664 Fibres nerveuses rétiniennes myélinisées associées à un pseudo trou maculaire

Abstract

To describe unilateral extensive peripapillary myelinated nerve fibers associated with macular pseudohole in a young girl of 26 years. Visual acuity, slit lamp biomicroscopy, automated perimetry, Optical coherence tomography (Stratus OCT). Visual acuity: odx 20/30, 20/20 sf -0,75, cyl -0,25 10° and osx 20/40, 20/25 sf -0,75. Fundus oculi demonstrates extensive peripapillary myelination in the left eye: the patch occurrs at the superior-inferior sectors of the optic nerve head and along the superior-inferior vascular arcades masking the down below vessels. An intraretinal pseudocyst occupies the inner part of the foveola and the foveal floor is elevated: on biomicroscopy stage 1B hole is diagnosed. Humphrey test shows an enlargement of blind spot with different extents corresponding to the area of myelination. Line test shows the superficial diffuse hyper-reflectivity along the myelinated nerve fibers area with deep hypodensity and intraretinal pseudocyst in the inner part of the foveola with evident increase in macular thickness and steepening of foveal contour and reflective epiretinal membrane layer on the surface of the retina. Fast Optic Disc test shows superficial diffuse hyper-reflectivity along the myelinated nerve fibers area with deep hypodensity and the lack of physiological excavation of the optic nerve head with presence of concavity turned toward the vitreous cavity. Myelination is attributed to a collection of oligodendrocytes within the inner retina. It blocks light transmission: that explains the visual impairment of the visual field. Pathogenic features between the myelination and the macular pseudohole are discussed. Myelination can be the primum movens in the dysfunction of internal limiting membrane: glial cells from the inner layers of the neurosensory retina proliferated through breaks in the internal limiting membrane, make a fibrocellular membrane that proliferates on the surface of the retina. Through it's contractile properties, the underlying retina is, in turn, distorted. Retinal myelinated nerve fibers are a benign pathology but it needs a periodic control when there are retinal alterations like described in this case.