Strabismus surgery remains a challenge because success rates are not always predictable.
The adjustable sutures technique has been available to strabismus surgeons for the last several decades. It gives us a second chance to modify unintentional undercorrections or overcorrections, enhancing the surgical outcome and reducing the reoperation rate.
The procedure is useful when there are fibrotic tissue adherences and unpredictable results.
Indications for using an adjustable suture are for correction of diplopia following thyroid disease and ophthalmologic surgery complications.
The adjustment can be performed at the same time as the surgery or up to 1 week later. However, the adjustable sutures technique has not gained universal acceptance for use in children, partly because of poor cooperation, the need for anesthesia, and the learning curve for accurate decision making during the adjustment.
This chapter covers the question of when adjustable sutures are useful, controversies, indications, patient selection, technique, types of anesthesia used, timing of the adjustment, improving comfort during adjustment, complications, and the use of a safety stitch to avoid overcorrection after inferior rectus recession.
32 Adjustable Sutures and Hang-Back Suture Technique
32.1 Adjustable Sutures Technique
The advantage of the adjustable suture is that it gives the surgeon the opportunity to modify the position of the operated muscles in the immediate postoperative period.
32.1.1 Are Adjustable Sutures Useful in All Cases? Controversies
The adjustment allows the surgeon to set the eye in an optimal alignment position, which could be a small overcorrection in a patient with exotropia and a tendency to drift out over time, or to place the eyes in a fusional position to eliminate diplopia.
Many surgeons agree that adjustable sutures are indicated when the surgical outcome is unpredictable. Published studies have shown better success rates in reoperations when using adjustable sutures rather than conventional strabismus surgery. 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13
The disadvantage of the adjustable suture is that it cannot be used in uncooperative patients who may require a second operation with general anesthesia.
Kamal et al, in a prospective study of adjustable and nonadjustable sutures in children, reported no statistically significant difference between the two groups; however, a higher clinical success rate was observed in children operated on with adjustable sutures. 17
Comparing adjustable and nonadjustable sutures in reoperations and in patients with exotropia and infantile esotropia, we found better results in reoperations and in patients with exotropia using adjustable sutures; however, no statistical differences were seen in the infantile esotropia group. 18
Leffler et al reported better results with adjustable sutures for horizontal muscles but not for vertical muscles. 19
Although the procedure has been used for many years, no randomized controlled trials have been done. 20 It remains a controversy, and Vasconcelos and Guyton have questioned why some surgeons almost exclusively use adjustable sutures whereas other surgeons do not. 11 , 12 , 13 , 15 , 17 , 21 , 22 , 23
Bata et al published that adjustable sutures were used for superior oblique tendon advancement for fourth nerve palsy. 24 Velez et al used an adjustable suture technique for rectus muscle plication in patients at risk for anterior segment ischemia. 25
Adjustable sutures are indicated in cooperative patients when the surgical outcome might vary and then precise alignment is required. Examples include elimination of diplopia in cases of restrictive strabismus, after retinal detachment repair, and in cases of orbital trauma, myopathy, strabismus reoperation, or slipped muscle or aberrant regeneration after cranial nerve palsy. Many surgeons use the procedure for complicated pediatric strabismus cases, although this requires additional general anesthesia.
32.1.3 Patient Selection
The patient´s ability to cooperate may be predicted by using an applanation test for intraocular pressure or simulating the adjustment experience with proparacaine on a cotton swab as in a forced duction test.
32.1.4 Anesthesia: Local versus General
A 5% solution of povidone-iodine is applied to both eyes to prevent infection before the surgery, and an artificial tear gel is used to protect the cornea. 26
Local anesthesia proparacaine drops or a sub-Tenon’s infusion of 4% lidocaine may be used in cooperative adult patients for the surgery and the adjustment.
General anesthesia is useful for reoperations or restrictive strabismus surgeries.
