Duane retraction syndrome is a congenital restrictive type of strabismus characterized by absent or partially developed abducens nucleus with co-contraction of the medial and lateral rectus muscles due to anomalous innervation of oculomotor nerve redirected to the lateral rectus muscle. Complex variable presentations, anomalous vertical movements, globe retraction and systemic anomalies makes it challenging for management and must be individualized to a patient based on type and amount of deviation, abnormal head posture and associated overshoots.
During this webinar, the following topics will be covered:
- Etiology, Pathophysiology and Systemic Associations of Duane Retraction Syndrome
Dr. Meenakshi Swaminathan, Sankara Nethralaya Hospital, India
- Variable Ocular Presentations of Duane Retraction Syndrome
Dr. Suma Ganesh, Shroffs Charity Eye Hospital, India
- Surgical Strategies for the Management of Duane Retraction Syndrome
Dr. Andrea Molinari, Hospital Metropolitano, Ecuador
- Etiology, Pathophysiology and Systemic Associations of Duane Retraction Syndrome
DR GANESH: I would like to invite you all to this educational webinar on Duane’s retraction syndrome. I truly appreciate Orbis/Cybersight for giving us this wonderful platform. We have three speakers and three panelists. Dr. Andrea Molinari from Quito, Ecuador, Dr. Meenakshi Swaminathan, and myself, also from India. We all three have been associated with Orbis for so many years and have taught so many pediatric fellows. Especially mentoring them and teaching them. It’s a wonderful opportunity. I would like to now invite Dr. Meenakshi Swaminathan to speak on the pathophysiology, causes, and systemic changes of Duane’s retraction syndrome.
DR SWAMINATHAN: Thank you, Suma. So happy to be part of this initiative. And thank you, Orbis, for this wonderful opportunity and platform. So I’m going to be speaking on the etiology, pathophysiology, and systemic associations of Duane retraction syndrome. Good morning. Good afternoon. And good evening to all of you. Whichever part of the world you are in. So let me start off by saying that no financial conflict of interest to disclose, and I have the consent of patients to share photos for educational purposes. So let’s get to know each other. I’d like to know all of you out there. Who you are. This is an audience poll. Are you an ophthalmologist? A resident who is a post graduate? A fellow in training? Are you an allied ophthalmic personnel? Optometrist, orthoptist, ophthalmic technician, in training, or others. And I’m going to wait a few seconds for you all to finish voting, and then let’s see who you all are, who have tuned in to our workshop today. All right. So the polls are here, and it says 44% are ophthalmologists, 19% residents. Quite a number of allied ophthalmic personnel. That’s close to 30%. Wonderful. So Duane’s retraction syndrome is classified as a CCDD, a congenital cranial dysinnervation disorder. And we’ll soon see how that eventually happened. So it is a constellation of a combination of any of the following signs. Complete or partial absence of abduction. Retraction of globe on adduction. Narrowing of palpebral fissure on adduction. Partial deficiency of adduction. Oblique movements with attempted adduction. Upshoot or downshoot of the globe with attempted adduction. And reduced convergence. Does it have other names? Yes. It’s also known as the Stilling-Turk-Duane syndrome. That’s Jacob Stilling from Germany, who first described a case of DRS in 1887, soon followed Sigmund Turk from Switzerland in 1896, published this in 1899, but it fell to Alexander Duane in the USA who published a case series describing in detail the clinical characteristics and findings. So now we move on to the epidemiology and demographics. 1 in 1,000 to 1 in 10,000 in the general population is the prevalence. 1 to 5% of all strabismus cases are DRS cases. It can be an isolated unilateral finding, which is usual, or can be found in conjunction with other congenital anomalies. Females are more affected than males. Susceptible genes are sex limited. Maybe that’s the reason. Also, perhaps, there is higher generate levels during embryogenesis. The left eye tends to be affected more than the right eye, in types I and II. Now we move on to the etiology. First postulated: Mechanical abnormalities causing DRS. Turk said maybe it’s the abnormally tight lateral rectus, which behaves like an inelastic band. This is what he postulated in 1899. Wolff subsequently noted that it’s a congenital anomaly, and also could this be related to birth trauma or nuclear aplasia? Were questions asked by other scientists later in the 20th Century. Dual insertion of the medial rectus, one in the usual place, and the other posteriorly, the contraction of which can cause globe retraction, was another theory supporting mechanical anomalies as the etiology. We do know that some acquired DRS or bands that occur in the orbits can simulate DRS, and Dr. Molinari has an excellent paper. But no support was found during surgery for this mechanical anomaly that was postulated. Could it be innervational anomalies? In 1956, Breinin studied the electrical potential generated by muscles in various gazes in DRS. No LR potentials were found in abduction and maximum lateral rectus potentials were found in adduction. He concluded that the lateral rectus is receiving innervation during adduction of the eye. Electromyography studies followed. All the studies so far found that the medial rectus innervation was normal. So Strachan and Brown quantified this paradoxical innervation. They also found that synergistic innervation between medial rectus in verticals and obliques. Metz in his paper in 1976 presented that there was slowing of abduction and adduction saccades during the saccadic velocity recordings that he did in patients with DRS. Next questions came: Could this DRS be explained by central nervous system anomalies? Well, the 6th nerve innervation was thought to be defective to the lateral rectus. Okay, but is this nuclear? Is there anomalous innervation by the ocular motor nerve at the nuclear level? Or maybe absent or hyperplastic abducens nucleus? These were the postulates. Or could the whole thing be infranuclear, the cavernous sinus, where the 3rd and 6th nerves are closer anatomically. Maybe there’s something going on there. What would support the neurologic anomalies theory? There is presence of synkinesis in patients with DRS. Marcus Gunn jaw winking and crocodile tears. Abducting nystagmus in the normal eye also supports the brain stem anomaly. But it was this paper, that came out of William Hoyt’s lab in California, in 1998, which was published in the American Journal of Ophthalmology, that showed by magnetic resonance imaging that there was absence of innervation of the abducens nerve in Duane syndrome. With all of this, it seemed befitting that DRS be classified as a congenital cranial dysinnervation disorder, as was put together in the paper in 2011, in Eye, by Assaf. A little bit about genetics. Well, 90% are sporadic. 