Hummelsheim procedure

The Hummelsheim procedure is a muscle transposition operation for lateral rectus palsy. The surgeon splits the superior and inferior rectus muscles lengthwise and moves the lateral half of each to the insertion of the paretic lateral rectus.¹ Most later transposition techniques for abducens paralysis derive from this procedure.²

A graded recess-resect procedure often succeeds if some lateral rectus function remains. If little or no abducting force remains, a transposition supplies a new source of abducting force, together with weakening of a contracted medial rectus.¹ The transposed muscles act mechanically, and the forced duction test must show free passive movement into the paretic field before any transposition.²

Splitting the vertical recti has the theoretical advantage of preserving one ciliary vessel on each muscle. Full-tendon transposition transfers more force but carries a higher risk of anterior segment ischemia.¹ Surgeons favor Hummelsheim or Jensen transpositions over the Knapp transposition if ischemia is a concern.³