Rectus extraocular muscle pulley displacement after surgical transposition and posterior fixation for treatment of paralytic strabismus

doi:10.1016/S0002-9394(01)01264-8

American Journal of Ophthalmology

Volume 133, Issue 1, January 2002, Pages 119-128

https://doi.org/10.1016/S0002-9394(01)01264-8 Get rights and content

Abstract

PURPOSE: To determine the effect of rectus extraocular muscle (EOM) transposition with posterior fixation (PF), we employed magnetic resonance imaging (MRI) to demonstrate pulley inflections in EOM paths before and after surgery in patients with paralytic strabismus.

DESIGN: Consecutive interventional case series.

METHODS: Five consecutive patients (three males and two females with a mean age 52 years, range 33 to 77 years) with paralytic strabismus were studied prospectively before and more than 6 weeks after EOM transposition and PF by means of contiguous cross-sectional MRI obtained in planes perpendicular to the long axis of the orbit. Muscle paths were determined in three dimensions (3-D) for each EOM by analysis of cross-sectional area centroids in normalized, oculocentric coordinate systems.

RESULTS: Four patients underwent full tendon transposition with PF of the vertical rectus EOMs. One other patient underwent full tendon transposition without PF of the horizontal rectus EOMs superiorly. For transpositions with PF, there was a large displacement of EOM path in central (straight ahead) gaze beginning in the posterior orbit. After surgical transposition, clear inflections representing pulley locations of the superior, medial, and lateral rectus paths occurred in central gaze. There was no clear path inflection for the inferior rectus in central gaze, but there was a small inflection in adduction. After all transpositions, the globe center shifted away from the transposed insertions.

CONCLUSIONS: Rectus EOM transpositions with PF shift EOM pulleys posteriorly and in the directions of the transposed EOM tendons, while translating the globe center. These changes may explain the superior effectiveness of PF in increasing duction towards the transposition.

Section snippets

Subjects and methods

: The study was designed as an interventional case series. Five patients were identified preoperatively in whom full tendon width transposition of EOM insertions was indicated for treatment of paralytic strabismus. All patients underwent complete ophthalmic examinations and photography in diagnostic gaze positions. After obtaining written informed consent according to a protocol conforming to the Declaration of Helsinki and approved by the local Human Subject Protection Committee, each patient

Results

Clinical information for the patients is summarized in Table 1. Three of the five patients underwent full tendon width transposition with PF11 of the superior rectus (SR) and inferior rectus (IR) muscles to the borders of the lateral rectus (LR) muscle 8 mm posterior to the superior and inferior LR insertion, respectively, to treat abducens paralysis. Preoperatively, all three patients had a primary position esotropia that markedly increased in the field of action of the paralyzed LR (Figure 4)

Discussion

Recent enhancements in both MRI techniques and image analysis have proved fundamental in advancing our understanding of normal orbital kinematics.6 In a similar fashion, these same techniques have advanced our understanding of EOM behavior after transposition surgery. At the same time, advances in transposition surgical techniques11 have presented a moving target to those attempting to quantitatively analyze the biomechanics of transposition surgery.

It is fortunate that the first study

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To report the results of adjustable graded augmentation of superior rectus transposition, a novel modification of superior rectus transposition (SRT) designed to reduce postoperative vertical or torsional diplopia.
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Citation Excerpt :
These sutures are designed to transpose the posterior EOM belly to match the surgical transposition of the EOM insertion, an addition not considered necessary until the discovery of EOM pulleys. The posterior fixation sutures directly increase the mechanical force of the tendon transposition by shifting the EOM pulley itself,33 improving the mechanical effectiveness of transposition surgery so profoundly that transpositions augmented with posterior fixation have virtually supplanted all prior transposition techniques. Abnormality of EOM pulley location has now been implicated in one of the leading forms of acquired adult strabismus, distance ET with normal near alignment.
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^☆: Grant Support: Supported by NEI grant EY-08313 to Joseph L. Demer. Robert A. Clark was a Rosalind W. Alcott Fellow, Heed Ophthalmic Fellow, Knapp-AOS Fellow, and Giannini-Bank of America Foundation Fellow. Joseph L. Demer received a Research to Prevent Blindness Lew R. Wasserman merit award and is Laraine and David Gerber Professor of Ophthalmology.

¹: Proprietary Interest: None.

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Original articleRectus extraocular muscle pulley displacement after surgical transposition and posterior fixation for treatment of paralytic strabismus1☆,

Abstract

Section snippets

Subjects and methods

Results

Discussion

Vision Res

J AAPOS

Ophthalmology

J AAPOS

Am J Ophthalmol

New insights in the human orbital connective tissue. Result of a new anatomical approach

Arch Ophthalmol

Evidence for fibromuscular pulleys of the recti extraocular muscles

Invest Ophthalmol Vis Sci

Innervation of extraocular pulley smooth muscle in monkeys and humans

Invest Ophthalmol Vis Sci

Original article
Rectus extraocular muscle pulley displacement after surgical transposition and posterior fixation for treatment of paralytic strabismus¹☆,