10% are familial. And the inheritance appears to be autosomal dominant if the DRS is part of a syndrome. Twin studies have also been done, and they show a unique phenomenon, in which one eye is affected in the right eye of the twin, and the other twin has the left eye. This is called mirroring. There’s no time to go into the details, but that’s fascinating. What about genes? Yes, the autosomal dominant variant has been localized to mutations of the CHN1 gene, the isolated variety to the DURS1 gene on 2q31, and the Duane radial ray syndrome into the SAL4 gene on chromosome 20. Well, a lot of information came through work from Dr. Elizabeth Engel’s lab. This was a fascinating paper, which looked at the CHN1 mutations. Hyperactive CHN1 mutations have been described in people with Duane syndrome with distinctive ocular motility patterns, that caused disaggregation with novel hyperactivating CHN1 mutations. They found all five clinically affected family members exhibited monocular or binocular supra-adduction deficits. MRI in four affected individuals demonstrated small or absent abducens nerves in all four, small oculomotor nerve in one, and small optic nerves in three. And superior oblique muscle volume was also decreased in three of the individuals, supporting trochlear nerve hypoplasia. Since there is a large number of trainees, I want to suggest this paper, which came out of LV Prasad, by my good friend, Ramesh Kekunnaya. It’s excellent, and I direct you to read more from this paper. We’ll go to the next audience poll. Are you ready? Which of the following can be seen in DRS? Absence or hypoplasia of abducens nucleus, anomalous innervation of oculomotor nerve, hypoplasia of the trochlear nerve, or all of the above. So we’ll wait for your response. So we’re waiting for a few seconds, for the poll results to be up. Fantastic. A large percentage of you have said that it’s all of the above. Fantastic. Okay. We’ll move on to systemic associations. Duane radial ray syndrome, or the Okihiro syndrome. This has an important association with DRS. And mutations in the SAL4 gene. Patients exhibit a shortened radius, abnormal angulation of the wrist, and/or thumb, as very well seen in this radiograph. What about other syndromes? Ah-ha. The Goldenhar syndrome. I’m sure many or most of you are familiar with it. Presence of ptosis, preauricular skin tags, epibulbar dermoid, deafness, coloboma, and pinna defects. DRS has also been associated with the Klippel Feil anomaly, and this is an excellent photograph that demonstrates short neck, usually you fusion of at least two vertebrae of the neck, Marcus Gunn jaw winking, among others. Holt Oram syndrome shows skeletal abnormalities of the upper limbs, among others. Wildervanck syndrome has deafness, nystagmus, myelinated nerve fiber, and limb deformities. And arthrogryposis multiplex congenita has multiple vertebral anomalies, cataract, staphyloma, spina bifida, and microphthalmos. Oculocutaneous albinism, a very important association, and of course, the fetal alcohol syndrome. This is a landmark paper on thalidomide embryopathy, published as a thesis in 1991, entitled a model for the study of congenital incomitant horizontal strabismus, by Dr. Marilyn Miller, a good friend and a mentor. So why is it really important to know the systemic associations? Because it’s a reminder, when we see a patient with DRS, to check the other systems. It also paves the way for future genetic studies. And children who need surgery for DRS may be difficult patients from the anesthesia perspective, because of their neck deformities. With that, I conclude my talk. Thank you for your attention. And now, I’m gonna move on to the next segment. And I take great pleasure in introducing my good friend, Dr. Suma Ganesh. Dr. Suma Ganesh is the director head of pediatric ophthalmology at the Shroff Charity Eye Hospital in New Delhi. She is a popular teacher, an avid researcher, an excellent clinician and surgeon, and a very dear friend. Over to you, Dr. Suma.
DR GANESH: Thank you, Dr. Meenakshi, for the kind words. I would start my presentation — that was an excellent presentation. And I think I would continue on it. I would be speaking on the classification, on the various presentations of Duane’s retraction syndrome. The topic was already introduced as a spectrum of neurological, mechanical, innervational, and genetic abnormalities. Various systems of classification are proposed to understand the mechanism and the presentation of DRS. We all know that Huber’s classification is the most popular, but it does not cover all types of cases. Ahluwalia et al. modified the classification based on the alignment in the primary gaze, and a recent paper published by the Korean Journal of Ophthalmology came up with a new classification, just this month, in fact. Type and angle of strabismus classification of Duane’s. So I would go to the Huber classification, the type one. We can see there is a limitation of abduction. Most common presentation is an esotropia. A normal or defective adduction. And we find there is narrowing of the palpebral finish *fissure and retraction of the globe on adduction. Also widening of the fissure on attempted abduction. Always the face turn is towards the involved side. I like this diagram by Rosenbaum, who says: How do you grade your limitation? -2, -3, -1. This is important, especially when thinking of surgical strategies. It is not seen in just one presentation. You may have varying types, like a type one. With a large esotropia and a large face turn, and you could have abduction deficit much better than -4, but with minimal globe retraction, one with no upshoots, downshoots, just small esotropia, small face turn, minimal globe retraction, or type one esotropia with small face turn and severe enophthalmos. So you need to see this before planning your strategy. Type two is limitation or absence of adduction, narrowing of the fissure on attempted adduction, normal or reduced abduction, and there’s a face turn which we see normally to the normal side. So we also get varying presentations like a large exo Duanes with upshoot, large face turn, you can see the incomitancy here. And here’s a small right esotropia. You can get small exotropia with a globe retraction. Around 12 prism diopters of exotropia. So there are varying presentations, and the type 3, which is much more common than the type 2, 15%, has limited abduction and adduction, retraction of the globe and narrowing of the fissure on adduction, but in these, we find they could be orthotropia, exotropia, or esotropia, and there is frequently upshoot and downshoot with attempted adduction in these cases. This is orthotropia, here you have esotropia with upshoot and downshoot, minimal face turn but severe globe retraction, exotropia with upshoot and downshoot, large face turn and globe retraction. So we see varying types, and it is important for us to find out what exactly is the patient coming for and what exactly we have to correct during surgery. This is a type 4, a synergistic divergence, or a divergent split. You see large exotropia, adduction deficit, and simultaneously abduction on attempted adduction. This demonstrates co-contraction and excessive LR firing. So you also have a type five. Where there is a vertical retraction syndrome. Where you have a horizontal DRS, plus globe retraction on vertical positions of gaze. So you can see there could be a limitation or no limitation of vertical eye movements. Here you can see there is a limitation on depression. So bilateral ESO DRS is also common. It’s not as common. It’s around 10%. And we find it could be fusion with small eso, ortho, or a face turn, or without fusion, like in this case, large esotropia, and a narrow fissure in each eye during adduction. You can have bilateral exo Duane’s with bilateral upshoot with face turn. This is a type 3. And you note there is a V pattern. So the patterns which are there — it could be A pattern, also is whenever you see A pattern, bilateral cause, and there is a Y pattern which is seen — a Y pattern also seen in cases of Duane’s. In males it is more common, 29%, but in this case, we see it in a female with bilateral exo Duane’s. The polling question is: What is the most common type of refractive error which is seen in DRS? Myopia, myopic astigmatism, hyperopia, or hyperopic astigmatism? Okay. The answer is… Hypermetropia is the most common refractive error which is seen, and the most common amblyopia is anisometropic and ametropic amblyopia. We should do cycloplegic refraction. And maybe the Duane’s does not require surgery. It could just be corrected with glasses. So it’s important to correct these to restore binocularity. An important paper on the grading of globe retraction. I love this paper, because it helps us to find out before and after the surgical results, how much you have