Ординатура / Офтальмология / Английские материалы / Strabismus Surgery and Its Complications_Coats, Olitsky_2007

Fig. 14.7a–e. Cinch knot adjustable suture technique. a Two options for suture placement in the muscle stump. b A cinch suture is placed around the muscle suture. c Appearance of the eye at the end of sur-

gery. d Adjustment is accomplished by sliding the cinch suture along the muscle sutures, as needed. e When the desired alignment has been achieved, the muscle sutures are tied securely over the cinch knot

Fig. 14.8a–d. Traction knot adjustable suture technique. a A knot is placed along each muscle suture. The free ends of sutures extend from the wound postoperatively. b The sutures distal to the knots are cut

if alignment is satisfactory; no other manipulation is needed. c The muscle can be advanced and a permanent knot tied, or d further recessed and a permanent knot tied

The needles of a double-arm absorbable suture are passed through the sclera at the desired recession position. Prior to permanently tying the muscle sutures together, the muscle is allowed to hang back 1–3 mm (>Fig. 14.9a). A suture, known as the ripcord suture, is passed under the muscle suture knot (>Fig. 14.9b). This is accomplished by loading the needle in the needle holder backwards, lifting the muscle suture knot off the sclera, and passing the needle and suture beneath the knot. The needle attached to the ripcord suture is then passed through the sclera anterior and lateral to the muscle insertion. When tied, this suture will place traction on the muscle suture and advance the muscle to the desired recession position (>Fig. 14.9c). If adjustment is needed postoperatively, the ripcord suture can be cut and removed, resulting in an additional programmed recession (>Fig. 14.9d). If ocular alignment is satisfactory, no manipulation of the ripcord suture is needed.

A similar ripcord procedure can be performed to allow a onestep programmed adjustment of a rectus muscle resection. After performing a standard resection, and prior to permanently tying the muscle suture ends into a knot, the muscle is allowed to retract 1–3 mm posterior to the insertion (>Fig. 14.10a). The ripcord suture is then placed as described above for a recession procedure (>Fig. 14.10b). If recession of the muscle is required postoperatively, the ripcord suture is removed and the muscle is allowed to recess as programmed (>Fig. 14.10c). If ocular alignment is satisfactory, no manipulation of the ripcord suture is needed.

Fig. 14.9a–d. Ripcord adjustable suture technique for rectus muscle recession. a The muscle is allowed to hang back 1–3 mm prior to tying the muscle suture ends together. b A ripcord suture is passed under the muscle suture knot. c When tied, the muscle is advanced to

the desired recession position. d The ripcord suture can be removed if further recession is needed postoperatively. If ocular alignment is satisfactory, no manipulation of the ripcord suture is needed

Fig. 14.10a–c. Ripcord adjustable suture technique for rectus muscle resection. a After performing a standard resection, the muscle is allowed to retract 1–3 mm posterior to the insertion and the muscle suture ends tied into a knot. b The ripcord suture is then placed. c The

ripcord suture can be removed if less resection effect is needed postoperatively. If ocular alignment is satisfactory, no manipulation of the ripcord suture is needed

References

1.Laby DM, Rosenbaum AL (1994) Adjustable vertical rectus muscle transposition surgery. J Pediatr Ophthalmol Strabismus 31:75–78

2.Goldenberg-Cohen N, Tarczy-Hornoch K, Klink DF, Guyton DL (2005) Postoperative adjustable surgery of the superior oblique tendon. Strabismus 13:5–10

3.Metz HS, Lerner H (1981) The adjustable Harada-Ito procedure. Arch Ophthalmol 99:624–626

4.Dawson E, Bentley C, Lee J (2001) Adjustable squint surgery in children. Strabismus 9:221–224

5.Coats DK (2001) Ripcord adjustable suture technique for use in strabismus surgery. Arch Ophthalmol 119:1364–1367

6.Hakim OM, El-Hag YG, Haikal MA (2005) Releasable adjustable suture technique for children. J AAPOS 9:386–390

Chapter 14

7.Ohmi G, Hosohata J, Okada AA, Fujikado T, Tanahashi N, Uchida I (1999) Strabismus surgery using the intraoperative adjustable suture method under anesthesia with propofol. Jpn J Ophthalmol 43:522–525

8.Luff AJ, Morris RJ, Wainwright AC (1993) Day case management in adjustable suture squint surgery. Eye 7 ( Pt 5):694–696

