Herpes zoster ophthalmicus with isolated trochlear nerve palsy in an otherwise healthy 13-year-old girl.

Herpes zoster ophthalmicus is rare in healthy children. It is occasionally associated with extraocular muscle palsies and rarely with isolated trochlear nerve palsy. We report a case of unilateral isolated trochlear nerve palsy associated with herpes zoster ophthalmicus in an immunocompetent 13-year-old girl who presented with diplopia and blurred vision in her right eye. The right cornea had multiple subepithelial opacities. Ocular motility returned to normal and diplopia and corneal opacification resolved with steroid therapy. To our knowledge, this is the first such case involving the troclear nerve in a child.