The surgical treatment of strabismus usually involves three types of procedures, which can be performed on rectus muscles or oblique muscles. Classical procedures involve variations of (1) weakening by recession, full or partial tenotomy, full or partial myotomy, or chemodenervation; (2) strengthening by resection, plication, tucking, or chemo-strengthening; and (3) transposition procedures designed to induce or correct torsion or shift vector forces. This chapter discusses two important forms of muscle strengthening, muscle or tendon plication and tucking. These procedures have advantages and disadvantages, which will be discussed. Indications and especially surgical technique will be emphasized with step-by-step descriptions and accurate illustration of surgical technique. Clinical and surgical pearls will be emphasized to allow the beginning and experienced strabismus surgeon to quickly master these techniques and add them to his or her surgical armamentarium.
24 Plications and Tucks
To strengthen a rectus muscle, the surgeon may shorten its length (resection), move its insertion toward the limbus and away from its origin (advancement), or tighten its fibers (plication or tucking). These procedures increase active muscle force and passive muscle tension as reflected in length–tension curves. Muscle strengthening procedures are often best performed in combination with ipsilateral antagonist muscle weakening procedures. However, rectus or oblique muscle strengthening can be indicated as a primary procedure in selected clinical situations, especially in incomitant strabismus. Resection is currently the gold standard and most commonly performed method of rectus muscle strengthening. It has a long history with well-known healing and stability characteristics. Several dose–response tables have been developed and are widely available and useful, especially on previously unoperated muscles (Chapter 23). However, rectus muscle resections, especially larger sizes, are associated with more technical risk of lost or slipped muscles and require transection of the anterior ciliary arteries, with increased risk of anterior segment ischemia (ASI). On the other hand, rectus muscle plication eliminates the technical risk of lost or slipped muscles and is reversible in the early postoperative period. The plication technique described in this chapter is designed to allow anterior ciliary vessel sparing, which decreases ASI risk, especially when performed through fornix incisions. Several minimally invasive strabismus surgery (MISS) techniques have been developed to facilitate plication techniques (Chapter 34). However, concern on the part of many strabismus surgeons for possible unsightly and uncomfortable anteriorly located muscle lumps from plicated muscle and tendon tissue, as well as possible instability and unpredictability of the plication procedure, has limited its widespread use in the past.
24.2 Rectus Muscle Plication
24.2.1 Plication Indications
Using new techniques developed by the author, rectus muscle plication has become a standard reliable and stable surgical technique in many clinical situations. I have found the technique very useful in the following:
Large plications rather than resections in the treatment of horizontal and/or vertical null point nystagmus where surgery on more than two rectus muscles may be required.
Difficult reoperations where previous surgical history is not clear, or if several rectus muscles may have already been operated upon and the status of other anterior ciliary vessels may be unknown. The technique is also useful for safely strengthening rectus muscles over scleral buckles or glaucoma setons.
Thyroid eye disease (TED) with residual restrictive strabismus after maximal recession surgery has been performed on antagonist rectus muscles. This group of patients is more prone to ASI, and the vessel sparing aspect of the plication procedure is valuable.
Any elderly patient with thin conjunctiva where fornix incision to spare limbal circulation is impossible or unsuccessful and where additional rectus muscles may require surgery in the future.
As an academician, the author feels that rectus muscle plication, with its reduced risk of muscle loss, can be a valuable patient safety strategy when teaching beginning residents or fellows. In fact, based on my experience with the technique over the last 30 years, plication could be considered in most if not all rectus muscle strengthening procedures.
