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

Fig. 9.7. Passage of the needles in the sclera using the “crossed swords” technique

Fig. 9.8. The muscle has been pulled up to its new insertion and the sutures have been tied and cut

Fig. 9.9a–c. Correcting malposition of the new muscle insertion. a The scleral sutures have been placed too close together, causing the central aspect of the muscle to sag posteriorly. This can be corrected by

Guyton and Repka [19] differed from earlier “loop” recessions, a term first coined and popularized by Gobin in the 1960s [20]. Gobin’s recession used two separate sutures that were placed at the edges of the muscle and the needles were widely separated [20]. This separation of the sutures makes measurement of the size of a recession more difficult.

Both experienced and occasional strabismus surgeons may effectively use hang-back and hemi hang-back techniques. The hang-back procedure can be used with recession of any of the rectus muscles. The muscle can be approached using either a limbal or fornix incision. The techniques have several potential advantages. The procedure is conducted at the original insertion site (hang-back) or more anterior then a conventional recession (hemi hang-back). Because of this, exposure is excellent regardless of the amount of recession being performed. This makes the surgeon much less dependent on the skills of a surgical assistant, especially for large recessions. Improved exposure and the more anterior location of the area to be manipulated during surgery may result in less tendency for deep needle passes, minimizing scleral and eye wall perforations, which may be more likely to occur with more posterior needle passes in areas where exposure is less optimal. This may be especially true for less experienced strabismus surgeons. In the event that a perforation does occur when using a hang-back approach, it is unlikely to result in damage to the retina because the rectus muscle insertions, with the exception of the superior rectus muscle insertion, are located anterior to the ora serrata.

Some strabismus surgeons have raised concerns about the use hang-back techniques. The most commonly raised concerns have been the issue of possible forward migration of the muscle before it has firmly reattached to the sclera. If this did indeed occur with any appreciable frequency, the number of undercorrections using this technique would be expected to be larger than with the conventional approach. Clinical studies, however, have not found this to be the case [21, 22]. Additionally, surgeons who perform adjustable suture surgery rarely express this same concern, even though the muscle is not directly secured to the sclera during adjustable procedures either.

b passing the needle through the central portion of the muscle, behind the original suture line, and c tying the suture to bring the center of the muscle forward

9.4.2.2 Securing the Muscle to the Sclera

The muscle is isolated and disinserted as previously described in Chap. 8 and toothed locking forceps are placed on the borders of the original insertion site. The suture needles are passed through the original insertion site in crossed swords fashion. The needles are passed at an angle that allows both to emerge anterior to the insertion and as close together as possible (>Fig. 9.10). If the distance between the needle exit sites is too large, measurement inaccuracies are more likely when recessing the muscle. If the needle exit sites are a large distance apart, an adjustment of the measurement made along the sutures in the next step can be added to compensate for the problem; in most cases an increase of 0.5 mm will be sufficient.

9.4.2.3 Measuring the Recession

The sutures are advanced anteriorly through the sclera until the muscle rests firmly against the posterior aspect of the insertion. Unexpected, additional recession will occur if the muscle is not brought fully anteriorly in this step. This is especially likely to occur when the muscle is tight and has an increased tendency to retract away from the insertion site during this step of the procedure.

Calipers are placed perpendicular to the globe at the insertion site and a locking needle holder placed across the sutures as directed by the caliper measurements (>Fig. 9.11). During this step, the caliper should rest gently on the insertion site. A smaller than intended recession will result if the caliper is pressed too firmly into the sclera during this step. To avoid errors during this step, we recommend that the surgeon hold the caliper against the globe and simultaneously place anterior traction on the muscle sutures to place the muscle in apposition with the original insertion site while the surgical assistant places the needle holder across sutures, as directed by the surgeon.

