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

ity of more reliable weakening procedures, most surgeons do not advocate use of the Z-splitting technique. The advantages of a graded weakening procedure include the ability to titrate surgical effect, ability to perform asymmetric bilateral surgery, the potential for reversibility and access to the operated tendon should further surgery be needed in the future.

12.3.1Technique of Superior Oblique Tenotomy and Tenectomy

A superior oblique tenotomy or tenectomy may be performed on the tendon either nasal or temporal to the superior rectus muscle. During isolation of the tendon, the surgeon should minimize disturbance of the fascial tissues surrounding the tendon, which will minimize the risk of scarring between the cut ends of the tendon and the sclera.

A fornix incision for both a nasal and temporal superior oblique tenotomy/tenectomy can be made in the superotemporal quadrant. Once bare sclera is exposed, the superior rectus muscle is isolated on a large muscle hook. A small muscle hook is used to retract the conjunctiva and Tenon’s fascia nasally (>Fig. 12.11a). A Desmarres retractor is placed along the nasal border of the superior rectus muscle and retracted posteriorly. The superior oblique tendon can be visualized through

Chapter 12

its surrounding fascia as white fibers running perpendicular to the superior rectus muscle against the sclera (>Fig. 12.11b). Once the superior oblique tendon is visualized, a small incision is made through Tenon’s fascia directly over the tendon (>Fig. 12.11c). The tendon is then hooked with a small muscle hook and brought through the incision, followed by placement of a second small muscle hook (>Fig. 12.11d). The exposed tendon is then transected (tenotomy) or a portion of the tendon excised (tenectomy) (>Fig. 12.11e). The exaggerated forced traction test (Chap. 8) is repeated to confirm that the entire tendon has been cut.

A superior oblique tenotomy/tenectomy can also be performed from the temporal side of the superior rectus muscle. The effect of a tenotomy or tenectomy of the superior oblique tendon is greater as the procedure is performed closer to the trochlea. Isolation of the tendon on the temporal side is easier compared to locating the tendon on the nasal side of the superior rectus muscle. Once the superior oblique tendon has been isolated on a muscle hook, temporal traction is placed on the tendon to expose as much of the nasal portion of the tendon as possible. Once the nasal portion of the tendon is adequately exposed, a tenotomy or tenectomy is performed (>Fig. 12.12).

12.3.2Technique for Guarded Superior Oblique Tenotomy

The superior oblique tendon is isolated and transected nasal to the superior rectus muscle. A nonabsorbable suture is placed between the cut ends of the tendon, providing a guarded weakening procedure, allowing retrieval of the cut end of the tendon if needed at a future date (>Fig. 12.13).

Fig. 12.12. Superior oblique temporal tenotomy and tenectomy. Traction is placed on the tendon to expose as much of the nasal portion of the tendon as possible and a tenotomy or tenectomy is performed temporal to the superior rectus muscle

Fig. 12.13. Guarded nasal superior oblique tenotomy. A suture is placed between the cut ends of the tendon

12.3.3Technique for Superior Oblique Tendon Expander

The technique for weakening the superior oblique muscle by placement of a silicone expander in the tendon was described by Wright [16]. The placement of an expander to lengthen the superior oblique tendon offers several potential advantages. A graded weakening procedure can be performed, the risk of creating an iatrogenic superior oblique palsy can be minimized, and the technique facilitates reoperation, if needed [16–19].

The superior oblique tendon is isolated nasal to the superior rectus muscle as previously described for a nasal tenotomy/tenectomy procedure. Disturbance of the fascial tissues surrounding the tendon should be minimized. Care should be taken to avoid excessive dissection of Tenon’s capsule overlying the tendon, as this may result in postoperative complications including restricted elevation of the globe, or acquired Brown syndrome [17].