9.Bacal DA, Hertle RW, Maguire MG (1999) Correlation of postoperative extraocular muscle suture adjustment with its immediate effect on the strabismic deviation. Binocul Vis Strabismus Q 14:277–284

10.Paris V, Saya H (1990) [The use of Healon in surgery with adjustable sutures for strabismus]. Bull Soc Belge Ophtalmol 239:37–41

11.Engel JM, Rousta ST (2004) Adjustable sutures in children using a modified technique. J AAPOS 8:243–248

12.Saunders RA, O’Neil JW (1992) Tying the knot. Is it always necessary? Arch Ophthalmol 110:1318–1321

Most of the procedures described in this textbook are standard procedures that are used on a routine basis by most strabismus surgeons. The list of surgical procedures that have been described for the treatment of strabismus and the variations that have been described for existing procedures is exhaustive and cannot be adequately covered in a single volume on strabismus surgery. This chapter reviews several procedures that are used infrequently but that are nevertheless important in the armamentarium of the strabismus surgeon. These procedures are generally more complex than standard strabismus surgery techniques and are typically only required to manage unusually complex strabismus and/or strabismus that has been refractory to traditional surgery.

15.1 Periosteal Flap Fixation of the Globe

Surgical management of complex paralytic strabismus can be challenging and surgical results disappointing. Paralytic strabismus due to oculomotor palsy is particularly difficult to effectively treat. Successful mechanical fixation of the globe in the primary position has been reported with use of various allograft [1, 2] and autogenous materials [3, 4]. Goldberg and coworkers [5] recently reported the use of apically based autogenous periosteal flaps to tether the globe in a fixed position near the primary position. We have found this technique to be an effective means of realigning the eyes of patients with complex paralytic strabismus, especially strabismus due to third cranial nerve paralysis. It is less complex than many previously reported procedures proposed to mechanically fixate the globe and does not involve surgery elsewhere on the body to obtain graft material.

The procedure is done in conjunction with an oculoplastic surgeon, unless the strabismus surgeon has experience with surgery in the posterior aspect of the orbit and with surgical manipulation of the periosteum. An apically based periosteal flap can be created from the medial, lateral, superior or inferior orbital walls (>Fig. 15.1a–c). The optimal approach for a medial periosteal flap is through a caruncular conjunctival incision.

After making the initial incision, blunt dissection is used to expose the periosteum and malleable retractors used to achieve adequate surgical exposure. A no. 12 Bard Parker blade is used to incise the periosteum to create a flap with its base in the orbital apex. We have used flaps based at the orbital rim

occasionally with success as well. The incision is initiated as far posteriorly as possible and should be carried anteriorly to the orbital rim (>Fig. 15.2a). The flap should be generously wide. A periosteal elevator is used to separate the flap from the underlying bone and a 5-0 Mersilene suture is secured to the anterior edge of the flap (>Fig. 15.2b).

The sclera anterior to the paralyzed rectus muscle is exposed by retracting the incision toward the limbus and bluntly dissecting the surrounding tissue. We typically pass the sutures through the sclera anterior to the paralyzed rectus muscle insertion (>Fig. 15.2c). Long scleral suture bites are recommended to reduce the risk of the sutures cheese-wiring out of the sclera when the sutures are tied. The globe is then rotated toward the periosteal flap, well beyond the primary position. While the assistant surgeon holds the eye in this position and retracts the surrounding tissues, the surgeon secures the periosteal flap to the sclera by tying the suture ends together. The highly stylized diagram demonstrating this step is for illustrative purposes only, and it should be recognized that the surgeon is not able to actually visualize the surgical site as the flap is secured into place on the sclera. In reality, the surgeon must secure the flap to the sclera by feel. Figure 15.3 shows an eye during this step of the procedure, clearly demonstrating that the surgeon has limited or no view of the surgical site during this step. The incision is then closed with interrupted absorbable suture.

We have yet to produce a long-term overcorrection with this procedure in a patient with strabismus severe enough to warrant its use. Initial overcorrection is the surgical goal and an initial overcorrection of 20–25 prism diopters is not unreasonable. The effect of the periosteal flap will degrade over the first few days to weeks after surgery.

15.2Recession and Periosteal Fixation of a Rectus Muscle

A rectus muscle can still have significant residual ability to move the globe despite a large recession or even a free tenotomy. This residual function occurs because of secondary connections between the muscle and the globe through Tenon’s fascia and surrounding structures. Even procedures that involve removal of the entire visible anterior portion of a rectus muscle without reattachment to the globe can be associated with some residual muscle function.

