Objective: To describe weakness of the orbicularis oculi muscle after external dacryocystorhinostomy (DCR) and propose an anatomic explanation for the complication.
Design: Retrospective, observational study.
Participants: Sixteen patients (13 female, 3 male) with a mean age of 60 years (median, 61 years; range, 34-85 years).
Methods: A retrospective chart review was performed of consecutive patients who had nasolacrimal duct obstruction repair by external DCR. Patients were identified who developed postoperative orbicularis oculi muscle weakness that manifested as hypometric blink or lagophthalmos with or without punctate keratopathy on the operated side. Patient parameters collected included demographic data, type of incision, incision length, use of lacrimal stent, length of follow-up, intraoperative and postoperative complications, and time to resolution of clinical findings. Statistical analysis was performed using a 2-tailed Fisher exact test with clinical significance designated at alpha = 0.05.
Main outcome measures: Identification of patients with orbicularis oculi muscle weakness after external DCR, documentation of incision type, clinical findings, and recovery of function.
Results: Among 215 patients and 247 surgeries, 16 individuals (7.4%) were identified who demonstrated abnormalities of eyelid closure in the postoperative period after external DCR. Of these, 13 patients had lagophthalmos with or without hypometric blink and 3 patients had hypometric blink alone. Eleven patients underwent surgery through a nasojugal incision, 4 patients underwent surgery through a vertical incision, and 1 patient underwent surgery through an eyelid margin incision. The degree of postoperative lagophthalmos was on average 1.5 mm. Four patients developed punctate keratopathy. Follow-up ranged from 3 to 50 weeks (mean, 20 weeks). Resolution of lagophthalmos was seen on average by 14 weeks with the longest time to resolution of 32 weeks. Three individuals continued to have residual hypometric blink at the time of last follow-up.
Conclusions: Damage to peripheral fibers of the zygomatic and buccal branches of the facial nerve as they course through the medial canthal area to innervate the upper eyelid orbicularis oculi muscle may occur during external DCR surgery. Such injury may be responsible for orbicularis oculi muscle weakness manifesting as postoperative abnormal eyelid closure and lagophthalmos. In our cohort of patients, these findings were temporary and typically resolved in several months.