managed to correct the globe retraction. No narrowing is 0, 1, less than 25%, 2, 25 to 50%, grade 3, 50 to 70%, and 4, 75 to 100%. So you take a scale, measure the palpebral fissure at the center, and compare it with the normal eye in the fully abducted position. Thus you can grade your globe retraction, whether it’s grade 1 through 4, and see after surgery how much the refraction has improved, or even in cases where you plan to do any transposition surgeries, you could do it in grade 1 or 2, but you would not prefer it in very severe globe retractions like in grade 3 or 4. The same paper also published about how to grade the upshoots. So the same way with the involved eye in adduction, you draw a line, which is drawn from the pupillary center to the normal eye, and then you find that grade 0 or grade 1 lies between the pupillary center, and here you have between the pupillary margin and the limbus, grade 2, grade 3, and grade 4, where the cornea disappears beneath the lid. We see anomalous vertical movements in DRS. Innervational and mechanical. Mechanical, an abrupt up and down movement, innervational, gradual elevation and depression. The characteristic is they may have vertical deviation in the primary position. Mohan found mechanical to be more common than innervational. We also find they’re associated with vertical deviations, so we need to see what is involved in the vertical deviations. We need to measure the side gazes. So this is a case where we have left hypertropia, which increased along with the Duane’s, in left gaze and left tilt. We have seen mostly an ipsilateral superior rectus contracture, in cases with a congenital palsy, but also in the case of Duane’s. This might be the case of longstanding upshoots. So the polling question is: Was the most common pattern seen in DRS a Y pattern, X pattern, V pattern, or A pattern? Very good. The answer is V Pattern. So how would you differentiate? If you know it’s a Duane’s case, you have to differentiate it from 6th nerve palsy, infantile esotropia, and Mobius syndrome. To rule out there is no — if you do a doll’s eye head like this, you know there is no abduction deficit. In Duane’s, the esotropia, the deviation, is much less than the limitation of abduction. Whereas in 6th nerve palsy, the limitation of abduction is equal to the amount of deviation. And Mobius syndrome, we get along with 7th nerve, and will also see the hypotrophy and aplasia of the tongue. That’s how you can differentiate it from each other. So to summarize, we need to look for an abduction deficit, adduction deficit, the amount of retraction, upshoot, downshoot, the abnormal head position, the primary position deviation, whether there is unilateral or bilateral, and the fusion. And depending on these, the surgical strategies have to be planned. And for this, we have none other than Dr. Andrea Molinari, who has been my mentor too, and she will be speaking on the surgical strategies of Duane’s retraction syndrome. So I think we all are waiting for the surgical strategies. I see many questions coming up on the surgical strategies. And we have none other than Dr. Andrea Molinari to address this.
DR MOLINARI: Thank you, Dr. Suma, for the invitation, your kind words, also very good friends of mine, Dr. Suma and Dr. Meenakshi, and thank you also to the Cybersight team for putting this educational event together, and thank you to the audience for taking the time from your COVID quarantine to spend it with us. And I’m going to address the topic on how to surgically manage patients with Duane syndrome. But I want to start by saying that in most patients with Duane’s, surgical treatment is not indicated. Be aware that surgical treatment can produce disappointing results. Therefore, it is advisable not to operate on orthophoric patients with no anomalous head posture or disfiguring globe retraction, like this case here. The patient must be informed that there is no surgical procedure that will restore the normal ocular motility. Surgery does not eliminate the fundamental abnormality of innervation. Indications for surgery in patients with Duane syndrome are very specific, and generally circumscribed to patients with marked anomalous head posture, noticeable ocular deviation in primary position, disfiguring retraction of the globe on attempted adduction, and cosmetically unacceptable vertical deviation of the eye in adduction. So having said that, I’m going to focus now on describing the surgical procedures that can be used in these patients, and suggest an algorithm of treatment for them. As in many strabismus cases, and this is especially true in Duane cases, different strategies can be adopted in order to reach the same goal, which in these cases are: Improving an anomalous head posture, correct any angle of strabismus, ameliorate globe retraction, and expand binocular field of single vision. Medial rectus recession of the affected eye is one of the most popular procedures performed in patients with esotropic Duane. It will improve or eliminate a face turn and correct an esotropia of up to 20 prism diopters. Recessions of the medial rectus of the affected eye shouldn’t be larger than 5 millimeters, since it may result in significant limitation of adduction. Producing a diplopia in the field of gaze, where the patient was diplopia-free before the surgery. It is better to leave the patient with a small residual anomalous head position, and not sacrifice the entire adduction capacity of the affected eye. There are three situations where you want to consider adding a contralateral medial rectus recession. In cases of large angle esotropia in primary position of more than 20 prism diopters, cases with esotropia and significant globe retraction where a lateral rectus recession has to be added to the medial rectus recession, in order to correct the globe retraction, and to prevent the recurrence of contracture in the medial rectus of the affected eye by creating a fixation duress on the non-affected eye, and driving the affected eye outward through Hering’s line. If asymmetric, larger recession should be considered on the other eye. Unilateral lateral rectus recession improves or eliminates a face turn, corrects exotropia up to 20 prism diopters in primary position, and will help alleviate severe globe retraction. If exotropia is over 25 prism diopters, adding recession of the contralateral rectus may be considered. As in medial recti, if asymmetric recession is chosen, the recession of the contralateral lateral rectus should be larger. Contrary to the medial rectus recessions, the lateral rectus recessions can be larger, up to 7 to 10 millimeters. It is very difficult to have an overcorrection in these cases. Transpositions of the vertical muscles in Duane cases have been advocated by different authors for a number of years. The goal of the surgery is to generate active abduction vector forces in order to enlarge the area of single binocular vision. This will bring several advantages over simple recession procedures, like improving the abduction capacity, and this will enlarge a single binocular vision field. And transpositions seem to induce less recurrences as recessions. But induced vertical or torsional deviations have been reported in up to 30% of the patients. There is also a higher risk of anterior segment ischemia and worsening of co-contraction with anomalous vertical movements, which will result in increased globe retraction. Which is one of the most common complaints of these patients, when it is present. And here you can see an example of a published paper, where you can recognize a narrower palpebral fissure in the post-op pictures. Even though her abduction improved. But in my experience, the globe retraction bothers the patients more than the limitation of abduction. Therefore, transpositions should be avoided in patients with significant globe retraction. There are different variants in the transposition procedures. You can transpose