Purpose
To report findings of spectral domain optical coherent tomography (SD-OCT) of myelinated nerve fibers (MNF) and propose a mechanism for axial myopia associated with MNF.
Methods
In this retrospective observational case series, 12 eyes from 12 patients (6 children and 6 adults) with MNF over 2 disc diameters underwent a full ophthalmologic examination including SD-OCT. The distribution of MNF in the fundus photography was compared with the regional excavation of the scleral excavation in vertical or horizontal scan and circular scan centered on the optic disc of SD-OCT.
Results
In all cases, SD-OCT visualized MNF as hyperreflective thickening of retinal nerve fibers and there were no morphologic abnormalities in the photoreceptor layers in the fovea. In eyes with temporally extended MNF, the tilting of Bruch’s membrane in vertical scans of SD-OCT was significantly associated with the major distribution of myelination (P < 0.001). The slope of Bruch’s membrane was much smaller in the adult group than in the child group (P = 0.008). The area of MNF in fundus photography and focal scleral excavation in the peripapillary circular SD-OCT scan images were significantly correlated (P <0.001).
Conclusions
Localized scleral excavation inducing axial myopia was strongly associated with the distribution of MNF especially in children, which indicates MNF itself or confined retinal areas with visual deprivation by MNF may directly induce axial myopia via local trophic effects on the underlying sclera in early life.
Keywords: 605 myopia •
677 refractive error development •
757 visual development: infancy and childhood