Adjustable Sutures for Strabismus Surgery

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Summary

The adjustable suture technique for strabismus is a method in which the surgical dosage may be altered postoperatively, with the intent to improve both short- and long-term outcomes by reducing postoperative under- or overcorrections.

History

One of the earliest accounts of an adjustable suture was by Bielschowsky in 1907 when he described creating a surgical loop, exposed through conjunctiva, which could be manipulated up to two days postoperatively. The excess suture was then removed on the third postoperative day.[1][2] In 1975, Jampolsky published his technique for adjustable sutures which utilized a bow-tie knot, allowing for manipulation of the muscle post-operatively, if necessary. Indications were scenarios in which the desired amount of strabismus surgery was unclear, such as in patients with thyroid eye disease or previous strabismus surgery.[3] Several years later, Jampolsky suggested that an adjustable suture technique should be considered “for almost all adult strabismus surgical corrections.”[4] Since this time, the adjustable suture technique has become more popular, with some surgeons recommending use of the technique in most or all adults.[5] Additionally, the technique is can also be utilized for strabismus surgery in children.[6]

Technique

Multiple techniques have been described since the origin of the adjustable suture. The original “bow-tie” technique remains in use today. Following disinsertion, the muscle is secured to the sclera at the insertion, and a knot is made allowing the muscle to hang-back the desired amount. A second knot is placed over the top of the first, but instead of fully tying this down, a bow-tie is formed, allowing the second knot to be easily removed and the surgical dosage to be adjusted, if desired.

Another technique is the sliding noose. In this technique, the muscle is secured to the sclera through the insertion as above, but the muscle suture itself is not tied down immediately. Instead, a surgical tie, typically consisting of the same material used for the muscle suture, is passed around the muscle suture and tied squarely down. The knot is able to slide along the length of muscle suture with effort to adjust the extraocular muscle position. The muscle is then allowed to hang-back the desired surgical dosage, held in position by the sliding noose. During adjustment, if less hang-back is desired, the noose is advanced toward the muscle. To increase the amount of recession, the noose can be pulled away from the muscle with careful counter traction beneath the noose. Once the desired amount of surgery is confirmed, the muscle suture is tied securely on top of the noose, and both tails are cut short.

The “short-tag noose” is a variation of the basic sliding noose.[7][8] This technique involves tying a sliding noose as above, but the noose is cut short. The muscle suture is also cut short, though enough length is left to allow for additional recession during the suture adjustment, if necessary. The primary advantage of this technique is that with the sutures left short, the conjunctiva is able to fully cover the surgical site. Thus, in the event that an adjustment is not needed, no further suture manipulation is necessary. Furthermore, it allows for the possibility of delayed adjustment without suture exposure.

A removable noose has been also described by Guyton.[9] With this technique, the muscle sutures are passed through sclera as above, but instead of simply wrapping a noose around the muscle suture, a clove hitch with three slip knots is constructed that allows not only for the noose to be adjusted to the surgical dosage, but also to be completely removed once the muscle is in proper position and has been tied down. The advantage of this technique is that suture material for the noose, typically remaining beneath the conjunctiva after adjustment, can be completely removed from the eye once the adjustment has been performed.

Additional methods for adjustable sutures have been described, including semi-adjustable, small incision and laser-assisted techniques, among others.[10][11] [12] Furthermore, adjustable sutures have been utilized for less common procedures such as rectus muscle transpositions, Harada-Ito procedures, superior oblique tendon procedures, and others.[13][14][15][16]

Efficacy

In adults

There is evidence supporting improved outcomes when using adjustable sutures in strabismus surgery compared with non-adjustable strabismus surgery, however current research consists mainly of retrospective studies. One randomized controlled trial (RCT) analyzed the use of adjustable sutures in 40 adults with intermittent exotropia and found no significant difference between the randomized adjustable and nonadjustable suture groups. The adjustable suture group did have a clinically higher postoperative success rate of 90% when compared to the nonadjustable suture group’s success rate of 85%, however the difference was not statistically significant (p = 0.3). Larger trials may be necessary to determine whether a benefit exists.[17]

A review of 11 studies on adjustable suture use was also not able to definitively conclude that adjustable suture surgery provides significant benefit over nonadjustable surgery.[18] In the analyses of postoperative success, only three out of seven studies showed statistically significant differences between groups. The three studies demonstrating significance were the largest of the studies with over 100 patients, whereas the studies failing to show significance each had under 100 patients. When considering patients undergoing reoperations, four out of five studies found statistical significance. Of these, two studies found significance only in horizontal strabismus surgeries. It is also important to note that the various studies differed in their definitions of success, which makes direct comparison difficult. Overall, while the data is inconclusive, it does suggest that benefit may vary amongst different types of patients. Further studies are needed to determine whether postoperative success and/or reoperation rates do in fact differ between the techniques.