both vertical muscles or just one. The muscles can be totally or partially transposed. Or they can even be transposed without disinserting them, like in the Nishida procedure. When only one muscle is transposed, it is usually the superior rectus. But in cases with V pattern or more limitation of abduction in depression, some authors prefer transposing the inferior rectus. One muscle transposition does not create as much globe retraction as bilateral rectus muscle transposition, and this is why lately most authors prefer the one muscle transposition. Also, these transpositions can be augmented with a resection of a transposed muscle, or with a Foster’s suture. Resecting the lateral rectus of the affected eye of Duane patients has been contraindicated for a long time, and this was so because of the concern that the globe retraction might worsen as a result. However, this procedure has been performed successfully in selected patients, and it has the advantage that it does not increase globe retraction, as you can see here, and does improve abduction as good as in vertical rectus transposition procedure. This procedure works best in patients with more than 25 diopters — prism diopters of esotropia in primary position, with mild globe retraction, with no adduction deficit, with very limited abduction capacity, and in absence of anomalous vertical movements. Resections of lateral rectus should never be more than 3.5 millimeters, and the recessions of the medial never more than 5 millimeters, in order to avoid overcorrections. Combining the medial and lateral rectus recession of the affected eye has proved to be a very useful procedure to diminish the globe retraction. The amount of recession required needs to be large, and in order to maintain balance in primary position, the lateral rectus is recessed more than the medial rectus. Faden procedures are used in two specific situations. On the lateral rectus of the affected eye, in order to avoid the side slipping of the muscle, in cases of significant up or downshoot of mechanical origin, of course, and on the contralateral medial rectus, of a Duane eye, with significant limitation of abduction, as you can see here, in order to limit the excursion of the operative eye, this one here, when looking towards the affected eye, to match the duction deficits. Y splitting is very useful in treating mechanical up and downshoot. And this was one of the questions that was written to us. The lateral rectus is split horizontally in half, from his insertion, as far back as possible, spreading the muscle halves 20 millimeters apart, as you can see in this picture. Each half of the muscle should be recessed a couple of millimeters or even more, if an exotropia in primary position is present. Recession of the superior rectus muscle is required in cases where a secondary contracture of the muscle results from severe and persistent upshoot of innervational origin. In such cases, a hypertropia exists in all superior fields of gaze, as you can see here. Superior rectus recessions in these cases must be large. This also ameliorates the globe retraction, which is present in some cases, as you can see in this case. So if you have a patient that is orthophoric, no anomalous head posture, no significant globe retraction or anomalous vertical movements, as you can see in the upper part, the wiser approach would be not to operate. But if significant globe retraction is present, as you can see here, you can consider recessing both horizontal recti in the same eye, and Y splitting or a Faden in the lateral rectus, to correct a noticeable up or downshoot. In patients with esotropia, if the esotropia is small, like in this case, consider recessing the medial rectus of the affected eye or an asymmetric bilateral medial rectus recession if the angle in primary position is 25 prism diopters or more. You can combine these procedures with a lateral rectus recession or a Y splitting or Faden of this lateral rectus, if you want to improve globe retraction or up and downshoots. In cases of large angle without much globe retraction, or much up or downshoot, you can consider transposition of the vertical recti or a recess/resect procedure. Here you can see both procedures done in similar patients, and recognize that they are equally effective. For example, in this case, a superior rectus transposition with Foster suture was done, and you can see how the abduction improves, without affecting the globe retraction in adduction. And the same result is obtained with a recess/resect. You can see here improvement of abduction, and not much globe retraction in the postoperative pictures. In patients with exotropia, consider recessing the lateral rectus of the affected eye and also adding a Y splitting if up or downshoot is present. Like, for example, in this case. You can see here — well, here it’s only right lateral rectus recession was done, because there was not much globe retraction. If the angle of exotropia is large, you can consider recessing the lateral rectus of the non-affected eye. However, recession of the contralateral rectus muscle should be avoided in cases with large globe retraction that may signify significant anomalous innervation of the affected lateral rectus. Like, for example, in this case here. So in this case, recessing the lateral rectus of the unaffected eye will elicit more innervation to the recessed lateral rectus in order to maintain fixation. As you can see here, this would be an anomalous branch of the third nerve, going to the lateral rectus. So this augmented innervation will also affect the medial rectus, through Hering’s law. If the lateral rectus of the affected eye is receiving a significant amount of abnormal innervation from the third nerve, it will also contract and thereby worsening the exotropia. This is why in cases like this, with huge globe retraction, you should not recess the contralateral lateral rectus. So, to conclude, there are no rigid rules regarding surgical treatment. Each case should receive individualized consideration, according to the clinical manifestations observed, and remember always that surgery does not eliminate the fundamental abnormality of innervation. So without further delay, I will start my case. This is a two-year-old boy that presents to my office with a significant chin-up posture, and also a face turn to the left. He had a right variable — a right eye variable ptosis. You can see here while sucking on his lollipop, you can see how the lid goes up and down. He had a very significant limitation of elevation of the right eye, the eye did not reach midline, and also, very important limitation of left abduction. This was a very interesting case, because it was a case that had several congenital cranial dysinnervation disorders in one and the same patient. He had in his one eye a monocular elevation deficit, ptosis, and Marcus Gunn, and on his left eye, he had the Duane retraction syndrome. So what did we do with this patient? Since this eye was hypotropic and esotropic, we transposed the medial rectus to the superior rectus with Foster suture, and on the other eye, superior rectus transposed to the lateral rectus with Foster suture, and also performed a medial rectus recession of 4 millimeters. The postoperative result was pretty good. We could correct the anomalous head posture completely. The patient was orthophoric in primary position. And as you can see here, there was a significant improvement of the elevation of the right eye, and a modest improvement of the abduction. The patient and their parents were very happy. You can see here the anomalous head posture disappeared completely. And the boy learned to open his lid by moving his mouth. So this is a clear example that in cases like this, transposition procedures are really powerful and useful. Thank you all for your attention, and now we’re going to listen to — let me stop sharing my screen — and we’re going to listen to Dr. Suma’s cases.