Fig. 9.10. Scleral needle passes during the hang-back recession technique. The needles are passed through the original insertion site to emerge side-by-side in a crossed swords pattern

The suture is then tied and trimmed with the needle holder in place. The needle holder is removed and the globe is rotated away from the muscle, which causes the muscle to retract posteriorly. Alternatively, the muscle can also be placed into its new position by gently pulling the suture through the suture tract with a needle holder until the suture knots restrict further movement. If desired, the final position of the muscle can be confirmed by caliper measurement (>Fig. 9.12).

Fig. 9.11. Marking the suture for hang-back recession. The muscle is pulled firmly forward against the original insertion site and the caliper is placed along the suture arms. A locking needle holder is placed across the sutures inside the proximal caliper tip

9.4.2.4 Hemi Hang-Back Modifications

In some animal experiments, very large rectus muscle recessions performed with the hang-back technique have been demonstrated to migrate anteriorly following the procedure. If this were to occur following hang-back surgery in patients, an undercorrection would result. To mitigate this potential prob-

Fig. 9.12. Completing the hang-back recession. The sutures are cut and tied against the needle holder. The muscle is moved to its new posterior position by gently pulling on the sutures. The accuracy of the recession can verified with a caliper, if desired

Fig. 9.13. Large recession using a hemi hang-back technique. The needles are passed halfway between the original insertion site and the desired new insertion position. The muscle is then further recessed using a standard hang-back technique

lem, some surgeons prefer to use the hemi hang-back recession technique for recessions larger than 8 mm. In this method, the suture needles are passed through the sclera approximately half the distance between the original insertion site and the desired new recession position. As with the hang-back procedure, it is important that the needles exit close to one another in a crossswords configuration. The muscle is then brought up to this midpoint and the remainder of the procedure is identical to the standard hang-back method (>Fig. 9.13).

9.5 Modified Recession Procedures

Most recession procedures are performed using one of the techniques described above. Occasionally, modifications are required to address A- and V-patterns, scleral abnormalities, explants, and other anatomical variations. A few of the most common modifications and indications are reviewed below.

Chapter 9

bined with a recession or resection of the muscles, will correct approximately 15 prism diopters of an A- or V-pattern. The amount of pattern correction is proportional to the amount of preoperative pattern that was present [24, 25]. Vertical offsets of the horizontal rectus muscles may be performed symmetrically and bilaterally, or may be confined to one eye.

9.5.2Recession Following Scleral Buckling Procedures

Strabismus surgery on patients who have undergone previous scleral buckling procedures can be complex. Both the ability to isolate a rectus muscle and the process of recession itself are rendered more difficult by the presence of an encircling element and other explants, as well as associated scarring that occurs as a result of retinal surgery. Modifications of surgical techniques that may be helpful in these situations are reviewed in Chap. 27.

9.5.1 A- and V-Patterns

Vertical transposition of the horizontal rectus muscles is an effective method for treating small to moderate A- and V-pattern horizontal strabismus [23]. This technique is commonly utilized to treat A- and V-patterns when oblique muscle dysfunction is not present. Offsetting the horizontal rectus muscle insertion up or down during recession or resection surgery weakens the action of that muscle when the globe is moved in the direction of the offset. For example, if the medial rectus muscles are up shifted one-half tendon width, their horizontal action is diminished in up gaze. It follows that moving the medial rectus toward the apex of an A- and V-pattern is appropriate for correcting the incomitant deviation. Conversely, moving the lateral rectus muscle toward the open end of the A- or V-pat- tern is also appropriate for correcting the incomitant deviation (>Fig. 9.14). This is true regardless of whether a recession or resection procedure is performed. It is generally accepted that offsetting up or down one-half tendon width of two horizontal rectus muscles, irrespective of whether it is performed on the medial rectus or the lateral rectus muscle, or whether it is com-

Fig. 9.14. Treatment of A- and V-pattern strabismus. The medial rectus muscles are shifted toward the “apex” of the pattern. The lateral rectus muscles are shifted toward the “open” end of the pattern

9.5.3 Recessions in Patients with Thin Sclera

In some patients, the sclera can be exceedingly thin and the risk of perforation substantially increased. Coats and Paysse [26] described a procedure to eliminate the risk of scleral perforation in susceptible patients. Their technique avoids placement of sutures directly into the sclera and is reviewed in Chap. 27.

