Synergistic convergence has been described only once in a patient who had congenital fibrosis syndrome and whose eye motility was limited in all directions in both eyes.2 Magnetic resonance imaging in this patient disclosed absence of the abducens nerves as well as hypoplasia of the oculomotor nerves with atrophy of the superior and medial rectus muscles of both eyes. Pronounced globe retraction depending on gaze direction was not present. By contrast, our patient had no ptosis, no extraocular muscle hypoplasia, and no family history to suggest the diagnosis of congenital fibrosis syndrome. Therefore, our patient's pathomechanism of synergistic convergence is most likely different. Her congenital, isolated synergistic convergence with globe retraction suggests aberrant nerve sprouting during embryogenesis as the underlying cause. It might be due to a pattern of aberrant innervation similar to that in Duane syndrome, which leads to synergistic divergence (type IV). However, instead of aberrant oculomotor nerve fibers, here we suspect a miswiring of abducens motor neurons to the medial rectus muscle. If most of the abducens nerve fibers were misdirected to the medial rectus muscle, intended abduction would lead to adduction of the eye, and the co-contraction of the lateral and medial rectus muscles would result in globe retraction and eyelid fissure narrowing (Figure 3). In contrast to Duane syndrome, in which there is evidence of primary abducens nerve hypoplasia4 that predisposes to the miswiring, our patient showed no clinical or neuroimaging signs of oculomotor nerve hypoplasia (Figure 2A and B). Contraction of the medial rectus muscles during convergence was normal; thus, we observed no obvious explanation of aberrant nerve sprouting. An unusual congenital sixth-nerve palsy similar to congenital third-nerve palsies5 should also be considered a cause of miswiring. Congenital third-nerve palsies often occur with anomalous reinnervation and no other neurologic or systemic abnormalities. Most regenerated abducens fibers would have been directed to the medial rectus muscle in our patient. However, a misdirection of regenerated nerve fibers to a muscle originally innervated by a different cranial nerve is less probable than a primary aberrant abducens nerve innervation.