Major ReviewSyndrome of Myelinated Retinal Nerve Fibers, Myopia, and Amblyopia: A Review
Introduction
First described by Virchow in 1856,53 myelinated nerve fibers of the retina appear as white or gray-white striated patches with frayed borders in a configuration coincident with the distribution of retinal nerve fibers.48 They are usually discovered incidentally during the course of ocular examinations, but have been linked to some disorders, such as vitreoretinopathy with skeletal malformations,52 neurofibromatosis, craniofacial abnormalities, and Gorlin syndrome.8
Patients with myelinated retinal nerve fibers (MRNF) may be completely asymptomatic or may have significant visual defects, especially in those with marked axial myopia and amblyopia in the affected eye. Despite refractive correction and occlusion therapy, many such patients do not respond well to treatment. The present article will review the pathogenesis, natural history, and treatment outcomes in patients with MRNF, myopia, and amblyopia and describe associated abnormal appearances that can be seen of the optic nerve.
Section snippets
Epidemiology
In a series of 3,968 consecutive autopsy cases, Straatsma and colleagues reported that MRNF were present in 0.98% of patients and in 0.54% of eyes examined, with bilateral involvement in 7.7% of patients. Multiple distinct lesions were found in the same eye in 12% of specimens. There was no statistical difference between males and females in the study by Straatsma and colleagues, although older studies have reported male predominance.48 Though rare, familial cases of isolated MRNF have been
Pathogenesis
The pathogenesis of MRNF has not been fully elucidated. Oligodendrocytes are one of the major glial cells in the central nervous system and are responsible for the myelination of neurons in the CNS, which insulate and accelerate conduction of signals along axons. During the prenatal period, these cells actively proliferate and produce myelin under the influence of neuro-hormonal signals.7 Normal myelination of optic nerve axons occurs through the migration of oligodendrocyte progenitors along
Natural History
Myelinated retinal nerve fibers appear as white to gray-white striated patches with feathery edges often distributed around or contiguous with the optic disk and surrounding the vascular arcades. In previous studies, MRNF have been most commonly located in the superior peripapillary region.48
These retinal lesions are commonly asymptomatic. The effect that MRNF have on visual function is highly variable and is influenced by the location and area of the plaque and by coexisting visual pathology.
Case Series and Discussion
Eleven patients with myelinated retinal nerve fibers, myopia, and amblyopia have been examined at the department of pediatric ophthalmology of the Cole Eye Institute at the Cleveland Clinic Foundation between 1986 and 2005. The ages of these patients at presentation range from 3 to 28 years. The left eye was affected in five cases, right eye in six cases, and none of the patients had bilateral involvement. Best corrected visual acuity ranged from hand motion only to 20/55. Refractive error
Treatment
Treatment is instituted for the conditions associated with myelinated retinal nerve fibers. Asymptomatic MRNF discovered on routine examination need no treatment and can be followed on subsequent visits. In patients with MRNF with neovascularization and recurrent vitreous hemorrhage, argon laser photocoagulation was useful in halting recurrent events.45 In patients with anisometropic amblyopia, occlusion therapy often produces variable results.
Prognosis
Patients with MRNF should receive corrective lenses for their myopia and astigmatism, and should undergo aggressive amblyopia therapy, because unexpectedly good visual results can be achieved.50 In a recent study by Kee and Hwang, 5 of 12 children studied with MRNF and anisometropic amblyopia had an improvement in visual acuity to 20/30 or better. Significant prognostic indicators were the amount of initial anisometropia, the area of myelination, and the appearance of the macula. Mean
Method of Literature Search
The authors performed a Medline search with Pubmed and Ovid for relevant articles. The search was restricted to publications related to humans, in English and other-language publications with English abstracts. Search terms included myelinated (or medullated) retinal nerve fibers (or fibres) and optic nerve hypoplasia. A search for optic nerve hypoplasia and pathogenesis was also performed and relevant articles were included. Articles and book chapters obtained from the reference lists of other
References (58)
- et al.
Progression of retinal nerve fiber myelination in childhood
Am J Ophthalmol
(1994) - et al.
An appraisal of the disc-macula distance to disc diameter ratio in the assessment of optic nerve size
Ophthalmic Physiol Opt
(1999) - et al.
Axonal signals in central nervous system myelination, demyelination, and remyelination
J Neurol Sci
(2005) - et al.
Optic nerve hypoplasia
Am J Ophthalmol
(1970) - et al.
Morphological consequences of myelination in the human retina
Exp Eye Res
(1997) - et al.
Monocular axial myopia associated with neonatal eyelid closure in human infants
Am J Ophthalmol
(1981) - et al.
Myelination of the rat retina by transplantation of oligodendrocytes into 4-day old hosts
Exp Neurol
(1991) - et al.
Visual prognosis of amblyopia associated with myelinated retinal nerve fibers
Am J Ophthalmol
(2005) - et al.
Optic nerve hypoplasia
Surv Ophthalmol
(1987) - et al.
Cell death and the elimination of retinal axons during development
Prog Neurobiol
(1988)
Progression of myelinated retinal nerve fibers
Am J Ophthalmol
Atrophy of myelinated retinal nerve fibers after acute optic neuropathy
Am J Ophthalmol
Myelinated retinal nerve fibers
Am J Ophthalmol
Myelinated retinal nerve fibers associated with ipsilateral myopia, amblyopia, and strabismus
Am J Ophthalmol
Disappearance of myelinated retinal nerve fibers after a branch retinal artery occlusion
Am J Ophthalmol
Population prevalence of tilted optic disks and the relationship of this sign to refractive error
Am J Ophthalmol
Acquired and progressive myelinated nerve fibers
Arch Ophthalmol
Acquired medullated nerve fibers
Br J Ophthalmol
New neuronal growth factors
Ann Rev Neurosci
Demyelination of retinal myelinated nerve fibers in Behcet's disease
Doc Ophthalmol
Medullated nerve fibers: a sign of multiple basal cell nevi (Gorlin's) syndrome
Arch Ophthalmol
Retinal break in an area with medullated nerve fibers
Acta Ophthalmol (Cophenh)
Myelinated nerve fibers, axial myopia, and refractory amblyopia: an organic disease
J Pediatr Ophthalmol Strabismus
Evidence that migratory oligodendrocyte-type-2 astrocyte progenitor cells are kept out of the rat retina by a barrier at the eye-end of the optic nerve
J Neurocytol
Familial myelinated retinal nerve fibres
Eye
Loss of myelinated retinal nerve fibres in diabetic retinopathy
Br J Ophthalmol
Myelinated retinal nerve fibres loss in Leber's hereditary optic neuropathy
Acta Ophthalmol Scand
Atrophy of myelinated nerve fibers fibers in pituitary adenoma
J Clin Neuroophthalmol
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The authors reported no proprietary or commercial interest in any product mentioned or concept discussed in this article.