Fig. 15.2a–c. Periosteal flap procedure. a After exposure of the periosteum, malleable retractors are used to improve surgical exposure and a flap is created with a no. 12 Bard Parker blade. A periosteal elevator is used to separate the periosteum from the underlying bone. b A 5-0

Mersilene suture is secured into the anterior edge of the flap. c The flap is then sutured to the muscle insertion or, as in this example, to the sclera anterior to the muscle insertion

Recession and transfer of a rectus muscle insertion to the adjacent periosteum has a powerful weakening effect on the action of the muscle. In theory, such a procedure is reversible, though we have yet had the opportunity to reverse such a procedure. Other than removing a muscle entirely, a procedure that is irreversible, transfer of the rectus muscle insertion to the adjacent periosteum is probably the most efficient way to maximally weaken a rectus muscle. Indications for this procedure are uncommon, and generally involve the need to weaken the antagonist of a completely paralyzed rectus muscle. The procedure is most commonly performed, in our experience, on the lateral rectus muscle as a component in the treatment of a complete third nerve palsy or Duane syndrome.

The procedure is optimally performed through a limbal incision because exposure through a fornix incision is not usually sufficient to safely accomplish surgery. The lateral rectus muscle insertion is isolated, hooked, and exposed as usual. It is then is secured with a 5.0 Mersilene suture and detached from the sclera at its insertion. Two techniques can be used to suture the muscle to the periosteum. This first involves blunt dissection to expose the periosteum followed by placement of the suture in the periosteal tissues under direct visualization. The second is passage of the suture through periorbital adipose tissues to reach the periosteum without actually exposing the periosteum. This is our preferred approach because of its simplicity. In order to successfully carry out this approach, a sturdy needle, such as an S-14 or S-24 needle, is required and the needle needs to be bent into a more acute angle with a hemostat prior to passing the suture through the periosteum. Additionally, a malleable retractor is recommended to protect the globe as retrieval of the suture from the periosteum is attempted. Figure 15.4 depicts the completed procedure.

15.3 Postoperative Traction Sutures

In rare situations, the use of traction sutures to fixate the globe into a particular position for a short period of time after surgery can be utilized to aid in the management of complex strabismus. There are no specific indications for their use, rather the surgeon develops a gestalt as to when postoperative traction sutures may be helpful. An example of when a traction suture might be helpful is following the dissection of extensive adhesions from the inferior aspect of the globe to treat a hypotropia. The surgeon may wish to fixate the eye in upward gaze for several days to a week following surgery to reduce the risk of recurrent adhesions, which would result in rapid recurrence of the hypotropia.

A sturdy double-arm suture, such as 5.0 or 6.0 Mersiline, is passed partial thickness through the sclera. Both arms of the suture are then passed through the conjunctival fornix and the adjacent periosteum. Finally, the sutures are externalized through the skin. The needles are then passed through a rubber bolster and tied over the bolster to fixate the eye into position (>Fig. 15.5). The suture are cut and removed several days to a week after surgery.

15.4 Marginal Tenotomy/Myotomy

Marginal tenotomy/myotomy was introduced in the early 1900s as a more controlled means of treating strabismus than was available through the use of myectomy or tenotomy, which was popular at the time. Marginal tenotomy/myectomy is rarely performed today, with one exception being marginal myotomy of the inferior oblique muscle, a favored weakening procedure for mild inferior oblique overaction by some surgeons. Marginal tenotomy/myotomy has potential value in two other situations that are occasionally encountered. The first is when there is a need to further weaken an already maximally recessed rectus muscle. Because a hang-back recession (Chap. 9)

Fig. 15.4. Transfer of a rectus muscle insertion to the periosteum of the adjacent orbital wall. Schematic of completed procedure

Fig. 15.5. Traction suture placed to temporarily maintain the eye in a fixed position after surgery, in this case upward gaze

can allow the surgeon to safely and effectively perform very large recessions, this scenario rarely occurs. The second clinical situation has been in the late repair of a lost muscle that has become so contracted that it cannot be attached to the sclera at or anterior to the equator without producing a large primary position deviation and a duction limitation. In these unusual situations, we have sutured the lost muscle to the sclera at the equator of the globe and performed a marginal myotomy to mitigate these concerns.