DR GANESH: I have a few questions for you, Dr. Andrea. The question is: Between Faden and Y split, which is the best for upshoots? I personally have not done it.
DR MOLINARI: I prefer Y splitting. I prefer Y splitting, because, as you know, Faden is always very messy, if you need to reoperate those patients.
DR GANESH: The next question is: If there is a large exotropia, won’t it be better to do a lateral rectus periosteal fixation?
DR MOLINARI: Yes. If there is a large exotropia, especially if there is also a significant anomalous innervation, in these cases periosteal fixations can be very useful, and in my experience, does not produce overcorrections.
DR SWAMINATHAN: There’s a question which says: If there is significant upshoot, and V pattern on clinical evaluation, but there is no tightness of lateral rectus, on FDT, is inferior oblique recession a better procedure or Y split?
DR MOLINARI: We have to determine if it is innervational or mechanical upshoot. The only way is to see how the eyes drift upward. If it’s abrupt or if it’s slowly. If it’s abrupt, I would prefer to do the Y splitting. If it’s slowly, then I would prefer to do the inferior oblique weakening procedure.
DR GANESH: I would like to add: In innervational upshoot, there will also be associated hypertropia in the primary position, so that could add, and you could see better if the hypertropia is increasing in any gaze. And you could plan an inferior oblique recession. There is a paper that says you could do inferior oblique myectomy in such cases. And also associated torsion. If in the fundus you have a torsion, you could plan the inferior oblique recession. Otherwise, if it’s mechanical and when it is abrupt, I think it is better to do a Y split procedure.
DR SWAMINATHAN: And there’s a question for you, Dr. Suma, which says: Can you please explain the differential diagnosis again?
DR GANESH: Oh, I think I went too fast. The differential diagnosis is basically — the first is 6th nerve palsy, whenever you have Duane’s presenting, esotropia and limitation of abduction, the first thing that comes to mind is maybe a 6th nerve palsy. 6th nerve palsy will have very large deviation, and the deficiency of abduction will be similar to the deviation. But in Duane’s it is a smaller deviation and you get a much larger limitation of abduction. And suppose it’s a small child and you’re not sure whether it is infantile esotropia, because infantile esotropia will also present with limitation of abduction. You need to do a doll’s eye maneuver in all these children, because that will tell you whether it is infantile esotropia with a large deviation and minimal amount of limitation of abduction, or is it Duane’s, with a smaller deviation, or whether it is a 6th nerve palsy. 6th nerve palsy is less common. But we need to rule out 6th nerve palsy, because it is a neurological cause, and there may be a neurological cause, and then we need to do imaging. The other thing is Mobius syndrome I said. Where there could be an associated 7th nerve, and hypertropic tongue. So this is how you will differentiate between the four cases of a child presenting with the same esotropia. I will go to two interesting cases, if we have time.
DR SWAMINATHAN: There are specific questions for Dr. Andrea. One is from Alejandro Ernesto, who says: Did you perform the Nishida procedure for these patients?
DR MOLINARI: Yes, I just typed the answer for that question. But let me tell this to you. No, personally, I have not. I have not. But there is a very nice paper. I don’t remember the author now. Who presented this technique with very, very nice results. And there was another question. Asking me how to perform the Faden. Well, for the Faden, you have to expose the muscle very well, and dissect it from the ligaments, because you have to go very far back. In the lateral rectus, the Faden is a little bit more complicated than on the medial rectus, because there is — where you have to place the Faden is usually placed on inferior oblique, so at one pole, there is not much problem, but on the other pole, it is. But I guess if you place it on the superior border of the muscle, alone, this will be enough.
DR SWAMINATHAN: Also, Mariam Gabriel asks about the role of Botox.
DR MOLINARI: I have no experience with Botox in Duane syndrome. I don’t know if you have.
DR SWAMINATHAN: No. No experience. Another attendee asked Suma: What about saccadic velocity?
DR GANESH: Yes, that is how you differentiate from restrictive strabismus. Saccadic velocity will be normal restrictive strabismus. But reduced in a paraleptic squint.
DR SWAMINATHAN: We’ll go on to your cases and go back to some questions.
DR GANESH: So this is a young male, 24-year-old male, who presented to the clinic. He has not been able to move the right eye temporally and nasally since birth, small right eye, significant face turn, but the rest of the history was not significant. We can see significant globe retraction and limitation of adduction and abduction. Best corrected visual acuity was normal. And the anterior segment and posterior segment was normal. So on examination, he had the right — he had exotropia, right hypertropia, around 20 prisms, and it was equal. Limitation of adduction and abduction. Severe globe retraction. We can grade it now. And also severe upshoot, grade 4 upshoot, with the pumpkin seed sign. And there was a deviation of 30 prisms. There was a question whether we need to do in all cases — in this case, I specifically asked for MRI, because we know that there are some literature which says there may be additional abnormalities in Duane’s, because of paradoxical innervation between horizontal rectus and vertical rectus muscles. And hypoplasia of vertical rectus muscles. I wanted to check that there was not abnormalities. So in patients where you have a doubt, you could go in for imaging. So here you can see the globe retraction. Which is seen on adduction and on depression. Around 72% grade 3 globe retraction. And also there is associated drooping of the upper lid, and elevation of the lower lid. This has been published by Dr. Isenberg, in the American Journal of Ophthalmology, seen in 52% of cases. So the question is: There is now a vertical deviation which is equal to the horizontal deviation. There is a face turn to the left, severe globe retraction, upshoot which is 4+, and I think from the videos you could make out there is mechanical and innervation upshoot, combined upshoot, and also limitation in abduction, and adduction, so many are asking whether we should do lateral rectus periosteal fixation or large lateral rectus recession for the large exotropia which is seen, but there is also associated upshoot. So should we do Y split? And what about the hypertropia? So I would like to ask: What would be Dr. Andrea’s plan? There is a tight medial rectus, lateral rectus, and superior rectus. So what would be the plan? And I will share with you what I went for.
