Multiple Patches of Myelinated Nerve Fibers
Myelinated nerve fibers, also called medullated nerve fibers, are patches within the retina in which axons of ganglion cells possess myelin sheaths. The axons normally do not have myelin sheaths until they reach the optic nerve. Therefore, this condition represents a congenital anomaly. It rarely causes any visual difficulty. In clinical practice, the biggest problem that they cause is the occasional instance in which they are misdiagnosed as a branch retinal artery occlusion, which can stimulate an unnecessary series of tests looking for vascular disease. It is estimated that myelinated nerve fibers are found in 1% of persons. There is an association of myelinated nerve fibers, amblyopia, and myopia. The prevalence of myelinated nerve fibers may be higher in neurofibromatosis, Down's Syndrome, and craniofacial dysostosis. Myelinated nerve fibers are stable throughout life in the absence of disease. However, after a branch or central retinal artery occlusion involving an area of the retina containing myelinated nerve fibers, the myelin may slowly disappear.