A marginal tenotomy/myotomy is simple to perform on a normal muscle that has not been previously operated on, yet the procedure is rarely indicated in this setting. On the other hand, marginal tenotomy/myotomy is very difficult to perform on a rectus muscle that has been recessed far from its original insertion, on a rectus muscle that is severely contracted, or that is otherwise difficult to surgically access. Exposure can be exceedingly difficult and muscle rupture due to excess traction, damage to a vortex vein, and other complications are possible. While many variations of marginal tenotomy/myotomy procedures have been proposed, we perform one simple technique using two overlapping incisions involving 75% of the muscle’s width. The incisions must overlap, because if any of the fibers remain intact longitudinally, there will be little or no effect from the procedure [6].

The descriptions and diagrams provided here are schematic in nature only. In reality, the actual performance of a marginal tenotomy/myectomy is difficult. The reason that the procedure is difficult is because, when indicated, surgical exposure is generally very poor and/or the muscle is extremely tight, both making it very difficult to safely perform this otherwise simple procedure. To reduce hemorrhage from the muscle, a hemostat is placed across the muscle in the area where the marginal tenotomy or myotomy is to be performed (>Fig. 15.6a). If a right angle hemostat is not available, it is acceptable to place the hemostat on the muscle in a diagonal orientation. The hemostat is left is placed for 30–60 s which results in crushing of the muscle and its associated vascular supply, reducing the risk of significant hemorrhage. Blunt-tipped scissors are used to perform the tenotomy/myotomy (>Fig. 15.6b). If the muscle is

particularly tight, the anterior tenotomy can be performed by cutting the muscle with a scalpel, using a muscle hook under the muscle insertion to protect the sclera (>Fig. 15.6c). Great care must be used with further manipulation the globe after the procedure has been completed, because the now structurally weakened rectus muscle can be easily ruptured. Later strabismus surgery on a muscle that has undergone marginal myotomy is complex and difficult due to scarring and adhesions and a relatively fragile remaining muscle. Therefore, the decision to perform this procedure should be made with caution.

15.5Treatment of Esotropia and Hypotropia Associated with High Axial Myopia

Patients with high axial myopia sometimes develop an unusual, restrictive strabismus characterized by development of a progressive esotropia and hypotropia with limitation of abduction and elevation. The condition is sometimes referred to as the heavy eye syndrome. Affected patients typically have myopia in excess of 10 prism diopters, usually much greater. Onset is typically during or after the fourth decade of life. Though initially believed to be caused by paralysis of the lateral rectus muscle due to pressure on the lateral rectus muscle as it was compressed between the lateral orbital wall and the enlarged globe [7], evidence now suggests that it is due to a mechanical problem of a different sort.

Krzizoh and coworkers [8] reported magnetic resonance imaging evidence of downward displacement of the lateral rectus muscle by an average of 3.4 mm in patients with this condition. Aoki and coworkers [9] also investigated the paths of extraocular muscles through the orbit in patients with acquired esotropia and high axial myopia using magnetic resonance imaging. They found not only a consistent tendency for the lateral rectus muscle path to be deviated inferiorly, but also for the superior rectus muscle path to be deviated nasally in comparison to control groups having high myopia without esotropia. Additionally, the posterior globe was consistently

Fig. 15.6a–c. Marginal tenotomy/myotomy. a A hemostat is placed across the muscle in the area where the tendon/muscle is to be incised and removed after 30–60 s and b two overlapping 75% tenotomies/

myotomies are performed. c A scalpel can be used to cut the tendon anteriorly, using a muscle hook under the muscle insertion to protect the sclera if the muscle is extremely tight

noted to have prolapsed superotemporally between the superior and lateral rectus muscles. Figure 15.7a shows the orbital magnetic resonance image of a patient with this condition. Finally, Venkatesh and coworkers [10] recently reported evidence of a mitochondrial myopathy in a female patient with acquired esotropic strabismus fixus related to high myopia, and suggested that the presence of a mitochondrial myopathy might contribute to development of the disorder.