In children

Whereas adults are able to cooperate prior to and during the postoperative adjustment, the use of adjustable sutures in children often requires anesthesia. This may pose concerns given the increased length of time and repeat general anesthesia exposure as well as logistical difficulties depending on the surgical facility. Therefore, adjustable sutures are not as widely used in children as adults. However, a recent study found topical anesthesia was sufficient for intraoperative suture adjustment in 89% of the children studied.[19]

Techniques employed for adjustable sutures in children are similar to those used in adults, although the use of the “short-tag noose” obviates the need for a second exposure to anesthesia in the event that an adjustment is not necessary.[7] Similar to research on adjustable sutures in adults, existing research in children consists predominantly of comparative retrospective studies. One RCT conducted on 60 children with horizontal deviations failed to demonstrate a statistical significance between randomized adjustable and nonadjustable suture groups, with success defined as a final deviation of 8 prism diopters or less at 6 months. Other comparative retrospective studies have shown mixed results. [20]

Controversies

Due to the lack of consensus regarding the benefit of adjustable sutures in strabismus surgery, the use of the technique remains at the surgeon’s discretion. The adjustable suture technique requires more time both in the operating room and postoperatively. Additionally, it is typically more expensive per individual case. Other considerations include patient discomfort during adjustment or surgeon anxiety regarding the adjustment and “adjusting out of a good result.” Despite these concerns, the adjustable suture technique for strabismus surgery is a useful tool for strabismus surgeons. While further research into the benefit of adjustable sutures in strabismus surgery is necessary, it remains an important option to consider particularly in complex cases.

References

  1. Bielschowsky A. Die neueren Anschauungen über Wesen und Behandlung des Schielens Med Klin 1907iii335–336.336. Translation by Catharina Latz, MD.1
  2. Nihalani BR, Hunter DG. Adjustable suture strabismus surgery. Eye. 2011; 25:1262–1276.
  3. Jampolsky A. Strabismus reoperation techniques. Trans Sect Ophthalmol Am Acad Ophthalmol Otolaryngol. 1975;79:704–717.
  4. Jampolsky A. Current techniques of adjustable strabismus surgery. Am J Ophthalmol. 1979; 88:406–418.
  5. Tripathi A, Haslett R, Marsh IB. Strabismus surgery: adjustable sutures-good for all. Eye. 2003; 17:739–742.
  6. Engel JM, Guyton DL, Hunter DG. Adjustable sutures in children. J AAPOS. 2014 Jun; 18(3):278-84.
  7. Nihalani BR, Whitman MC, Salgado CM, et al. Short tag noose technique for optional and late suture adjustment in strabismus surgery. Arch Ophthalmol. 2009;127(12):1584–90.
  8. Granet DA, Banuelos LR, Wang G, et al. Adjustable sutures for delayed adjustment or no procedure. Paper presented at: American Association for Pediatric Ophthalmology and Strabismus Annual Meeting; March 22, 2001; Orlando, FL.
  9. Deschler EK, Irsch K, Guyton KL, Guyton DL. A new, removable, sliding noose for adjustable-suture strabismus surgery. J AAPOS 2013;17(5):524–527.
  10. Kushner BJ. An evaluation of the semiadjustable suture strabismus surgical procedure. J AAPOS. 2004;8(5):481–487.
  11. Chang MY, Pineles SL, Velez FG. Adjustable small-incision selective tenotomy and plication for correction of incomitant vertical strabismus and torsion. J AAPOS. 2015 Oct; 19(5): 410-6.
  12. Hannon AA, Elalfy M, Elborgy ES, Hegazy SM. Laser-Assisted Adjustable Suture Technique in Strabismus Surgery. Clin Ophthalmol. 2020;14:4347-4354. Published 2020 Dec 11. doi:10.2147/OPTH.S281756
  13. Carlson MR, Jampolsky A. An adjustable transposition procedure for abduction deficiencies. Am J Ophthalmol. 1979;87:382–7.
  14. Phamonvaechavan P, Anwar D, Guyton DL. Adjustable suture technique for enhanced transposition surgery for extraocular muscles. J AAPOS. 2010;14:399–405.
  15. Metz HS, Lerner H. The adjustable Harada-Ito procedure. Arch Ophthalmol. 1981;99:624–626.
  16. Goldenberg-Cohen N, Tarczy-Hornoch K, Klink DF, Guyton DL. Post-operative adjustable surgery of the superior oblique tendon. Strabismus. 2005;13:5-10.
  17. Gawęcki M. Adjustable Versus Nonadjustable Sutures in Strabismus Surgery-Who Benefits the Most?. J Clin Med. 2020;9(2):292. Published 2020 Jan 21. doi:10.3390/jcm9020292.
  18. Gawęcki M. Adjustable Versus Nonadjustable Sutures in Strabismus Surgery-Who Benefits the Most?. J Clin Med. 2020;9(2):292. Published 2020 Jan 21. doi:10.3390/jcm9020292.
  19. Franco F, Bolletta E, Mancioppi S, Franco E, Migliorelli A, Perri P. Topical Anesthesia in Children With Intraoperative Adjustable Strabismus Surgery. J Pediatr Ophthalmol Strabismus. 2019; 56: 173-177.
  20. Gawęcki M. Adjustable Versus Nonadjustable Sutures in Strabismus Surgery-Who Benefits the Most?. J Clin Med. 2020;9(2):292. Published 2020 Jan 21. doi:10.3390/jcm9020292.
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