9.5.4 Free Tenotomy of a Rectus Muscle

Occasionally the need arises to perform a free tenotomy of a rectus muscle without reattaching it to the sclera, a procedure that is not unlike that described by Dieffenbach in 1839 [1]. Indications may include complete third nerve palsy, congenital fibrosis syndrome and other strabismus disorders where there is a need to maximally weaken a rectus muscle. Merely cutting the muscle free from its attachment to the globe is often unpredictable. The muscle may reattach to the globe and continue to exact some force on the globe. This may be especially true when the lateral rectus muscle is disinserted in order to treat the exotropia associated with a third nerve palsy. To reduce this residual effect, the muscle should be allowed to retract through Tenon’s capsule and the opening within the capsule closed with sutures. Simultaneous resection of a portion of the distal aspect of the muscle will reduce the tendency for forward migration of the muscle and reattachment to the globe. Obviously, the surgeon should be relatively certain that later reversal of the procedure will not be required. If there is a possibility that the disinsertion procedure might later need to be reversed or modified, a nonabsorbable suture can be placed through the muscle and secured to the inner surface of Tenon’s capsule.

9.5.5Recession with Fixation

to the Adjacent Orbital Wall

An alternative procedure for use when maximum weakening of a rectus muscle is desired is to both recess the rectus muscle and to suture it to the periosteum of the adjacent orbital wall using nonabsorbable suture. This procedure, most often indicated for use on the lateral rectus muscle, is described in Chap. 15.

9.5.6 Y Splitting of the Lateral Rectus

An upshoot or downshoot may be seen in some cases of Duane syndrome. Upshoots and downshoots may occur secondary to a tight lateral rectus muscle „slipping“ over the surface of the globe during adduction. This has been characterized as the „leash phenomenon.“ Co-innervation of a horizontal and vertical rectus muscle has also been suggested as a cause of upshoots and downshoots, though this has not been demonstrated electromyographically.

Upshoots and downshoots can be corrected by splitting the anterior aspect of the lateral rectus muscle into a „Y“ formation. The two ends of the muscle are then sutured to the globe approximately 10 mm apart from each other, reducing the tendency of the muscle to side slip along the globe during adduction. A small concurrent recession is required to prevent development of exotropia in the primary.

References

1.Berg F (1967) The Chevalier Taylor and his strabismus operation. Br J Ophthalmol 51:667–673

2.Dieffenbach J (1839) An die schielen und die heilung. Berlin Med Zeitung 46:27

3.Jameson P (1922) Correction of squint by muscle recession with scleral suturing. Arch Ophthalmol 51:421–432

4.Damanakis AG, Arvanitis PG, Ladas ID, Theodossiadis GP (1994) 8 mm bimedial rectus recession in infantile esotropia of 80-90 prism dioptres. Br J Ophthalmol 78:842–844

5.de Gottrau P, Gajisin S, Roth A (1994) Ocular rectus muscle insertions revisited: an unusual anatomic approach. Acta Anat (Basel) 151:268–272

6.Souza-Dias C, Prieto-Diaz J, Uesugui CF (1986) Topographical aspects of the insertions of the extraocular muscles. J Pediatr Ophthalmol Strabismus 23:183–189

8.Barsoum-Homsy M (1981) Medial rectus insertion site in congenital esotropia. Can J Ophthalmol 16:181–186

9.Keech RV, Scott WE, Baker JD (1990) The medial rectus muscle insertion site in infantile esotropia. Am J Ophthalmol 109:79–84

10.Kushner BJ, Preslan MW, Vrabec M (1987) Artifacts of measuring during strabismus surgery. J Pediatr Ophthalmol Strabismus 24:159–164

11.Helveston E (1993) Surgical management of strabismus. An atlas of strabismus surgery, 4th edn. Mosby, St. Louis, Mo.