Two double-armed 5-0 or 6-0 Mersilene sutures are placed in the tendon. The first suture is placed approximately 3 mm nasal to the border of the superior rectus muscle and the sec-

Fig. 12.14a–e. Superior oblique tendon silicone expander. a Tenon’s capsule overlying the nasal portion of the superior oblique tendon is incised and the tendon isolated on a muscle hook. b Two doublearmed 5-0 or 6-0 Mersilene sutures are placed in the tendon and

c the tendon between these two sutures is transected. d A silicone 240 retinal band is sutured between the cut ends of the tendon using a horizontal mattress technique. e Tenon’s capsule overlying the tendon and expander is closed with absorbable suture

ond suture is placed approximately 2 mm nasal to the initial suture (>Fig. 12.14a, b). The tendon is then transected between these two sutures (>Fig. 12.14c). A silicone

band that has been cut to the desired length is sutured the cut ends of the superior oblique tendon using a mattress technique (>Fig. 12.14d). Tenon’s capsule the tendon and expander is then closed with absorbable (>Fig. 12.14e). Care should be taken to avoid excessive tion of Tenon’s capsule overlying the tendon, as this

in postoperative complications including restricted

of the globe, or acquired Brown syndrome [17]. The length of the silicone band used is determined by the amount of superior oblique overaction present (>Table 12.1). For Brown syndrome a length of 6 mm is used in most cases.

Chapter 12

Superior oblique recession offers several potential advantages including allowing for graded weakening of superior oblique muscle function, the potential for postoperative adjustment, and potential reversibility [14, 20–22]. A recession of the superior oblique tendon is performed after the tendon is isolated temporal to the superior rectus muscle. A double-armed absorbable suture is secured in the tendon approximately 4 mm from its insertion into the sclera (>Fig. 12.15a). The tendon is then detached at its insertion and the sutures passed through the sclera at the insertion site and the tendon is allowed to

Posterior tenotomy/tenectomy of the superior oblique tendon is performed at its insertion site into the sclera. The procedure provides a predictable weakening of the function of the superior oblique muscle for the treatment of A-pattern strabismus, primarily weakening its depression and abduction functions [23]. The superior oblique tendon is isolated temporal to the superior rectus muscle at its insertion. The posterior 7/8ths of the insertion is detached and a small wedge of the posterior tendon excised (>Fig. 12.16).

Fig. 12.15a,b. Superior oblique tendon recession. a A double-armed absorbable suture is secured in the tendon approximately 4 mm from its insertion into the sclera and the tendon detached from the globe.

b The sutures are passed through the sclera at the insertion site and the tendon allowed to “hang-back” for the desired recession

Fig. 12.16. Posterior 7/8ths tenotomy of the superior oblique tendon

References

1.Santiago AP, Rosenbaum AL (1997) Grave complications after superior oblique tenotomy or tenectomy for Brown syndrome. J AAPOS 1:8–15

13.Jin YH, Sung KR, Kook MS (1999) The immediate effect of bilateral superior oblique tenotomy on primary position horizontal binocular alignment. Binocul Vis Strabismus Q 14:33–38

14.Drummond GT, Pearce WG, Astle WF (1990) Recession of the superior oblique tendon in A-pattern strabismus. Can J Ophthalmol 25:301–305

diatr Ophthalmol Strabismus 27:136–140

4.Plager DA (1992) Tendon laxity in superior oblique palsy. Ophthalmology 99:1032–1038

5.Sato M, Amano E, Okamoto Y, Ota Y, Hirai T (2005) Interexaminer differences in the traction test of the superior oblique tendon. Jpn J Ophthalmol 49:216–219

6.Saunders R, Tomlinson E (1985) Quantitated superior oblique tendon tuck in the treatment of superior oblique muscle palsy. Am Orthopt J 35:81–89

7.Saunders RA (1986) Treatment of superior oblique palsy with superior oblique tendon tuck and inferior oblique muscle myectomy. Ophthalmology 93:1023–1027

8.Morris RJ, Scott WE, Keech RV (1992) Superior oblique tuck surgery in the management of superior oblique palsies. J Pediatr Ophthalmol Strabismus 29:337–346; discussion 347–348

9.Helveston EM, Ellis FD (1983) Superior oblique tuck for superior oblique palsy. Aust J Ophthalmol 11:215–220

