Myelinated Retinal Nerve Fiber Layer, Myopia and Amblyopia

Introduction. The triad of myelinated retinal nerve fiber layer (RNFL), myopia, and amblyopia is a rarely reported syndrome. Myelinated RNFL is present in approximately 1% of eyes and associated with a variety of ocular and systemic conditions. This lecture presents a case of myelinated RNFL, myopia, and amblyopia as a platform for discussion of the pathogenesis of myeliated RNFL, ocular and systemic conditions associated with myelinated RNFL, and visual prognosis in this triad. Case Presentation. A 52 year old black female presents with longstanding decreased vision in the right eye. BCVA: OD 20/610 and 20/20 OS. Manifest refraction: -14.00-0.75x060 OD and +0.50-0.25x082 OS. Fundus examination reveals extensive superior temporal RNFL myelination OD. Macula optical coherence tomography reveals thinning with a central thickness of 175 microns OD. Deviation From the Expected. In patients with the triad of myelinated RNFL, myopia and amblyopia the prognosis of visual acuity is variable and may be worse than 20/200 even with aggressive amblyopia treatment. Discussion. The pathogenesis of myelination of retina is unknown but there are a few hypotheses including loss of barrier function of the lamina cribrosa and abnormal migration of oligodendrocyte precursors. Regression of myelination has been shown in certain conditions such as optic neuritis, pituitary adenoma, glaucoma, and Behcet’s disease. Conclusion. It is important for the clinician to have a guarded prognosis in the treatment of amblyopia for patients with this triad. Although myelination of the RNFL is usually a benign clinical finding, it is important to be aware of its associated conditions.