12.Kushner BJ, Lucchese NJ, Morton GV (1989) The influence of axial length on the response to strabismus surgery. Arch Ophthalmol 107:1616–1618

13.Kushner BJ, Qui CO, Lucchese NJ, Fisher MR (1996) Axial length estimation in strabismic patients. J Pediatr Ophthalmol Strabismus 33:257–261

14.Clark RA, Rosenbaum AL (1999) Instrument-induced measurement errors during strabismus surgery. J AAPOS 3:18–25

15.Clark RA, Demer JL (2006) Magnetic resonance imaging of the effects of horizontal rectus extraocular muscle surgery on pulley and globe positions and stability. Invest Ophthalmol Vis Sci 47:188–194

16.Meyer DR, Simon JW, Kansora M (1996) Primary infratarsal lower eyelid retractor lysis to prevent eyelid retraction after inferior rectus muscle recession. Am J Ophthalmol 122:331–339

17.Kushner BJ (1992) A surgical procedure to minimize lower-eye- lid retraction with inferior rectus recession. Arch Ophthalmol 110:1011–1014

18.Jampolsky A (1979) Current techniques of adjustable strabismus surgery. Am J Ophthalmol 88:406–418

19.Repka MX, Guyton DL (1988) Comparison of hang-back medial rectus recession with conventional recession. Ophthalmology 95:782–787

20.Gobin MH (1968) Recession of the medial rectus muscle with a loop. Ophthalmologica 156:25–27

21.Breckenridge AL, Dickman DM, Nelson LB, Attia M, Ceyhan D (2003) Long-term results of hang-back medial rectus recession. J Pediatr Ophthalmol Strabismus 40:81–84

22.Rodrigues AC, Nelson LB (2005) Long-term results of hemi- hang-back lateral rectus recession. J Pediatr Ophthalmol Strabismus 42:296–299

23.Knapp P (1959) Vertically incomitant horizontal strabismus: the so-called “A” and “V” syndromes. Trans Am Ophthalmol Soc 57:666–699

24.Scott WE, Drummond GT, Keech RV (1989) Vertical offsets of horizontal recti muscles in the management of A and V pattern strabismus. Aust N Z J Ophthalmol 17:281–288

25.Ribeiro GD, Brooks SE, Archer SM, Del Monte MA (1995) Vertical shift of the medial rectus muscles in the treatment of A-pat- tern esotropia: analysis of outcome. J Pediatr Ophthalmol Strabismus 32:167–171

Resection of the Rectus Muscles and other “Strengthening” Procedures

10

Though rectus muscle resection is commonly referred to as a strengthening procedure, this characterization is technically inaccurate. In reality, resection surgery alters the relationship of the rectus muscle to the globe, changing its length–tension curve. Like the clinical effect of recession, the “strengthening” of a muscle is generally seen only in the change that occurs in the alignment of the eye(s) upon which the resection is performed. A significant change in the movement of the eye is not clinically obvious following standard rectus muscle resection surgery.

Compared to rectus muscle recession, a resection procedure generally produces greater postoperative discomfort and conjunctival injection. Additionally, the muscle that is sutured to the original insertion site after the resection has taken place is thicker than the tendon, and may become visible beneath the conjunctiva postoperatively. This is especially true for the medial rectus muscle, a finding that can be cosmetically distressing to some patients. Dellen formation is more likely to occur due to greater edema of the conjunctiva adjacent to the limbus following resection surgery (Chap. 19). Large resections of the medial rectus muscle may result in mild to moderate anterior displacement of the plica semilunaris, which can be a cosmetic concern. For these reasons and others, many surgeons prefer to perform recession procedures when possible. Despite these drawbacks, rectus muscle resection procedures are effective and they do play an important role in the treatment of strabismus. Common indications in which a resection may be preferred include the desire to limit surgery to only one eye and treatment of a consecutive or recurrent deviation in a patient who has previously undergoing recession surgery. This chapter will review several commonly used rectus muscle resection techniques. Additionally, rectus muscle tucking procedure will be reviewed.