24.2.2 Plication Results
Several recent high-quality publications in the ophthalmologic literature have demonstrated the advantages, predictability, and stability of rectus muscle plication surgery. Chaudhuri and Demer published a retrospective review of the outcomes of rectus muscle resection or plication in patients operated on between 2005 and 2013. 1 Their study included 31 patients who had undergone resection or recess/resect of a horizontal rectus muscle compared to 21 patients who had undergone plication or recess/plicate of a horizontal rectus muscle and 6 patients who underwent plication of a vertical rectus muscle. In their hands, plication was equally effective compared to resection for esotropia, exotropia, and hypertropia. They documented dose–response curves similar to the Parks surgical dose tables (Chapter 23), with a slightly decreased effect of plication at higher doses in exotropia. In their discussion, they emphasized several advantages of rectus muscle plication including simplicity; shorter operating time; less surgical trauma, inflammation, or hemorrhage; early reversibility; and the ability to use plication with MISS techniques. The authors felt plication was not useful for adjustable suture surgery. This author has found, however, that plication can be easily performed using a standard crossed-sword sliding noose adjustable suture technique for rectus muscle strengthening. This may even be utilized in transposition surgery, where the amount of transposition is limited only by the size of the plication performed (i.e., a 7-mm plication can only be transposed 7 mm away from the normal muscle force vector, etc.).
Oltra et al investigated the effect of rectus muscle resection and plication on the anterior segment circulation in humans. 2 Previously, plication had been shown to preserve anterior segment circulation in monkeys. This study evaluated anterior segment circulation assessed by masked examiner using iris angiography before and after strabismus surgery in 14 human patients, 8 with plication of one rectus muscle with or without recession of another on the same eye and 6 patients who underwent tenotomy (recession or resection) of one or two rectus muscles on the same eye. The authors demonstrated iris-filling defects in 67% of patients who underwent tenotomy for recession or resection compared to only 12.5% of patients after plication. This difference was especially remarkable for vertical rectus muscles, in which three of three (100%) eyes with tenotomy demonstrated filling defects, as compared to only one of four (25%) eyes following plication. The effect was less noticeable in horizontal rectus muscles, with filling defects in one of eight (12.5%) eyes following tenotomy, as compared to none of the five eyes following plication. The authors concluded that “rectus muscle plication spares the ciliary vessels and may be considered a safer alternative to resection for patients at risk for anterior segment ischemia, especially when surgery involves vertical rectus muscles.”
Sonwani et al performed a prospective randomized clinical trial to compare the dose effect of patients undergoing horizontal rectus muscle recession and resection to those undergoing recession and plication. 3 They randomized 40 patients into two equal groups, which were comparable in age, strabismus onset and duration, and size of deviation. They also evaluated quantity of postoperative inflammation and scar visibility, as well as surgical success rate and dose effect. They found that the inflammatory scores, scar visibility, success rate, and long-term stability were not statistically different between the groups. They also determined that the dose response with both techniques was statistically similar.
In contradiction to the publications previously described, Alkharashi and Hunter 4 retrospectively studied the medical records of patients who had undergone rectus muscle resection or plication performed by a single surgeon over a 5-year period at the Boston Children’s Hospital Medical Center. The study included 48 resections and 24 plications. Interestingly, in their hands, postoperative surgical alignment was significantly better in the resection group (89%) than in the plication group (58%) at both 6 and 12 weeks following surgery and at mean final follow-up of 19 (± 13) months. They also noted a reoperation rate of 12.5% in the plication group and no reoperations in the resection group. Adjustable sutures were used in all patients of both groups, which may have contributed to the difference in their hands. In addition, this study suffers from all the pitfalls associated with retrospective studies, including differences in patient selection for the various procedures, which may have affected surgical success and dose response.
We recently reviewed our experience with resection and plication in a particularly difficult group of complex strabismus patients, mainly those with severe TED, who continued to have significant residual esotropia or hypotropia following maximal recession of restricted medial or inferior rectus muscles. Traditionally, strabismus surgeons were taught not to resect antagonist muscles in TED because resection may increase inflammation-associated scarring in these patients. In addition, it was felt that resection against restricted enlarged rectus muscles, even after very large recessions, would further limit ductions, resulting in increased incomitance. Nevertheless, this author began performing resections and plications of antagonist superior and lateral rectus muscles in these patients over 10 years ago with success and recently reviewed the results. Of 431 patients with TED operated on between 2000 and 2015 at the Kellogg Eye Center, 20 had undergone resection or plication for residual deviations following maximal inferior and medial rectus recessions. Of those, good or excellent results (fusion or continued deviation of less than 10 PD correctable with prism) were noted in 18 of 20 patients, and 3 required small prisms for fusion. Further follow-up for up to 8 years revealed 16 of 18 with stable alignment and 2 who improved slightly over time. None became worse and no further surgeries were required. Most interestingly, the dose response for surgeries in these patients was identical in the plication and resection groups, as shown in Table 24‑1. Resection or plication corrects approximately 2.2 PD/mm when treating horizontal rectus muscles, and 3.9 PD/mm when treating vertical rectus muscles, in these difficult patients.
