![]() Jean-Louis G, Katz BJ, Digre KB, Warner JE, Creger DD. Progression of retinal nerve fiber myelination in childhood. Brain 1997 120: 2071–2082.Īli BH, Logani S, Kristi L, Kozlov BA, Arnold AC, Bateman B. ![]() Direct observation of myelination in vivo in the mature human central nervous system. Evidence that migratory oligodendro type 2 astrocytes progenitors are kept out of the retina by a barrier. Exp Eye Res 1997 65(6): 809–819.įfrench-Constant C, Miller RH, Burne JF, Raff MC. Morphological consequences of myelination in the human retina. Am J Ophthalmol 1981 91: 25–38.įitzGibbon T, Nestorovski Z. It is possible that familial myelinated retinal nerve fibres are more common than stated as they are generally asymptomatic and family members are not regularly screened. 4 The mechanism by which an inheritable defect could affect this process is still unknown. It has been postulated that astrocytes in the lamina cribrosa are specialised to act as a barrier via the orientation and number of their glial filaments. The formation of aberrant myelinated retinal nerve fibres is thought to be due to failure to prevent oligodendrocyte lineage cells from passing through the lamina cribrosa or optic nerve head. These migrate only short distances, slowly producing oligodendrocytes. The third phase involves consolidation of myelin, via mature progenitors. Secondly, progenitors generate oligodendrocytes responsible for early myelination. The progenitors are thought to end migration when a local axonal signal falls below a critical level. Firstly, the oligodendrocyte lineage disseminates, via migratory oligodendrocyte progenitors, along large axons. Normal myelination of optic nerve axons is thought to occur in three phases. 9, 10 The findings of myelinated fibres, in both mother and daughter, suggest that a genetic factor could play a role. 1, 8 There are, however, very few reports of familial myelination of retinal nerve fibres. 7 Myelinated retinal nerve fibres occur more commonly in association with neurofibromatosis, Down's syndrome and craniofacial dysostosis. 5, 6 Rarely regression or disappearance of the aberrant myelin has been noted following optic neuritis or ischaemia. It is usually considered to be nonprogressive, although there are two cases in which progression has been confirmed. Retinal myelination is usually observed as an asymptomatic, isolated finding following routine examination. The ophthalmic examination was otherwise unremarkable including normal pupil reactions and full fields. The left eye had a small area of myelination on the inferior disc margin ( Figure 1). The right was more significantly affected, with myelination of the nasal peripapillary, up to half a disc diameter from the optic nerve margin. Routine fundoscopy revealed peripapillary myelinated nerve fibres in both eyes. External inspection showed anterior blepharitis, consistent with her symptoms. ![]() On examination, visual acuity was 6/5 in both eyes with +1.50 RE and +2.00 LE. Case reportĪ 22-year-old female presented to our department with symptoms of ocular irritation. 3, 4 Here, we describe two cases of myelinated retinal nerve fibres, in a patient and her mother, suggesting that an inherited defect may be responsible in certain cases. 1, 2 Although myelination has been extensively studied, the cause of abnormal retinal myelination is subject to debate. Myelinated retinal nerve fibres occur in 1% of the population.
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