Strabismus Surgery: A Guide to Advanced Techniques [1st ed. 2023] 9811984328, 9789811984327

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Strabismus Surgery A Guide to Advanced Techniques Jitendra Jethani Editor

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Strabismus Surgery

Jitendra Jethani Editor

Strabismus Surgery A Guide to Advanced Techniques

Editor Jitendra Jethani Director Baroda Children Eye Care and Squint Clinic Panorama Complex, R. C. Dutt Road Vadodara, Gujarat, India

ISBN 978-981-19-8432-7    ISBN 978-981-19-8433-4 (eBook) https://doi.org/10.1007/978-981-19-8433-4 © Springer Nature Singapore Pte Ltd. 2023 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

My father Mr. Nenumal Jethani and my mother Mrs. Chandra Jethani who together built me and made me reach to this point. Indebted to them

Preface

Change and evolution have made us what we are today. Evolution and advancement in any science are key to unlocking the new horizons which everyone of us wants to reach to. Surgical advances are not only a constant improvement, but also a need which cannot be overemphasized. Something which was right in the past may not be so absolute with new data or better understanding of the same old problem just like in order to stand at the same place you have to keep running! In the last two decades, there have been a lot of advancements in strabismus surgery secondary to more understanding of the disease and deviations. For a surgeon, it is important to know how, where, and when to use these advanced surgical techniques for helping the patients of strabismus. Although adjustable muscle surgery was described way back in 1970s, there are still many surgeons who are not either aware or not using this particular technique. Surgeries like loop myopexy came up after the better understanding of the pathophysiology of heavy eye syndrome. A similar surgery superior rectus transposition in Duane’s retraction syndrome came up just in the last decade and is now a well-­ accepted technique in selected cases. The techniques described in this book may not be recent, but we have revisited some surgeries which are not commonly performed and have tried to cover as many as possible. There is always a scope for improvement, addition, and innovation at all levels, and it would be good to know and have the feedback of readers about more surgeries that could be added in future. Baroda, Gujarat, India 11th October 2022

Jitendra Jethani

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Contents

 Another Take in Strabismus Surgery: Adjustable Suture Techniques ��������   1 Srikanth Ramasubramanian and Meenakshi Swaminathan  Anterior Ciliary Vessel Sparing Procedure in Strabismus Surgery��������������  15 Nitin Jain  Recent Advances in Inferior Oblique Strabismus Surgeries ������������������������  23 Jitendra Jethani and Shruti Nishanth  Superior Oblique Split Lengthening (SOSL) Surgery ����������������������������������  35 Jitendra Jethani  Lateral Rectus Transposition in Third Nerve Palsy���������������������������������������  41 Jaspreet Sukhija and Savleen Kaur  Periosteal Fixation for Exotropic Duane Retraction Syndrome��������������������  45 Medha Sharma, Rohit Saxena, and Pradeep Sharma Superior Rectus Transposition��������������������������������������������������������������������������� 49 Pratik Chougule and Ramesh Kekunnaya  Loop Myopexy for Strabismus Fixus ��������������������������������������������������������������  59 Shashikant Shetty and Shruti Agarwal  Plications and Miniplications for Small Angle Strabismus����������������������������  71 Jitendra Jethani  Globe Fixation in Complete Third Nerve Palsy����������������������������������������������  77 Pradhnya Sen and Elesh Jain True Muscle Transplantation for Very Large Angle Esotropia Strabismus����������������������������������������������������������������������������������������  87 Jitendra Jethani  Adjustable Faden: A Unique Strabismus Surgery������������������������������������������  93 Jitendra Jethani

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Another Take in Strabismus Surgery: Adjustable Suture Techniques Srikanth Ramasubramanian and Meenakshi Swaminathan

1 Introduction Adjustable suture strabismus surgery is a technique whereby the alignment of the eyes can be titrated post-strabismus surgery to achieve the desired position postoperatively. This is usually done in two stages. In the first stage, the strabismus surgery is performed using a technique whereby sutures are tied in an adjustable manner. The second stage consists of fine-tuning of alignment using adjustable knots during a variable postoperative period. This procedure is meant to improve ocular alignment both short and long term, by giving a second chance to correct overcorrections or undercorrections early after surgery.

2 History The history of adjustable surgery in strabismus dates back to the early 1900s when Bielschowsky had first described an adjustable procedure in 1907 in great detail [1]. The father of modern adjustable sutures is Jampolsky who described in 1975, a procedure wherein he tied a bow tie suture on the operated muscle, which was 4–24 h later adjusted and converted to a permanent knot [2].

S. Ramasubramanian (*) · M. Swaminathan Medical Research Foundation, Sankara Nethralaya, Chennai, Tamil Nadu, India

© Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_1

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Ever since the earlier descriptions of adjustable sutures, there have been countless modifications reflecting different needs and styles.

3 Indications There are certain situations where the use of adjustable sutures at the time of strabismus surgery can be extremely useful [3–6]. 1. Restrictive strabismus (Graves’ disease, scleral buckle, or anesthetic myotoxicity) 2. Previous trauma or surgery 3. Slipped, lost, or disinserted muscles 4. Incomitant deviations (Duane syndrome, Moebius syndrome, myasthenia gravis, or paralytic strabismus) 5. Combined horizontal, vertical, and torsional deviations 6. Any long-standing complex strabismus 7. “Any patient who can cooperate”—pass the “Q tip test”

4 Patient Selection Any patient who can cooperate for a Forced Duction Test (FDT), Goldmann applanation tonometry and pass the “Q tip test” (manipulation of the nasal or temporal bulbar conjunctiva with a cotton bud without anesthesia) can be considered as a potential candidate for adjustable surgery and that they can potentially tolerate the postop suture adjustment. A few contraindications for the surgery would include: 1. Very thin friable extraocular muscles 2. Uncooperative patients 3. Mentally challenged patients 4. Thyroid Eye Disease-induced Strabismus (relative contraindication)

5 Conventional Technique Earliest described techniques for adjustable sutures are the “Bow tie” and “sliding noose.”

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Fig. 1  Adjustable bow tie

5.1 Bow Tie This is the most popular adjustable technique. After scleral passes, the sutures attached to the muscle pole sutures are tied to each other using a bow tie, as with a shoelace. During adjustment, the bow is untied, the muscle position adjusted, and the bow is retied. Once the desired alignment is obtained, the bow is cut and converted to a square knot [7] (Fig. 1).

5.2 Cinch or Sliding Noose Technique In this technique, the pole sutures are positioned to emerge from the sclera tunnels 1 mm apart, with the ends secured to each other with an overhand knot. A noose is then created by tying a separate piece of suture around the pole sutures with a square knot which is slid across the muscle sutures for manipulation of the noose during adjustment. Once the desired alignment is obtained, most surgeons secure the pole sutures to each other with a permanent square knot and trim the noose.

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a

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Fig. 2  Sliding noose

A study comparing the force required to tighten a sliding noose among various types of noose knots: the sliding noose knot with a double wrap of suture (Fig. 2), the cinch knot with a single throw on both sides of the pole suture (Fig. 3) and a single-throw square knot (Fig.  4), has been done and concluded that the sliding noose knot generates the most frictional force and also maintains the most friction after subsequent repositioning [8].

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Fig. 3  Cinch knot technique

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Fig. 4  Square knot technique

6 Modified Techniques 6.1 Short Tag Noose The “short tag noose” technique replaces long sutures with short tags that can be left under the conjunctiva after adjustment. This is a variation of the sliding noose technique except for the fact that a short suture end would be left after the procedure and would not be necessary to cut off the excess suture the following day at the time of adjustment. The short tag noose technique, therefore, simplifies the logistics of suture adjustment and avoids the need for sedation in children who do not require adjustment [9].

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6.2 Guyton’s Technique This technique was a sliding noose that left no additional suture material beneath the conjunctiva and was described in 2003. No excess suture material remains after adjustments have been completed, helping to reduce discomfort, inflammation, and scarring [10]. The noose knot was tied around the muscle sutures in the operating room and later during the adjustment slid forward or backward along the muscle sutures until the desired ocular alignment is obtained. The muscle sutures are then tied down on top of the noose knot. The noose was basically a “cow hitch” with a “handle” for removal where a clove hitch with three slip knots was constructed that allows not only for the noose to be adjusted to the surgical dosage, but also to be completely removed once the muscle is in proper position and has been tied down.

6.3 Ripcord Technique The procedure allows a one-time, single-stage adjustment of a recessed or resected muscle in a predetermined, all-or-nothing step facilitated by releasing a ripcord suture referred to as the “ripcord adjustable suture technique” because of its all-or-­ nothing effect, a feature similar to that of pulling the ripcord to deploy a parachute. A conventional resection or recession is done after which the suture ends are secured into a knot, but only after suspending the muscle to 1.5–2  mm posterior to the desired final position of the muscle. A second adjunct suture is placed anteriorly in a position that will be readily accessible postoperatively, if an adjustment is needed. After passing the ripcord suture through the sclera, the needle is then loaded backward in the needle driver and is passed under the previously tied muscle suture knot. The posterior end of the needle is advanced first to prevent damage the overlying muscle suture and underlying sclera. The ripcord suture ends are then tied either in a square knot or in a small bowknot. As the ripcord suture is tied, tension is exerted on the muscle suture, advancing the muscle to the new scleral insertion (Fig. 5). The amount of additional recession cannot be titrated, in this all-or-nothing step. If alignment is satisfactory, the ripcord suture is left intact [7].

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Fig. 5  Ripcord technique

7 Adjustable in Children 7.1 Releasable Adjustable in Children This technique is especially useful in children where cooperation is a major issue. After conventional muscle recession, the muscle is secured to the sclera at the predetermined recession position after suspending it 1.50–2.00 mm farther. A second, releasable suture was placed at the original insertion site, passed under the

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Fig. 6  Releasable adjustable suture

previously tied muscle suture knot, and tied in a strengthened loop knot, advancing the muscle to the new scleral insertion (Fig. 6). The looped end was left long enough to be kept in the inferior fornix. The next day, if the child was undercorrected, intranasal midazolam was given and the releasable suture was drawn out, providing additional muscle recession. This is also an all-or-none technique to correct any undercorrections immediately post-op [11].

7.2 Scleral Pass Adjustable Sutures One horizontal muscle was placed on an adjustable suture. A separate slipknot was placed around the sutures connected to the muscle (the pole sutures). The muscle was allowed to hang back from the partial-thickness scleral tunnels in the original insertion line; the amount hung back on was based on preoperative measurements of the patient’s strabismus. A separate partial-thickness scleral pass was then made in the area of the fornix incision such that there was an additional 6 or 7 mm of suture left beyond the adjustable knot. The pole sutures were then tied, and any excess suture was trimmed to approximately 2 mm from the knot (Fig. 7). Tying the knot secured the muscle so that it could not slip. The conjunctiva was then closed with 7-0 gut chromic sutures, thereby covering all the sutures and the muscle. Once the child was sedated, the area of the fornix incision was opened, and the pole sutures were exposed. The muscle was adjusted using standard techniques for adjustable sutures [12]. The pole sutures were then tied with tying forceps, the sutures trimmed to 11 within 2 mm of the knot, and the fornix incision closed with sutures.

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Fig. 7  Scleral pass adjustable

8 Adjustable Superior Oblique Procedures 8.1 Adjustable Harada-Ito The Harada-Ito procedure has been used for years to improve the torsional deviation in patients with SO palsy without substantial vertical deviation, but accurate guidelines for how much the SO muscle should be tightened are not available. Metz and Lerner performed an adjustable Harada-Ito technique where the suture was sewn through the anterior fibers of SO tendon, which were then severed from the globe [13]. The anterior half of the tendon was reattached to the eye 4 mm anterior and 6 mm temporal to the original insertion. A sliding noose of absorbable suture was then secured anteriorly to the SO suture attachment (Fig. 8). The conjunctiva was closed and the long ends of the suture were extended 5 mm to allow for adjustment (and tucked into the cul-de-sac). During adjustment, the noose was repositioned as required. Nishimura and Rosenbaum described an adjustable Harada-Ito procedure that used a split tendon approach and thus did not require detachment of the SO tendon fibers [14]. They performed adjustment 1 day after surgery, adjusting for zero torsion on double Maddox rod testing in primary position.

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Fig. 8 Adjustable Harada-Ito

8.2 Adjustable Superior Oblique Tendon Advancement This technique is useful in the independent adjustment of the vertical and torsional components after superior oblique tendon advancement. The tendon of the superior oblique is disinserted and reattached with or without resection of the tendon depending on laxity, at the superior edge of the lateral rectus muscle 8–10 mm posterior to its insertion [15–17]. Adjustments of the advancement with a sliding noose technique, symmetrically or asymmetrically, for torsional or vertical residual strabismus can be done postoperatively.

9 Semiadjustable Sutures Kushner described a “semiadjustable” technique in an effort to secure the inferior rectus muscle more firmly to the globe (and against gravity), thus reducing the incidence of muscle slippage while preserving the potential for adjustment [18]. The process involves attaching the corners of the IR muscle firmly to sclera with fixed sutures while placing the center of the muscle on an adjustable suture (Fig. 9). A trade-off of this procedure is that it limits the capability to increase the amount of recession at the time of adjustment. By targeting an initial overcorrection, this downside is limited.

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Fig. 9  Semi-adjustable sutures

10 Timing of Adjustment The timing of when to adjust the adjustable is controversial. Most surgeons perform the suture adjustment within the first 24 h after surgery. Spierer found that muscle adjustments performed 8 or 24  h after horizontal strabismus surgery had similar outcomes [19]. Velez et al. also found no difference between performing adjustment on the same day of surgery or the next day with respect to pain before, during, or after adjustment, to the ease of performing the adjustment, and to the final alignment [20]. Even intraoperative suture adjustment is practiced. Yi et al. found that intraoperative adjustment was useful for comitant horizontal strabismus surgery and provided the opportunity to avoid a large overcorrection, especially in cases of moderate-­ angle horizontal muscle surgery [21]. Cogen et al. stated that intraoperative adjustment offers many practical benefits to both the surgeon and patient, such as sterile conditions and availability of all ancillary personnel and instruments if needed [22]. In addition, the cost of extended time for patients and staff in the recovery room is eliminated. But some studies recommend otherwise as there is a major difference in measurements immediately post-operative versus at 24 h post-surgery.

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Adjustable suture surgery has not gained universal acceptance, partly because evidence of its advantages is lacking [23], and partly because the learning curve for accurate decision-making during suture adjustment may span a decade or more.

11 Conclusions Adjustable sutures do not guarantee excellent results, but they can be especially useful when more than usual uncertainty exists about the expected degree of correction, and all strabismus surgeons should be capable of offering this technique to their patients.

References 1. Bielschowsky A. Die neueren Anschauungen über Wesenund Behandlung des Schielens. Med Klin. 1907;iii:335–6. 2. Jampolsky A.  Strabismus reoperation techniques. Trans Sect Ophthalmol Am Acad Ophthalmol Otolaryngol. 1975;79:704–17. 3. Leuder GT, Scott WE, Kutschke PJ, Keech RV.  Long term results of adjustable strabismus surgery for strabismus secondary to thyroid ophthalmopathy. Ophthalmology. 1992;99:993–7. 4. Ogut MS, Onal S, Demirtas S. Adjustable suture surgery for correction of various types of strabismus. Ophthalmic Surg Lasers Imaging. 2007;38:196–202. 5. Tripathi A, Haslett R, Marsh IB.  Strabismus surgery: adjustable sutures-good for all? Eye. 2003;17:739–42. 6. George ND. Adjustable sutures: who needs them? Eye. 2003;17:683–4. 7. Nihalani BR, Hunter DG. Adjustable suture strabismus surgery. Eye. 2011;25(10):1262–76. https://doi.org/10.1038/eye.2011.167. 8. Miller KE, et al. Slipping the knot: a comparison of knots used in adjustable suture strabismus surgery. J AAPOS. 2015;19:496–9. 9. Nihalani BR, Whitman MC, et al. Short tag noose technique for optional and late suture adjustment in strabismus surgery. Arch Ophthalmol. 2009;127(12):1584–90. 10. Deschler EK, Irsch K, Guyton KL, Guyton DL. A new, removable, sliding noose for adjustable-­ suture strabismus surgery. J AAPOS. 2013;17(5):524–7. 11. Hakim OM, et al. Releasable adjustable suture technique for children. J AAPOS. 2005;9:386–90. 12. Mark Engel J, et  al. Adjustable sutures in children using a modified technique. J AAPOS. 2004;8:243–8. 13. Metz HS, Lerner H. The adjustable Harada-Ito procedure. Arch Ophthalmol. 1981;99:624–6. 14. Nishimura JK, Rosenbaum AL. The long-term torsion effect of the adjustable Harada-Ito procedure. J AAPOS. 2002;6:141–4. 15. Bata BM, Leske DA, Holmes JM. Adjustable bilateral superior oblique tendon advancement for bilateral fourth nerve palsy. Am J Ophthalmol. 2017;178:115–21. 16. de Faber JT, editor. Strabismus 2006 proceeding of the joint congress the Xth meeting of the ISA. Rio de Janeiro: Cultura Medica; 2006. p. 303–7. 17. Ludwig IH, Clark RA, Stager DR Sr. New strabismus surgical techniques. J AAPOS. 2013;17(1):79–88. 18. Kushner BJ.  An evaluation of the semiadjustable suture strabismus surgical procedure. J AAPOS. 2004;8:481–7. 19. Spierer A. Adjustment of sutures 8 vs 24 hours after strabismus surgery. Am J Ophthalmol. 2000;129:521–4.