Change in deviation
Horizontal resect (8)
Horizontal plication (4)
Vertical resect (2)
Vertical plication (6)
Box 24.1 summarizes our experience and the advantages of plication over resection of rectus muscles in TED, as well as in less demanding strabismus surgery. Plication of rectus muscles is technically simple with less risk, especially for surgical trainees, when performed using the technique described below. The surgery is reversible in the early postoperative period, and facilitates anterior ciliary vessel sparing with reduced ASI risk, especially when performed via the fornix incision approach. The results have been stable and, importantly, the surgical dose is similar to that of resection. We are able to use standard surgical tables or adjustable sutures with the sliding noose technique. In addition, we have found that plicated muscles can be transposed during plication to treat torsion or change force vectors, up to the size of the plication.
Box 24.1 Advantages of Plication over Resection
Technically simple with less risk (surgical trainees).
Less muscle trauma/hemorrhage.
Can use absorbable 6–0 polyglactin suture.
Must achieve muscle to sclera apposition?
Plicated fold directed out—atrophies by removal of sarcomeres?
Possible decreased risk of ASI.
Anterior ciliary vessel sparing.
Surgical dose similar to resection—can use Parks table.
Adjustable suture possible using sliding noose technique.
Can transpose proximal muscle for torsion—up to size of plication.
24.2.3 Plication Surgical Technique
Multiple techniques have been described to strengthen rectus muscles through plication. While other procedures may be effective, the secret to a successful, stable plication effect is to use a unique muscle imbrication technique, which creates a stable strengthening effect and spares the anterior ciliary vessels from transection or strangulation.
By definition, plication of a rectus muscle or muscle tendon requires folding of the muscle or tendon such that there is muscle-to-sclera contact, unlike tucking, which folds the muscle or tendon with muscle-to-muscle or tendon-to-tendon contact. Many strabismus surgeons have favored muscle resection over plication because it was thought that plicated muscle would produce a bulky, cosmetically disfiguring lump at the muscle insertion. However, when plication is properly performed using newer surgical techniques and suture materials, postoperative inflammation is seen to rapidly subside, with normalization of the overlying conjunctival surface, and an excellent cosmetic result. It is thought that the elimination of tension on the plicated muscle fibers leads to the removal of sarcomeres and atrophy of muscle tissue. This process also occurs after large extraocular muscle recessions. In addition, when operating on adjacent rectus muscles, exploration of the insertion of a previously plicated muscle on two occasions showed a relatively normal appearing insertion with remarkably little scarring and excellent preservation of the original anterior ciliary vessels. The vessels remained in their normal locations on the surface of the muscle, crossing onto and penetrating the sclera at the typical location. This healing process, with return to a normal appearance, is illustrated in Fig. 24‑1.
Rectus muscle plication can be performed through either a well-placed fornix incision, a conjunctival incision, or a limbal incision as described in Chapter 23. A fornix incision is always preferred whenever possible, to preserve the limbal circulation and protect against ASI. It is important to place the fornix incision in the true fornix, which is only 7 to 8 mm posterior to the limbus, to allow muscle access through the thinnest Tenon’s capsule, with minimal scarring.
The insertion of the rectus muscle to be plicated is isolated, cleaned of overlying Tenon’s capsule and intermuscular septum posteriorly to near the pulley, and then exposed between two large Jameson muscle hooks as described in Chapter 23. Proper imbrication of the muscle belly is the secret to successful and stable strengthening as well as preservation of the ciliary vessels. This technique is illustrated in Video 24.1. A double-armed 18-in 6–0 Vicryl suture with S-29 needle is recommended for this procedure. This suture was originally developed by Marshall Parks, MD, for his crossed-sword rectus muscle recession technique. Many surgeons, and this author was initially one of them, feel that the plicating suture must be of a nonabsorbable type such as 6–0 braided polyester, since no cut muscle surface will be created to firmly fuse the plicated muscle in its new location. However, this author has found that using a standard 6–0 Vicryl suture works just as well, retaining its strength long enough to provide a stable strengthening effect without slippage. This appears to be because, as previously discussed, the plicated bulk of muscle atrophies, shortening the muscle naturally. This then results in a new shorter muscle before the suture loses tensile strength. The Vicryl suture provides an additional advantage by completely dissolving upon healing, unlike nonabsorbable suture, which remains present at the insertion, where it can often erode or become infected as the conjunctiva thins with age.
