Transposition Surgeries in Strabismus

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Introduction

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Indications

Indications for transposition surgeries include Paralytic squint: The most common indication for transposition surgeries in squint is paralytic squint. Transposition surgeries must be planned only when the forced duction test is free and active force generation test reveals absence of any active force generation.(Figure1) Duane’s Retraction Syndrome Lost or slipped muscle


Mechanism of Action

The main aim of transposition surgeries is to realign the eyes in primary position,(1) although the results of transposition procedure are usually good but patients must understand that the ductions in the direction of action of paralyzed muscle might not improve much, further addition of posterior fixation sutures can improve the results. The mechanism of action of transposition procedure is still controversial, some authors believe that improvement in the primary position can be due to transfer of function of transposed muscle in the direction of action paralyzed muscle through the change in the direction in vector forces of the transposed muscle. Other hypothesis states it to be due to the passive restraint to hold the eye in primary position. In augmented procedures with posterior fixation sutures, it has been suggested that rectus muscle pulley are diverted posteriorly in the direction of transposition while translating the centre of the globe. Probably more than one mechanism act together to achieve alignment in the primary position.

Transposition procedures for Sixth nerve palsy

Full tendon transposition

Full tendon transposition involves full tendon transposition of vertical recti, after dis inserting them.(2) To prevent the risk of anterior segment ischemia the vertical recti must be carefully dissected to conserve the anterior ciliary artery branches. Extensive dissection should be avoided. (Figure2)


Hummelsheim procedure

Technique

After making a limbal based incision superiorly and inferiorly the temporal halves of superior and inferior rectus are secured, disinserted and further transposed towards the lateral rectus. The transposed halves of both the vertical recti are further inserted near the insertion of the lateral rectus. While splitting and disinserting the vertical recti, care must be taken to protect the anterior ciliary circulation.(3) (Figure3)


Modified Hummelsheim

To increase the effectiveness of Hummelscheim procedure, resection of the transposed tendon can be added along with recession of medial rectus. (Figure4)

Effectiveness of Hummelsheim procedure Modified Hummelsheim procedure has been reported to correct a preoperative deviation of 43 Δ ± 5 Δ to postoperative 6 Δ ± 7 Δ .(4)

Jensen’s procedure

Jensen’s procedure is indicated in sixth nerve palsy, and was first described by Jensen et al in 1964.(5) In this procedure the muscle belly is not dis-inserted and therefore does not predispose to anterior segment ischemia, however anterior segment ischemia has been reported with the Jansen’s procedure.

Technique

When performing Jensen’s procedure for lateral rectus palsy, limbal base incision is made to expose the bellies of lateral, superior and inferior rectus, intermuscular septa of all the three muscles is dissected to expose 12-15 mm of the muscle belly behind its insertion. Muscle bellies of each of the exposed recti are split with the help of a muscle hook, utmost care must be taken to preserve at least one anterior ciliary artery undisturbed. A 5-0 ethibond suture is then used to form a loop around each of the muscle belly. The sutures are then tied to bring the muscle bellies close approximately 12 mm behind the insertion. (Figure 5) Effectiveness of Jensen Procedure Cline et al in their study on 26 patients who underwent Jansen’s procedure with medial rectus recession found that at 6 months follow up 18 eyes had less than 20% of normal abduction saccadic velocity; 9 eyes had 20% to 40%, and 2 patients could not be assessed with saccadic velocities.

Modifications of Jensen Procedure

Vessel sparing modification In this modification instead of looping the suture around the entire rectus muscle segments, the suture can be passed beneath the anterior ciliary vessels present on the orbital surface of each muscle

Nishida’s Procedure

Technique The technique was described by Nishida et al in 2003.(6) In this technique after making a limbal based conjunctival peritomy the vertical recti are hooked. Intermuscular septum and fascia along the lateral margin of each of the vertical recti are carefully dissected and the vertical muscle belly is then longitudinally split from the centre of the muscle insertion for about 15 mm with a short muscle hook. Following this 8 to 10mm posterior to the insertion of each of the vertical recti 6-0 nylon monofilament sutures are passed. These sutures are further passed through the sclera 8mm posterior to the insertion of lateral rectus beside the superior or inferior margin. One scleral suture can be added on the inside edge of each transposed muscle to the sclera.(Figure6)

Effectiveness of Nishida According to Nishida et al, the surgery resulted in an average correction of 42.4PD.


Modification Of Nishida's Procedure

Indications Besides abducens nerve palsy, modified Nishida’s technique has been used in patients of monocular elevation deficit(7) and in cases of transected and lost medial rectus(8,9) Nishida et al further modified the procedure and omitted the step of muscle splitting to prevent further damage during the surgical manipulation. (10) Technique A limbal based incision is made which helps in better exposure of the vertical recti. 6-0 polypropylene or ethibond sutures are passed through the temporal margins of the vertical recti at a distance of 8 to 10 mm behind the insertion points of the vertical recti. The sutures can be tied there to avoid muscle breakage due to tension during transposition. The same suture is then passed through each scleral wall at a distance of 10 to 12 mm behind the supero-temporal and infero-temporal limbus, following this temporal margin of each vertical rectus is transposed and anchored onto the sclera. (Figure6)


Transposition Procedures for Third Nerve Palsy

Superior oblique tendon transfer

Technique The procedure was initially described by Peter in 1934. A limbal based peritomy is performed in the superonasal quadrant which is sufficient to provide exposure to both medial and superior recti. The superior oblique is isolated and dissected free of surrounding fascial attachments along the tendon, following underneath and along the nasal side of the superior rectus. The superior oblique tendon is engaged on a small muscle hook on the nasal side of the superior rectus muscle and is secured with a double-armed 6-0 absorbable suture The tendon is disinserted and brought down toward the superior edge of the medial rectus insertion. The tendon is then sutured to the sclera at the superior border of the medial rectus insertion at the point on the tendon thus bringing the eye to a centred position. (Figure7)


