Vertical Rectus Muscles Transposition in Large Exotropia with Medial Rectus Muscle Transection Following Endoscopic Sinus Surgery

Purpose: To evaluate the effect of transposition procedures on the vertical rectus muscle (VRM) in the patients who underwent a medial rectus muscle (MR) transection after endoscopic sinus surgery (ESS). Methods: In 4 patients with exotropia (XT) and a lack of adduction after ESS, orbital CT or MRI revealed a complete transection of the midportion of the MR. Full‐tendon VRM transposition was performed within 3 months after injury (early surgery) in 2 patients with 40△ XT. Two patients with 70△ and 85△ XT underwent an X‐type augmented Hümmelsheim procedure, which involved pulling each half‐tendon and crossing it through the undersurface of the severed MR to the other end of the MR insertion, concurrently with an ipsilateral lateral rectus (LR) recession 11 months and 36 months after ESS, respectively. The adduction deficits were divided into ‐1 through to ‐8. The patients were followed up for more than than 1.5 years. Results: Postoperatively, 3 patients showed orthophoria and no diplopia in the primary position. The adduction deficits improved to ‐3.5 or –4. One patient who underwent an X‐type augmented Hümmelsheim procedure showed a residual XT of 25△. Conclusions: VRM transposition is effective in correcting a large XT secondary to a MR transection after ESS. When a longstanding large‐angle XT with severe contracture of the ipsilateral LR and massive scarring of the adjacent tissues is present, the X‐type augmented Hümmelsheim procedure coupled with an ipsilateral LR recession had an augmenting effect.