a minimal amount.
Dotan: I agree. I've done surgery in cases in which getting a driver's license was an issue. I've done it in cases in which I performed bilateral medial rectus recessions for esotropia and then I performed bilateral lateral rectus tenotomies and reattachment for the nystagmus.
Nelson: Did it improve in your patients?
Dotan: In my experience, with this type of surgery you can get one line of improvement on the Snellen visual acuity chart. I think it is legitimate to offer it to the patient if he knows what can be achieved through the surgery. For such a patient, there is also the option of doing bilateral me-dial recessions if I see improvement in the nystagmus while converging.
Nelson: The last case is a 5-year-old boy with congenital nystagmus who did have a Kestenbaum procedure for a left face turn at age 3 years that resolved the face turn. But now he has 20/30 visual acuity with pictures, a slight left face turn, and a 15- to 20-degree left head tilt.
Dotan: I would perform a horizontal transposition of the vertical recti muscles, shifting the left superior rectus muscle nasally and the left inferior rectus muscle temporally. In the right eye, I would transpose the right superior rectus muscle temporally and the right inferior rectus muscle nasally.
Miller: I would check for torsion first using a dilated fundus examination to see if there's anything I could fashion with oblique muscles to not have to go back on all of that.
Nelson: You wouldn't do an oblique muscle surgery?
Miller: Maybe. The surgery might have unmasked torsion that was hidden in the large preoperative turn.
Nelson: What would you do?
Miller: It depends on what I saw.
Nelson: You saw a left head tilt. Let's even assume the patient never had a Kestenbaum procedure, comes in with nystagmus, and has a null position with a left head tilt.
Miller: With a left tilt, the left eye is intorted and the right is extorted. Reducing the ability for this torsion pattern may help, for instance, a left eye recession of the anterior fibers of the superior oblique and right eye inferior oblique recession.
Strominger: These are difficult cases. The first thing that I try to determine is why they are developing the face tilt, because it could be the torsion, to try to dampen nystagmus, or they have an inferior oblique overaction. So I'll patch the eye and see if the head straightens out. And I want to know if this is binocularly driven. If I patch the eye and it straightens out, I know it's binocularly driven. Sometimes I'll go for the oblique because they can have a little oblique overaction and I might anteriorize the inferior oblique on the right side of the head tilted left. I would do an anterior transposition on the right.
Nelson: What would you do on the left?
Strominger: I might just watch it and see what happens, because if it is binocularly driven and I cover the right eye and they're straighter, then I might be able to get away with that. In terms of trying to displace vertical muscles, I'll see if I can simulate with prisms in the office. I've had patients who still tilt when I patch one eye. It may be a nystagmus dampening process, but I've gone in and operated on them and 3 months later they're back to where they were and I've displaced the horizontal muscles to try and get their eyes straight. I don't know why they continue to tilt. It may be to dampen the nystagmus, but my muscle displacement just isn't enough to affect it.
Nelson: Thank you all for participating.
This Eye to Eye session was conducted on Sunday, March 18, 2018, during the annual meeting of the American Association for Pediatric Ophthalmology and Strabismus in Washington, DC.