10.Fells P (1974) Management of paralytic strabismus. Br J Ophthalmol 58:255–265

11.Harada M, Ito Y (1964) Surgical correction of cyclotropia. Jpn J Ophthalmol 8:88–95

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

syndrome and superior oblique overaction. J Pediatr Ophthalmol Strabismus 28:101–107

17.Pollard ZF, Greenberg MF (2000) Results and complications in 66 cases using a silicone tendon expander on overacting superior obliques with A-pattern anisotropias. Binocul Vis Strabismus Q 15:113–120

18.Stager DR Jr., Parks MM, Stager DR Sr., Pesheva M (1999) Longterm results of silicone expander for moderate and severe Brown syndrome (Brown syndrome “plus”). J AAPOS 3:328–332

19.Wright KW, Min BM, Park C (1992) Comparison of superior oblique tendon expander to superior oblique tenotomy for the management of superior oblique overaction and Brown syndrome. J Pediatr Ophthalmol Strabismus 29:92–97; discussion 98–99

20.Sood S, Simon JW, Zobal-Ratner J (2002) Asymmetric “hangback” superior oblique recession. J AAPOS 6:198–200

21.Astle WF, Cornock E, Drummond GT (1993) Recession of the superior oblique tendon for inferior oblique palsy and Brown’s syndrome. Can J Ophthalmol 28:207–212

22.Buckley EG, Flynn JT (1983) Superior oblique recession versus tenotomy: a comparison of surgical results. J Pediatr Ophthalmol Strabismus 20:112–117

23.Shin GS, Elliott RL, Rosenbaum AL (1996) Posterior superior oblique tenectomy at the scleral insertion for collapse of A-pat- tern strabismus. J Pediatr Ophthalmol Strabismus 33:211–218

The purpose of transposition procedures is often misunderstood. Transposition procedures have a limited, but specific and important role in the treatment of strabismus. Transposition procedures are used only in cases of muscle paralysis or severe paresis. Common indications for rectus muscle transposition surgery include treatment of sixth nerve palsy, including Duane syndrome with severe abduction limitation, and paralysis of any single rectus muscle that is innervated by the third cranial nerve. In general, when referring to transposition procedures, one is referring to rectus muscles transposition procedures and that is the primary focus of this chapter. Transposition of the superior oblique tendon, a procedure rarely performed for the treatment of a third nerve palsy, is also reviewed in this chapter. Though anterior transposition of the inferior oblique muscle can be used to treat paralysis of the inferior rectus muscle, it is primarily indicated for treatment of conditions not caused by muscle paralysis and this procedure is discussed separately in Chap. 11.

Rectus muscle transposition procedures work best when the function of only one rectus muscle in the eye to be operated is severely compromised. Transposition procedures can still be effective if the function of one or more rectus muscles to be transposed is only mildly compromised, but are almost entirely ineffective if the transposed muscles themselves are severely weakened. Transposition procedures do not involve the entire rectus muscle, but rather involve only the anterior third of the muscle that is not restrained by the rectus muscle pulley system [1]. The posterior portion of transposed rectus muscles remains in a relatively unchanged position after transposition surgery.

The goal of transposition surgery is primarily to realign the deviating eye, optimally to the primary position, and hopefully achieving single vision with or without the aid of prism spectacles after surgery. The results of transposition surgery are usually good, but never perfect. Despite obtaining single vision in the primary position, the field of single vision may be limited following transposition surgery. Patients should recognize prior to surgery that ductions produced in the direction of the paralyzed muscle will not usually improve significantly following surgery, and any improvement in ductions will be minimal. There are reports in the literature of mild to moderate improvement of ocular ductions following transposition surgery that has been augmented through the placement of posterior fixation sutures, though scientific validation of these claims has yet to be established [2, 3].