The first stage under general anesthesia is to place the adjustable suture. In the second stage, with the patient awake, the alignment is fine-tuned using a local anesthetic such as proparacaine drops or sub-Tenon’s infusion of 4% lidocaine. This allows the eyes to be adjusted to an orthotropic position, or to an intentional over- or undercorrection as needed.
General anesthesia has the advantage of allowing us to evaluate the position of the eyes, perform the forced duction test and the spring-back forces test, and also change surgical plan if necessary, all while the patient is under anesthesia.
32.1.5 Rectus Muscle Recession with Sliding Adjustable Suture
Adjustable sutures are best used with muscle recessions, as it is easier to adjust the slackened recessed muscle. Adjustable resection is possible, but a 2-mm resection is added, as it is easier to pull the muscle forward than to let it slip back.
18.104.22.168 Traction Suture
A black silk 6–0 suture, which is used to rotate the globe, is passed 1 to 2 mm from the limbus perpendicular to the muscle. This improves exposure of the surgical area.
22.214.171.124 Conjunctival Incision
Before making the limbal incision, a cotton swab with lidocaine and epinephrine is applied to the surgical area for hemostasis. A limbal approach is routinely used, as it provides easier access to the muscle and the suture at the time of the adjustment. For better exposure of the surgical area, two radial relaxing incisions are made and the conjunctival flap is pulled back before the muscle is isolated. This approach is useful for elderly patients with friable conjunctiva.
Marking sutures. A Vicryl (Ethicon) 7–0 suture is used to identify the edge of the conjunctiva for easier closing at the end of the surgery (Fig. 32‑1).
Fornix incisions are not useful in reoperations due to limited exposure of the surgical field.
126.96.36.199 Muscle Disinsertion
The muscle is isolated with a Jameson muscle hook, and a Green hook is placed to secure the muscle. Tenon’s fascia is cleaned off with Westcott scissors (Fig. 32‑2).
A Vicryl 5–0 or 6–0 double-armed suture on a spatulated needle is placed through the entire thickness of the muscle tendon and sheath. It is then secured with locking bites at both ends of the muscle tendon, which is then disinserted from the globe (Fig. 32‑3).
The sutures are passed through the insertion stump and emerge at almost the same point. The amount of hang-back recession is measured with a caliper.
188.8.131.52 Muscle Reattachment
There are two tying techniques: the bow tie and the sliding knot.
184.108.40.206.1 Bow Tie Technique
The sutures are tied together in a single-loop bow tie. This is quick but has an increased risk of muscle slippage.
220.127.116.11.2 Sliding Knot Technique
A Vicryl suture is used for the sliding knot. This wraps around the muscle suture with moderate tension to constrict the muscle suture. The tension of the slipknot is maintained by using two needle holders. This knot should be able to slide along the length of the muscle suture with some effort. It is moved up and down to smooth out the surface of the muscle suture, and then three to four knots are tied to allow easier grasping of the sliding knot (Fig. 32‑4). The ends of the sliding knot suture are cut very short (Fig. 32‑5, Video 32.1).
As the fibrotic muscle has a tendency to slip, another bow tie is thrown with the muscle suture (Fig. 32‑6)
An optional handle suture is placed near the muscle insertion to assist with grasping and manipulation of the globe during the adjustment procedure. Both the handle and the adjustable sutures are tucked under the conjunctiva at the end of surgery (Fig. 32‑7).
18.104.22.168 Closure of the Conjunctiva
The conjunctiva is closed at the end of surgery with 7–0 Vicryl sutures. Instead of recessing the conjunctiva and leaving a bare sclera behind the knots of the adjustable sutures, the conjunctiva is placed at the limbus guided by the marking sutures. This option is more comfortable for the patient and reduces the risk of infection (Fig. 32‑8).
At the end of surgery antibiotic, lidocaine, and dexamethasone solutions are infused into the sub-Tenon’s space to reduce infection, pain, and inflammation (Video 32.2).