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20. Velez FG, Chan TK, Vives T, Chou T, Clark RA, Keyes M, Rosenbaum AL, Isenberg SJ. Timing of postoperative adjustment in adjustable suture strabismus surgery. J AAPOS. 2001;5:178–83. 21. Yi JH, Chung SA, Chang YH, Lee JB. Practical aspects and efficacy of intraoperative adjustment in concomitant horizontal strabismus surgery. J Pediatr Ophthalmol Strabismus. 2010:48. 22. Cogen MS, Guthrie ME, Vinik HR.  The immediate postoperative adjustment of sutures in strabismus surgery with comaintenance of anesthesia using propofol and midazolam. J AAPOS. 2002 Aug;6(4):241–5. 23. Hunter DG. Do we need evidence for everything. Am Orthopt J. 2010;60:59–62.

Anterior Ciliary Vessel Sparing Procedure in Strabismus Surgery Nitin Jain

1 Anatomy and Physiology The blood supply to the anterior segment is derived from the long posterior ciliary arteries, the anterior ciliary arteries, and the conjunctival arteries (Fig. 1). The anterior ciliary arteries are thought to provide approximately 70% of the blood supply to the anterior segment with the long posterior ciliary arteries supplying most of the remainder, and the conjunctiva arteries supplying a minor component of the blood supply to this region of the eye [1]. The anterior ciliary arteries are derived from the ophthalmic artery where they begin as the muscular arteries that supply the rectus muscles before dividing into the anterior ciliary arteries. They actually emerge from within the substance of the muscle a short distance posterior to the transition point from muscle to tendon. The vessel then assumes a position on the surface, serving as a conduit for blood flow between the deeper orbital region and the globe. The anterior ciliary arteries travel along the tendons of the rectus muscles and give off anterior conjunctival arteries just before piercing the sclera. The superior, medial, and inferior rectus muscles each carry two anterior ciliary arteries, while the lateral rectus muscle generally carries only one (Fig. 2). The surface location of the vessel as well as their envelopment by the loose connective tissue provide a potential plane of surgical dissection between the vessel and the underlying muscle and sclera. Anatomy and blood flow have been investigated using a variety of techniques including post-mortem injection studies as well as in vivo fluorescein angiography and indocyanine green video angiography.

N. Jain (*) Elite Children Eye Care and Squint Clinic, Surat, Gujarat, India

© Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_2

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16 Fig. 1  Normal anatomy of the eye

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Fig. 2  The circulation of the eye shows two anterior ciliary arteries of superior rectus, inferior rectus and medial rectus and one anterior ciliary artery of the lateral rectus muscle

2 Anterior Segment Ischemia 2.1 Incidence Severe anterior segment ischemia is a rare but potentially sight-threatening complication following strabismus surgery. The incidence of anterior segment ischemia is unknown but a survey of pediatric ophthalmologists published in 1986 estimated that significant anterior segment ischemia occurred in approximately 1 in 13,000 cases [2]. This reported incidence probably underestimates its true occurrence, as mild cases of anterior segment ischemia almost certainly occur without clinical detection. The low incidence of clinically significant anterior segment ischemia probably reflects the protection offered by the rich collateral blood supply from both the long posterior ciliary and anterior ciliary arteries that continue to supply blood to the anterior segment when the anterior ciliary and conjunctival arteries are disrupted. The blood supplied by the posterior ciliary arteries, however, is probably not

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a significant factor, as evidenced by the fact that anterior segment ischemia does not occur with occlusion of only the posterior ciliary arteries [3]. Therefore, it appears that surgery of the extraocular muscles, specifically the rectus muscles, leads to anterior segment ischemia in at-risk patients, by alteration of the anterior segment circulation through disruption of the anterior ciliary arteries. Disinsertion of a single vertical rectus muscle will result in hypoperfusion to the region of the anterior segment adjacent to the detached muscle. An anterior ciliary artery that has been detached from the globe does not reestablish a direct communication with the distal aspect of the vessel [4]. The circulation that is reestablished to the anterior segment is not equivalent to that which was present prior to disruption of the vessel, leaving the patient with a net loss of blood flow to the anterior segment even after maximum collateral circulation has been established. This is important to keep in mind when planning surgery on patients who have had previous strabismus surgery.

2.2 Risk Factors 2.2.1 Increasing Age: Elderly Patients Disorders affecting the blood flow Hemoglobinopathies Leukemia, polycythemia Hypertension Diabetes Atherosclerosis 2.2.2 Orbital and Ocular Disorder Thyroid orbitopathy Uveitis Congenital anomaly like absence of some rectus muscle 2.2.3 Prior Ocular Surgery Retinal surgery Strabismus surgery on rectus muscles 2.2.4 Proposed Surgery Increasing number of rectus muscles in one eye like three or four Limbal incision

2.3 Sign and Symptom Anterior segment ischemia can range from mild and self-limiting to severe and vision threatening. Anterior segment ischemia has been classified into four grades of severity as by Lee and Olver [5].

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2.4 Classification of Anterior Segment Ischemia Grade 1 Reduced iris perfusion Grade 2 Pupillary abnormalities Grade 3 Postoperative uveitis Grade 4 Keratopathy (mild to severe).

2.5 Treatment Mild anterior segment ischemia is generally treated with topical agents and more severe cases are often treated with oral corticosteroids. The use of hyperbaric oxygen was reported by de Smet and co-workers [6] in a patient in whom the use of corticosteroids was contraindicated. Animal studies have shown that the use of prostaglandin synthetase inhibitors, such as diclofenac sodium, may have a role in the prevention and/or treatment of anterior segment ischemia [7]. There are no data to suggest that any specific treatment of anterior segment ischemia improves the outcome.

2.6 Prevention of ASI 2.6.1 Strategies to Prevent Anterior Segment Ischemia Limit the number of rectus muscles that are detached from the globe Preservation of anterior ciliary arteries Staging surgical procedures Utilization of a fornix incision Nonstandard techniques, such as mechanical fixation of the globe

3 Anterior Ciliary Vessel Sparing Surgery When surgical correction of strabismus requires operation on multiple rectus muscles, or on the third or fourth muscle of a patient who has undergone previous rectus muscle surgery and who is at risk for anterior segment ischemia, a potentially useful approach is surgical sparing of the anterior ciliary arteries. A nearly absolute contraindication to performing successful vessel-sparing surgery is prior surgery on the same muscle. Because the anterior ciliary vessels do not recanalize, vessel sparing is not possible during reoperation. Scar tissue and adhesion may preclude successful dissection and preservation of anterior ciliary vessels.

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3.1 Surgical Technique 3.1.1 Incision Fornix incision is better as it requires less dissection anterior to the tendon insertion. This reduces the chance of damaging the vessel in front of the tendon insertion and preserves the perilimbal conjunctival vessel also. 3.1.2 Rectus Muscle Isolation As the muscle insertion is exposed care is taken to avoid damaging the vessels on the surface of the tendon or on the surface of the sclera. Intermuscular septum is cut carefully. 3.1.3 Preserving the Vessels (Fig. 3a, b) Identify the big vessels, especially on the edge of the muscle. Now try to create a surgical dissection plane is beneath each vessel using microvascular forceps to grasp the connective tissue adjacent to the vessel and making a spreading motion with the vannas scissor. Sometimes it is easier to have some tissue along with this particular vessel. It is easier to lift the vessel off the tendon 2–4 mm posterior to the tendon insertion. Dissection proceeds posteriorly to the point where the vessels emerge from the muscle and anteriorly just in front of the tendon insertion. Direct grasping of the vessel is avoided and traction is obtained by grasping the surrounding tissue. Vessel patency can be observed intraoperatively by directly visualizing the vessel refilling.

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Fig. 3 (a, b) Shows the isolation of the vascular bundle of the rectus muscle

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3.2 Completing the Rectus Muscle Procedure 6-0 Vicryl is passed through the muscle taking care not to touch the vessel directly. Tenotomy can be done by using the fine tips of the corneo scleral scissors to avoid damage to the dissected vessels. Traction should be reduced to avoid abrupt tendon snap back which may cause inadvertent vessel damage. For resections, single suture techniques are preferred to reduce the risk of vessel damage. Recession, resection or transposition is carried out routinely (Fig. 4). Surgical technique determines the success or failure of the procedure. The rate of inadvertent vessel damage during surgery is 10%. Successfully spared vessels may be damaged during the cutting of the last few tendon fibers. If well recognized, it provides the surgeon an opportunity to continue, modify, or terminate the procedure if the risk of ASI is high.

Fig. 4  Isolated anterior ciliary vessels after cutting the muscle

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References 1. Wilcox LM, Keough EM, Connolly RJ, Hotte CE. The contribution of blood flow by the anterior ciliary arteries to the anterior segment in the primate eye. Exp Eye Res. 1980;30:167–74. 2. France TD, Simon JW. Anterior segment ischemia syndrome following muscle surgery: the AAPO&S experience. J Pediatr Ophthalmol Strabismus. 1986;23:87–91. 3. Virdi PS, Hayreh SS. Anterior segment ischemia after recession of various recti. An experimental study. Ophthalmology. 1987;94:1258–71. 4. Olver JM, Lee JP.  The effects of strabismus surgery on anterior segment circulation. Eye. 1989;3(Pt 3):318–26. 5. Lee JP, Olver JM. Anterior segment ischaemia. Eye. 1990;4(Pt 1):1–6. 6. de Smet MD, Carruthers J, Lepawsky M. Anterior segment ischemia treated with hyperbaric oxygen. Can J Ophthalmol. 1987;22:381–3. 7. Ino-ue M, Shirabe H, Yamamoto M. Blood-aqueous barrier disruption in experimental anterior segment ischemia in rabbit eyes. Ophthalmic Res. 1999;31:213–9.

Recent Advances in Inferior Oblique Strabismus Surgeries Jitendra Jethani and Shruti Nishanth

1 Introduction The Inferior oblique muscle originates from the periosteum of the orbital plate of maxilla near the lacrimal fossa (Fig. 1). It is 37 mm long, travels lateral and posterior at an angle of 51° to the visual axis, and inserts 10  mm behind the inferior border of the lateral rectus insertion [1]. It is an extorter, an elevator in adduction, and an abductor. It is supplied by the inferior division of the oculomotor nerve, which enters the inferior oblique as a taut neurovascular bundle 2 mm lateral to the temporal margin of the inferior rectus. According to Demer [2], inferior oblique overaction can be better described as “overelevation in adduction,” as there is no muscle hypertrophy, but rather a combination of muscle and pulley factors that cause the overelevation. There are several procedures described for the correction of overelevation in adduction caused by inferior obliques like myotomy/myectomy, denervation/extirpation, graded recession, anterior transposition, and Mim’s modification of anterior transposition surgery [3]. The recent advances in technique are anterior and nasal transposition surgery, nasal myectomy, orbital wall fixation, and muscle belly transposition.

J. Jethani (*) Baroda Children Eyecare and Squint Clinic, Vadodara, Gujarat, India S. Nishanth M.N. Eye Hospital Pvt. Ltd., Chennai, Tamil Nadu, India

© Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_3

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51 degrees

A-Origin of inferior oblique

Lateral Rectus

10 mm

B- Insertion of inferior oblique

Inferior Rectus

C- Neuro-vascular bundle

Fig. 1  Origin and insertion of Inferior oblique muscle

2 Brief History The earliest surgery on inferior oblique was described in 1906 by Duane [4], where he performed a transcutaneous tenotomy of the muscle. The preferred procedures performed now are myectomy, graded recessions, and anterior transpositions. Myectomy [5, 6] involves clamping the muscle belly at two points 5  mm apart, removing the intervening muscle and cauterizing the ends (Fig. 2). This procedure can now be considered only in select conditions like severe overactions, inferior rectus aplasia, traumatic inferior rectus avulsions, and residual inferior oblique overactions after surgery. Inferior Oblique recession was first described by White et al. [7] in 1942. Due to its unique origin and insertion and the peculiar placement, it cannot be recessed beyond 12 mm theoretically (Fig. 3). A graded response surgical dosage table was described by Apt and Call [8] where the insertion point can be measured from the inferior rectus and titrated based on the grade of overelevation (Figs. 4 and 5). In both these procedures, postoperative residual overaction ranging from 1.7 to 5% have been reported [9, 10]. Even postoperative asymptomatic inferior oblique underaction can be found in about 35% cases [9]. The Elliot and Nankin’s Anterior Transposition surgery [11] is a strong procedure that involves attaching the inferior oblique muscle fibers along the temporal border of inferior rectus insertion (Figs.  5 and 6). However, a significant “Anti-­ elevation effect” has been reported in this technique, creating a “Y pattern exotropia” and excyclotorsion in up-gaze [12, 13]. By attaching the fibers anteriorly, the taut neurovascular bundle takes over as the functional origin of the muscle, sometimes creating an undesirable limitation of elevation beyond midline. To minimize

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Lateral Rectus

Inferior Rectus

Fig. 2  Inferior oblique myectomy—5 mm muscle is clamped and removed

5 mm

4 mm

Lateral Rectus 12 mm Inferior Rectus

C-Neuro-vescular bundle

Fig. 3  Pseudo insertion and true insertion of Inferior Rectus. Maximum recession effect of Inferior oblique can be 12 mm

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Fig. 4  Apt & Call’s surgical dosage table for graded recession

this effect, this surgery can be graded depending on the amount of overelevation in adduction [14]. Another modification is to suture the anterior fibers of the inferior oblique at the insertion of the inferior rectus and posterior fibers 5 mm inferiorly, along the temporal border of the lateral rectus (Figs. 5 and 7). This can minimize pull on the posterior fibers by the neurovascular bundle, hence minimizing anti-elevation.

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Lateral Rectus

Inferior Rectus

B

A C

D

E

Fig. 5 (a) Fink’s recession—muscle is placed 6 mm posterior and inferior to inferior border of lateral rectus insertion—corresponds to 8 mm of pure recession effect. (b) Apt and Call’s point where muscle is placed 6 mm inferior to temporal border of true insertion of inferior rectus—corresponds to maximum recession of 12 mm. (c) Scheie Parks point where muscle is placed 3 mm inferior and 2  mm lateral to temporal border of inferior rectus true insertion—corresponds to 10 mm recession effect with mild anteropositioning effect. (d) Elliot & Nankin’s Anterior transposition procedure where muscle is attached at the temporal border of true insertion of inferior rectus. (e) Mim’s anterior transpositioning where muscle is attached 1 mm or more anterior to the temporal border of inferior rectus true insertion

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Inferior Rectus

Lateral Rectus

rior Infe ique l Ob

Fig. 6  Elliott & Nankin’s Anterior transposition surgery, where the inferior oblique muscle is attached at the temporal border of inferior rectus. The taut neurovascular bundle acts as the new functional origin creating ‘Anti-elevation’ effect

Recent Advances in Inferior Oblique Strabismus Surgeries Fig. 7  Modified Elliott & Nankin’s surgery where the posterior fibers of the muscle are attached 5 mm inferior to the anterior fibers along the temporal border of inferior rectus— this reduces the pull of the taut neurovascular bundle, thereby reducing the ‘anti-elevation’ effect

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Inferior Rectus

Lateral Rectus

rior Infe ique l b O

3 Recent Advances in Surgical Technique 3.1 Anterior and Nasal Transposition Surgery This recently described procedure can be an effective at minimizing anti-elevation, while correcting higher degrees of overelevation and excyclotorsion. This was first described by Stager [15] in 2001.

3.1.1 Principle Placing the insertion of the inferior oblique muscle on the nasal side of the inferior rectus muscle brings it nasal to the y-axis of Fick and anterior to the x-axis, thus making it an intorter and a tonic depressor in adduction, respectively. This procedure can correct hypertropia in primary gaze and higher grades of overelevation in adduction, while minimizing the effect of “Anti-elevation.” 3.1.2 Indications • Superior oblique palsy • Dissociated vertical deviation • V pattern exotropia • Grade 4 overelevation in adduction • Excyclotorsion • Absent Superior oblique tendons

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3.1.3 Technique An exaggerated forced duction test should be done initially. The inferior oblique muscle is approached through an inferotemporal fornix incision. After dissection through conjunctiva and tenon’s tissue, the temporal aspect of the inferior oblique muscle is hooked and disinserted close to insertion. The ends are cauterized and tagged with 6-0 double-armed polyglactin 910 sutures and brought onto the nasal side of the inferior rectus. The posterior fibers are then reattached to the sclera 2 mm nasal and 2 mm inferior to the nasal border of the inferior rectus, while the anterior fibers are attached 3 mm nasal to the initial suture (Fig. 8).

Inferior Rectus

Lateral Rectus

2 mm

rior Infe ique l Ob

2 mm

Fig. 8  Stager’s Anterior and Nasal transposition, where muscle is attached 2  mm inferior and nasal to nasal border of inferior rectus insertion. This changes the muscle into an anti-elevator and intorter in adduction

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Care is to be taken in the following aspects: • As the vortex vein lies adjacent to the inferior oblique muscle belly, it is important to use only blunt dissection while manipulating and isolating the inferior oblique muscle. Any inadvertent nick of the vortex vein can cause significant bleeding. • The orbital fat pad is also situated close to the inferior oblique, and sharp dissection could potentially cause a prolapse. This might lead to “Fat adherence syndrome” postoperatively, which can contribute to up-gaze restriction. • As, the macula is situated just 2 mm away from the insertion of inferior oblique, it is recommended to first clamp the muscle, disinsert it, cauterize the ends, then tag the muscle with sutures. Postoperatively, a mean correction of 14–17 PD hypertropia and 18.5° of excyclotorsion has been reported [16, 17]. A study by Farid [16] compares anterior transposition to antero-nasal transposition surgery, and found both procedures to be equally effective in correcting hypertropia, with antero-nasal transposition performing better in DVD patients.