As illustrated in this video of a plication of the right lateral rectus muscle, the size of the plication is measured with a caliper, and a half-muscle width, half-thickness bite of the rectus muscle is taken using a double-armed 6–0 Vicryl suture exiting at exactly the point measured by the caliper. The suture is then pulled halfway through the muscle.
The next step differs slightly from the standard locking bite technique used with muscle recession and resection. To avoid imbricating the anterior ciliary vessels, which run along the surface of a rectus muscle, a second bite from the muscle edge exiting in the center is passed just beneath the muscle surface and beneath the ciliary vessels. This stitch is pulled nearly tight, except for leaving a loop of suture along the muscle edge.
Imbrication of the inferior pole is completed by again passing the needle through nearly the same exit point, but this time full thickness from front to back, the tip being brought up through the loop at the muscle border. Just prior to completely tightening this last bite, the loop is removed by traction and the pole suture finally tightened to complete the lock bite. This results in all fibers of the sutured half of the muscle being supported by suture but with no suture passing across a ciliary vessel and strangulating it. The identical procedure is then completed using the other pole of suture to secure the opposite pole of the muscle with pole suture exiting at exactly the measured distance from the sclera.
The plication is completed by securing the superior and inferior pole sutures through the sclera in a crossed-swords fashion, just anterior to the original muscle insertion. Each needle enters the sclera in such a fashion as to maintain normal muscle width when the plication is complete. Care is taken to enter and exit the sclera away from, and to pass the sutures completely under, all anterior ciliary vessels. The needles of the crossed-sword configuration exit the sclera through almost the same exit wound far from the vessels. This again prevents any compression of ciliary vessels as they pass over and penetrate the anterior sclera.
Finally, one or both poles of the muscle insertion are grasped with a locking forceps and the muscle hook removed to allow the plication (folding of the muscle on itself) as the sutures are tightening and tied off. The plicated muscle tissue can be forced beneath the plication using an iris sweep or allowed to naturally prolapse outward above the plication. Both techniques have been described by experienced strabismus surgeons. I prefer to allow the muscle to plicate outward, as I feel this results in less compression of the ciliary vessels, which allows them a greater chance to remain patent. Once the plication is complete, the conjunctival wound can be massaged back into the fornix using a dry cotton swab or Stevens muscle hook, and the self-closing incision, if properly positioned, does not require sutures to close. When possible, a properly placed fornix incision more easily covers the redundant plicated muscle mass far from the incision site, and often does not require closing sutures. The plication procedure can also be performed through a limbal incision, although coverage of the plicated muscle tissue may be more difficult. It is important to make the limbal incision precisely at the limbus, wide enough that any relaxing incisions are far from the plicated muscle after closure. This assures adequate coverage of the plication, and allows proper healing and muscle resorption (Video 24.1).
18.104.22.168 Use of Adjustable Sutures
This procedure can also be done with an adjustable suture using the sliding noose technique as described in Chapter 32. When performing an adjustable plication, the sutures are placed 1 or 2 mm more posteriorly than the table suggests, allowing the plicated insertion to recess by a similar amount at the completion of surgery. This allows the new effective muscle insertion to be either advanced, for increased strengthening, or recessed back to its original position, for overcorrection. In addition, as discussed previously, the new scleral insertion can be transposed vertically for horizontal rectus muscles, or horizontally for vertical rectus muscles, by transposing the new scleral bites. This allows for fixed or adjustable transposition up to the full size of the plication itself. This is useful to correct small vertical deviations during horizontal strabismus surgery, small horizontal deviations during vertical strabismus surgery, or torsion with either type of procedure.