DR MOLINARI: Well, in these cases, you always have to address the main concern of the patient. Which in this case is the retraction, the globe retraction. And the hypertropia. The exotropia is also present, but it’s not as important as the other two features. So the other thing you have to also acknowledge is that the upshoot here has a double etiology. One is a mechanical etiology. And the other one is the innervation etiology. The mechanical etiology can be easily addressed with a Y splitting of the muscle, of the lateral rectus muscle, and also the hypertropia, with a recession of the superior rectus. Which has to be large. There was one question about doing periosteal fixation. Yes, you could do that too. But actually, my position is always: Go from less invasive procedures to more invasive procedures. And so I would start with a Y splitting and lateral rectus recession. If this doesn’t work, you can always go back and take the lateral rectus and fixate it to the periosteum, if it didn’t work as expected. So in my opinion, this case, what I would do is what you did. Which is superior rectus recession, and lateral rectus recession with Y splitting.
DR GANESH: So yes, I went ahead with a large recession of the lateral rectus, because it was tight, and Y split, and a superior rectus recession also. We could do a lateral rectus periosteal fixation, but then how do we manage the vertical — the hypertropia?
DR MOLINARI: With a superior rectus recession.
DR GANESH: Yes, you could do a superior rectus recession and a transposition.
DR MOLINARI: A transposition? You mean transposing —
DR GANESH: A partial —
DR MOLINARI: No. My preference in this case would be what you did.
DR GANESH: Okay. So Dr. Meenakshi, any comments?
DR MOLINARI: You got a fantastic result, as I can see.
DR SWAMINATHAN: Yes, you have a great result. And I agree with Andrea. I’m also comfortable — and your plan. I’m comfortable doing a lateral rectus Y split as the first procedure. And since the FDT was positive, you have to do — recess the superior rectus as well. And when we go on to more and more muscles, it’s going to then — your risk for anterior segment ischemia as well, and more the number of recti that undergo large recessions, it starts becoming wider and bigger, so you have a new cosmetic problem as well to remember. So I would have done exactly what you have done. And I think the patient’s improvement in head posture and the considerable improvement to the upshoot are proof that your plan worked well.
DR MOLINARI: And let me add one thing, Dr. Suma, regarding what you asked about a transposition. I would not recommend transposition procedures in cases with significant globe retraction. And this patient had a significant globe retraction.
DR GANESH: The globe — it was still not perfect. So I was thinking of whether I should add one more medial rectus recession. It was tight, but there’s already a -2 adduction limitation. So should I go ahead and do —
DR MOLINARI: As I said, Dr. Suma, remember, these cases will never be perfect, never. So you have to compromise, and actually try to solve what bothers most the patient.
DR SWAMINATHAN: I agree with Andrea, and I would always very clearly state what are the indications for surgery in every single case. And as Dr. Andrea very nicely said, there is no one answer. Each case has to be looked at individually. And so in this particular patient, your clear indication was the abnormal head posture. Which was driven by the cosmetically bothersome upshoot and cosmetically bothersome vertical. You have addressed and solved most of these. I think you’ve done good.
DR GANESH: If it was very large — the one question which asked how would you titrate if you had to do also a medial rectus recession, in downshoots of exotropias, where you would do lateral rectus recession, and if you want to add on a medial rectus recession — because there is no surgical table as such. So how much would you do the medial rectus recession? This was asked, one of the questions.
DR MOLINARI: I have — I’m doing this for now 35 years. And I have really many disappointing results at the beginning, when I did large medial rectus recessions. Right now, I’m very conservative with medial rectus recessions. Of the affected Duane’s eye. Maybe I will be more permissive or more — it’s more forgiving, the recession of the medial rectus of the sound eye. But of the affected eye, I try not to do large recessions, and right now the most larger number I’ve performed for medial rectus recession is five. No more than that. I used to do more before. But not now.
DR GANESH: Yeah, I have cases who have later on gone into a consecutive esotropia, and then you have limitations in adduction and abduction. Divergent splits. It becomes a synergistic divergence. And then you do not know how to treat.
DR MOLINARI: If the patient gets diplopia, in a field of gaze where he before the surgery he did not, he gets disappointed. And he complains about that.
DR SWAMINATHAN: I wanted to add that these patients already are known to have poor convergence, defective convergence, and then when you go on adding medial rectus recessions, larger and larger, you’re going to make the convergence even worse, and this is something to consider in these patients.
DR GANESH: I looked up the literature. There is very few literature. I just found three to four publications on the vertical deviations with Duane’s. It is more commonly with A pattern associated that they have done a superior rectus recession. And also they have — Dr. Mohan has done a vertical rectus recession for innervational upshoot and downshoot. It has worked in this case. But case two — we go to the next case. So this is a simple case, but this is mainly being put up so that we know which cases to do a superior rectus transposition, which cases not to do a superior rectus transposition. But I think that’s a question nowadays. Everybody asks, and even the parents asking. So this is a child with a 25 prism esotropia. With minimal globe retraction. We can see that it’s around grade 1. And there is an abduction deficit of -4. And so in this case, superior rectus transposition will work. So any other views — because now it is established — I’ve checked so much review of literature on superior rectus transpositions, and all are recommending that we could do superior rectus transposition for an abduction improvement. They have not found any vertical torsion diplopia or any vertical squints. Postoperatively. In cases — in some cases, they have even done inferior rectus transposition, where there is a V pattern, or in A pattern, they have done a superior rectus transposition, along with the horizontal. And so it is now being recommended in few cases. So what is your opinion? I have done a few cases. Any takes on this. Both of you.
DR MOLINARI: I think these types of cases are particularly good for doing the superior rectus transposition. But not only that technique — you can also do a recess/resect procedure, like I explained. And if you ask me, I have done both procedures. But right now, I favor the recess/resect. And actually, it must not be a resection. It can be also a plication. And the good thing about plication is that you disturb less the anterior segment circulation. So if you ask me with this case, superior rectus transposition would work very well, but I prefer to do a medial rectus recession, up to 5 millimeters, and plication up to 3.5 millimeters. Not more than 3.5 millimeters. If you do a plication, you can always go back and do a transposition procedure afterwards, if you’re not satisfied with the result. But as I said with these two cases that were very similar, and also similar to this case, both give you exactly the same result or a very similar result.
DR GANESH: Would you agree? I personally have never done a resection for an eso Duane’s.