Lateral rectus to Medial Rectus transposition

Technique Limbal based peritomy is performed over the lateral, superior, and medial rectus muscles. The attachments and intermuscular septa of lateral rectus muscle is dissected, the muscle is secured with 6/0 vicryl suture and disinserted The lateral rectus muscle suture is then passed beneath the superior rectus muscle in the direction of the medial rectus muscle, thus pulling the lateral rectus muscle in that direction. Lateral rectus is then sutured neat the superior margin of the medial rectus insertion. (Figure8) Effectiveness The procedure was initially described by Taylor and was found to be effective, later Morad et al described the procedure in a case of combined third and fourth nerve palsy


Full tendon medial transposition of lateral rectus with augmentation sutures

Saxena R et al introduced a modification of full tendon transposition, in cases with hypertropia along with exotropia, the disinserted lateral rectus was passed under the inferior oblique, inferior rectus muscle and was reattached just below the insertion of the medial rectus muscle. Augmentation sutures with 5–0 Ethibond were placed 8mm behind the new insertion of transposed lateral rectus muscle which included at least a third of the muscle fibres in each bite On the other hand in their series patients with hypotropia, lateral rectus muscle was passed under superior rectus, superior oblique after posterior tenectomy of the muscle and reattached at the upper border of the medial rectus along with augmentation sutures.


Medial transposition with Y splitting of lateral rectus

Technique Limbal based peritomy is performed, lateral rectus is hooked and intermuscular septa is dissected 15mm posterior to the insertion. Muscle is then split 15mm posterior to the insertion, towards the posterior septum. The split portions of the lateral rectus are than secured with the help of 6-0 polyester suture, and disinserted. The upper half of the muscle is then passed beneath the superior oblique, and inferior half is moved beneath the inferior rectus and inferior oblique. The two halves of lateral rectus are then inserted near the insertion of medial rectus. (Figure9) Effectiveness of the procedure Gokyigit et al, inserted the lateral rectus 1mm posterior to medial rectus found a success rate of 90 per cent with the procedure with the mean pre-op deviation being 73.7Δ ± 8.9Δ and post-op deviation being 11.8Δ ± 1.0Δ


Augmentation of the split lateral rectus

Indications The procedure has been used in third nerve palsy and synergistic divergence in Duane’s retraction syndrome. Technique The surgery is undertaken through four fornix conjunctival incisions in each quadrant after performing a forced duction test to confirm a free lateral rectus muscle. The lateral rectus is hooked, split in half up to at least 15 mm posteriorly after placing 6-0 Vicryl sutures. Superior oblique is hooked and posterior tenectomy is done as in conventional surgeries. Posterior tenectomy of superior oblique helps in free movements of the transposed muscle under it, reduces the abduction effect and hence brings out greater correction. The superior half of the split In this modification, in addition to the above surgical steps, equatorial fixation sutures are put 8 mm behind the new insertion of the split muscles with 5-0 Ethibond passing them through the transposed ends incorporating 25℅ of the muscle.



Vertical Muscle Palsy

Knapp’s procedure

Knapp’s procedure is indicated in patients of monocular elevation deficit, the horizontal recti (both medial and lateral recti are disinserted and transposed superiorly.

Modified Knapp’s

In modified Knapp’s procedure, both the horizontal recti are split into two halves. The lower half is used for correction of horizontal deviation and the superior half is transposed superiorly.

Augmented Knapp’s

Augmented Knapp’s procedure is similar to Knapp’s the addition involves a foster suture Transposition procedure for double depressor palsy

Inverse Knapp’s

The procedure is relatively less commonly performed, the common indications include double depressor palsy and congenital absence of inferior rectus. In this procedure, the horizontal recti are transposed to the level of inferior rectus. (Figure10)


Complications

References

1)Rosenbaum AL. The efficacy of rectus muscle transposition surgery in esotropic Duane syndrome and VI nerve palsy;Costenbader Lecture.J AAPOS. 2004 Oct; 8(5):409-19.

2)Schillinger RJ. A new type of tendon transplant operation for abducens paralysis. J Int Coll Surg. 1959;31:593–600.

3)Hummelsheim E. Weitere Ertahunger mit partiellar Sehnenuberpflanzung an der Augenmuskln (abstract) Arch Augenheilkd. 1908–1909;62:71.

4)Couser NL, Lenhart PD, Hutchinson AK. Augmented Hummelsheim procedure to treat complete abducens nerve palsy. J AAPOS. 2012;16(4):331‐335.

5)Jensen CD. Rectus muscle union: A new operation for paralysis of the rectus muscles. Trans Pac Coast Otoophthalmol Soc Annu Meet. 1964;45:359–87.

6)Nishida Y, Inatomi A, Aoki Y, et al. A muscle transposition procedure for abducens palsy, in which the halves of the vertical rectus muscle bellies are sutured onto the sclera. Jpn J Ophthalmol 2003;47:281–286.

7)Murthy SR, Pappuru M. Modified Nishida's procedure for monocular elevation deficiency. J AAPOS. 2018;22(4):327‐329.e1.

8)Kong M, Zhang LJ, Dai S, Li JH. A new application of modified Nishida muscle transposition procedure for medial rectus muscle transection following endoscopic sinus surgery without tenotomy or splitting muscles. J AAPOS. 2019;23(5):287‐289.

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10) Nishida Y, Hayashi O, Oda S, Kakinoki M, Miyake T, Inoki Y, et al. A simple muscle transposition procedure for abducens palsy without tenotomy or splitting muscles. Jpn J Ophthalmol 2005;49:179-80.