Correlation of magnetic resonance imaging optic nerve parameters to optical coherence tomography and the visual field in glaucoma

Background: To determine the viability of using magnetic resonance imaging measurement of optic nerve morphology as an objective analysis of glaucomatous damage. Design: Retrospective study conducted at Tohoku University Hospital. Participants: Thirty-eight eyes of 19 patients with open-angle glaucoma. Methods: Patients were scanned with T2-weighted and 3-T diffusion tensor magnetic resonance imaging, and parameters of the optic nerve, including fractional anisotropy, apparent diffusion coefficient and cross-sectional area, were determined. Conventional parameters of glaucomatous damage, including circumpapillary and macular retinal nerve fibre layer thickness, and mean deviation and average total deviation of the central 16 test points from the Humphrey Field Analyzer, were then compared with the magnetic resonance imaging-derived parameters. Spearman's coefficient of correlation was calculated to determine the significance of the correlation. Main Outcome Measure: Correlation coefficient between the magnetic resonance imaging parameters and the parameters of glaucomatous damage. Results: Mean deviation was significantly correlated with all magnetic resonance imaging parameters (fractional anisotropy: r=0.53, apparent diffusion coefficient: r=-0.44, cross-sectional area: r=0.70). Circumpapillary retinal nerve fibre layer thickness was significantly correlated with fractional anisotropy (r=0.60) and cross-sectional area (r=0.47), but not apparent diffusion coefficient (r=-0.29). Central macular function and macular retinal nerve fibre layer thickness were also significantly correlated with magnetic resonance imaging parameters. Conclusions: Optic nerve magnetic resonance imaging parameters were significantly correlated to glaucomatous damage. Magnetic resonance imaging analysis of the optic nerve may, thus, have value as an objective instrument to assess glaucomatous degeneration, including the function of the macula.