Acquired bilateral myelinated retinal nerve fibers after unilateral optic nerve sheath fenestration in a child with idiopathic intracranial hypertension

PurposeTo report the unusual development of bilateral myelinated retinal nerve fibers (MRNF) adjacent to the optic nerve in a child after treatment of idiopathic intracranial hypertension (IIH) with unilateral optic nerve sheath fenestration (ONSF) and to discuss the etiology of acquired MRNF.MethodsThe patient's clinical history, including visual acuity, refractive error, ocular alignment, fundus examination, and optic nerve photographs, was retrospectively reviewed. A literature review was performed for acquired MRNF in children using PubMed. The results of the demographic and clinical findings of our patient were compared with those of previously reported cases.ResultsThe child developed bilateral MRNF adjacent to the optic nerve 5 months after unilateral ONSF. In reviewing the literature, 8 of 10 cases of acquired MRNF in children had previous abnormalities of the optic nerve, 4 of 10 had associated bilateral optic nerve head drusen, 3 of 10 had associated optic nerve glioma, and 3 of 10 had a history of significant increased intracranial pressure requiring surgical intervention.ConclusionsAlthough the etiology of acquired MRNF is uncertain, this case plus a review of the literature suggest that it may be related to changes in the lamina cribosa combined with possible optic nerve injury caused by optic nerve head drusen, optic nerve glioma, or increased intracranial pressure and that it can occur months to years after intervention.