Loop myopexy with true muscle transplantation for very large angle heavy eye syndrome patient.

A 42-year-old man presenting with complaints of squint for last 20 years. His visual acuity was 20/400 in right eye (RE) and 20/30 in left eye (LE) with glasses. His refraction was RE -16.75/-2.5 D cycl 180 and LE was -14.5/-1.5 D cycl 180. His axial length was 31.23 mm In RE and 29.72 mm in LE. On examination we found he had RE large esotropia with hypotropia measuring 130 pd base out and 40 pd base up in RE. A computerized tomography scan revealed that the superior rectus (SR) was shifted nasally, and lateral rectus (LR) was shifted inferiorly. A RE medial rectus (MR) recession and LR resection with muscle transplantation on the MR was done. A loop myopexy was done to correct the path of the LR and SR. The patient had only 18 pd eso and 20 pd hypo on follow-up after 3 months. Loop myopexy in conjunction with muscle transplantation is a safe and effective procedure for large angle esotropia associated with heavy eye syndrome.

Loop myopexy has been introduced as a solution to large esotropia with hypotropia in high myopes with displacement of the superior rectus (SR) nasally and lateral rectus (LR) inferiorly on neuroimaging.[12345] However, almost all the patients reported in the literature reported to have some residual angle postoperatively. True muscle transplantation has been proposed for very large angle strabismus patients.[678] We did a true muscle transplantation in a patient with an extremely large angle esotropia with abduction restriction and hypotropia and did a loop myopexy between SR and LR to correct and align the muscle path.

Case Report

A male Muslim adult patient aged 48 years presented to us with complaints of poor vision and squint in right eye (RE) since last 20 years. He did not have any old pictures and therefore the duration of squint could not be assessed.

On examination, his vision was RE 20/400 and left eye (LE) 20/30 with glasses. His refraction was RE −16.75/−2.5 D cycl 180 and LE was −14.5/−1.5 D cycl 180. His fundus examination showed posterior staphyloma in RE, but no peripheral breaks in either eye. He had large RE esotropia with hypotropia with poor fixation in RE. He was not able to bring the RE to midline [Fig. 1a]. Both abduction and elevation was restricted to −5 and −4 respectively. Forced duction test (FDT) was positive for abduction (the eye could not be brought to even midline easily and mildly positive for elevation. With contact lenses we tried to measure the angle with the help of Krimsky's test and found it to be approximately 130 pd esotropia and 40 pd hypotropia. A scan of RE showed an axial length of 31.23 mm and LE 29.72 mm. To find out whether the SR and LR muscle paths were displaced a computerized tomography (CT) scan was ordered. Coronal CT scan sections showed that the SR was displaced nasally, and LR was displaced inferiorly [Fig. 1b].

Figure 1

(a) The large angle right eye esotropia with hypotropia(b) Coronal computerised tomography scan section showing displaced lateral rectus inferiorly and superior rectus medially(c)Schematic diagram showing the muscle transplantation and loop myopexy (d) Postoperative picture showing residual esotropia and hypotropia

True muscle transplantation was planned along with the loop myopexy between SR and LR was planned.

Surgical Procedure

The surgery was done under peribulbar block. An FDT was done and positive for abduction meaning medial rectus (MR) was tight. First the RE MR was dissected and separated via a fornix incision in the lower nasal quadrant. A nonabsorbable 6-0 prolene suture was tied at the muscle insertion. The muscle was incised from its insertion. The FDT was negative after the muscle was detached from its insertion. Next the LR muscle was hooked, it was found to be obliquely placed. Two 6-0 vicryl sutures were placed at 9 mm from the insertion as is done in a routine resection of rectus muscle and another pair of 6-0 vicryl was placed at the insertion. The muscle was then incised from its insertion and the posteriorly (distally) placed 6-0 vicryl sutures were passed through the original insertion as in a routine rectus muscle resection. The stump was then cut. The stump was then placed at the MR site and the distal end of this stump was sutured with the proximal end of MR with the 6-0 prolene already placed on the MR [Fig. 1c]. The now elongated muscle was sutured at 6 mm from the original insertion site of MR as is done in a routine rectus muscle recession.

Now the SR was hooked and a 4-0 ethibond suture was passed under the muscle belly. This suture was then passed through the sclera 16 mm from the limbus and then looped around the LR muscle, and the two ends were tied to complete the loop myopexy. The conjunctiva sutured with 8-0 vicryl.

Postoperative the patient had a small residual esotropia and a persistent hypotropia [Fig. 1d] On follow-up at 3 months, the patient still has a small esotropia measuring 18 pd and a 20 pd hypotropia of RE. The patient has almost normal abduction and adduction though the elevation is still restricted (−2).

Discussion

Loop myopexy has become a standard procedure of choice for large angle esotropia in high myopic patients with displaced SR and LR on neuroimaging. The reports suggest significant improvement in angle and motility with single muscle recession, recession resection along with loop myopexy.

Almost all the reports show that there is a residual esotropia postsurgery. Moreover, such a large angle has not been reported to have improved with loop myopexy. Therefore, we thought that a combination of muscle transplantation and loop myopexy should help.

A muscle transplantation procedure has been described earlier though not much popularized.[678] There is very little literature with an actual surgical results on humans (only a total of 6 cases in the literature).[78] The other options for elongation of muscle could be a silicone band or nonabsorbable sutures. Silicone bands have been used successfully in Brown's syndrome for muscle elongation and so are chicken sutures. However, these bands are used as spacers and between the cut ends of the tendon and not at the insertion. Since there was little experience with these bands and suture, we felt it was safer to use the muscle stump for such a procedure. The muscle transplantation effectively gives you the opportunity to correct very large angle cases with a single eye surgery. The RE was the severely amblyopic eye and therefore it becomes even more important to correct as much of an angle as much as possible with a single surgery. With the help of muscle transplantation, the effective length of the muscle could be increased and therefore the results could be improved. The chances of any rejection of the transplanted muscle are virtually nil. The movement restriction in the extreme gaze on the side of the muscle transplantation is seen as a result of excessive weakening of the muscle, but the muscle is still anterior to the equator and therefore the motility restriction is minimal.

We believe that muscle transplantation coupled with loop myopexy is a useful option in patients with very large angle strabismus and displaced SR and LR.