Objective: To determine whether damage to the optic radiation (OR) in multiple sclerosis (MS) is associated with optic nerve injury and visual dysfunction. Design: Case-control study. Setting: Referral center. Participants: Ninety referred patients with MS and 29 healthy volunteers. Main Outcome Measures: Magnetic resonance imaging indices along the OR were reconstructed with diffusion tensor tractography. Retinal nerve fiber layer thickness and visual acuity at high and low contrast were measured in a subset of the MS group (n=36). Results: All tested magnetic resonance imaging indices (fractional anisotropy [FA]; mean, parallel, and perpendicular [λ⊥] diffusivity; T2 relaxation time; and magnetization transfer ratio) were significantly abnormal in patients with MS. Mean retinal nerve fiber layer thickness was significantly correlated with FA (r=0.55; P<.001) and λ⊥ (r=-0.37; P=.001). The retinal nerve fiber layer thickness in the nasal retinal quadrant was also specifically correlated with FA and λ⊥ in the synaptically connected contralateral OR. In individuals with less severely damaged optic nerves (mean retinal nerve fiber layer thickness>80 μm), letter acuity scores at 2.5% contrast were correlated with OR-specific FA (r=0.55; P=.004), λ⊥ (r=-0.40; P=.04), and magnetization transfer ratio (r=0.54; P=.01), as well as the fraction of OR volume made up of lesions (r=-0.69; P<.001). Conclusions: Fractional anisotropy and λ⊥ are potentially useful quantitative magnetic resonance imaging biomarkers of OR-specific damage in MS. Such damage is associated with retinal injury and visual disability.
ASJC Scopus subject areas
- Clinical Neurology