The mechanism by which a transposition procedure produces improvement in primary position eye alignment is controversial. Some surgeons believe that some of the “function” of the transposed muscles is transferred in the direction of the paralyzed muscle through resting tone of the transposed muscles or a change in vector forces of the transposed muscles. Others believe that the transposed muscles act primarily as a passive restraint to hold the operated eye in the primary position. Yet another theory suggests that the rectus muscle pulleys, particularly following a posterior fixation suture augmented muscle transposition, are diverted posteriorly in the direction of the transposition while translating the center of the globe [4]. It is likely that more than one mechanism combines to create the improvement in primary position alignment achieved with transposition procedure. The ocular alignment results of a transposition procedure can be enhanced by weakening the antagonist of the paralyzed muscle, either through recession or through injection of botulinum toxin. Weakening of the yoke muscle in the sound eye may, in some cases, result in better alignment and a larger field of single vision when combined with a transposition procedure.

The surgeon should carefully plan all transposition procedures, recognizing that additional strabismus surgery may be warranted on the patient in the future. The risk of anterior segment ischemia is increased, particularly in susceptible patients, when more than two rectus muscles are operated simultaneously in close sequence in the same eye (Chap. 20). Techniques to preserve one or more anterior ciliary vessels may be warranted in selected patients. Additionally, several months should be allowed to elapse before additional muscles are operated in the same eye in patients who are susceptible to anterior segment ischemia, allowing time for revascularization and the development of collateral blood flow, thus decreasing, but not eliminating, the risk of anterior segment ischemia. The surgeon who plans today for possible surgery tomorrow is likely to be rewarded for this effort by availability of a greater variety of surgical options if reoperation is later required.

A large number of transposition procedures have been described over the last century with varying degrees of logic and success. Several procedures of historical interest will be briefly discussed and techniques still in common use today will be reviewed in detail including full tendon transposition, augmented full tendon transposition as described by Foster [3], and Buckley [5], Hummelsheim-type procedures, augmented Hummelsheim-type procedures as described by Brooks and

coworkers [6], the Jensen procedure, and superior oblique tendon transposition. Adjustable sutures can be used on many transposition procedures and are described in Chap. 14. Anterior transposition of the inferior oblique muscle is reviewed in Chap. 11 rather than here, because this procedure is not commonly indicated for treatment of muscle paralysis.

Hummelsheim [7] is credited with describing the first transposition procedure for paralytic strabismus. He described a partial transposition procedure involving the lateral halves of the superior and inferior rectus muscles to treat long-standing lateral rectus muscle paralysis. In Hummelsheim’s procedure, the transposed muscle segments were sutured directly to the lateral rectus muscle near its insertion (>Fig. 13.1a). If a large esotropia was present, a resection of the lateral rectus muscle and/or recession of the medial rectus muscle was often required. The effect of Hummelsheim’s procedure was reportedly enhanced by transposing the nasal halves of the vertical rectus muscles rather than the temporal halves of these muscles [8] (>Fig. 13.1b). Wiener and Scheie [9] advocated transecting a paralyzed horizontal rectus muscle posteriorly, splitting the muscle longitudinally, and suturing the proximal cut end of each muscle to the superior and inferior muscles, respectively (>Fig. 13.1c). Schillinger [10] recommended transposing the entire insertion of the vertical rectus muscles to compensate for a paralyzed horizontal rectus muscle. Likewise, transposition of the entire horizontal rectus muscle insertions was proposed as a treatment for vertical rectus muscle paralysis by Knapp

Chapter 13

[11]. This discussion highlights but a few of the historical aspects of transposition surgery to treat rectus muscle paralysis. Many authors have reported a wide variety of procedures and techniques not discussed here. The most common transposition procedure used today is a full tendon transposition or a variation of this procedure (>Fig. 13.1d).

13.1Surgical Exposure

for Transposition Procedures

Transposition procedures can be performed through a 180° limbal incision or through two fornix incisions in adjacent quadrants. The incisions are placed as shown in Fig. 13.2. Either approach is acceptable and often depends entirely upon the surgeon’s preference. Surgeons who prefer a limbal incision believe this approach improves exposure and indeed exposure is superior with a limbal incision. Those who favor a fornix incision feel that patients are more comfortable postoperatively following surgery using this approach and that the surgical exposure available through a fornix incision is sufficient to allow safe transposition surgery. There is evidence in an animal model that leaving the limbal conjunctiva undisturbed may play a role in reducing the risk of anterior segment ischemia [12] (Chap. 20).

