management of a complex strabismus secondary to complicated endoscopic dacryocystorhinostomy

purpose: to report a patient with exotropia due to medial rectus muscle entrapment as a complication of endoscopic dacryocystorhinostomy (edcr). case report: a 34-year-old female was referred with left exotropia 18 days after edcr for treatment of primary nasolacrimal duct obstruction. she had a large angle left exotropia in primary position as well as complete limitation of adduction and partial limitation of abduction in the left eye. forced duction test was positive in adduction and abduction, and force generation test revealed total paralysis of the left medial rectus. ct scan showed a large fracture of the medial orbital wall in which the medial rectus muscle was entrapped. she underwent the first operation through a medial canthal incision for releasing the entrapped muscle as well as repair of the medial orbital wall defect. after two additional surgeries including medial transposition of vertical rectus muscles and left lateral rectus muscle disinsertion she had 10 pd exotropia and her diplopia disappeared in primary position. in addition the patient had developed optic atrophy and superior arcuate visual field defect in her left eye probably because of intraoperative trauma to the optic nerve after edcr. conclusion: to the best of our knowledge, this is the first report of medial rectus entrapment following edcr. this complication should be kept in mind in the approach to a patient with strabismus following endoscopic sinus and nasal surgeries in order to select appropriate diagnostic and therapeutic measures.