Interocular differences in optic nerve head topography of the subjects with unilateral peripapillary myelinated nerve fibers

Purpose: To determine the interocular differences in optic nerve head topography of the subjects with unilateral peripapillary myelinated nerve fibers. Materials and Methods: A total of 21 healthy subjects with unilateral peripapillary myelinated nerve fibers were included into the study. Patients had no ocular disease except refractive disorders. Optic nerve head topographic analyses of both eyes of each subject were performed using a confocal scanning laser ophthalmoscope, HRT-II (Heidelberg Retina Tomography II, version 1.6). The disc area, topography standard deviation, and a total of 12 topographic parameters were calculated by the HRT-II. Results: The mean age of the subjects was 28.3 +/- 3.4 years. The mean refractive error of the eyes with and without myelinated nerve fibers were - 3.56 +/- 1.73 D and - 0.98 +/- 0.66 D, respectively (P < 0.05). There were no significant interocular differences in the disc area of the eyes with and without peripapillary myelinated nerve fibers (P > 0.05). Eyes with peripapillary myelinated nerve fibers were found to have significantly less "neuroretinal rim area" and "neuroretinal rim area-to-disc area ratio" than those eyes with no myelination (P < 0.05 for both). All other parameters were found not to reveal any significant interocular differences (P > 0.05 for all of them). Sectorial analysis of the parameters including neuroretinal rim area and neuroretinal rim area-to-disc area ratio did not reveal any significant differences between the groups (P > 0.05). Conclusions: Neuroretinal rim area and rim area-to-disc area ratio of the eyes with peripapillary myelinated nerve fibers were found to be significantly less than that of the fellow eyes with no myelination. This should be taken into consideration when monitoring glaucoma suspects with peripapillary myelinated nerve fibers.