3.1.4 Complications Consecutive hypotropia [18], limitation in elevation in adduction, consecutive exotropia, and torsional diplopia [16] are reported complications, as the procedure might mechanically restrict elevation of the eye more in adduction than in abduction. The effects of the procedure on alignment are more pronounced in up-gaze, thereby increasing the risk of induced torsion and esotropia in up-gaze.

3.2 Orbital Wall Fixation of Inferior Oblique This was first described by Ela-Dolman et al. [19], where the muscle can be sutured to the periosteum using nonabsorbable sutures. The periosteum can be accessed through a lateral wall orbitotomy, through blunt dissection. It was found to correct  >15 PD of hypertropia. This can be tried in residual overactions and higher grades of overelevation in adduction.

3.3 Muscle Belly Transposition This procedure was described by Yang et al. [20]. In small angle hypertropia, the inferior oblique muscle belly (around 11 mm from the insertion) can be transposed (without disinserting) and attached at about 5 mm inferior to the nasal insertion of inferior rectus, using 6-0 double-armed absorbable polyglactin 910 sutures (Fig. 9). The authors have limited experience with this particular procedure.

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Inferior Rectus

Lateral Rectus

rior Infe ique l b O

5 mm

Fig. 9  Inferior oblique muscle belly transposition where the muscle is tagged around 11 mm form its insertion and sutured 5 mm below the nasal border of the inferior rectus

3.4 Adjustable Inferior Oblique Surgery Despite the inferior oblique being a “self-adjusting” muscle, there are certain situations, where perfect alignment might be essential such as diplopia, residual overactions, and grade 4 overelevations. In such cases, an adjustable bow tie suture may be placed at the reattachment site, which can allow for further modifications in the immediate postoperative period. The placement and bow tie suture is similar to those done in rectus muscle adjustment and are typically done in anterior transposition of inferior oblique. The problem with adjustable inferior oblique surgery is that the muscle has two vectors horizontal and vertical when it comes to weakening. Whereas the vertical

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placement with regards to inferior rectus attachment gives the anti-elevation effect, the horizontal placement also affects the recession and anti-elevation effect. The adjustment in inferior oblique recession can be done only in the vertical component and the prime indication is anterior transposition whereas the surgeon feels that anti-elevation may occur or if there is a small asymmetric vertical angle preoperative and surgeon wants to correct it in bilateral surgery.

3.5 Inferior Oblique Nasal Myectomy This procedure, described by Ludwig et al. [21] is indicated as a secondary procedure, in residual inferior oblique overactions post anterior transposition surgeries or recessions. It weakens the inferior oblique muscle nasally from the origin, while preserving the temporal fibers. As the taut neurovascular bundle acts as a new point of origin, the anti-elevation effect is maintained and the vascular supply is not compromised. An incision is made through Tenon’s capsule just temporal to the inferior rectus muscle and the muscle is retracted superiorly. A hook is placed under the inferior oblique muscle insertion just temporal to the inferior rectus muscle, and the muscle is pulled temporally. Another hook is then placed near the nasal border of the inferior rectus muscle to retract the capsule and muscle as far nasally as possible. The two hooks are separated as far as possible, and a hemostat is placed in the thicker portion of the inferior oblique near the nasal border of the inferior rectus muscle. The inferior oblique muscle is then disinserted as close as possible to its origin. No bleeding occurs from the nasal end that is attached to the orbital bone. The entire segment of inferior oblique muscle from its origin to the hemostat near the inferior rectus muscle is then removed. The newer advances in inferior oblique surgery are promising in terms of safety and outcomes. It is important that the surgeon chooses the appropriate procedure based on thorough clinical evaluation and surgical planning.

References 1. Von Noorden G. Summary of gross anatomy of extraocular muscles. In: Binocular vision and ocular motility 6th Ed. 2002;39−51. 2. Kono R, Demer JL.  Magnetic resonance imaging of the functional anatomy of the inferior oblique muscle in superior oblique palsy. Ophthalmology. 2003;110:1219–29. 3. Stager D, Dao LM, Felius J. Uses of the inferior oblique muscle in strabismus surgery. Middle East Afr J Ophthalmol. 2015;22:292–7. 4. Duane A. Tenotomy of inferior oblique and consideration of the conditions that may call for the operation. Br Med J. 1906;2(2400):1867–8. 5. Dyer JA. Tenotomy of the inferior oblique muscle at its scleral insertion. An easy and effective procedure. Arch Ophthalmol. 1962;68:176–81. 6. Parks MM. A study of the weakening surgical procedures for eliminating overaction of the inferior oblique. Trans Am Ophthalmol Soc. 1971;69:163–87. 7. White JW. Surgery of the inferior oblique at or near the insertion. Trans Am Ophthalmol Soc. 1942;40:118–26.

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8. Apt L, Call NB.  Inferior oblique muscle recession. Am J Ophthalmol. 1978;85(1):95–100. https://doi.org/10.1016/s0002-­9394(14)76672-­3. 9. Bhatta S, Auger G, Ung T, Burke J.  Underacting inferior oblique muscle following myectomy or recession for unilateral inferior oblique overaction. J Pediatr Ophthalmol Strabismus. 2012;49:43–8. 10. Elliot RL, Parks MM. A comparison of inferior oblique by anterior transposition or denervation-­ extirpation. Binocul Vis Eye Muscle Q. 1992;7:205–10. 11. Elliott RL, Nankin ST.  Anterior transposition of the inferior oblique. J Pediatr Ophthalmol Strabismus. 1981;18:35–8. 12. Kushner BJ.  Restriction of elevation in abduction after inferior oblique anteriorization. J AAPOS. 1997;1:55–62. 13. Stein LA, Ellis FJ. Apparent contralateral inferior oblique muscle overaction after unilateral inferior oblique weakening procedures. J AAPOS. 1997;1:2–7. 14. Guemes A, Wright KW. Effect of graded anterior transposition of the inferior oblique muscle on versions and vertical deviation in primary position. J AAPOS. 1998;2:201–6. 15. Stager DR Sr, Beauchamp GR, Stager DR Jr. Anterior and nasal transposition of the inferior oblique muscle: a preliminary case report on a new procedure. Binocul Vis Strabismus Q. 2001;16:43–4. 16. Farid MF. Anterior transposition vs anterior and nasal transposition of inferior oblique muscle in treatment of dissociated vertical deviation associated with inferior oblique overaction. Eye (Lond). 2016;30(4):522–8. 17. Saxena R, Sharma M, Singh D, Sharma P. Anterior and nasal transposition of inferior oblique muscle in cases of superior oblique palsy. J AAPOS. 2017;21(4):282–5. 18. Fard MA. Anterior and nasal transposition of inferior oblique muscle for dissociated vertical deviation associated inferior oblique overaction. J AAPOS. 2010;14:35–8. 19. Ela-Dalman N, Velez FG, Felius J, Stager DR Sr, Rosenbaum AL.  Inferior oblique muscle fixation to the orbital wall: a profound weakening procedure. J AAPOS. 2007;11(1):17–22. 20. Yang S, Guo X, Tien DR. Inferior oblique belly transposition for small angle hypertropia with inferior oblique overaction: a pilot study. J Pediatr Ophthalmol Strabismus. 2018;55(1):43–6. 21. Ludwig IH, Clark RA, Stager DR Sr. New strabismus surgical techniques. J AAPOS. 2013;17(1):79–88.

Superior Oblique Split Lengthening (SOSL) Surgery Jitendra Jethani

Superior oblique muscle is one of the most unique muscle used for ocular motility. The muscle is one of the longest with a very long tendon. The anatomic insertion is between the eyeball but the functional insertion is actually reflected from the trochlea which is situated anterior to the eyeball. The action of the muscle is intorsion and depression and it also aids in abduction along with the inferior oblique. Understandably, the overaction of the superior oblique muscle would lead to an A pattern mainly because of its abduction effect in downgaze, its intorsion effect causing the inferior rectus to be an abductor, especially in downgaze. The overaction of superior oblique may be seen with dissociated vertical deviation (DVD) as a complex of exotropia, DVD, and A pattern, also may be seen in primary overaction of superior oblique in infantile esotropia, occasionally superior oblique may be a tight muscle (may cause no pattern or a V pattern).

1 Other Surgeries for Superior Oblique Weakening (a) Tenotomy/Tenectomy of superior oblique [1, 2] A very strong surgery for weakening superior oblique. This may cause iatrogenic superior oblique palsy and is done mainly in large overaction of superior oblique muscle. Few authors have done this in conjunction with inferior oblique weakening in Brown’s syndrome. (b) Posterior tenectomy of superior oblique [3] A relatively weak surgery as this involves mainly removing a part of superior oblique at the insertion level and leaving 1/8th of the anterior fibres of superior oblique. The anterior fibres of superior oblique are meant for the torsional effect J. Jethani (*) Baroda Children Eye Care and Squint Clinic, Alkapuri, Vadodara, Gujarat, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_4

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and retaining those fibres would be essential to prevent any postoperative ­diplopia by inducing unwanted torsional changes. The surgery is done mainly for mild-to-moderate superior oblique overaction with A pattern. (c) Silicone expander/Chicken sutures [4, 5] These surgeries are similar to superior oblique split lengthening and work mainly on the principle of elongating the total length of the muscle and thereby weakening it on the basis of muscle tension. The overall length of the muscle is increased and the effective power of the muscle is thereby reduced. The surgery is mainly meant for patients with Brown’s syndrome. Chicken sutures are a modification of silicone expander where it could be adjustable. The surgery is a good option for all cases of superior oblique overaction except that there is always a risk of extrusion of silicone band used for the surgery. The chicken sutures’ surgery do have a risk of ends of superior oblique sticking to the sclera and causing underaction or overaction of the muscle. (d) Superior oblique translational recession [6, 7] Superior oblique translational recession is a strong but fixed procedure where the muscle insertion is placed 6 mm nasal to superior rectus and around 12 mm from the limbus. The torsional change due to this is large up to 12°. It is a good procedure for large A pattern and a large superior oblique overaction. Superior oblique split lengthening [8] is a relatively uncommon procedure performed for superior oblique overaction and for brown’s syndrome [9–12]. It is similar to the silicone expander with an advantage that the tendon is expanded with its own tissue. The change in torsion is also comparable to silicone expander surgery for superior oblique overaction [10] with an advantage of being able to grade the surgery also just like chicken suture and silicone expander.

2 Surgical Technique The superior oblique muscle was approached through a superior fornix conjunctival incision preferable a temporal incision. The temporal incision is advantageous as the fornix in the upper temporal area is bigger and the forniceal shortening may not occur there which may occur in the nasal side. The superior rectus muscle is isolated first and then the conjunctival is retracted in such a way that the nasal part of the superior rectus is now under direct visualization. Next, a small buttonhole is created close to the nasal insertion of the superior rectus and with the two-hook technique superior rectus is hooked completely with Jameson’s hooks. The superior oblique is then isolated at the nasal end of the superior rectus muscle under direct visualization. Few tips to fish out the superior oblique muscle: (a) Once the superior rectus is hooked completely shift the hook temporally and ask the assistant to hold it. Take a steven’s hook or Barbie’s retractor (if available) and get a better view here in the superior nasal part of the eyeball. The

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superior oblique muscle will be visible as a thin band of tendon passing which can be hooked directly. (b) If no such band is visible nasally, go back temporally 6–8 mm inferior to superior rectus. A small whitish band of fibres would be passing horizontally. Hook the fibres and then hook the complete muscle keeping in mind that the muscle insertion is very close to macula and a vortex vein is close to its insertion. Once the tendon/muscle is hooked completely pass a nonabsorbable suture through the entire thickness of the muscle as an encirclage. Pass this suture under the superior rectus to the nasal side keeping the entire tendon of the muscle inside the encirclage. The superior oblique tendon is then spread out on two larger muscle hooks for a distance of 8–10 mm. In addition to being spread lengthwise to expose about 10 mm of the tendon, the tendon is also flattened between the hooks to aid in splitting it. One blade of blunt-tip scissors is to be pushed through the flattened tendon making every effort to split the tendon in the middle. Using two small Stevens muscle hooks, the split is teased and extended as gently as possible in each direction for a distance of the requisite amount as decided for the surgery (Fig. 1). After the split had been extended, single-armed 6-0 prolene sutures (any nonabsorbable sutures) are placed. One is placed through the posterior split segment of the tendon as far distal as possible, and the other was placed in the anterior split segment as far proximal or nasal as possible. Each suture is tied after being passed twice through the tendon. To complete the Z-cut, the posterior tendon is cut with

Fig. 1  The length of superior oblique muscle is split in two halves. The dotted line shows the area from where the Z split would be created

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tenotomy scissors distal to the preplaced suture and the anterior piece of the tendon is cut proximal or nasal to the suture (Fig. 2). Now, there are two cut ends that have sutures over them. The two cut ends are to be connected with the needle from each suture being passed through the opposite cut end of the tendon just behind the preplaced suture. The sutures are then tied producing the desired amount of split Z-tendon lengthening of the superior oblique muscle (Fig. 3). Fig. 2  The two ends are split with suture on them

Fig. 3  The two ends are tied with each other thereby effectively lengthening the muscle

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3 Advantages 1. The lengthening done is through the part of the muscle only. No expander or silicone material has been used and therefore no chance of extrusion is there. 2. No free ends of the tendon or muscle have been left over and no loose sutures have been left and so no chance of changes postoperatively. 3. The surgery can be graded based on the amount of overaction. A practical guide [10] used by the authors is: (a) For (+2) overaction: 4 mm split lengthening (b) For (+3) overaction: 5.5 mm split lengthening (c) For (+4) overaction: 7 mm split lengthening. 4. A good surgery is something that can be easily and predictable reversed. The superior oblique split lengthening surgery gives a chance to revisit and find out if anything goes wrong. 5. A possible disadvantage is that the sutures may give way. It is important to guard against this particular complication and always secure the split ends nicely. The ends should have proper suturing otherwise there is a chance that the sutures may give way and come undone.

References 1. Crawford JS. Surgical treatment of true Brown’s syndrome. Am J Ophthalmol. 1976;81:289–95. 2. von Noorden GK, Olivier P. Superior oblique tenectomy in Brown’s syndrome. Ophthalmology. 1982;89:303–9. 3. Prieto-Diaz J. Posterior tenectomy of the superior oblique. J Pediatr Ophthalmol Strabismus. 1979;16:321–3. 4. Wright KW.  Superior oblique silicone expander for Brown syndrome and superior oblique overaction. J Pediatr Ophthalmol Strabismus. 1991;28:101–7. 5. Suh DW, Guyton DL, Hunter DG. An adjustable superior oblique tendon spacer with the use of nonabsorbable suture. J AAPOS. 2001;5:164–71. 6. Prieto-Diaz J.  Management of superior oblique overaction in A-pattern deviations. Graefes Arch Clin Exp Ophthalmol. 1988;226:126–31. 7. Sharma P, Thanikachalam S, Kedar S, Bhola R. Evaluation of subjective and objective cyclodeviation following oblique muscle weakening procedures. Indian J Ophthalmol. 2008;56:39–43. 8. Jampolsky A. Oblique muscle surgery of the A-V patterns. J Pediatr Ophthalmol Strabismus. 1965;2:31. 9. Bardorf CM, Baker JD. The efficacy of superior oblique split Z-tendon lengthening for superior oblique overaction. J AAPOS. 2003;7:96–102. 10. Jethani J, Shah K, Amin S. Effect of bilateral superior oblique split lengthening on torsion. Indian J Ophthalmol. 2015;63(3):250–3. 11. Moghadam AA, Sharifi M, Heydari S. The results of Brown syndrome surgery with superior oblique split tendon lengthening. Strabismus. 2014 Mar;22(1):7–12. 12. Stolovitch C, Leibovitch I, Loewenstein A. Long-term results of superior oblique tendon elongation for Brown’s syndrome. J Pediatr Ophthalmol Strabismus. 2002;39(2):90–3.

Lateral Rectus Transposition in Third Nerve Palsy Jaspreet Sukhija and Savleen Kaur

Complete third nerve palsy is a surgical challenge for the ophthalmic surgeon. It leaves the lateral rectus and superior oblique to act unopposed and due to the absence of an antagonist’s muscle to oppose their action, the eye is fixed in an abducted and intorted position. The goal of surgery in such cases is to achieve orthotropia in primary position.

1 Introduction There are several surgical options to treat this disorder. Results of the conventional recession resection procedures are unsatisfying as they cause a large exotropic shift [1]. Shortening procedures like resection, advancement or plications do not work well in paralysed muscles because of their inability to contract. A more static position of the globe may be accomplished after a supramaximal recession of the LR procedure, but movement in the field of action of the paralysed muscle is not accomplished. Lateral rectus disinsertion and periosteal fixation is a reversible way of totally inactivating the lateral rectus and abolishing abduction [2]. Several modifications of globe anchoring procedures have also been devised. Then again, ductions remain fairly limited even after surgery as active movement in the direction of extraocular muscle paralysed cannot be obtained. Hummelsheim in 1907 devised a procedure to transfer part of the action of the superior and inferior rectus muscles to the field of action of the lateral rectus (LR) muscle in cases of sixth nerve palsy [3]. This transposition procedure has undergone modifications over the centuries.

No third party material. J. Sukhija (*) · S. Kaur Advanced Eye Centre, PGIMER, Chandigarh, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_5

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Taylor suggested a medial transposition of the lateral rectus muscle in a case of isolated third nerve palsy [4], which was later modified by Kaufmann [5] and Gokyigit [6]. We have reported the outcome of nasal transposition of lateral rectus in three cases of total third nerve palsy and described our experience with this procedure [7]. There are other case series of LR muscle transposition to the superior nasal and inferior nasal globe [4, 8–10].

