Adjustable suture is a technique that allows the position of the extraocular muscles to be readjusted after strabismus surgery, changing the amount of surgery. It aims to reduce postoperative undercorrection or overcorrection and improve both short- and long-term outcomes.
The earliest report was by Bielschowsky in 1907. He created a surgical loop exposed through the conjunctiva, which could be manipulated up to 2 days postoperatively. The excess suture was removed on the third postoperative day.
In 1975, Jampolsky introduced adjustable sutures using a bow-tie knot. Indications included cases with uncertain target surgical amounts, such as thyroid eye disease and reoperations. Later, Jampolsky advocated that adjustable sutures should be considered for almost all adult strabismus surgeries. Since then, some surgeons recommend this technique for all adult cases. It is also applicable to children.
Adjustable sutures are particularly useful in reoperations and unpredictable cases 1). Specific indications are as follows:
Proponents of adjustable sutures cite the opportunity for readjustment to achieve a satisfactory eye position and the ability to minimize the risk of postoperative diplopia as advantages1).
They are not necessarily required for all cases. They are particularly useful in cases where postoperative eye position is difficult to predict, such as reoperations and restrictive or paralytic strabismus1). In simple concomitant strabismus, good results are often obtained even with non-adjustable sutures.
Adjustable sutures are a surgical technique, not a disease itself. The postoperative symptoms that are targets for adjustment are as follows.
The need for adjustment is determined by eye position tests such as the alternate cover test. Adjustment is performed under topical anesthesia while confirming the eye position with both eyes open.
Items to be confirmed in the postoperative evaluation are as follows.
The causes of overcorrection or undercorrection in strabismus surgery are diverse.
The reoperation rate varies by disease but is generally reported to be 20–30%.
Prior to strabismus surgery, the following examinations are performed.
The timing of adjustment varies depending on the surgeon’s preference. It may be performed immediately after surgery in the operating room, a few hours later, or delayed until a few days later1).
Under topical anesthesia, perform the alternate cover test and adjust the position of the sliding noose while checking ocular alignment. If sub-Tenon anesthesia is used, wait about 6 hours until the anesthetic effect on eye movements wears off before adjustment. On the first postoperative day, the tendon adheres to the sclera, making adjustment difficult.
It depends on the surgical technique. Generally, on the first postoperative day, the tendon adheres to the sclera and adjustment becomes difficult. With the short-tag noose technique, the conjunctiva can cover the surgical site, allowing somewhat delayed adjustment. If sub-Tenon anesthesia is used, it is necessary to wait for recovery of eye movements, and adjustment is performed about 6 hours later.
The adjustable suture technique is based on the hang-back recession procedure.
Detach the muscle tendon from its insertion and pass a suture through the insertion using the hang-back technique. Instead of tying a knot, create a sliding noose with another suture (6/0 Vicryl®). Postoperatively, under topical anesthesia, perform the alternate cover test and adjust the position of the noose to fine-tune ocular alignment. Once the desired correction is achieved, tie the hang-back suture and trim the excess suture.
Bow-tie method
Principle: The first adjustable suture technique was devised by Jampolsky (1975).
Procedure: The muscle is fixed to the sclera at the insertion site, and a knot is made to set the hang-back amount. A second half-bow knot is placed on top.
Adjustment: The half-bow knot is untied to change the amount of surgery.
Sliding Noose Technique
Principle: A method in which the muscle is held by a separate knot from the muscle suture.
Procedure: A surgical noose is passed around the muscle suture and tightened with a square knot. The knot slides along the suture.
Adjustment: Advancing the noose toward the muscle decreases the amount of recession, while moving it away increases the recession.
Short-Tag Noose Technique
Principle: A modification of the sliding noose, where the suture is cut short.
Advantage: The conjunctiva can completely cover the surgical site, so no additional manipulation is needed if adjustment is not required. It also allows for delayed adjustment.
Removable Noose Technique
Principle: Devised by Guyton. Combines a clove hitch with three slip knots.
Advantage: The noose suture material can be completely removed after adjustment, leaving no foreign material under the conjunctiva.
Other techniques such as the semi-adjustable technique, small incision method, and laser-assisted procedure have also been reported. Adjustable sutures are applied not only to rectus muscle recession but also to special procedures such as rectus muscle transposition, Harada-Ito procedure, and superior oblique tendon surgery 1).
In inferior rectus recession, the semi-adjustable suture technique may reduce unexpected muscle drift 1). Since overcorrection in downgaze is poorly tolerated, it is recommended to aim for slight undercorrection and use adjustable sutures 1).
Usually, topical anesthesia is sufficient. In studies involving children, topical anesthesia alone was adequate in 89% of cases. In adults, the procedure is performed under local anesthesia, so severe pain is unlikely, but discomfort may occur.
Strabismus surgery corrects eye alignment by changing the attachment position of extraocular muscles, altering muscle tension and direction of action. Weakening procedures include recession, tenotomy, and posterior fixation; strengthening procedures include resection and advancement.
In recession, the muscle tendon is detached from its insertion and sutured to the sclera at a predetermined distance posteriorly. The maximum correction is achieved in the direction of action of the recessed muscle. In adjustable sutures, the fixation is temporarily tied so that the position can be changed postoperatively.
It takes 3 to 4 months for the muscle suture site to stabilize. During this period, adhesion between the muscle and sclera progresses, determining the final eye alignment. The immediate postoperative alignment does not always match the long-term alignment, and this unpredictability is a limitation of adjustable sutures.
Surgeons who do not use adjustable sutures point out that the alignment immediately after surgery may change within days to weeks postoperatively, and argue that immediate postoperative adjustment does not guarantee long-term outcomes 1).
The Tenon’s capsule in children is thick and requires adequate management. Since pediatric strabismus surgery is generally performed under general anesthesia, using adjustable sutures may require a second anesthesia exposure for adjustment. The short-tag noose technique can avoid a second anesthesia when adjustment is unnecessary, making it suitable for children.
Current evidence on the efficacy of adjustable sutures is not conclusive.
A randomized controlled trial analyzed the effect of adjustable sutures in 40 adults with intermittent exotropia. The success rate was 90% in the adjustable group and 85% in the non-adjustable group, but the difference was not statistically significant (p = 0.3).
In a review of 11 studies, only 3 out of 7 studies showed a statistically significant difference between the adjustable and non-adjustable groups. All three studies that showed significance were large-scale studies with over 100 participants. When using reoperation rate as an indicator, 4 out of 5 studies showed a significant difference. However, direct comparison is difficult because the definition of “success” varied across studies.
A randomized controlled trial involving 60 children with horizontal strabismus found no statistically significant difference in success rates at 6 months postoperatively between the adjustable and non-adjustable groups (success defined as residual deviation of 8 prism diopters or less).
In children, recent studies have reported that intraoperative suture adjustment was possible with topical anesthesia alone in 89% of cases.
The role of adjustable sutures in thyroid eye disease (TED) remains controversial 1). Some surgeons advocate for better outcomes, while others avoid them due to concerns about late overcorrection and muscle slippage 1). Alternative techniques such as permanent sutures (polyester) and relaxed muscle positioning are also being explored.
Current evidence does not confirm a clear advantage. Large studies suggest a reduction in reoperation rates, but small studies have not shown significant differences. There may be benefits, especially in reoperation cases or unpredictable scenarios.