DR SWAMINATHAN: I have only done a couple of patients, where I’ve done small amounts of resection or plication. I have done more superior rectus transpositions. I’ve also burned my fingers with that procedure. It is really quite a powerful procedure, especially if you combine it with medial rectus recession. If you do not have access to adjustable suture in children, you have to be really, really cautious, because I have had a patient where they developed an exotropia right away. Even with a very modest medial rectus recession, and a superior rectus transposition, with a Foster suture, and so it is ideal if you can titrate the amount of medial rectus recession. More important is to really quantify the amount of esotropia, preoperatively, because if the esotropia is of a smaller degree, I would be much more inclined to do Andrea’s plan. Than risk doing an SRT and creating exotropia and diplopia and the patient is miserable.
DR MOLINARI: But Dr. Meenakshi, remember that also my suggestion of recess/resect is with patients of at least — with at least 25 diopters of esotropia in primary position. If it’s less, I don’t do recess/resect.
DR GANESH: So this patient had 25 prisms of esotropia in primary position. But a small amount of recession with an SRT did work well for her. She had no vertical diplopia, torsional diplopia, and she had no torsion. Like I checked on the fundus, and we dilated her and checked the fundus, and found there was no torsion. She was not complaining. So I would go ahead with the superior rectus transposition in such cases. If we have time for the last case, this is a 6-year-old girl with an abnormal head posture. And a squinting of eyes since the age of 1 year. She had visual acuity was normal. With best corrected visual acuity was normal. Fundus showed torsion. Extorsion in the left eye. And she presented with exotropia with hypertropia in the primary position. I don’t have a video for this, but there was gradual elevation of the left eye. There is a small amount of globe retraction, though it is very small. If you have to grade it, maybe that is why it will help. It was around a globe retraction of 1. And she had also a face turn. So with a V pattern also. What would be the plan of — because the questions which in my mind are exactly what had been asked to questioners: Should I go ahead with inferior oblique recession or myectomy? Here we can see that there is an incomitant exotropia, which is seen, and even the past three step test, if you see here, is not very significant. It was just a small left hypertropia, increasing on left tilt. So what would be the plan? The fundus showed torsion. So would you go ahead with an inferior oblique recession?
DR MOLINARI: Dr. Meenakshi, you go first.
DR SWAMINATHAN: I was just gonna say: I think it’s very important to be able to see the video, and to be able to distinguish, really, what we are dealing with. Are we dealing with a mechanical or an innervational upshoot? I think as you yourself have very nicely illustrated in your talk, I think a video is invaluable to be able to make the distinction, and that would help guide our surgical plan. But it is clear that the patient does have a large V pattern, which needs to be addressed. So if you decide that this is not really a case for inferior oblique weakening, then I would go for a bilateral lateral rectus recession. With a shift to take care of the pattern. Which probably would be my plan. How about you, Andrea?
DR MOLINARI: Well, actually, even only with the pictures, I doubt that this is a mechanical upshoot. There is no retraction. I see no retraction at all in this picture here. So I think this is an inferior oblique overaction. And I would — there is a significant V pattern. There is also an underaction of the superior oblique in this picture. So I would go — yeah, I would correct the exotropia with lateral rectus recession. Although she has only 18 prism diopters, maybe I would go only for a one lateral rectus recession and inferior oblique weakening, a small inferior oblique weakening in this eye. And that’s all that I would do.
DR GANESH: So that is exactly what has been done. I did a large lateral rectus recession. And small weakening of the inferior oblique. And this is the result. But in this case, she does have esotropia. And now residual diplopia in this gaze now. Postoperatively. Although she is ortho in the primary gaze. So maybe I should have done a little bit lesser amount of lateral rectus recession. Or maybe that’s what I feel. Because now she does have diplopia in this gaze. And though in preoperatively, it was a large angle. So these are the cases.
DR MOLINARI: I think this is —
DR GANESH: The questions remaining. Which we have.
DR MOLINARI: What we can do is keep answering the questions by typing them, if it’s possible. If the Cybersight team is okay with this. So we can answer all the questions.
>> Dr. Molinari, we prefer if you answer them live on the session. If you don’t have time now, we can have you answer them by email, and post them later.
DR MOLINARI: Okay.
>> So if you want to answer a couple more live —
DR MOLINARI: Yeah, we can answer a couple more questions. Here it says: In innervational upshoots, how it know if it is inferior oblique overaction or due to abnormal superior rectus innervation? That’s a good question. Well, one thing could be: Look at the fundus, and see if there is excyclotorsion. If there is excyclotorsion, there is no doubt there is inferior oblique overaction. And also, if there is abnormal superior rectus innervation, you usually will have a hypertropia that is also present when the patient is looking towards the affected eye. In abduction. When you have an inferior oblique overaction, you will have the hypertropia will be larger in adduction. When you have an abnormal superior rectus innervation, you will have the hypertropia also in abduction. So in all superior fields of gaze. Dr. Suma, why don’t you answer another question, so we do one-one-one? Excuse me. When I do RNR surgery in Duane?
DR GANESH: I personally do not do RNR surgery in Duane syndrome. Unless in cases where there is a divergent split or divergent synkinesis. A large amount of exotropia, underacting medial rectus, there I would do a lateral rectus periosteal fixation, and along with it, I would add a medial rectus resection. In exotropia, I have still done in a few cases, a medial rectus resection. Where I find that there is an underacting medial rectus, but I have not done a case of esotropia lateral rectus resection.
DR SWAMINATHAN: Dr. Suma, there’s a question — I think they confused you with me — but they asked: In Dr. Meenakshi’s third case, is there any use of adjustable suture in lateral rectus recession? Your concern was that you introduced a little bit of consecutive esotropia in the left gaze. Is there any use for adjustable suture is the question.
DR GANESH: Yes, we could do adjustable, lateral rectus recession on adjustable. Especially in this case, where you find that there was a lot of incomitance, like in one gaze it was 45 prisms and another gaze was just 2 prisms, you could go ahead and do an adjustable. I’m not a very big adjustable fan myself. And especially in small children. Because I have initially done it in my initial years, but now I leave it to only cases where I find that there is a lot of incomitancy, or there is diplopia and not sure — there is a variable deviation. In those cases, I go ahead with an adjustable. Otherwise, I guess I would agree with you that adjustable would have been a better option.
DR SWAMINATHAN: There has also been more than one question on: Would you titrate your recession dosage, based on finding a tight muscle? In cases like this, with tight LR, is it better to do lesser amount of recession? Would you titrate it based on tightness?