2 Technique The surgical technique can be performed under local anaesthesia. Due to the large standing exotropia with adduction limitation, various levels of contracture of the lateral rectus muscle in the affected eye can be expected and hence confirmed before beginning the surgery. A 360° conjunctival peritomy is performed. The LR muscle is isolated and separated from attachments to the surrounding tenons, pulleys and inferior oblique. The muscle is split longitudinally as far back as possible till 18  m–24  mm into two equal halves The upper and lower halves of the LR muscle are secured at the insertion with a 6-0 polyglactin 910 sutures (Vicryl; Ethicon). The superior half of the muscle is then detached from its insertion and is passed beneath the superior rectus and superior oblique before being inserted in the superonasal quadrant. The lower half of the LR muscle is secured in the inferonasal region after routing the muscle below the inferior oblique and inferior rectus. The point of insertion of both halves is governed by the tightness of the muscle and the deviation in primary position. It may be attached near the medial rectus insertion, or about 4 mm posterior to medial rectus insertion with or without a foster suture (Fig.  1). Kaufmann introduced a modification of the lateral rectus transposition of the halves to a retroequatorial point near the vortex veins

SR

LR MR

IR Fig. 1  The Lateral rectus is split into two equal halves and transposed to the superior and inferior insertion of the Medial rectus

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[5]. The transposition can also be done on adjustable sutures [11]. If the lateral rectus is tight one can use hang back technique.

3 Mechanism Transposition surgery is based on changing the location of the muscle insertion so the muscle pulls the eye in a direction different than the normal action of the muscle (i.e., changes the vector of force). Extraocular muscle transposition changes the mechanics of LR muscle but innervation to this muscle remains the same as preoperatively, and the muscle continues to obey Hering’s law. This movement may be due to a “spring load” effect created by the transferred muscles and activated when the antagonist relaxes according to Sherrington’s law during attempts to look in the field of action of the paralysed muscle [3]. It acts like a tether holding the eye in primary position without giving any functional advantage. Hence, it serves to align the globe in primary position but no meaningful area of single binocular vision is obtained.

4 Efficacy A single case report by Morad et al. [10] described the procedure in a 15-month-old child combined with MR resection reducing the 70 pd deviation preoperatively to orthotropia over a 1-year follow up. In Gokyigit modification of the technique [6], additional muscle surgery was required in 5 of the 10 cases. All these patients requiring resurgery had a nearly 90 PD deviation preoperatively. Among our reported series of patients, a 90-PD deviation could not be corrected by transposition as well as medial rectus resection [7]. The undercorrection by the procedure in many reports could partially be explained to the coexisting atrophy of the lateral rectus muscle, which is often present in such long standing cases. A later modification by Saxena et al. increased the effectiveness of the procedure by using posterior fixation sutures [12]. The results of the procedure can be fairly unpredictable and can vary with different case scenarios. This procedure alone will fail to maintain the eye in the primary procedure in cases of complete third nerve palsy and other secondary procedures will still need to be performed. Surgery in such cases should be tailored keeping in mind the primary position deviation and the tightness of the LR. Theoretically speaking the procedure should improve adduction as the transposed lateral rectus can add a mechanical effect.

5 Considerations 1. Long-term paralysis needs weakening of the overacting antagonist without which the transposition will be useless. Mechanical restrictions must be eliminated before carrying out the extraocular muscle transfer by surgery or botox.

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2. Caution should be taken in cases of LR contracture. In cases of severe tension, if the muscle still does not come across to the nasal globe when moderate pressure is applied, it may be best to abandon this approach and select another procedure [11]. 3. Induced torsional and vertical deviations can occur after transpositions surgery. 4. No improvement 6 months after the onset of palsy with stability of deviation achieved for at least 12 weeks should be ensured before taking the patient for surgery. 5. There is a minimal risk of reduced vision from choroidal effusions or optic nerve compromise, risk of undercorrection or a Duane syndrome–like co-contraction. 6. For adequate horizontal position alignment, medial rectus resection can be combined with this surgery. To conclude, medial transposition of the lateral rectus muscle does not require complicated calculations and introduces no foreign tissues or materials into the orbit. The transposed lateral rectus provides a mechanical effect to the medial rectus and brings the globe in primary position.

References 1. Metz HS. 20th annual Frank Costenbader lecture—muscle transposition surgery. J Pediatr Ophthalmol Strabismus. 1993;30:346–53. 2. Srivastava KK, Sundaresh K, Vijayalakshmi P. A new surgical technique for ocular fixation in congenital third nerve palsy. J AAPOS. 2004;8:371–7. 3. Helveston EM. Muscle transposition procedures. In: Surgical management of strabismus: an atlas of strabismus surgery. 4th ed. St Louis, CV: Mosby; 1993. p. 291. 4. Taylor JN. Surgical management of oculomotor nerve palsy with lateral rectus transplantation to the medial side of the globe. Aust N Z J Ophthalmol. 1989;17:27–31. 5. Kaufmann H. “Lateralis splitting” in total oculomotor paralysis with trochlear nerve paralysis. Fortschr Ophthalmol. 1991;88:314–6. [in German] 6. Gokyigit B, Akar S, Satana B, Demirok A, Yilmaz OF. Medial transposition of a split lateral rectus muscle for complete oculomotor nerve palsy. J AAPOS. 2013;17(4):402–10. 7. Sukhija J, Kaur S, Singh U. Nasal lateral rectus transposition combined with medial rectus surgery for complete oculomotor nerve palsy. J AAPOS. 2014;18(4):395–6. 8. Yu YS, Choi DG. Medial transposition of the lateral rectus muscle in experimentally induced medial rectus paralysis. Korean J Ophthalmol. 1991;5(1):9–14. 9. Taylor JN. Transplantation of the lateral rectus muscle to the medial side of the globe in third nerve palsy. Aust N Z J Ophthalmol. 1993;21(4):282. 10. Morad Y, Nemet P. Medial transposition of the lateral rectus muscle in combined third and fourth nerve palsy. J AAPOS. 2000;4(4):246–7. 11. Shah AS, Prabhu SP, Sadiq MA, Mantagos IS, Hunter DG, Dagi LR.  Adjustable nasal transposition of split lateral rectus muscle for third nerve palsy. JAMA Ophthalmol. 2014;132(8):963–9. 12. Saxena R, Sharma M, Singh D, Dhiman R, Sharma P. Medial transposition of split lateral rectus augmented with fixation sutures in cases of complete third nerve palsy. Br J Ophthalmol. 2016;100(5):585–7.

Periosteal Fixation for Exotropic Duane Retraction Syndrome Medha Sharma, Rohit Saxena, and Pradeep Sharma

1 Introduction Duane retraction syndrome (DRS) is a type of congenital cranial disinnervation disorders (CCDDs) where the underlying pathophysiology is a congenital misinnervation of the lateral rectus muscle [1]. Most cases have a variable degree of globe retraction on attempted adduction due to co-contraction of the lateral and medial rectus muscles. Duane patients are now classified as esotropic, exotropic, or orthotropic, based on primary gaze presentation [2]. Exotropic Duane retraction syndrome is relatively uncommon and accompanied by a compensatory head posture away from the affected side. The surgical goal is to correct the deviation, improve the head posture, reduce the anomalous movement, improve ocular rotations, and enlarge the binocular field of vision. Different surgical options include differential recession of the lateral and medial rectus muscles [3], large recession of lateral rectus [4], Y splitting of lateral rectus [5], vertical rectus muscle transposition [6], and orbital wall fixation of the lateral rectus muscle [6–9]. These procedures primarily correct the exodeviation in the primary position and the head posture. Often, there is persistence or recurrence of the effects of anomalous lateral rectus because a large recession does not eliminate residual aberrant force. Complete inactivation of lateral rectus muscle force by orbital wall fixation can eliminate all residual aberrant functions [8]. This procedure removes the lateral rectus muscle from the crest of the globe, thereby reducing globe slippage, upshoots, downshoots, and also addresses exotropia.

M. Sharma NMC Royal Hospital, DIP, Dubai, United Arab Emirates R. Saxena (*) · P. Sharma Strabismus Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_6

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Indications  Complete functional inactivation of lateral rectus is not required in majority of the exotropic Duane syndrome patients, but beneficial in those with severe lateral rectus contraction on attempted adduction. Other indications of this procedure include complete third nerve palsy where even a supramaximally recessed lateral rectus will take up slack and can abduct the eye over time, superior oblique palsy, and dissociated vertical deviation [9, 10]. Technique  Conjunctival incision can be selected based on surgeon preference. Limbal conjunctival incision provides a better exposure and authors describe the technique using this approach. Using a limbal conjunctival incision, the lateral rectus muscle is exposed and isolated on a muscle hook. Surrounding intermuscular ligaments are cleared 15 mm posterior to insertion. A non-absorbable suture like 5-0 ethibond is woven, and the muscle is disinserted. The globe is then retracted medially, and a blunt dissection is performed using Wescott scissors outside the muscle cone to expose the adjacent periosteum approximately 5 mm posterior to the lateral orbital rim. Retractors are used to create an adequate area of exposure. The muscle is then attached to the adjacent orbital periosteum with two periosteal bites using pre- placed non-absorbable sutures. The Tenon capsule is then closed over the muscle with 8-0 polyglactin in two layers, to avoid any reattachment (Fig. 1). The conjunctiva is closed with multiple interrupted 8-0 polyglactin suture (Vicryl suture). Intraoperative force duction is performed before and after lateral muscle was disinserted from globe and attached to the periosteum. Advantages and Limitations  Periosteal fixation is a profound weakening procedure. Technique causes permanent disinsertion of the muscle from globe and prevents any residual function. Suturing the rectus muscle to the orbital wall also reduces the risk of globe perforation compared to technically challenging maximal

Fig. 1  Schematic diagram of the periosteal anchoring of the lateral rectus muscle to lateral periosteum

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recessions. Another advantage is the possibility to reverse the procedure or convert it into a different weakening procedure [6–9]. Potential complications of this procedure may include injury to the lacrimal gland, eyelid position changes, periocular inflammation, and bleeding. It may be technically difficult to expose the adjacent periosteum. There is a complete loss of movement in the gaze of muscle action. Some authors have noted a slight improvement in abduction over time which could probably happen due to force transmitted via posterior connections of the lateral rectus through Tenon tissues. Consecutive esotropia is rarely noted in patients with small preoperative exotropia [7–9]. Conclusion  The orbital fixation of the lateral rectus muscle can be an alternative surgical modality for exotropic DRS because it completely abolishes the action of the misinnervated lateral rectus and corrects exotropia simultaneously. A longer learning curve to master the technique is a potential limitation of this procedure.

References 1. Gutowski NJ, Chilton JK. The congenital cranial dysinnervation disorders. Arch Dis Child. 2015;100(7):678–81. https://doi.org/10.1136/archdischild-­2014-­307035. 2. Ahluwalia BK, Gupta NC, Goel SR, et  al. Study of Duane’s retraction syndrome. Acta Ophthalmol. 1988;66(6):728–30. 3. Sprunger DT.  Recession of both horizontal rectus muscles in Duane syndrome with globe retraction in primary position. J AAPOS. 1997;1(1):31–3. 4. Natan K, Traboulsi EI. Unilateral rectus muscle recession in the treatment of Duane syndrome. J AAPOS. 2012;16(2):145–9. https://doi.org/10.1016/j.jaapos.2011.11.012. 5. Jampolsky A.  A new surgical procedure for upshoots and downshoots in Duane syndrome. In: Santiago AP, editor. Clinical strabismus management. Philadelphia: WB Saunders; 1999. p. 325–46. 6. Sharma P, Tomer R, Menon V, Saxena R, Sharma A. Evaluation of periosteal fixation of lateral rectus and partial VRT for cases of exotropic Duane retraction syndrome. Indian J Ophthalmol. 2014;62(2):204–8. https://doi.org/10.4103/0301-­4738.121145. 7. Saxena R, Phuljhele S, Sharma P, et  al. Periosteal fixation procedures in the management of incomitant strabismus. Middle East Afr J Ophthalmol. 2015;22(3):320–6. https://doi. org/10.4103/0974-­9233.159736. 8. Velez FG, Thacker N, Britt MT, et  al. Rectus muscle orbital wall fixation: a reversible profound weakening procedure. J AAPOS. 2004;8(5):473–80. https://doi.org/10.1016/ S1091853104001314. 9. Morad Y, Kowal L, Scott AB. Lateral rectus muscle disinsertion and reattachment to the lateral orbital wall. Br J Ophthalmol. 2005;89(8):983–5. https://doi.org/10.1136/bjo.2004.051219. 10. Ela-Dalman N, Velez FG, Felius J, et al. Inferior oblique muscle fixation to the orbital wall: a profound weakening procedure. J AAPOS. 2007;11(1):17–22. https://doi.org/10.1016/j. jaapos.2006.06.009.

Superior Rectus Transposition Pratik Chougule and Ramesh Kekunnaya

Duane retraction syndrome (DRS) is a complex form of strabismus. Huber [1] has described three types of Duane syndrome, out of which Type 1 is characterised by limited abduction along with retraction of the globe on adduction. DRS type 1 with esotropia is the commonest presentation of DRS [2–5] In this condition the lateral rectus muscle is congenitally malformed and gets anomalous innervation from the medial rectus at the time of adduction resulting in retraction of globe, limited abduction, with or without esotropia and abnormal head posture. Resection of the anomalous lateral rectus muscle will increase the retraction of the globe further and may even cause limitation of adduction and hence is not advocated. Lateral rectus (LR) palsy is another condition in which there is limitation of abduction. Moreover, long-­ standing LR palsy may lead to contracture of the medial rectus (MR) and may cause restriction to abduction. In LR palsy if the muscle is too lax, resection or any strengthening procedure of LR will not be effective in improving the primary deviation or abduction motility. In both these conditions, strengthening the weakened muscle will not produce the desired effect, and this makes the management of these conditions difficult and complex. Conventional mode of surgery for DRS type 1 and LR palsy has been unilateral or bilateral MR recession [6–11]. This may take care of the primary deviation and the abnormal head posture (AHP) associated with it but does not address the limitation in abduction. Vertical rectus transposition (VRT), along with its several modifications, has been studied extensively and may improve abduction in these cases [12–17]. However VRT has its own limitations such as iatrogenic vertical strabismus following VRT [14, 18, 19]. Moreover, in long-standing esotropia, MR may be contracted and needs to be recessed. In such a case, operating on all three muscles, in a single sitting increases the chances of anterior segment ischemia [20, 21].

P. Chougule (*) · R. Kekunnaya Child Sight Institute, LV Prasad Eye Institute, Hyderabad, Telangana, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_7

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Johnston et al. proposed an innovative technique of transposing only the superior rectus close to the insertion of LR along the spiral of Tillaux [22]. Several authors have since then described the efficacy of superior rectus transposition (SRT) for the treatment of DRS type 1 and LR palsy with and without MR recession [23–28]. SRT has also been described for the management of congenital exotropia with bilateral anomalous medial rectus muscle [29].

1 Technique (Fig. 1) After performing MR recession using fixed or adjustable sutures, a superotemporal incision is made in the conjunctival fornix and the superior rectus muscle is isolated. The muscle is then cleared of surrounding attachments, including the superior oblique tendon and the levator palpebrae superioris (LPS). The muscle is then secured with a double armed, 6-0 polyglactin 910 suture and detached from the globe. The posterior surface of the muscle is inspected for remaining attachments to the superior oblique tendon. The SR is attached close to the LR insertion such that the temporal pole of SR is adjacent to the superior pole of LR while the nasal pole of SR is attached away from LR insertion along the spiral of Tillaux. Thereafter an augmentation suture 5–0 polyester Dacron-Foster’s Augmentation was passed 8 mm behind the lateral rectus insertion incorporating one-fourth thickness of each of the superior and lateral rectus muscles and the underlying sclera [27, 28].

a

b

c

d

Fig. 1  SR is disinserted (a) and reattached (b and c) close to LR insertion. (c) Fosters augmentation suture (d) 8 mm behind the LR insertion using non-absorbable suture (5-0 polyester Dacron)

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Mehendale et al. used adjustable sutures for MR recession along with Foster’s augmentation of SRT, using a double-armed 6-0 polyester suture, by passing one needle through the lateral one-quarter of the superior rectus muscle and the other needle through the superior one-quarter of the lateral rectus muscle, without taking scleral bites, and positioning this suture 8–12 mm posterior to the insertion of the two muscles [23]. Yang et al. adopted the intra-operative monitoring of torsion technique to prevent vertical deviations in vertical muscle transpositions as described by Holmes [24, 30].

2 Efficacy In our experience, we found that SRT alone corrects about 15 PD of esotropia. Beyond this, additional MR recession was necessary. It should be borne in mind that the response to surgery also depends on tightness of the medial rectus muscle, the amount of misinnervation of the lateral rectus muscle in DRS and patient age. Conventionally, bilateral MR recession is needed in patients with >25 PD of esotropia. However, patients may not give consent to operate on the contralateral sound eye. Addition of SRT to ipsilateral MR recession effectively corrected up to 45 PD of esotropia with unilateral surgery, in cases of both DRS, thus obviating the need to operate on the other “good” eye. The abnormal head posture (AHP) decreased from a mean of 14° (range, 8–20) to 2° (range, 0–7) in patients undergoing SRT for DRS and from 21.6° to 7.2° for LR palsy [27, 28]. It should be borne in mind though that SRT is not an alternative to MR recession. In most cases, SRT needs to be combined with MR recession to obtain optimal results. However, the total amount of MR recession required for correction of esotropia is reduced significantly if SRT is combined with MR recession. We found that the average reduction in esotropia/mm of medial rectus recession was 4.1 PD/mm (range, 2.3–6.7) when SRT was combined with MR recession as compared to 2.6 PD/mm (range, 1.2–4.2) with MR recession alone [27, 28]. The greatest advantage of SRT over MR recession is that it significantly improves abduction. In our experience, there is a 1.2-unit improvement in abduction following SRT with or without MR recession in DRS group and 2 unit improvement in abduction in the LR palsy group [27, 28]. Yang et  al. reported a trend towards improvement in abduction and a decrease in esodeviation with time. They found that at the final follow up, the abduction had progressively improved with time compared to immediate post-operative period and the esodeviation decreased with time [24]. They also found that the abduction was greatest in elevation. The improvement in abduction was greater than the limitation in adduction induced by SRT and hence, concluded that the field of single binocular vision may enhance in patients treated with SRT. The improvement in abduction has been found to be comparable to that of vertical rectus transposition (VRT) [27]. However, the chances of Anterior segment ischemia are very rare with SRT compared to VRT.

