Elsevier

Survey of Ophthalmology

Volume 52, Issue 6, November–December 2007, Pages 588-596
Survey of Ophthalmology

Major Review
Syndrome of Myelinated Retinal Nerve Fibers, Myopia, and Amblyopia: A Review

https://doi.org/10.1016/j.survophthal.2007.08.016Get rights and content

Abstract

Myelinated retinal nerve fibers are developmental anomalies that are present in approximately 1% of all eyes. They may be associated with ipsilateral high myopia and amblyopia, and also may occur in association with various ocular and systemic abnormalities. Lesions may be congenital or acquired, static or dynamic, and can regress in the setting of several described conditions. The pathogenesis is thought to be due to the presence of ectopic oligodendrocyte-like cells in the retina as a result of a development or acquired insult. Visual acuity is typically poor to begin with, and the improvement of visual function in patients undergoing occlusion therapy has been, in general, limited. We discuss a series of 11 patients seen at the Cole Eye Institute with the condition of myelinated retinal nerve fibers, myopia, and amblyopia and describe the clinical characteristics. Three patients also had optic nerve dysplasia and a discussion of the literature related to this association was also performed.

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

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    The authors reported no proprietary or commercial interest in any product mentioned or concept discussed in this article.

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