Restoration of binocular single vision following multiple treatments for longstanding bilateral internuclear ophthalmoplegia and unilateral third nerve paresis in Chiari II malformation

Aim: To present a patient with longstanding bilateral internuclear ophthalmoplegia and unilateral third nerve paresis in Chiari II malformation who achieved binocular single vision with the help of prisms following two surgical and two botulinum toxin procedures. Method: The case is discussed of a 34-year-old man who presented with a longstanding exotropia and a gradually increasing abnormal head posture to achieve fixation. Investigation, treatment and follow-up to discharge are described. Results: The patient initially underwent surgery with the aim of improving cosmesis of the exotropia and the abnormal head posture, but functionally beneficial stereopsis and field of binocular single vision were achieved with multiple treatments including Fresnel prisms. Conclusion: Functional results are achievable, even in cases of longstanding strabismus associated with complex ocular motility and neurological defects.