10.1 Technique of Rectus Muscle Resection

The approach to resection of the rectus muscles is similar in many ways to the techniques used for rectus muscle recession surgery. The techniques for exposure and isolation of the muscle and closure of the conjunctiva are reviewed in detail in Chap. 8 and will not be reviewed here. Many surgeons perform additional steps during resection procedures to produce added

Chapter

10

security when reattaching the muscle to the globe to reduce the risk of developing a slipped or lost muscle after surgery. This risk may be higher following resection procedures because there is greater tension on the muscle following surgery compared to that for a recessed muscle. This increases the risk that a suture will break or the muscle will be damaged. Loss of a muscle during any strabismus surgery is always problematic. This is particularly so if this complication occurs during resection surgery because recovery is generally more difficult.

10.1.1Preparation of the Muscle for Resection

Once the rectus muscle has been isolated, the intermuscular membrane, muscle capsule, and other fascial tissues are dissected to allow for suture placement posterior to the insertion site of the muscle. During dissection, the surgeon should be careful to avoid penetrating Tenon’s capsule which can promote intrusion of extraconal fat into the operative site. This complication not only makes surgery more difficult, but it can also produce restrictive strabismus that is difficult to repair (Chap. 25).

10.1.2 Resection of the Muscle

A second large hook is placed between the muscle and the sclera posterior to the hook that has been used to isolate the muscle insertion. A caliper is used to mark the position of the posterior limit of the resection. We often find it helpful to use a sterile gentian violet skin-marking pen to coat the tip of the caliper prior to this step (>Fig. 10.1a). When the caliper makes contact with the muscle, the ink will be transferred to the muscle surface, facilitating later steps of the procedure. A central safety knot is placed in the muscle at the caliper mark (>Fig. 10.1b). Transverse passes are made, followed by locking bites at the borders of the muscle. A small straight hemostat is placed anterior to the suture and the posterior muscle hook removed.

The muscle is then detached from its insertion on the globe (>Fig. 10.2a) and the distal portion of the muscle is excised.

Fig. 10.1a–c. Measuring and marking the resection. a After coating the tip of the caliber with ink from a sterile gentian violet skin-mark- ing pen, a caliper is used to mark the resection position on the muscle.

b A central knot is placed at this site, and c transverse passes and locking bites are placed in the muscle and a hemostat is placed anterior to the sutures

During this step, the surgical assistant should ensure that sutures are retracted from the surgical site, to avoid inadvertently cutting them during this step (>Fig. 10.2b). The surgical assistant may place the shaft of a muscle hook across the sutures to help protect them during this step. Some surgeons prefer to cauterize the distal edge of the muscle prior to removal of the hemostat, though this step is not universally necessary. The hemostat can be left in place and used to help hold the muscle in position at the insertion while suturing, if desired.

10.1.3 Reattaching the Muscle to the Sclera

The sutures are then passed through the original insertion site of the muscle and the remaining muscle pulled up to the original insertion site. The surgical assistant may facilitate this process by retracting the globe toward the muscle using locking forceps attached to the insertion site to reduce the amount of tension placed on the muscle during this step of the procedure, or the hemostat may be used to hold the muscle in position if it has not yet been removed (>Fig. 10.3). The sutures are then tied and trimmed. Occasionally, the muscle is noted to have retracted posteriorly during the process of tying the sutures. In the event that the muscle does move posteriorly and this is noted after the sutures have been tied, a suture may be passed through each pole of the muscle as needed and brought through the insertion site. The sutures are then tied and cut to bring the muscle back to its proper position (>Fig. 10.4). If the hemostat was left on the muscle, it is removed at this point.