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3 Adverse Events Due to unbalanced transposition of the superior rectus towards the insertion of lateral rectus, one can expect vertical and torsional deviations to be induced by SRT.  Surprisingly, no such significant vertical or torsional deviation has been observed. None of our patients undergoing SRT for DRS and only one patient of LR palsy developed a post-operative hypotropia (4PD), however, it was not clinically significant and did not require further intervention [27, 28]. Mehendale et al. reported two patients with hypotropia [23]. It is possible that in these cases hypotropia may become evident with time, and a longer follow-up would be desirable to document the development of vertical deviations. On the other hand, Velez et  al. reported hypertropia in five of seven patients with abducens nerve palsy in their series, one of which was clinically significant (14PD) [26]. The reason for the induced hyperdeviation is unclear. Rosenbaum described a possible restrictive effect of the transposed superior rectus muscle with an induced hypertropia in patients undergoing VRT [15]. SR makes an angle of 23° with the visual axis and is directed laterally. Because of the direction of the muscle, it acts as an intorter of the globe. SRT further displaces the SR towards the LR and is expected to induce intorsion of the globe, which may result in torsional diplopia or a compensatory head posture. However, clinically significant torsional diplopia has not yet been reported. Velez et  al. reported objective torsion measured using fundus photos in three of four patients and subjective torsion measured using Double Maddox Rod (DMR) in all their patients [26]. However, it was not clinically significant. We had one patient who complained of torsional diplopia in the immediate post-operative period. Even though the torsion persisted as measured on DMR, the patient did not complain of torsional diplopia on subsequent visits [28]. Considering the trend in improvement in SRT function with time as described by Yang et al., it would be worthwhile to observe these patients for a longer period of time to detect late onset of torsion as well as vertical deviation. Velez et al. recommend that pre-operative torsional measurement is a must in all patients undergoing this procedure and that one should be especially cautious in patients with pre-existing preoperative intorsion [26]. Adduction limitation has been reported with SRT.  In our experience, post-­ operative limitation of adduction was observed in three of eight patients (37.5%) in

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patients undergoing SRT. The adduction limitation was −0.5, −0.5, and −2 in the three patients. It has also been suggested that patients with exotropia in adduction pre-operatively, may be predisposed to develop consecutive exotropia after transposition surgery in Duane syndrome [31]. The above observation of adduction limitation in the initial three cases made us reduce the MR recession dosage in patients undergoing SRT. We suggest that the maximum recession of the ipsilateral medial rectus muscle should be limited to 5–5.5 mm in combination with SRT [27].

4 Mechanism of Action and Why No Torsion? Transposition of a functioning SR laterally with fixation to LR increases the vector forces for abduction. However, in spite of an unbalanced SR transposition, clinically significant vertical and torsional diplopia are rare. Mehendale et al. suggest that because the transposition also involves a slight advancement of the superior rectus muscle (to follow the spiral of Tillaux), the procedure increases the effective strength of the superior rectus muscle to counterbalance the weakening of the vertical effect that results from the transposition. However, extending the temporal edge of SR to the LR tendon insertion and then augmenting the procedure with a foster’s suture at 8 mm from LR insertion, should lead to significant torsion, theoretically. To our surprise this does not happen in the real world. Enhanced modelling of the forces operating within the orbit may be required to begin to explain this apparent inconsistency [23].

5 Summary The improvements in primary deviation, AHP and abduction limitation in DRS and LR palsy are comparable to the present alternative procedures but SRT has less likelihood of adverse events like adduction limitation in case of MR recession or anterior segment ischemia as with VRT. Vertical deviation or torsional diplopia seen in few cases does not appear to be clinically significant requiring additional intervention. Therefore, SRT with or without MR recession is an effective option for treatment of DRS type 1 esotropia and LR palsy (Figs. 2, 3, 4, 5, 6, and 7).

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Fig. 2  Pre-operative 9 gaze photos of a 2-year-old child with left eye DRS type 1. Deviation in primary gaze measured with modified krimsky test was 25 PD ET and −4 limitation abduction in left eye

Fig. 3  Left eye 6-week post-SRT child is orthotropic in primary position, and abduction limitation in left eye improved to −2

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Fig. 4  Six months post-operative pictures showing orthotropia in primary gaze and −2 limitation of abduction

Fig. 5  Improvement in AHP of child from 15° left face turn to no AHP in post-operative 6 weeks and 6 months post-operative period

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Fig. 6  A case of bilateral sixth nerve palsy, following trauma 2 years ago, showing a large esodeviation (95–100 PD ET) in the primary position and −5 abduction limitation in both eyes

Fig. 7  6 months post EOMS PD residual ET, with abduction limitation of −3 and −2 in right and left eye respectively and −1 adduction limitation in both eyes

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References 1. Huber A. Electrophysiology of the retraction syndromes. Br J Ophthalmol. 1974;58(3):293–300. 2. O’Malley ER, Helveston EM, Ellis FD.  Duane’s retraction syndrome—plus. J Pediatr Ophthalmol Strabismus. 1982;19:161–5. 3. Raab EL.  Clinical features of Duane’s syndrome. J Pediatr Ophthalmol Strabismus. 1986;23:64–8. 4. Ro A, Gummeson B, Orton RB, Cadera W. Duane’s retraction syndrome: southwestern Ontario experience. Can J Ophthalmol. 1989;24:200–3. 5. Kekunnaya R, Gupta A, Sachdeva V. Duane retraction syndrome: series of 441 cases. J Pediatr Ophthalmol Strabismus. 2012;49:164–9. 6. Pressman SH, Scott WE, et  al. Surgical treatment of Duane’s syndrome. Ophthalmology. 1986;93(1):29–38. 7. Kraft SP.  A surgical approach for Duane syndrome. J Pediatr Ophthalmol Strabismus. 1988;25:119–30. 8. Kubota N, Takahasi H, Hayashi T, Sakaue T, Maruo T. Outcome of surgery in 124 cases of Duane’s retraction syndrome (DRS) treated by intraoperatively graduated recession of the medial rectus for esotropic DRS, and of the lateral rectus for exotropic DRS.  Binocul Vis Strabismus Q. 2001;16:15–22. 9. Barbe ME, Scott WE, Kutschke PJ. A simplified approach to the treatment of Duane’s syndrome. Br J Ophthalmol. 2004;88:131–8. 10. Farvardin M, Rad AH, Ashrafzadeh A. Results of bilateral medial rectus muscle recession in unilateral esotropic Duane syndrome. J AAPOS. 2009;13:339–42. 11. Dotan G, Klein A, Ela-Dalman N, Shulman S, Stolovitch C. The efficacy of asymmetric bilateral medial rectus muscle recession surgery in unilateral, esotropic, type 1 Duane syndrome. J AAPOS. 2012;16:543–7. 12. Molarte AB, Rosenbaum AL. Vertical rectus muscle transposition surgery for Duane’s syndrome. J Pediatr Ophthalmol Strabismus. 1986;27:171–7. 13. Foster RS.  Vertical muscle transposition augmented with lateral fixation. J AAPOS. 1997;20:20–30. 14. Velez FG, Foster RS, Rosenbaum AL.  Vertical rectus muscle augmented transposition in Duane syndrome. J AAPOS. 2001;5:105–13. 15. Rosenbaum AL. Costenbader lecture. The efficacy of rectus muscle transposition surgery in esotropic Duane syndrome and VI nerve palsy. J AAPOS. 2004;8:409–19. 16. Kinori M, Miller KE, Cochran M. Plication augmentation of the modified Hummelsheim procedure for treatment of large-angle esotropia due to abducens nerve palsy and type 1 Duane syndrome. J AAPOS. 2015;19:311. 17. del Pilar GM, Kraft SP. Outcomes of three different vertical rectus muscle transposition procedures for complete abducens nerve palsy. J AAPOS. 2015;19:150–6. 18. Ruth AL, Velez FG, Rosenbaum AL. Management of vertical deviations after vertical rectus transposition surgery. J AAPOS. 2009;13:16–9. 19. Rosenbaum AL.  Adjustable vertical rectus muscle transposition surgery [letter]. Arch Ophthalmol. 1991;109(10):1346. 20. Saunders RA, Phillips MS.  Anterior segment ischemia after three rectus muscle surgery. Ophthalmology. 1988;95(4):533–7. 21. Murdock TJ, Kushner BJ. Anterior segment ischemia after surgery on 2 vertical rectus muscles augmented with lateral fixation sutures. J AAPOS. 2001;5(5):323–4. 22. Johnston SC, Crouch ER Jr, Crouch ER.  An innovative approach to transposition surgery is effective in treatment of Duane’s syndrome with esotropia. [ARVO abstract]. Invest Ophthalmol Vis Sci. 2006;47:e-abstract 2475. 23. Mehendale RA, Dagi LR, Wu C, Ledoux D, Johnston S, Hunter DG. Superior rectus transposition and medial rectus recession for Duane syndrome and sixth nerve palsy. Arch Ophthalmol. 2012;130:195–201.

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24. Yang S, MacKinnon S, Dagi LR, Hunter DG. Superior rectus transposition vs medial rectus recession for treatment of esotropic Duane syndrome. JAMA Ophthalmol. 2014;132:669–75. 25. Kekunnaya R. Superior rectus transposition versus medial rectus recession for esotropic Duane retraction syndrome (DRS). J AAPOS. 2014;18(4):e18. 26. Velez FG. Assessment of torsion after superior rectus transposition with or without medial rectus recession for Duane syndrome and abducens nerve palsy. J AAPOS. 2014;18(5):457–60. 27. Tibrewal S, Kekunnaya R, et al. Comparison of augmented superior rectus transposition with medial rectus recession for surgical management of esotropic Duane retraction syndrome. J AAPOS. 2015;19(3):199–205. 28. Patil-Chhablani P, Kekunnaya R, et al. Augmented superior rectus transposition with medial rectus recession in patients with abducens nerve palsy. J AAPOS. 2016;20(6):496–500. 29. Kodsi SR.  Bilateral superior rectus transposition for congenital exotropia associated with anomalous medial rectus muscles. J AAPOS. 2015;19(5):462–3. 30. Holmes JM, Hatt SR, Leske D. Intraoperative monitoring of torsion to prevent vertical deviations during augmented vertical rectus transposition surgery. J AAPOS. 2012;16(2):136–40. 31. Velez FG, Laursen JK, Pineles SL. Risk factors for consecutive exo-tropia after vertical rectus transposition for esotropic Duane retraction syndrome. J AAPOS. 2011;15:326–30.

Loop Myopexy for Strabismus Fixus Shashikant Shetty and Shruti Agarwal

1 Introduction Axial high myopia is sometimes responsible for a characteristic strabismus with distinct ocular motility abnormalities. This is a rarely acquired strabismus that affects highly myopic adults. The axial length frequently exceeds 30 mm. The eye moment is mechanically restricted in abduction and supraduction resulting in esotropia and hypotropia. In most advanced form, strabismus fixus, affected eye is so tightly fixed in an esotropic and hypotropic position that no movement in any other direction is possible, even passively. This condition is called convergent strabismus fixus or myopic strabismus fixus. However, myopia strabismus does not always take the form of strabismus fixus. Several authors have proposed a variety of etiologies, but the mechanism of development remained unknown until substantial progress was made in imaging techniques such as computed tomography and magnetic resonance imaging. Hugonnier and Magnard (1969) were first to direct attention to restrictive motility disturbances in severe myopia which they believed was caused by an unspecific myositis. Since then it has become obvious that progressive strabismus occurring in high myopes may be due to more than one mechanism. One cause is a disproportion between the size of the orbit and the volume of an enlarged or elongated myopic globe. The extreme form of strabismus has been given a variety of names; the heavy eye syndrome by Bagshaw; convergent strabismus fixus by Bagolini; and myopic strabismus fixus by Strum.

S. Shetty Department of Pediatric Ophthalmology and Strabismus, Aravind Eye Care System, Madurai, Tamil Nadu, India S. Agarwal (*) Department of Pediatric Ophthalmology and Strabismus, Aravind Eye Care System, Madurai, Tamil Nadu, India Pramod Netralaya, Baghpat, Uttar Pradesh, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_8

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2 Etiopathogenesis The cause of esotropia and hypotropia is a combination of restriction, because of massive expansion of posterior globe against a tight medial rectus muscle, and displaced lateral and superior rectus muscle that change the vector forces [1, 2]. The lateral rectus muscle shows the most displacement, probably due to laxity of its pulley system. Slippage of lateral rectus muscle below the globe weakens the abduction vector and pulls eye down, thus contributing to esotropia and hypotropia [2, 3]. Many hypotheses regarding the etiology of AEHM have been reported. Several researchers have paid special attention to shift of the extraocular muscle (EOM) path reporting that shifting of the EOM path was caused by a posterior prolapse of an elongated eyeball beyond the muscle cone in the orbit, which stretches and shifts the EOMs [2]. Ohta and associates and Krzizok and Schroeder reported that the lateral rectus (LR) muscle was significantly dislocated by the elongated eyeball due to high myopia (HM) [4, 5]. Conversely, Yokoyama and associates reported that both the lateral rectus and the superior rectus (SR) paths were significantly dislocated [2]. Therefore, reports suggest that eyeball elongation due to HM and dislocation of EOM path might be related to AEHM. Conversely, there are various degrees of ocular deviation and ocular motility disturbance in AEHM. Esotropia fixus is the most severe form of AEHM.

3 Diagnosis 3.1 Clinical Presentation • Acquired esotropia with high myopia (AEHM) is associated with obvious esodeviation and hypodeviation. • Mean axial length is 32 mm as most eyes fall in the range of 31–33 mm. The shortest axial length Yokohama came across was 27.7 mm, which was unilateral convergent strabismus fixus.

Image courtesy: Paediatric Ophthalmogy Department; Aravind Eye Hospital. A 65-year-­ old lady with large angle esotropia in both eyes, with eyes fixed in adduction. FDT was positive for abduction

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3.2 Imaging Even though recent studies have clarified the pathogenesis of AEHM, some questions remain [6]. First, which extraocular muscle significantly shifts in AEHM: only the LR as mentioned by Krzizok or Ohta, or both the lateral and superior recti as described by Yokoyama? Or other EOM? Second, is high myopia always accompanied by EOM path shift, even when it shows normal eye position and normal eye movement? Third, is there a correlation between the degree of the EOM path shift and the severity of AEHM or between the degree of the posterior eyeball prolapse from the muscle cone and the severity? Fourth, can EOM path shift and posterior eyeball prolapse be used as signs indicating likely onset of AEHM and esotropia fixus? To answer these questions, EOM path shift and posterior eyeball prolapse from the muscle cone were measured by Yoshiko Aoki, MD, Yasuhiro Nishida et al. in patients with AEHM, in various myopic subjects without ocular deviation nor ocular restriction and in normal subjects, using magnetic resonance imaging (MRI) [6]. Orbital Measurement  For the orbital measurement, a coronal slice image 6  mm anterior to the eyeball—optic nerve junction was chosen. Lines were drawn between both orbital centroids (horizontal reference line) and between each orbital centroid and each EOM centroid (extraocular muscle line). An angle called the EOM angle was formed by the horizontal reference line and each EOM line was measured to evaluate each EOM path location. Only the EOM angle in the medial rectus (MR) was measured from the nasal side of the horizontal reference line. In all others (that is, the lateral, superior, and inferior recti and the superior oblique), the EOM angle was measured from the temporal side. When the EOM centroid was located above the horizontal reference line, we defined the angle value as plus and that below the line as minus [6].

Left image shows a normal globe with horizontal and vertical reference lines passing through center of globe, EOM in their normal position. Right image shows herniation of globe in case of high myopia, change in extraocular muscle path with reference to the horizontal reference line

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4 Measuring Angle of Dislocation of the Globe

4.1 Differential Diagnosis 1. Sagging eye syndrome: Causes of strabismus in highly myopic elderly patients include both HES and SES, but the anatomical relationships of the globe to the extraocular muscles that underlie these two syndromes appear different. SES is a manifestation of age-related, orbital connective tissue degeneration. Although most strabismus in SES is associated with severe elongation of the LR-SR band ligament leading to its rupture, all rectus EOM pulleys become centrifugally displaced in SES, a presumably gradual process that markedly elongates the resting lengths of the EOMs. Bilaterally symmetrical downward displacement, termed sag, of the LR pulleys in SES may asymptomatically and symmetrically reduce supraduction but symptomatically cause “divergence paralysis” esotropia for distant targets. Bilaterally asymmetrical LR pulley sag results in hypotropia and excyclotropia of the eye with the greater sag, causing symptomatic cyclovertical diplopia [3]. Orbital MRI demonstrates inferior lateral rectus displacement and medial superior rectus displacement with severe superotemporal prolapse of the myopic globe in Heavy eye syndrome whereas only inferior displacement of the lateral rectus results from degeneration of the LR-SR band is seen in Sagging eye syndrome. 2. Congenital Fibrosis Syndrome: Congenital fibrosis syndrome is a group of rare congenital disorders in which extraocular muscle restriction is present and fibrous tissue replaces these muscles. There are several variations of this entity. Generalized fibrosis is the most severe form, affecting all the extraocular muscles of both eyes, including the levator muscle. Strabismus fixus involves the horizontal recti, usually the medial rectus muscles, causing severe esotropia. The condition usually is sporadic and can be acquired late [1].