13.2 Transposition Surgery Techniques

13.2.1Technique for Full Tendon Transposition

A full tendon transposition procedure is indicated when there is paralysis or severe paresis of a rectus muscle. The procedure is most commonly used for treatment of a lateral rectus paralysis. The two adjacent rectus muscles are transposed to a position next to the insertion of the paralyzed muscle. Many surgeons reattach the transposed muscles to the sclera so that they roughly follow the spiral of Tillaux.

In this example, the technique for treating a right lateral rectus paralysis is demonstrated, though a similar procedure can be used to treat paralysis of any single rectus muscle. The intermuscular septum of the superior and inferior rectus muscles is generously dissected for approximately 10–12 mm posterior to

Fig. 13.3. Full tendon transposition of the superior and inferior rectus muscle insertions for treatment of a lateral rectus muscle paralysis

the insertion. These two muscles are then detached from their insertions on the globe and transposed to a position adjacent to the insertion of the lateral rectus muscle (>Fig. 13.3). Practically speaking, the temporal border of the transposed muscle insertion will be placed adjacent to the upper border of the lateral rectus muscle for the superior rectus muscle (inferior border for the inferior rectus muscle) while the nasal border will be positioned at or near the temporal edge of the muscle’s previous insertion.

13.2.2Technique for Full Tendon Transposition with Posterior Fixation Suture Augmentation (Foster Procedure)

Foster [3] reported a technique in 1997 which represented a significant advance in the treatment of paralytic strabismus. His modification, though simple, powerfully influences the impact of a transposition procedure on primary position ocular alignment and has been reported to improve ductions in the field of action of the paralyzed muscle [2, 3], although the claims of improved ductions have not been scientifically validated. After a full tendon transposition has been completed, nonabsorbable sutures are used to augment the procedure by redirecting the belly of the muscle toward the paralyzed muscle. Posterior fixation sutures are used to secure the transposed muscle bellies to the sclera adjacent to the borders of the paralyzed muscle 12–14 mm posterior to the limbus (>Fig. 13.4). Concurrent recession of the antagonist muscle in the paralyzed eye has been associated with large overcorrections [3], and may be contraindicated. Recession of the yoke muscle in the sound eye has been recommended as an adjunct procedure if satisfactory primary position alignment is not achieved with augmented full tendon transposition alone [3]. Critics of the procedure often cite the potential for perturbations of vertical alignment, a complication that we have rarely encountered.

13.2.3Technique for Full Tendon Transposition with Lateral Rectus Muscle Fixation

Buckley [5] described an augmentation procedure that involved posterior fixation suture augmentation affected by suturing the belly of the transposed muscles directly to the belly of the paralyzed muscle. The sutures are placed proximally 8 mm posterior to the muscle insertion, redirecting the transposed muscle’s force vector in the direction of the paralyzed muscle (>Fig. 13.5). Caution should be used to avoid ligating

the anterior ciliary vessel associated with the paralyzed muscle to minimize the risk of anterior segment ischemia.

13.2.4Techniques for Vessel-Sparing Full Tendon or Near Full Tendon Transposition

Patients who are susceptible to anterior segment ischemia (Chap. 20) may still be candidates for transposition surgery, though modifications may be warranted to preserve all or part

Fig. 13.4. Augmented full tendon transposition procedure described by Foster. The belly of each transposed muscle is sutured to the sclera adjacent to the borders of the paralyzed rectus muscle

Fig. 13.5. Augmented full tendon transposition procedure described by Buckley. The belly of each transposed muscle is sutured to belly of the paralyzed rectus muscle

of the anterior segment circulation. Protection from anterior segment ischemia is afforded by procedures that avoid cutting the anterior ciliary arteries. Careful dissection and sparing of one or both anterior ciliary vessels associated with each vertical rectus muscle can be done prior to transposition of the muscles [13] (>Fig. 13.6). Many surgeons prefer microscope magnification for this procedure. Coats and coworkers [14] reported near full tendon transposition of rectus muscles involving repositioning of four-fifths of the transposed rectus muscles leaving the remaining muscle and its anterior ciliary vessels intact (>Fig. 13.7). Avoidance of the need for tedious dissection of the anterior ciliary vessels is an advantage of this technique.

