Surgical management of longstanding bilateral complete 6th nerve palsy: presentation of a challenging case

Purpose: Bilateral complete 6th nerve palsy is a rare and challenging strabismus condition characterized by a large-angle esotropia and complete inability to abduct the eyes past the midline. Patients often present with diplopia and a compensatory face turn. While various surgical techniques, including transposition procedures, have been developed to address this condition, the risk of anterior segment ischemia remains a significant concern. Methods: A 23-year-old man presented with a history of head trauma 3 years prior, resulting in a severe ocular deviation and face turn. Ophthalmic examination revealed over 120 Prism Diopters (PD) of esotropia and a 5+ limitation of abduction in both eyes, confirming a diagnosis of bilateral traumatic complete 6th cranial nerve palsy. The patient underwent bilateral medial rectus recessions. Additionally, a modified Nishida procedure was performed on the right eye, and a Nishida procedure was performed on the left eye. Results: Postoperatively, the esotropia was successfully reduced to 20 PD. The patient experienced no complications, most notably no signs of anterior segment ischemia and no induced vertical deviation. Discussion: Surgical management of bilateral complete 6th nerve palsy presents a significant challenge. This modified surgical approach – bilateral medial rectus recession with a modified Nishida procedure in one eye and a Nishida procedure in the other – proved to be a safe and effective strategy for correcting a large-angle esotropia in this patient.