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3. Thyroid ophthalmopathy: Thyroid ophthalmopathy is an autoimmune disease associated with inflammation of the extraocular muscles. Initially, there is an acute phase during which there is a lymphocytic infiltration of the extraocular muscles, resulting in extraocular muscle enlargement and proptosis. This active phase usually lasts several months to more than a year. Orbital imaging studies show thickened extraocular muscles, especially posteriorly. The second phase is a cicatricial phase with quiescence of inflammation and secondary contracture of the muscles. All muscles are usually involved, but the inferior rectus and medial rectus are most severely affected. Strabismus is caused by tight fibrotic muscles and can develop in both phases but is most pronounced in the cicatricial phase. A restrictive hypotropia caused by tight inferior rectus muscles is the most common type of strabismus, followed by esotropia associated with tight medial rectus muscles [1].

4.2 Treatment Generally, there have been two main procedures performed to help correct the restrictive strabismus associated with high myopia. These are resect-recess procedures which mainly alter muscle forces; or transposition-type procedures which affect the direction of muscle actions. Three main surgical management techniques were found in the literature, namely, Yokoyama’s procedure, Yamada’s procedure, and partial Jensen’s procedure. Other studies found in the literature were performed based on these three procedures, with modifications in various details of the surgery, such as being with or without medial rectus (MR) muscle recession, scleral fixation, or the use of materials for muscle union. All three surgical procedures were based on the concept of pathogenesis described by Yokoyama et al. Yokoyama found that myopic strabismus fixus is caused by the superotemporal herniation of the globe, treated patients with myopic strabismus with a full (loop) myopexy of LR and SR. The approximation of the muscle bellies of superior rectus and lateral rectus results in a “sling” of muscle that supports the elongated eye, pushing it back into the muscle cone. In all patients, postoperative magnetic resonance imaging demonstrated the herniation was significantly reduced and eye movement was improved.

5 Surgical Technique by Yokohama All patients had surgery under general anesthesia. Forced duction tests were performed to confirm the restriction. Union suture of SR and LR was performed for all patients as described below.

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5.1 Technique A forniceal conjunctival incision is created in the superotemporal quadrant approximately 8 mm posterior to the limbus. LR and SR muscles are then identified and isolated with a 4’O silk suture (Mersilk, Ethicon). The temporal half of the SR muscle and the superior half of the LR muscle are sutured with a nonabsorbable 5-O polyester suture 14 mm behind the limbus. The SR and LR muscles were not disinserted. If the union suture alone was insufficient to recover the movable range of the globe due to very tight medial rectus (MR) and inferior rectus (IR), concurrent ipsilateral recession or disinsertion of MR and/or IR recession may be performed. The MR and IR muscles were sutured with 6’O vicryl (coated vicryl, Ethicon) by hang-back technique [1].

5.2 Characteristics of the Operated Eyes Best Snellen corrected visual acuity of the operated eyes ranged from light perception to 0.4 (median  =  0.1). Axial length of the operated eyes ranged from 27 to 36.77 mm (mean = 30.80). The spherical equivalent of the refractive error of the operated eyes ranged from −9.00 D to −26.00 D (mean = 19.08).

5.3 Presentation

Image courtesy: Aravind eye hospital, Madurai. Preoperative picture of a 65-year-old lady with Vn RE:? Vn LE: figure counting; with large face turn and great difficulty. Hirschberg test revealed BE large angle esotropia. Severe limitation of all gazes with eyes fixed in adduction

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Image courtesy: Aravind eye hospital, Madurai. Postoperative picture of same patient; Yokohama procedure in the right eye. V.A: OD − 6/18 (with + 1 dsp): FUNDUS; OU: AXL: OD − 32.12 mm. OS − 6/12 (with + 1 dcyl @ 180°): MYOPIC: OS − 32.04 mm. “No E/O Ant. Seg.Ischemia”

5.4 Surgical Outcomes Preoperatively, the mean angle of esodeviation was 80.9  ±  24.25 PD.  The mean angle of deviation was 6.93 ± 27.37 PD; 7.33 ± 28.30 PD; and 7.35 ± 30.66 PD at postoperative 1 week, 3 months, and 1 year, respectively. There is a significant improvement in postoperative angle of esodeviation at 1 week, 3 months, and 1 year follow-up compared with the preoperative angle.

6 Other Surgical Techniques 6.1 Yamada’s Technique He performed an operation consisting of hemitransposition of the SR and LR combined with a recession of MR. During surgery, he confirmed that the path of the SR deviated nasally and that of the LR deviated inferiorly. The insertions of both recti were normal. Both the SR and the LR were partially divided by half their width for approximately 15 mm from the muscles’ origin. The temporal half of the SR and the superior half of the LR were secured to the sclera between the SR and the LR, 7 mm posterior from the limbus. Recession of the MR was also performed. He found that postoperatively the patient became able to fixate in primary gaze. Eye position improved to 10° esotropia. Motility markedly improved in all directions, although impairment of supraduction and abduction persisted to some degree. Visual acuity also improved to 20/200 in the right eye and to 20/40 in the left eye. The patient’s findings remained stable throughout 1 year of follow-up. Magnetic resonance imaging revealed that the widths of the SR and the LR were extended, and that the paths of both were corrected.

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6.2 Loop Myopexy with Transposition The surgery is done under peribulbar block. An FDT is done and positive for abduction means medial rectus (MR) is tight. First, the MR is dissected and separated via a fornix incision in the lower nasal quadrant. A nonabsorbable 6-0 prolene suture is tied at the muscle insertion. The muscle is incised from its insertion. Next, the LR muscle is hooked, it is found to be obliquely placed in such cases. Two 6-0 vicryl sutures are placed at 9 mm from the insertion as is done in a routine resection of rectus muscle and another pair of 6-0 vicryl is placed at the insertion. The muscle is then incised from its insertion and the posteriorly (distally) placed 6-0 vicryl sutures are passed through the original insertion as in a routine rectus muscle resection. The stump is then cut. The stump is then placed at the MR site and the distal end of this stump is sutured with the proximal end of MR with the 6-0 prolene already placed on the MR. The now elongated muscle is sutured at 6 mm from the original insertion site of MR as is done in a routine rectus muscle recession. Now, the SR is hooked and a 4-0 ethibond suture passed under the muscle belly. This suture is then passed through the sclera 16 mm from the limbus and then looped around the LR muscle, and the two ends are tied to complete the loop myopexy. The conjunctiva was sutured with 8-0 vicryl [7].

6.3 Modifications of Loop Myopexy Surgery In other studies, various modifications have been performed based on the three surgical procedures mentioned above (i.e., Yokoyama’s, Yamada’s, and partial Jensen’s). To eliminate the risk of scleral perforation, some authors preferred not to suture the muscle bellies onto the globe. In some studies, a hang-back technique that did not touch the sclera was also preferred in the MR recession. To minimize the possibility of anterior segment ischemia, some authors advocated a union of parts of the muscle belly because the unsecured parts of the SR and LR muscles would contribute to the circulation of the anterior segment. Moreover, given the potential complications of muscle cheese-wiring and the disadvantage of the irreversibility of suture loop myopexy, different materials, mainly silicone bands, have been applied in the surgery.

6.4 Shenoy et al. Performed a novel modification of loop myopexy with a silicone band in 15 patients with high myopic strabismus. They believed that there was an increased risk of migration of the silicone band, especially in eyes with great axial length, so they advocated the scleral fixation of the band. This technique was proven to be effective and can improve alignment significantly. However, two patients in that study presented with complications of foreign body sensation, which required removal of the silicone band [8].

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Preoperative no of cases: 15 Strabismus preop: 79.3 ± 32.3Δ esotropia and 8.9 ± 10.1Δ hypotropia. Procedure: Union of the SR and LR 14–16  mm from the limbus through a 3–4 length scleral tunnel with 240 silicone band and 5-0 nonabsorbable polyester suture; recession of the MR for 5–7.5 mm. Patients Outcome 16.9  ±  17.4Δ esotropia, 0.6  ±  1.3Δ hypotropia, and success rate (deviation ≤20Δ) 73%.

6.5 Wong et al. Performed silicone band loop myopexy in a 63-year male with a history of bilateral esotropia since his teenage. His vision was hand movement in OD and counting fingers in OS. Dilated fundoscopy showed bilateral myopic degeneration. Both eyes were fixed in extreme adduction and depression. The patients then underwent bilateral MR recession (10 mm) and lateral rectus resection (10 mm) with no effect. Two months later they performed staged surgery first in left and then in right eye 2 months apart. The procedure consisted of slinging of LR and SR muscles with a 240 band (Bausch and Lomb, St. louis, MO) and tightening the loop with a silicone sleeve (Mira, Uxbridge MA) 12 mm form limbus without suturing to sclera. Postoperatively the patient had satisfactory alignment with a 14-D right exotropia. Motility improved in all directions although there was a slight limitation of abduction (−1) in right eye and restriction of elevation in both eyes (−1). The results were stable 14 months postoperation [9–11].

7 Selection of a Surgical Procedure Based on Degrees of Strabismus The selection of a surgical procedure is based mainly on the surgeon’s preference and proficiency in a certain technique. All three procedures discussed above have been proven to be effective in the treatment of high myopic strabismus. However, there exist some differences in the applicable scope of each procedure, which is a consideration that might be beneficial when planning a surgery. Shenoy et al. found that full loop myopexy of the SR and LR alone can correct up to 40Δ of esotropia. After a thorough review of the application of Yokoyama-based procedures (i.e., full loop myopexy), we found it to be more effective in patients with esotropia of 12–85Δ when combined with recession of the MR muscle. Furthermore, the partial Jensen’s procedure combined with MR recession has a wider range of applications; patients with large esotropia, usually over 90Δ, also have satisfactory outcomes after surgery.

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8 Conclusion LR and SR shift significantly in AEHM, whereas the MR, IR, and superior oblique do not significantly shift. High myopia is accompanied by neither EOM shifts nor superotemporal eyeball prolapse before the axial length attains the critical level. The EOM shift and the superotemporal eyeball prolapse from the muscle cone reflect the severity of AEHM. The EOM angle and the prolapse ratio are indexes that indicate the critical periods when AEHM or esotropia fixus occurs. Ohta and colleagues and Krzizok and Schroeder emphasized the inferior shift of only the LR, but according to Yokohama’s hypothesis, there is a shift in both SR and LR which is due to posterior elongation of eyeball in high myopia. Inferior shift of LR causes reduced abduction and increased infraduction. Nasal shift of SR causes reduced supraduction and increased adduction. Consequently, AEHM shows esodeviation and hypodeviation due to increased adduction, reduced abduction, increased infraduction, and reduced supraduction. Demer and associates physiologically and morphologically studied the Connective tissue and called it the “pulley.” According to this study, the pulley is located at the portion 6–16 mm posterior to the top of the eyeball. It envelopes and tightly supports the EOMs as the pulley sleeve. The length of the pulley is 13–19 mm. Our observational slice 6 mm anterior to the eyeball– optic nerve junction includes the pulley. Miller and associates mentioned that the EOM portion enveloped by the pulley sleeve did not move even when EOM transposition surgery is performed. Therefore, the pulley tightly stabilizes the EOM path. An elongated eyeball causes neither EOM path shifts nor superotemporal eyeball prolapse before its axial length attains the critical level. Once the axial length attains the critical level, the orbital connective tissues cannot maintain the anatomical structure because of the mechanical compression of the elongated eyeball. Consequently, superotemporal eyeball prolapse from the muscle cone and EOM shifts occur. In conclusion, orbital measurements using MRI have clarified the findings closely related to the pathogenesis of AEHM. Orbital MRI measurement values, such as EOM angle and superotemporal prolapse ratio, can be indexes that show the severity of AEHM, accompanying ocular deviation and ocular restriction. These values may be useful not only for diagnosing and evaluating AEHM, but also for deciding the timing of strabismus surgery.

References 1. Wright KW. Complex strabismus; High myopia and strabismus. p. 351–352. 2. Bagshaw J. The heavy eye phenomenon. Br Orthopt J. 1966;23:75–8. 3. Yokoyama T, Tabuchi H, Ataka S, Shiraki K, Maki T, Mochizuki K. The mechanism of development in progressive esotropia with high myopia. In: de Faber JT, editor. Transactions of the 26th meeting. European Strabismological Association. Barcelona: SwetsZeitlinger; 2000. p. 218–21. 4. Tan RJD, Demer JL. Heavy eye syndrome versus sagging eye syndrome in high myopia. J AAPOS. 2015;19:500–6.

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5. Ohta M, Iwashige H, Hayashi T, Maruo T. Computed tomography findings in convergent strabismus fixus. Nippon Ganka Gakkai Zasshi Soc. 1995;99:980–5. 6. Krzizok TH, Schroeder BU. Measurement of recti eye muscle paths by magnetic resonance imaging in highly myopic and normal subjects. Invest Ophthalmol Vis Sci. 1999;40:2554–60. 7. Godeiro KD, Kirsch D, Tabuse MK, Cronemberger M.  Yamada’s surgery for treatment of myopic strabismus fixus. Int Ophthalmol. 2009;29:305–8. 8. Larsen PC, Gole GA. Partial Jensen’s procedure for the treatment of myopic strabismus fixus. J Aapos. 2004;8:393–5. 9. Shenoy BH, Sachdeva V, Kekunnaya R.  Silicone band loop myopexy in the treatment of myopic strabismus fixus: surgical outcome of a novel modification. Br J Ophthalmol. 2015;99(1):36–40. 10. Aoki Y, Nishida Y, Hayashi O, et al. Magnetic resonance imaging measurements of extraocular muscle path shift and posterior eyeball prolapse from the muscle cone in acquired esotropia with high myopia. Am J Ophthalmol. 2003;136(3):482–9. 11. Wong I, Leo S-W, Khoo B-K.  Loop myopexy for treatment of myopic strabismus fixus. J AAPOS. 2005;9(6):589–91.

Plications and Miniplications for Small Angle Strabismus Jitendra Jethani

Strabismus surgery would mainly involve recession which would change the position of the muscle on the globe. Though regarded as a weakening procedure, it is known and understood that it does not weaken the muscle but actually changes its effective position on the globe thereby changing the globe position that is the position of eyeball. The resection is another procedure usually done along with recession to complement the “weakening” with the strengthening. Resection would essentially involve removal of the segment of the muscle (actually tendon) thereby bringing the tension in the muscle and effective reduction of the muscle length and theoretically improvement in the muscle tension. Though resections have remained the mainstay of tightening the muscle, the obvious disadvantages are the loss of ciliary blood supply and there may be risk of anterior segment ischemia [1, 2]. Plications and miniplications have been described recently as having similar results as resections with advantages of sparing of anterior segment blood supply and also no risk of muscle slip [2–7]. There have been contrasting reports regarding the effectiveness of the procedure. Our experience shows that the results for both the miniplication and plications [7] both adjustable or otherwise are slightly lower for the same numbers when done for resection. Alkharashi and Hunter have recently published similar results [6] though the previous studies by Chaudhari and Demer [4] and Velez et  al. [8] published that the results were similar to the standard resection. Folding the muscle or plicating the muscle to strengthen it is actually an old concept [9] which was earlier described more as a tuck or double breasting of the muscle over itself. This particular procedure was found to lose its effect over time and therefore for rectus muscles this particular surgery was almost stopped [5]. Wright and Lanier described a muscle-to-scleral tuck known as plication [1] and another miniplication [3] for small angles and an adjustable plication were also described later by Chang [10] and Alkharashi [6]. J. Jethani (*) Baroda Children Eye Care and Squint Clinic, Vadodara, Gujarat, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_9

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Both the plications and miniplication have similar techniques for the sake of discussion we have split them into two groups to discuss the effect and results separately.

1 Plications Under peribulbar block or general anesthesia, the muscle is isolated from the fornix incision as would be normally done for any rectus muscle procedure. Once the muscle is isolated and separated from the check ligaments and connections with fascia, the ends of a double arm 6-0 polyglactin is used to take locking bites on each end of the rectus muscle. The two needles are then passed just close to the muscle insertion on the sclera and tied separately. The sutures are taken from the muscle avoiding the blood vessels. A variant of this technique is to use a double arm 6-0 polyglactin and take locking bites avoiding the ciliary vessels. Once the suture is in place, the two needles are passed close to the insertion under the muscle again taking care of avoiding the blood vessels. The plication goes under the insertion and the two ends are now tied with each other. This could be tied in a bow tied manner if planning for an adjustment later (Fig. 1a, b).