10.1.4 Dual Suture Modification

Fig. 10.3. Reattachment of the muscle. The assistant may place anterior traction on the muscle using the hemostat to place the muscle in apposition to the insertion site

We recommend a dual suture modification for large resections and/or in situations where the resected muscle will be placed under a significant amount of tension after it has been sutured to the sclera. A second double-armed suture is secured in the muscle posterior to the primary muscle suture prior to muscle

detachment from the sclera (>Fig. 10.5). The muscle is then secured to the insertion using both of these muscle sutures. This technique is slightly more time-consuming and the additional suture may be cumbersome to work with, but the added security can be of value in selected cases.

Fig. 10.4a–c. Correcting posterior movement of the muscle during resection. a The suture has been tied and the muscle is not in direct contact with the original insertion site. b To correct this, a suture is

passed through the insertion site and behind the muscle suture, and c the newly placed sutures are tied and cut, to bring the muscle to the desired location

Fig. 10.6a,b. Resection clamp technique. a A muscle clamp is placed across the muscle so that the posterior border of the clamp rests at the intended resection site. A double-armed suture is passed through

10.2 Resection Clamp Technique

A muscle clamp is placed across the rectus muscle so that the posterior border of the clamp is at the desired resection position (>Fig. 10.6a) and the muscle is detached from the sclera. Two double-armed absorbable sutures are passed through the insertion site of the muscle in an anterior to posterior direction, one at each pole of the insertion site. The sutures are then passed through the muscle, just posterior to the resection clamp . The muscle is advanced anteriorly using the muscle clamp until the muscle just posterior to the clamp is adjacent to the muscle insertion site (>Fig. 10.6b) and the sutures are

Fig. 10.5. Dual suture technique. Two double-armed sutures are placed in the muscle using a transverse pass and locking bites and the muscle is then secured to the sclera using both of these sutures for added security

each pole of the muscle stump and then through the muscle posterior to the muscle clamp. b The muscle is pulled anteriorly to the insertion and the sutures tied

tied and cut. The resection clamp is removed and the tendon/ muscle anterior to the clamp is excised.

10.3Rectus Muscle Tuck (Plication) Technique

Tucking procedures can be used in place of a rectus muscle resection. Tucking procedures have the potential advantage of preserving the anterior ciliary circulation and reducing the risk of anterior segment ischemia in susceptible patients [1, 2]. A primary disadvantage of the procedure is the bulk of tissue

that is produced by the tuck which may be visible under the conjunctiva postoperatively.

Two double-armed sutures are placed in the muscle at a position required to create the desired tuck. These two sutures are placed adjacent to each other and include transverse passes, incorporating the entire width of the muscle and locking bites at the borders of the muscle. Care should be taken to avoid disruption of the anterior ciliary vessels as the sutures are placed. The sutures are then passed into the sclera adjacent to each border of the insertion (>Fig. 10.7a). When these sutures are tied together, the effect will be to tuck or fold the portion of muscle anterior to the sutures (>Fig. 10.7b). This muscle fold can be sutured to the remainder of the muscle if desired (>Fig. 10.7c).

Fig. 10.7a–c. Rectus muscle tuck (plication). a After placement of two double-armed sutures in the muscle posterior to the insertion, the sutures are passed into the sclera adjacent to the muscle insertion or

References

1.Park C, Min BM, Wright KW (1991) Effect of a modified rectus tuck on anterior ciliary artery perfusion. Korean J Ophthalmol 5:15–25

2.Wright KW, Lanier AB (1991) Effect of a modified rectus tuck on anterior segment circulation in monkeys. J Pediatr Ophthalmol Strabismus 28:77–81

through the muscle insertion. b The sutures are tied, c creating a tuck of the anterior portion of the muscle