Standard surgical techniques of recession and resection are almost universally ineffective in correcting the strabismus in this condition. Krzizok and coworkers [11] recommended treatment options which appear to be highly effective. Recognizing that the path of the lateral rectus muscle was deviated inferiorly in affected patients, they performed surgery to fixate the lateral rectus muscle back in the physiologic horizontal meridian at the equator of the globe using a silicone loop or nonabsorbable suture as a retroequatorial myopexy (poster­ ior fixation suture) along the horizontal meridian. Using this procedure, they were able to achieve good primary position alignment with improvement of abduction and elevation in affected patients. We have also achieved excellent results by the utilization of nonabsorbable sutures to create a union between the muscle belly of the entire lateral rectus muscle and the temporal half of the superior rectus muscle (>Fig. 15.7b). The muscles are not detached from the globe for this procedure. Two nonabsorbable sutures are placed approximately 12 mm and 16 mm posterior to the limbus, respectively, to bring the muscle bellies of the superior and lateral rectus muscles in contact with each other in the superotemporal quadrant. This maneuver forces the posterior portion of the globe into the posterocentral orbit and results in immediate alignment of the globe on the operating table. Ductions are also noted to improve following surgery. Figure 15.7c and d demonstrates the preoperative and postoperative alignment of a patient who underwent this procedure.

15.6Horizontal Transposition of the Vertical Rectus Muscles to Treat Isolated Ocular Torticollis/Torsion

In most cases, a head tilt is caused by hypertropia or cyclotropia and responds well to standard surgical strengthening or weakening procedures on the cyclovertical muscles. Occasionally, an ocular head tilt occurs in the absence of cyclovertical strabismus. This situation may be seen in isolation or in association with congenital nystagmus. The basic concept of surgical treatment is to rotate the eyes in the direction of the head tilt, which will result in improvement or resolution of the abnormal head tilt. The procedure presumably produces a tilt in the patient’s subjective visual environment, prompting the patient to straighten the head to relieve the induced image tilt [12]. Though several techniques have been suggested to accomplish this goal, we prefer the technique reported by von Noorden and coworkers [13] using horizontal transposition of the vertical rectus muscles. A full tendon transposition is done on both eyes as shown in Fig. 15.8. If the patient has significant amblyopia in one eye, the procedure is required only on

Chapter 15

the fixating eye. While von Noorden and coworkers [13] predicted that the effect of surgery might diminish with time due to mechano-elastic properties of the orbit, this has not been our experience.

15.7Posterior Fixation Suture (Retroequatorial Myopexy, Fadenoperation)

Cuppers [14] first described the posterior fixation suture technique to treat incomitant strabismus. The procedure has also been referred to as the “fadenoperation.” The term faden is the German word for suture or string. Therefore, it is incorrect to describe this procedure as a “faden suture.” The use of a posterior fixation suture may be employed in the treatment of incomitant strabismus in a variety of settings. It has also been used in the treatment of esotropia with a high accommodative convergence to accommodation (AC/A) ratio as well as dissociated vertical deviation.

The mechanism of action of the posterior fixation suture procedure that has historically been taught is that the procedure shifts the effective insertion site of the rectus muscle posteriorly. According to this theory, this shift in the muscle’s insertion site reduces the effectiveness of muscle contraction on movement of the globe. Recently, this mechanism has been challenged. Clark and co-workers [15] quantified duction in the field of action following posterior fixation suture placement in a series of patients. The patients then underwent magnetic resonance imaging to verify anatomic changes. They also performed computed tomography in a cadaver containing radiographic markers to determine the effect of posterior fixation suture placement on the position of the medial rectus muscle insertion relative to its pulley. The results of their study indicated that posterior fixation sutures do not significantly reduce muscle torque during contraction. They found that posterior fixation sutures posteriorly displaced the pulley sleeve during contraction of the muscle resulting in a mechanical restriction after surgery accounting for limitation of ductions seen after the procedure.

Posterior fixation sutures have been used in the treatment of esotropia with a high AC/A, though there is not universal approval of their use for this purpose. Kushner and co-workers [16] compared the use of the medial rectus muscle recessions combined with posterior fixation suture to standard medial rectus muscle recessions augmented to target the near angle in patients with a high AC/A. They found that a higher percentage of patients in the augmented recession group achieved satisfactory alignment and were able to discontinue wearing bifocals postoperatively compared to patients in the posterior fixation group. A 15-year follow-up of these patients continued to show that surgery for the near angle provided excellent motor and sensory results in these patients.

Traditionally, a posterior fixation suture is used to suture a rectus muscle to the sclera using one or two nonabsorbable sutures 12–16 mm posterior to the limbus (>Fig. 15.9). The suture can be placed with or without prior recession of the muscle.