2 Miniplications Small angle comitant strabismus is difficult to treat because of the unpredictability of standard recession and resection. The minimum number of recession and resection makes it difficult to treat angles in the range of 8–10 prism diopters (pd). Miniplication was described by Leenheer et al. to treat small angles strabismus [3]. A similar surgery of linear tucking was described by Romero Apis et al. where the muscle was plicated on itself and not with the sclera [11].

a

b

Fig. 1 (a) Plication surgery. The arrow shows the sutures coming out under the rectus muscle. It shows the hump which is present once the sutures are tightened. (b) The sutures can be tied in a regular fashion. They could be tied in a bow tie manner as shown in the figure for adjustments

Plications and Miniplications for Small Angle Strabismus Fig. 2 (a) The miniplication surgery. The lower arrow shows the 6-0 polyglactin passed 5 mm posterior to the insertion of superior rectus taking central 3 mm. The upper arrow shows the suture passed from the sclera at the insertion of the muscle. (b) Shows the muscle hump once the suture is tightened

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Suture passed through scleral Insertion

Suture passed through muscle

b

The muscle hump after plication

3 Surgical Technique 3.1 Miniplication The surgery is done under local anesthesia although it may be done under topical anesthesia [1–3]. The muscle is hooked under direct visualization via a fornix incision. The muscle is then separated from the intermuscular septum but preserving the muscle sheath over it. A single arm 6-0 polyglactin suture is passed 5 mm from the insertion of the muscle taking 3 mm in the bite avoiding the central blood vessels if any. The knot is tied with two-one-one throws. The muscle is ready for miniplication. The suture is not passed from the sclera just anterior to the insertion and is tied with a bump/fold in the muscle (Fig. 2a, b).

3.2 Muscle Plication The surgery is done under local anesthesia and the muscle is hooked and separated. Now a double 6-0 polyglactin is passed from the center of the muscle at the desired length. This is marked with the caliper on the muscle. The knots are placed to secure the central pass and next the two arms are passed on lateral sides of the muscle with locking bites. The two arms are now brought forward and passed from the sclera just

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anterior to the muscle. The suture is pulled and a muscle bump is seen. The sutures are tied and secured with three throws.

4 Advantages and Indications A standard recession or resection would not be applicable for small-angle strabismus. Patients with diplopia are prescribed glasses if the angle is small [12]. Leenheer et  al. [3] described miniplication for small angle strabismus. In a series of nine patients, they found a mean correction of 6.7 ± 3.5 pd. The vertical deviations were reduced by 5.75 ± 2.9 pd and the esodeviations by 10.2 ± 5.3 pd and the esodeviations by 8 ± 0.7 pd. However, a break of these patients shows that three were only miniplication and the rest had second surgery as miniplication. All our patients had miniplication has the first surgery (Fig. 3). We got an improvement of 7.6 ± 2.1 pd for esotropia which is less than the results of Leenheer et al. [3]. This could be because of the large variation in the correction and two of the patient improved up to 14 pd [3]. The vertical deviation patients underwent inferior rectus mini placation in the study of Leenheer et al. They got an improvement of 5.8 ± 2.9 which is similar to our study of around 6.3 ± 2.3 pd. The number of patients with exotropia was only one in the study by Leenhneer et al. [3] and they got an improvement of 8 pd. In our patients of exotropia, we got an improvement of 7.7 ± 2.1 pd (in nine patients) (Fig. 4). Velez et al. [8] and Chaudhuri et al. [4] described adjustable muscle plication and its advantages over routine resection. A total of five patients were reported by Velez et al. [8] who underwent adjustable muscle plication and had satisfactory results.

Fig. 3  The upper pictures show the small angle exotropia with left inferior oblique overaction. The patient underwent medial rectus miniplication with left inferior oblique recession The lower pictures show well-aligned eyes with normal action of inferior oblique

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Fig. 4  Another patient showing small angle right eye exotropia. The miniplication of medial rectus helped in correction of the eye position as seen in the lower pictures

Chaudhuri et al. [4] presented their comparison of muscle plication with standard resection in a series of 22 patients (muscle plications) versus 31 patients (muscle resections). All the surgeries were with antagonist muscle recession. They found the results were comparable with both techniques. Our cases were purely small angles and underwent only single muscle plication with central anchoring. Since the procedure is new and there are limited reports on this, our recommendations for this procedure are: (a) There are variations in the amount of correction achieved depending on which muscle is operated. The Medial rectus placation (for exotropia) gives maximum results in terms of improvement of deviation. (b) The inferior rectus gives more results than the lateral and superior rectus (almost equal). So if a patient has hyper deviation it is better to operate that eye for inferior rectus if the angle is more than 8 pd. (c) Wright et al. [13] have described a mini tenotomy for small angle squint. This procedure only corrects a mean of 2.3 pd for vertical and 1.3 pd for esotropia. The miniplication seems to be better than this procedure since the amount of correction is optimal for small angle deviations. (d) Although it is a reversible procedure, a further modification of adjustable suture has also been described [8], which gives an additional advantage of refining the improvement to more accurate results in the early postoperative period.

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(e) Though we did not encounter any restriction of contralateral movement in the eye, Leenhneer et al. [3] do mention an abduction restricted with muscle plication and therefore recommend it for say an exotropia which increases in right gaze would be appropriately corrected with right medial rectus plication. (f) The fact that plication also spares the ciliary circulation [2] is also an important reason why this procedure can also be done safely when two recti have been already operated upon.

References 1. Wright KW, Lanier AB. Effect of a modified rectus tuck on anterior segment circulation in monkeys. J Pediatr Ophthalmol Strabismus. 1991;28:77–81. 2. Oltra EZ, Pineles SL, Demer JL, Quan AV, Velez FG.  The effect of rectus muscle recession, resection and plication on anterior segment circulation in humans. Br J Ophthalmol. 2015;99:556–60. 3. Leenheer RS, Wright KW. Mini-plication to treat small-angle strabismus: a minimally invasive procedure. J AAPOS. 2012;16:327–30. 4. Chaudhuri Z, Demer JL. Surgical outcomes following rectus muscle plication: a potentially reversible, vessel-sparing alternative to resection. JAMA Ophthalmol. 2014;132:579–85. 5. Wright KW. Rectus muscle plication procedure. JAMA Ophthalmol. 2015;133:226–7. 6. Alkharashi M, Hunter DG. Reduced surgical success rate of rectus muscle plication compared to resection. J AAPOS. 2017;21:201–4. 7. Jethani J. Miniplication for small angle comitant strabismus: a new and effective approach. Indian J Pediatr Ophthalmol Strabismus. 2016;4:21−4. 8. Velez FG, Demer JL, Pihlblad MS, Pineles SL. Rectus muscle plication using an adjustable suture technique. J AAPOS. 2013;17:480–3. 9. Hamtil LW. A study in tucking extraocular muscles to correct strabismus. Ann Ophthalmol. 1983;15:136–7. 10. Chang MY, Pineles SL, Velez FG. Adjustable small-incision selective tenotomy and plication for correction of incomitant vertical strabismus and torsion. J AAPOS. 2015;19:410–6. 11. Romero Apis D, Martinez Oropeza S.  Strabismus surgery by means of marginal myotomy combined with lineal tucking. Am Orthopt J. 1983;33:74. 12. Phillips PH. Treatment of diplopia. Semin Neurol. 2007;27:288–98. 13. Wright KW. Mini-tenotomy procedure to correct diplopia associated with small-angle strabismus. Trans Am Ophthalmol Soc. 2009;107:97–102.

Globe Fixation in Complete Third Nerve Palsy Pradhnya Sen and Elesh Jain

1 Introduction The complete third nerve palsy is characterised by paralysis of medial rectus, superior rectus, inferior rectus and inferior oblique muscles leading to eye being fixed in an “out and down position” due to unopposed action of spared lateral rectus and superior oblique [1]. It is probably one of the most difficult condition to correct surgically [2]. The challenges include a large angle with horizontal and vertical components, lack of vertical and horizontal motility and misfiring associated with aberrant extraocular muscle (EOM) innervation. Moreover, there are more number of muscles that are paralysed than spared [3]. Hence, even the most efficient surgeon sometimes may get frustrated for not being able to restore alignment and adequate motility in complete third nerve palsy. As with any other extraocular muscle palsies one needs to wait to look for spontaneous recovery [4]. In cases with partial recovery, satisfactory result can be obtained with just recess and resect procedure. However, if there is no recovery then conventional surgical procedures are generally ineffective. Although several procedures have been described in literature to align eyes with this condition, the results are variable [5]. Supramaximal Lateral Rectus recession and Medial Rectus resection give only short-term alignment [6]. As both Superior Rectus and Inferior Rectus are paralysed, vertical rectus transposition is not useful in this condition. Superior oblique transposition in long run may lead to hypertropia [7]. In fact none of the procedure has shown long-term satisfactory outcome. Medial globe fixation to place the eye in the primary position by far gives the most stable alignment.

P. Sen (*) · E. Jain Children Eye Care Centre, Sadguru Netra Chikitsalya, Chitrakoot, Madhya Pradesh, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_10

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2 Techniques for Medial Globe Fixation in Third Nerve Palsy 2.1 Globe Fixation with Silicon Band The idea of globe fixation was introduced by Scott et al. [8] in 1992 for lateral rectus and superior oblique palsy. They used a silicon band as an eye muscle prosthesis to fix the globe to the adjacent periosteum. The procedure involved use of an expensive silicon band made with sophisticated technology. It also necessitated the use of complicated mathematical calculations with a special software for implantation. Even then it did not give reproducible outcomes.

2.2 Globe Fixation with Silicon Tube Bicas et al. [9] used a silicon tube to anchor globe medially. They used this elastic material to improve the rotation of the eye in two cases of third nerve palsy. Postoperative alignment was fair but there was no restoration of paralysed ocular rotators.

2.3 Globe Fixation with Autologous Fascia Lata Salazae Leon et al. [10] first used autologous fascia lata and 5-0 silk suture in 1994 to anchor globe to nasal periosteum using a skin approach combined with large lateral rectus recession. After harvesting autologous fascia lata they attached it to medial palpebral ligament at one end and medial rectus insertion at another end. The technique was easy, inexpensive and with acceptable cosmesis, but it prolonged the surgical time and was not suitable for children less than 2 years of age.

2.4 Globe Fixation with Superior Oblique Tendon Villasenor Solares et al. [11] used the superior oblique (SO) tendon as a tethering material for globe fixation along with supramaximal lateral rectus recession and medial rectus resection. About 12–14 mm of SO tendon was dissected, disinserted and split into two ends. One of the ends was fixed to nasal periosteum and the other to medial rectus insertion. However, this procedure is technically challenging.

2.5 Periosteal Flaps as Globe Tethers Goldberg et  al. [12] used periosteal flap technique as an excellent tether for the globe. Superior, medial and lateral periosteal flaps were created and then attached to extraocular muscle insertion points under appropriate tension to position the globe

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with small overcorrection. Extensive dissection was the major limitation of this technique.

2.6 Other Materials as Tether in Globe Fixation Bagheri et al. [13] used temporalis fascia whilst Yonghong [14] used medial rectus tendon as tethering material. Bone anchors and screws have been used but being foreign material chances of extrusion, infection, inflammation and progressive loosening were associated problems [15].

3 Titanium Plate and Suture as a Platform for Globe Alignment Tse et al. [16] used a titanium T plate and suture for anchoring globe to the nasal bone. The concept being T plate and suture system provides a strong fulcrum at the orbital apex for the suture to position the eye towards midline against the active resistance of the antagonist and the passive resistance imparted by orbital fibrosis from prior muscle surgeries. The T plate is implanted subperiosteally with long arm towards orbital apex and short one fixed to nasal bone with screws. Non-absorbable suture is then tied from the insertion of the muscle to the end near orbital apex. Though this system allows only a limited range of globe motion and creates a narrow field of binocular single vision, it can be a step towards achieving mobile and well-aligned eye.

4 Globe Fixation with Non-absorbable Suture Several authors [17–19] have used non-absorbable suture like 5-0 ethibond or 6-0 prolene suture for anchoring globe to nasal periosteum along with weakening of the Lateral Rectus. This procedure is technically easier than periosteal flaps or titanium T plate and has fewer complications than with silicon tubes and metal screws [15]. In this technique, the globe is fixated to medial palpebral ligament at anterior lacrimal crest using non-absorbable 5-0 polyester sutures along with large (12–16 mm) lateral rectus recession. Medial palpebral ligament and anterior lacrimal crest were approached using a dacryocystectomy skin incision. A 5-0 polyester suture passes through anterior lacrimal crest and needles are brought anterior to medial rectus insertion. After taking superior and inferior scleral bites sutures are tightened enough to align eye in a slightly adducted position. Mihir Kothari et al. [20] noted two limitations of this technique: (1) skin incision leading to visible scar and (2) passage of needle from nasal to temporal which can inadvertently damage the globe. They recommended the use of precaruncular

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approach to medial wall of orbit and use of Wright needle from temporal to nasal which can feed both ends of sutures to bring them anterior to medial rectus insertion. Saxena et al. [21] used precaruncular approach to reach medial periosteum and non-absorbable sutures as a tethering agent along with a 12–14 mm recession of lateral rectus.

5 Preferred Technique of the Authors Involves precaruncular approach of globe fixation with full tendon width of medial rectus using 5-0 prolene suture along with deactivation of lateral rectus (LR).

6 Procedure 6.1 Deactivation of LR LR deactivation not only eliminates the action of LR fully but also prevents its reattachment to the globe thereby preventing its recurrence of abduction. In addition to this, it eliminates misinnervations which are common in third nerve palsy. Under peribulbar block with or without general anaesthesia a limbal conjunctival incision is given in the temporal area. The limbal conjunctival incision is preferred as lateral rectus deactivation needs greater exposure. LR is hooked, isolated, secured with 5-0 prolene suture and disinserted (Fig. 1). Canthotomy at lateral canthus is done to expose periosteum covering lateral orbital rim. Two ends of 5-0 prolene suture from lateral rectus are passed separately through lateral forniceal conjunctiva

Fig. 1  Disinserted LR muscle after securing with 5-0 prolene suture (schematic representation with surgical photograph as in doted square)

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Fig. 2  5-0 Prolene suture from lateral rectus passed subconjunctively via lateral forniceaal conjunctiva and passed through periosteum posterior to lateral orbital rim

and tied them to the periosteum 2–3 mm posterior to lateral orbital rim (Fig. 2). For complete deactivation, compartmentalization of muscle is done by suturing tenons with 6-0 vicryl suture to prevent reattachment of LR to globe. Canthus is formed using a 6-0 vicryl suture.

7 Globe Fixation at Nasal Periosteum Medial palpebral ligament and nasal periosteum are exposed using precaruncular incision. As this area is very vascular 0.5 ml of 1:1000 adrenaline with 2% xylocaine is injected into the caruncular area. Fixation forceps are applied at superior and inferior limbal areas to expose the caruncular area. Bowman’s lacrimal probes are placed to secure the canaliculi. Radio Frequency (RF) cautery is used to give a curved incision at the junction of medial conjunctiva and canthal area (Fig. 3). With blunt dissection periosteum posterior to posterior lacrimal crest is exposed (Fig. 4). Two ends of 5-0 prolene suture are passed through periosteum and tied (Fig. 5). The needle is then cut. Medial Rectus (MR) is exposed and isolated through limbal conjunctival incision. The full muscle tendon is secured along with adjacent sclera using 5-0 prolene suture (Fig. 6). Castroviejo needle holder is passed subconjunctively from temporal to nasal direction (Fig. 7). Tenting of tenons and connective tissue is done and nick is given over it by blade no. 15. The needle holder tips are fed with both ends of prolene suture and are then brought anterior to MR insertion. This avoids inadvertent damage to the globe. Periosteal sutures are then tied to MR tendon and scleral suture to leave the eye in approximately 5° esotropia (Fig.  8). Suture from MR tendon strengthens and prevents cheese wiring of scleral suture. Superior and

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Fig. 3  Precaruncular injection is made using RF cautery (blue)

Fig. 4  Blunt dissection is done to expose periosteum posterior to posterior lacrimal crest (orange)

inferior scleral sutures help to adjust hypotropia. Precaruncular incision is closed using running 8-0 vicryl suture. Limbal conjunctival incisions are closed with interrupted 8-0 vicryl suture after conjunctival recession and resection over temporal and nasal conjunctiva respectively. In conclusion syringing is performed to check the patency of lacrimal system. Postoperative care includes systemic antibiotics and Non-Steroidal-Anti-­ Inflammatory Drugs, topical antibiotic ointment and ocular topical steroid antibiotic drops which are tapered within 4 weeks (Fig. 9).

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Fig. 5  5-0 Prolene suture passed through periosteum and tied

Fig. 6  Medial rectus muscle is secured with 5-0 prolene suture along with adjacent superior and inferior scleral bites

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Fig. 7  Castroviejo needle holder is passed subconjunctively in temporal to nasal direction and tip is fed with two ends of 5-0 prolene suture

Fig. 8  Periosteal sutures are brought anterior to MR and tied to MR tendon and scleral sutures

Fig. 9  Before surgery and after globe fixation (similar patient described above)

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8 Conclusion Globe fixation to nasal periosteum with non-absorbable suture along with weakening of LR is the preferred technique in non-recovered complete third nerve palsy. Although with this technique eye is still non-mobile, it is better for eye to be fixed in primary position than to be fixed in down and out position. Lack of motility in this technique remains a challenge for strabismologists. Though patients with good vision will have diplopia in all gazes except in primary gaze, patients with congenital third cranial nerve palsy with amblyopia or acquired third nerve palsy with optic atrophy will not have post-operative diplopia with this approach. A technique that is easy to perform, reproducible and that can provide acceptable alignment of eyes along with adequate motility is still elusive.

