Transposition of plicated horizontal muscles

Abstract

Various surgical techniques exist for simultaneous correction of a strabismus with both horizontal and vertical components. Transposition of horizontal muscles is most commonly performed on recessed and resected muscles. We describe a novel surgical technique that combines horizontal rectus muscle plication with a vertical transposition and present a small case series in which the technique was used to successfully correct both horizontal and vertical deviations.

There are several surgical approaches for deviations with both horizontal and vertical components. The surgeon can operate on both horizontal and vertical rectus muscles. Horizontal rectus muscle recession and/or resection may be combined with a vertical transposition (or offset).¹ Muscle plication also may be used to strengthen a muscle,² with the benefit of better preserving, compared with resection, anterior ciliary circulation^3-6 and reducing the risk of a lost muscle Plication can also be performed using an adjustable suture technique.⁷

Subjects and Methods

Surgical Technique

A horizontal rectus muscle plication may be combined with vertical transposition as follows. Unilateral surgery is performed using a fornix approach, with a standard fixed recession, with vertical transposition performed first. For the plication, single-armed 6-0 polyglactin 910 sutures are passed through the muscle edge at the desired distance from the muscle insertion and tied (Figure 1A). The suture needles are then passed partial thickness through the sclera, just anterior to the muscle insertion, with a vertical offset, as required (Figure 1B-C). This results in a triangular fold in the muscle (Figure 1D).

FIG 1.

Combined right medial rectus muscle plication with vertical transposition. A, Suture is passed through muscle edges (arrows). In this case, an 8 mm plication with full-tendon-width transposition was performed. B, The inferior muscle suture (white arrow) is passed through the sclera, anterior to the superior pole of the muscle edge. C, The superior muscle suture (black arrow) is passed through the sclera one full-tendon width (7 mm) superior to the first scleral pass. D, Appearance after sutures are tied, with a triangular fold in the muscle.

The amount of transposition for both the recessed and plicated muscles is based on the surgeon’s standard approach for transposition performed with recession-resection procedures: transposition of one-third to one-half tendon width for deviations of 4^Δ-10^Δ deviation; transposition of one-half to two-thirds tendon width for deviations of 10^Δ-14^Δ; and (maximal) transposition of one full tendon width for deviations of ≥15^Δ. Up to 15^Δ of vertical deviation can be corrected with a full-tendon-width transposition of both the recessed and plicated muscle. The maximum vertical correction that can be achieved is proportional to the surgical dose of the plication performed for the horizontal deviation. The same technique can be applied to horizontal transposition of a vertical rectus muscle, if necessary. See Video 1.

Case Series

Ethics approval for this study was obtained through the University of Pittsburgh Institutional Review Board. The medical records of patients undergoing horizontal rectus muscle plication combined with vertical transposition at the University of Pittsburgh Medical Center during the period September 2018-May 2019 were reviewed retrospectively. The minimum postoperative follow-up was 6 months. In all patients, the procedure was performed by a single surgeon (MSP).

Results

A total of 3 children (median age, 4; age range, 14 months to 8 years) and 1 adult (age, 74 years) underwent unilateral horizontal rectus muscle recession-plication procedures combined with vertical transposition to treat a combined horizontal and vertical deviation. Details of the preoperative deviations, surgery performed, and postoperative results are provided in Table 1. All of the pediatric patients had complex strabismus and general medical history. The vertical deviation measured between 4^Δ and 15^Δ. In the adult patient, the recession was performed using an adjustable suture technique.

Table 1.

Patient characteristics, preoperative deviation, surgery performed, and postoperative outcomes

Case	Age	History	Pre-op deviation, PD	Surgical detail	Post-op deviation, PDa
1	14 mos	Craniosynostosis Treacher Collins syndrome Orbital asymmetry with right inferior orbital rim hypoplasia	50 R-XT′, 15 R-HoT′; right upgaze limitation −2	R-LR recess 9 mm with full-tendon superior trans; R-MR plic 8 mm with full-tendon superior trans	Orthotropic at distance and near, with full ocular motility
2	4 yrs	HSV encephalitis Left occipital stroke	45 R-XT, 10 R-HoT	R-LR recess 7.5 mm with 1/3-tendon-width superior trans; R-MR plic 6 mm with 1/3-tendon-width superior trans	Flick E with 2-4 R-Ho(T)
3	8 yrs	Congenital stationary night blindness, latent nystagmus Previous surgery left eye recess-resect for XT	40 L-XT, 12 L-HoT	R-LR recess 8 mm with 1/2-tendon-width inferior trans; R-MR plic 6 mm with 1/2-tendon-width inferior trans	Flick E
4	74 yrs	X(T) with convergence insufficiency pattern L-HT Diplopia with horizontal and oblique components POAG both eyes Pseudophakia both eyes Right amblyopia, patching in childhood	18 L-X(T) with 4 L-H(T), 30 L-X(T)′; right gaze: 10 X; left gaze: 5 X with 5 L-H(T); 1-2+ overelevation in adduction of left eye	L-LR recess 5 mm with 1/3-tendon-width inferior trans on adjustable suture (post-op adjustment with advancement of 1 mm); L-MR plic 5 mm with 1/3-tendon-width inferior trans	2 X, 5 X′

HoT, hypotropia; Ho(T), intermittent hypotropia; HSV, herpes simplex virus HT, hypertropia; H(T), intermittent HT; L-, left; PD, prism diopter; Plic, plication; POAG, primary open-angle glaucoma; R-, right; Recess, recession; Resect, resection; Trans, transposition; X, exophoria; X′, X at near; XT, exotropia; XT′, XT at near; X(T), intermittent XT; X(T)′, X(T) at near.

^aAt 8 months’ follow-up for cases 1-3; 6 months, for case 4.

All 4 patients achieved the postoperative target alignment, with the vertical deviation measuring between 0^Δ and 2^Δ. There were no intra- or postoperative complications or unexpected shifts in ocular alignment during the follow-up period. There were no overcorrections.

Discussion

The novel surgical technique described here effectively treated combined horizontal and vertical strabismus in all 4 reported cases of complex strabismus. Theoretically, the risk for anterior segment ischemia caused by future ipsilateral surgery is mitigated by this approach. To the extent that plication mitigates damage to the anterior ciliary vessels, eyes that had previous ipsilateral surgery could also be spared ischemia effects of surgery.

Literature Search

The PubMed database was searched (1966 to present) on June 1, 2019, using the following keyword combination: strabismus AND plication AND ((transposition) OR offset).