Incomitant esotropia secondary to lateral rectus injury.

Incomitant esotropia simulating a sixth nerve palsy from lateral rectus injury is an unusual diagnosis. Two patients are presented both with abduction defects thought secondary to either a restrictive orbitopathy or sixth nerve palsy. Force generation testing revealed a paretic process. Neuroimaging demonstrated transection of the lateral rectus muscle in both patients. One was secondary to a lateral wall fracture and the other iatrogenic during lateral wall decompression surgery for thyroid orbitopathy. Lateral rectus injury should be considered in patients with a history of trauma or orbital surgery. Forced duction and generation testing, and neuroimaging can reveal the diagnosis.