DR MOLINARI: I think the recessions should be calculated with several factors. As we said before, each case is the case. So each case has a specific — has to receive a specific plan for their clinical characteristics. And I usually calculate the amount of recession I’m going to do with several factors, not just the measurement in primary position, but also how tight the muscle is, and how much innervation anomaly the patient has. So this is something — there are no tables. In Duane’s, there are no tables that you can follow, as in other types of strabismus.
DR SWAMINATHAN: And there’s also been a lot of questions on the timing of surgery. How early should you operate? If you’re able to examine the patient, how early would you operate, or would you wait for a little while? I will give my answer after I hear from both of you.
DR MOLINARI: Dr. Suma?
DR GANESH: Oh, sorry?
DR MOLINARI: I can answer first.
DR GANESH: Sorry. I was looking at the questions.
DR MOLINARI: I usually don’t operate very early. I would say in a one-year-old, or even maybe in a two-year-old. Because you want to see all the characteristics the patient has, in order to plan for the best surgical approach. And, you know, a one-year-old or even two-year-olds are really difficult to examine. You want to know how much abduction deficits there is. How much adduction deficit there is. You want to measure the patient if possible. So I wait ’til the patient is cooperative enough, and I don’t say an age. Because some children are very cooperative with two or three years, and some others, they are not cooperative, since they are seven years old. So if I can have the amount of information I want, that’s the moment I do the surgery.
DR GANESH: Most of them have a face turn and may endanger binocular vision. So when we want to operate early, the main concern is whether they have a good binocular vision potential. I think they have a good sensory. As long as she said that you would wait to get a good assessment, and once you have a good assessment, I remember in a two-year-old or one-year-old, a 6th nerve palsy — in those patients, I waited and found out later there was significant globe retraction seen in the child, so I would wait before I go ahead, maybe. The youngest I’ve done is a three or four-year-old. Because the child also had an associated hypertropia. There was a vertical deviation along with it if
so that is why I operated. I think around 3 or 4 years of the child. So that is a reason I have gone early and operated.
DR MOLINARI: I would like to add to what both of you already said, and I completely agree with you. I definitely want to rule out presence of amblyopia, and treat the amblyopia, because they can have just the anomaly itself — can drive the abnormal head posture, and sometimes you can’t presume that there will be binocularity. So it’s good to know, it’s good to be able to test that, it’s good to be able to get reliable vision, and you really want to be able to assist the patient in their entirety. You want to get all the characteristics clearly made out and visible, so that you can titrate the plan for that particular individual. It would be nice before the patient turns 7 or 8, before they become more conscious about their appearance, before they have to turn their face so much in their activities and interaction with their peers and in school — it would be nice to be able to intervene before that. But not at the cost of a good examination.
DR MOLINARI: There is a very interesting question here. It’s a patient that was previously diagnosed with a 6th palsy, secondary to an infectious process. It resolved in one month, and one and a half years later, presents with esotropia, limited abduction, narrowing of the lid, upper palpebral fissure, and they’re asking if this could be a Duane with later onset. Actually, I have never seen — Duanes are congenital problems. But what I have seen are cases that mimic Duane’s syndrome. That have — for example, cicatricial or restrictive issues, secondary to contractures, that can mimic Duane cases. But they are not Duanes. What’s your experience?
DR GANESH: You can have an acquired Duane’s. An acquired Duane’s that presents in certain cases, but that will present like an inverse Duane’s.
DR MOLINARI: It looks like a Duane. But it’s not a real Duane. The innervation anomaly, this characteristic of Duane.
DR SWAMINATHAN: It’s possible that you get something like a pseudo-Duane’s. Maybe the orbital infection caused retraction, and that eventually causes globe retraction, limitation of adduction and narrowing, and could present like a pseudo-Duane’s. Is the only way to explain this.
DR MOLINARI: When you say large recession of the superior rectus, how much do you mean? Around how many millimeters? Well, the vertical — the superior rectus recession has to be large. I would say at least 7 to 10 millimeters, and you can do even more.
DR GANESH: I have done around 7 millimeter recessions. 20 prisms of hypertropia. It had worked. So the muscle was very tight you. *very tight. So that is why I planned to do just a 7 millimeter recession.
DR MOLINARI: For example, the case I showed — it was more. It was 8 or 10 millimeters and he still had residual hypertropia, in primary position.
DR GANESH: How do you treat vertical DRS? We have completed this. Vertical DRS. In a type 4, what is your management? Most of us go ahead with the lateral rectus periosteal fixation. And along with it, add a medial rectus dissection. For the divergent split, what is the method of treatment? How do you manage type 4 DRS? The divergent split and divergent synkinesis?
DR MOLINARI: A divergent split, like the one during your talk? I would do a periosteal fixation in this case.
DR SWAMINATHAN: Yes.
DR GANESH: Have you done a lateral rectus splitting to the medial rectus in such cases? As seen in third nerve palsies?
DR MOLINARI: Are you asking Dr. Meena?
DR GANESH: I’m asking you, Dr. Andrea.
DR MOLINARI: If I have done Y splitting —
DR GANESH: You split the lateral rectus and the splits are brought towards the medial rectus like in the case of third nerve palsy, where you have limited adduction. And then you take the split half of the lateral rectus, and bring it to the medial rectus.
DR MOLINARI: No, I have not done that. I prefer to do other types of procedures.
DR GANESH: I think we have answered most of the questions. Yes. We have answered most of the questions. I think it was very wonderful session. And I enjoyed doing this webinar. And I would like to thank the audience for being such a great audience. And also, I hope each of you have learned much more, and if any questions, you could directly email Dr. Andrea or me, or Dr. Meenakshi. And I’m sure Orbis Cybersight can help us — help you all with sending us the questions. And I think we could end the session here. And I thank you all for being here. And I thank Orbis Cybersight for once again — I know there’s been a lot of effort behind this. Arranging all this. Jonathan, Lawrence, thank you so much. For helping us out.
>> Of course. Thank you all. Have a great day.
DR MOLINARI: Thank you.
DR SWAMINATHAN: Have a great day. Bye-bye.
DR SWAMINATHAN: Thanks, everybody, and thanks Lawrence. Bye.
April 30, 2020
2 thoughts on “Lecture: Duane Retraction Syndrome: Pathophysiology, Variable Presentations and Management Strategies”
Nice and clear presentation