Muscle Transpositionn

Muscle Transposition

• Horizontal rectus muscle transposition in A & V pattern.

Horizontal muscle transposition for A and V-patterns

• Vertical transposition of horizontal muscle insertions is an effective means of collapsing an A- or V-pattern. This is true only if there is no significant oblique overaction.
• If oblique overaction is present, appropriate oblique strabismus surgery should be used.
• The rationale for vertical transposition is based on the observation that the strength of a horizontal rectus muscle is increased when the eye is vertically rotated in the direction opposite to the direction of its transposed insertion.
• Lowering the insertion of a horizontal rectus muscle improves the effect of this muscle when the eye is in elevation.
• Therefore, an esotropic V-pattern would be best improved by moving a recessed medial rectus muscle inferiorly, which produces more adduction in up gaze and less in down gaze.
• Similarly, displacing a resected lateral rectus muscle insertion superiorly decreases its abducting effect in up gaze while increasing the effect in down gaze.
• A medial rectus muscle, whether resected, recessed, or simply transposed is always moved toward the apex of the pattern. Thus the medial rectus muscle is displaced inferiorly in V-patterns and superiorly in A-patterns.
• The most important points: Determining the site for scleral reattachment of the muscle, as it is important not to advance or recess the muscle inappropriately.
• Measuring the distance to muscle’s new insertion radially from the limbus.

PREOPERATIVE V pattern esotropia

V pattern Esotropia

PREOPERATiVE

POSTOPERATIVE