13.2.5Technique for HummelsheimType Transposition

Hummelsheim [7] described a procedure for treatment of a longstanding lateral rectus palsy in which the temporal halves of the superior and inferior rectus muscles were partially transposed to the lateral rectus muscle insertion. The transposed muscle insertions were sutured directly to the lateral rectus muscle near its insertion. Today, half tendon transpositions of adjacent rectus muscles to treat a rectus muscle paralysis are generally accomplished by suturing the transposed muscle segments directly to the sclera adjacent to the paralyzed muscle’s insertion. Though technically incorrect, this modified procedure is often referred to as a Hummelsheim procedure. Though originally described for treatment of a lateral rectus muscle paralysis, a similar procedure can be used to treat any isolated rectus muscle paralysis in an eye.

The superior and inferior rectus muscles are split longitudinally taking care to ensure that at least one anterior ciliary vessel is spared in each muscle. One half of each of the superior and inferior rectus muscles is transposed and sutured to the sclera adjacent to the paralyzed muscle insertion using 6.0 polygalactin suture (>Fig. 13.8).

Fig. 13.7. Transposition of four-fifths of the rectus muscles with sparing of one anterior ciliary vessel in each transposed muscle

13.2.5.1Augmentation of a HummelsheimType Procedure

Brooks and coworkers [6] described a simple procedure to augment the effect of a Hummelsheim-type transposition procedure. In this modification, a 5-mm resection of the transposed muscle segment is made prior to suturing the trans-

Fig. 13.9. Augmented Hummelsheim-type procedure. A 5-mm resection of each transposed muscle segment is made prior to suturing them to the sclera adjacent to the borders of the paralyzed rectus muscle insertion

posed muscle segment to the sclera adjacent to the borders of the paralyzed rectus muscle insertion (>Fig. 13.9).

13.2.6Technique for the Knapp Transposition Procedure

Knapp [11] described a procedure for transposing a functioning medial and lateral rectus muscle to a position adjacent to and perpendicular with the superior rectus muscle insertion to treat patients with monocular elevator deficiency (>Fig. 13.10a). Today, the transposed muscle segments are more commonly

sutured in position adjacent to the superior rectus muscle insertion following the spiral of Tillaux (>Fig. 13.10b). This modification is still referred to as a Knapp procedure by many people, through this characterization is technically incorrect. Whether the muscle is sutured as originally described by Knapp or along the spiral of Tillaux probably has little effect on the success of the procedure. Reoperation, however, is technically easier if the new muscle insertion is placed along the spiral of Tillaux.

13.2.7 Technique for the Jensen Procedure

The Jensen procedure was reported in 1964 as a treatment for chronic lateral rectus muscle paralysis [15]. The Jensen technique involves manipulation of the muscle bellies of the superior, inferior and lateral rectus muscles so that adjacent halves of these rectus muscles are brought into contact with each other using a nonabsorbable suture. The muscles are not disinserted for this procedure. Although the Jensen procedure has been proposed to avoid the risk of anterior segment ischemia, the condition has been reported following the Jensen transposition procedure [16, 17], including one case in a 10-year-old child [16]. The procedure, as described by Jensen, includes a medial rectus muscle recession if the primary position deviation was greater than 25 prism diopters. Though originally described as a treatment for sixth nerve palsy, the procedure can be similarly performed to treat paralysis of any single rectus muscle in an eye, assuming good to excellent function of the adjacent rectus muscle. The procedure is still most commonly performed for lateral rectus muscle paralysis but has mostly been replaced by various full tendon and partial tendon transposition procedures.

When performing a Jensen procedure for lateral rectus muscle paralysis, the lateral rectus, superior rectus, and inferior rectus muscles are isolated and the muscle capsule and intermuscular septum of each muscle dissected to exposed the muscle for 12–15 mm posterior to each muscle’s insertion. A