References 1. Miller NR, Newman NJ, Hoyt WF, Walsh FB. Walsh and Hoyt’s clinical neuro-ophthalmology. 5th ed. Baltimore, MD: Williams and Wilkins; 1998. 2. Abbas Bagheri MD, Morteza Borhani MD, Mehdi Tavakoli MD, Salehirad S. Clinical features and outcomes of strabismus treatment in third cranial nerve palsy during a 10‑year period. J Ophthalmic Vis Res. 2014;9(3):343–9. 3. Schatz NJ, Savino PJ, Corbett JJ. Primary aberrant oculomotor regeneration: a sign of intracavernous meningioma. Arch Neurol. 1977;34:29. 4. Kim K, Noh SR, Kang MS, Jin KH.  Clinical course and prognostic factors of acquired third, fourth, and sixth cranial nerve palsy in Korean patients. Korean J Ophthalmol. 2018;32(3):221–7. 5. Singh A, Bahuguna C, Nagpal R, Kumar B. Surgical management of third nerve palsy. Oman J Ophthalmol. 2016;9(2):80–6. 6. Gottlob I, Catalano RA, Reinecke RD. Surgical management of oculomotor nerve palsy. Am J Ophthalmol. 1991;111:71. 7. Chaudhary KP. Extraorbital use of a disinserted superior oblique as a sling in third nerve palsy: a new single-stage surgical technique. Ann Ophthalmol. 1990;22:326. 8. Scott AB, Miller JM, Collins CC. Eye muscle prosthesis. J Pediatr Ophthalmol Strabismus. 1992;29:216–8. 9. Bicas HE. A surgically implanted elastic band to restore paralyzed ocular rotations. J Pediatr Ophthalmol Strabismus. 1991;28:10–3. 10. Salazar-León JA, Ramírez-Ortíz MA, Salas-Vargas M.  The surgical correction of paralytic strabismus using fascia lata. J Pediatr Ophthalmol Strabismus. 1998;35(1):27–32. 11. Villaseñor Solares J, Riemann BI, Romanelli Zuazo AC, Riemann CD.  Ocular fixation to nasal periosteum with a superior oblique tendon in patients with third nerve palsy. J Pediatr Ophthalmol Strabismus. 2000;37:260–5. 12. Goldberg RA, Rosenbaum AL, Tong JT. Use of apically based periosteal flaps as globe tethers in severe paretic strabismus. Arch Ophthalmol. 2000;118:431–7. 13. Bagheri A, Erfanian-Salim R, Salour H, Yazdani S. Globe fixation with homologous temporalis fascia transplant for treatment of restrictive esotropia strabismus: an interventional case report and review of the literature. Binocul Vis Strabolog Q Simms Romano. 2011;26:236–42. 14. Yonghong J, Kanxing Z, Wei L, Xiao W, Jinghui W, Fanghua Z. Surgical management of large-­ angle incomitant strabismus in patients with oculomotor nerve palsy. J AAPOS. 2008;12:49–53. 15. Ela-Dalman N, Schwarcz RM, Velez FG.  Suture fixation system as globe tethers in severe paralytic strabismus. J AAPOS. 2006;10:371–2.

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16. Tse DT, Shriver EM, Krantz KB, Tse JD, Capo H, McKeown CA. The use of titanium T-plate as platform for globe alignment in severe paralytic and restrictive strabismus. Am J Ophthalmol. 2010;150(3):404–411.e1. 17. Mora J. An adjustable medial orbital wall suture for third nerve palsy. Clin Exp Ophthalmol. 2004;32:460–1. 18. Srivastava KK, Sundaresh K, Vijayalakshmi P. A new surgical technique for ocular fixation in congenital third nerve palsy. J AAPOS. 2004;8:371–7. 19. Sharma P, Gogoi M, Kedar S, Bhola R.  Periosteal fixation in third-nerve palsy. J AAPOS. 2006;10:324–7. 20. Mihir Kothar MS.  Letters to the editor, Periosteal fixation in third nerve palsy. J AAPOS. 2007;11(2):207–8. 21. Saxena R, Sinha A, Sharma P, Phuljhele S, Menon V. Precaruncular approach for medial orbital wall periosteal anchoring of the globe in oculomotor nerve palsy. J AAPOS. 2009;13:578–82.

True Muscle Transplantation for Very Large Angle Esotropia Strabismus Jitendra Jethani

Surgical strategies for very large angle strabismus are very few. Most of the surgeries are either partially effective or the surgeries are highly incomitant. The muscle transplantation surgery (Fig. 1) described in the literature is an effective and stable option [1–4]. The surgery has been done for resurgeries [2] and for incomitant large esotropia [5]. It has not been established that muscle transplantation is effective and although the tissue loses its contractile properties it remains viable [1, 2]. The surgery is now gaining popularity and especially in cases where single eye surgery is desired with a large angle esotropia of more than 70–80 prism diopters. Originally described in animal studies by Hiatt et  al. [1] in 1973, some cases were reported by Diamond et al. [2] who did this for resurgeries and by Amitava et al. [3]. Both the authors reported good success and suggested an improvement of around four prism diopter correction per mm that is amount of recession + twice of resection since the resected muscle stump is sutured on the antagonist muscle to increase the effective length of the muscle. We reported one of the largest series of 22 patients and also had a follow-up of around 2 years now [4].

1 Surgical Technique (Figs. 1, 2, 3, 4, 5, and 6) The surgery can be done under local or general anesthesia. The medial rectus (MR) muscle is isolated through a fornix incision in the lower nasal quadrant. The muscle is separated from its adhesions and intermuscular septum. It is not that the muscle is prepared to accept the transplant from the antagonist that is the lateral rectus muscle of the same eye. A nonabsorbable 6-0 prolene suture is tied at the muscle insertion. The muscle is then incised from its insertion. The medial rectus is ready for receiving the lateral rectus muscle stump once we get the resected portion. The lateral rectus muscle is J. Jethani (*) Baroda Children Eye Care and Squint Clinic, Vadodara, Gujarat, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_11

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A

B

Resection

Fig. 2  The isolated medial rectus muscle with two single-arm prolene sutures on each end

Fig. 3  Two pairs of 6-0 polyglactin sutures and the segment (anterior) which would be cut

hooked through the fornix route in the lower temporal fornix. Two single arm 6-0 Vicryl sutures were placed at the desired distance from the insertion as is done in a routine resection of rectus muscle. The amount of this is predecided. This would be at least 8 mm from the insertion since the cases selected are at least 70–80 prism diopter angle of strabismus. Another pair of 6-0 Vicryl is placed at the insertion.

True Muscle Transplantation for Very Large Angle Esotropia Strabismus Fig. 4  The anterior part of lateral rectus (the resected portion), the stump which would be grafted to the medial rectus

Fig. 5  The muscle stump is being sutured with the nonabsorbable suture to the medial rectus

Fig. 6  The stump has been successfully transplanted or grafted to the medial rectus with the help of 6-0 prolene interrupted sutures

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This could be a double-arm or two separate single-arm sutures. The muscle is then incised from its insertion and the posteriorly (distally) placed 6-0 Vicryl sutures are passed through the original insertion as in a routine rectus muscle resection. The excess muscle stump has to be removed. This has a pair of vicryl 6-0 attached anteriorly. The stump is then placed at the medial rectus muscle site. The distal end of this stump, which is the unsutured end, is sutured with the end of medial rectus muscle with the 6-0 prolene already placed on the medial rectus muscle. The now elongated muscle was sutured at desired site from the original insertion site of medial rectus as is done in a routine rectus muscle recession. The muscle can be transposed, put on adjustable and recessed as we would do in a normal recession.

2 How Does It Work? True muscle transplantation gives an extra amount of correction apart from the routine recession and resection. The surgery works for large angle strabismus. The resected portion of muscle which is transplanted further weakens the antagonist keeping the arc of contact and the actual insertion of the muscle anterior to the functional equator thereby preserving the actual pulling effect of the muscle but reducing the overall strength of the base on the muscle tension curve. The overall length of the muscle is thus increased.

3 Why Transplantation? Some concerns regarding the stability of the procedure have been now answered by the long follow up by the author [4]. Other concerns are that the surgery would be similar to a hemihang-back sutures. Indeed, for such a large angle we believe that the options could be hemihang-back, very large unconventional recessions of the MR muscle or very large unconventional resections. The large recession that is the supramaximal surgery would lead to severe underaction of the medial rectus and supramaximal resection of lateral rectus would lead to not only the restriction of adduction but also would lead to significant palpebral fissure changes. The fact that the actual insertion of the muscle remains anterior to the functional equator and yet the elongated length of the muscle results in good primary position alignment. The other option could be an elongation of muscle. This could be achieved by marginal myotomies or adding a silicone band or nonabsorbable sutures. The marginal myotomies though a good option in resurgeries almost always make any other future surgeries very difficult. The muscle strength is forever reduced. The authors normally reserve them for already incomitant esotropia where a resurgery is needed. Silicone bands have been used successfully in Brown’s syndrome for muscle elongation and so are chicken sutures [6, 7]. However, these bands are used as spacers and between the cut ends of the tendon and not at the insertion. If we were to use it close to the insertion under the palpebral conjunctiva, it would certainly lead to extrusion.

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Fig. 7  The upper photograph shows the right eye’s large angle esotropia. The lower photographs show the excellent alignment in the primary position and good adduction of right eye in the lower right photo

With the help of muscle transplantation, the effective length of the muscle could be increased and therefore the results could be improved. The chances of any rejection of the transplanted muscle are virtually nil since it is the patient’s own tissue and that too the rectus muscle. We believe that the movement restriction in the extreme gaze on the side of the muscle transplantation is seen as a result of the excessive weakening of the muscle, but the muscle is still anterior to the equator, and therefore the motility restriction is minimal. This, however, cannot be compared with a large conventional large recession which would place the new insertion posterior to the functional equator. The ocular motility in a muscle transplant postsurgery remains excellent [4, 5, 8]. The unconventionally large recession invariably ends up in having motility loss. We present pre- and postoperative pictures of patients who underwent muscle transplant for a large angle esotropia (Fig.  7). The postoperative pictures clearly show minimal adduction loss even after muscle transplantation. A hemihang-back recession will also have two major problems, first, the muscle may creep forward with such a large recession on hang back (we are doing close to 14–15 mm from the insertion and almost 20 mm from the limbus), and the second obvious problem that it would attach to a point which would be posterior to the arc of contact, and hence, the restriction of ocular motility in the ipsilateral direction would make it a big incomitant procedure.

4 Advantages Though the surgery has been described long back there have been few published reports on its results in the literature. The current study by the author was one of the largest series [4] on the long-term stability and results of this surgical technique. The amount of correction is around 4 prism diopter per mm (that is calculated by adding the amount of recession  +  amount of resection  +  amount of transplanted stump and dividing the total amount of deviation by this amount):

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(a) First and foremost is the large angle that can be treated with a single eye surgery. The mean correction was around 92.4 prism diopter [4]. (b) The motility is a lot better with only a few patients having restriction of adduction when done for esotropia. (c) The palpebral fissure changes are not much. With such a large recession and resection, fissure changes are expected. However, these changes are not seen and are a great cosmetic advantage to the patients who undergo this surgery mainly for cosmesis to improve the large angle esotropia. (d) The technique is much simpler and almost similar to the technique of a standard recession and resection. This is very important since surgeons can easily switch over to this technique. This is important for any new technique for more acceptability of the technique. (e) The surgery is a wonderful addition to resurgery cases. For example, a case with bilateral medial rectus has been done and comes back for resurgery and has a large esotropia. Muscle transplantation is very effective. (f) Muscle transplantation can be combined with adjustable suture and also with horizontal transposition both upward or downward.

References 1. Hiatt RL. Extraocular muscle transplantation. Trans Am Ophthalmol Soc. 1973;71:426–58. 2. Diamond GR. True transposition procedures. J Pediatr Ophthalmol Strabismus. 1990;27:153–6. 3. Amitava AK, Goswami AK, Mishra A. Large-angle strabismus and primary true muscle transplantation. J Pediatr Ophthalmol Strabismus. 2005;42:211–5. 4. Jethani J, Shah N, Amin S, Jethani M. Stability and effects of muscle transplantation for very large angle esotropia: a study of 22 patients. Indian J Ophthalmol. 2017;65:607–9. 5. Jethani J, Amin S. Loop myopexy with true muscle transplantation for very large angle heavy eye syndrome patient. Indian J Ophthalmol. 2015;63:71–2. 6. Wright KW. Results of the superior oblique tendon elongation procedure for severe Brown’s syndrome. Trans Am Ophthalmol Soc. 2000;98:41–8. 7. Wright KW.  Superior oblique silicone expander for Brown syndrome and superior oblique overaction. J Pediatr Ophthalmol Strabismus. 1991;28:101–7. 8. Jethani J.  The muscle transplantation and loop myopexy in so-called heavy eye syndrome. Indian J Ophthalmol. 2015;63:558–9.

Adjustable Faden: A Unique Strabismus Surgery Jitendra Jethani

Combined recession and resection of rectus muscle have been called an adjustable faden procedure. Scott [1] suggested a procedure that was based on a principle for improving incomitance in gaze away from the primary position. The faden suture or procedure, is basically a retroequatorial myopexy, which would normally not affect primary position alignment and is difficult technically and is ineffective on the lateral rectus due to large arc of contact. Scott et al. [1] and Thacker et al. [2] performed a resection of a rectus muscle and then recessed the muscle, using a standard hang-back/adjustable technique. The different surgeons have done it in a different way with some doing more resection and less recession and some surgeons doing more recession and less recession on adjustable sutures [2–5]. It is understood that this adjustment helps in keeping the primary position diplopia free. The reattachment of the muscle to sclera at a posterior insertion point produced the mechanical effect of faden operation. The combined recession–resection procedure has a useful role in the management of symptomatic incomitant strabismus. This would be particularly valuable when dealing with incomitance on lateral gaze due to limitation of ocular movement, and the contralateral overacting muscle can be operated upon. It helps in expanding the field of single binocular vision which helps the patient have a more diplopia-free field.

1 Indications Incomitant strabismus with some limitation of movement. The contralateral muscle or the yoke muscle would be overacting. This yoke muscle can undergo adjustable faden to reduce the muscle function in its primary action of the muscle.

J. Jethani (*) Baroda Children Eyecare and Squint Clinic, Vadodara, Gujarat, India © Springer Nature Singapore Pte Ltd. 2023 J. Jethani (ed.), Strabismus Surgery, https://doi.org/10.1007/978-981-19-8433-4_12

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(a) For example, if the Right eye has inferior movement restricted and has a large right hypertropia in downgaze and no angle in primary position, an inferior rectus recession cannot be done which would cause diplopia in primary position. A left eye inferior rectus adjustable faden would help in reducing the incomitance in downgaze but will not affect the primary position. The adjustable surgery would help keep the patient diplopia free in primary position. (b) If the patient has a right eye partially recovered lateral rectus paresis, the left eye medial rectus would be overacting with minimal esotropia in primary position. An adjustable faden would help in taking care of the primary position esotropia and would have an added effect on the right gaze. (c) Patient with a high AC/A ratio or even convergence excess esotropia can undergo a bimedial recession with adjustable faden. The amount of recession can be added to the recession resection on adjustable.

2 Measurements of Recession and Resection The amount of recession and resection to be done is debatable. The authors have their own experience with this technique. The authors do recommend an equal amount of recession and resection and the primary position angle can be added to the recession amount. For example, a patient with esotropia for near of 50 prism dioptre and for a distance of 30 prism dioptre can undergo bimedial recession 4.0 mm and would need a recession resection of 4 mm. So, we have to do a 7.5-mm recession with resection of 3.0 mm with medial rectus on adjustable which can be pulled back if need for primary position angle. The authors believe that for each mm of recession and resection, the effect is correction of an incomitance of around 4–4.5 pd. Another example is a partially recovered lateral rectus paresis. The primary position angle is 14 prism dioptres base out and dextroversion is 30 prism dioptres secondary to right eye abduction restriction and levoversion 4 prism dioptres base out. The amount of left eye medial rectus recession is 3.5  mm and then since the incomitancy is 16 prism dioptres around 3.5 mm of recession and resection should be added to the primary position angle. The total medial recession would be 7.0 mm with 4.0 mm resection and adjustable.

3 Surgical Technique The rectus muscle is isolated and identified with normal technique via a forniceal conjunctival incision. The muscle is taken on two Jameson hooks to spread it properly (Fig. 1).

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Fig. 1  Shows medial rectus separated and two Jameson hook placed for exposure. The dotted lines show the medial rectus muscle. The dotted link joining the two lines depicts the proposed point for resection

Fig. 2  Shows the 6-0 vicryl sutures tied on superior and inferior edge of the muscle depending upon the desired amount of resection of the muscle

The 6-0 polyglactin suture is taken and the muscle is sutured on either end (Fig. 2) after measuring the amount of intended resection from the insertion with callipers. The muscle is incised proximal to the sutures and the stump is also removed from the insertion. Now, the muscle is resutured in a hang-back fashion and the recession is done as intended on a bow tie suture (Fig. 3) which could then be adjusted after seeing the patient postoperatively. The adjustment is mainly depending on the primary position angle postoperatively since the primary position should be diplopia free.

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Fig. 3  The bow tie know tied for hangback of the muscle as done for adjustable suture. The knot can be opened up for adjustment postoperatively

References 1. Scott AB. Posterior fixation adjustable and without posterior sutures. In: Lennerstrand G, editor. Proceedings VIIth Congress International Strabismological Association. Boca Raton: CRC Press; 1995. p. 399–402. 2. Thacker NM, Velez FG, Rosenbaum AL. Combined adjustable rectus muscle resection--recession for incomitant strabismus. J AAPOS. 2005;9(2):137–40. 3. Ghali MA. Combined resection-recession versus combined recession-retroequatorial myopexy of medial rectus muscles for treatment of near-distance disparity Esotropia. Clin Ophthalmol. 2017;6(11):1065–8. 4. Roper-Hall G, Cruz OA.  Results of combined resection-recession on a single rectus muscle for incomitant deviations-an alternative to the posterior fixation suture. J AAPOS. 2017;21(2):89–93.e1. 5. Hoover DL.  Results of a combined adjustable recession and posterior fixation suture of the same vertical rectus muscle for incomitant vertical strabismus. J AAPOS. 1998;2(6):336–9.