Damage to the optic radiation in multiple sclerosis is associated with retinal injury and visual disability.

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 [lambda( perpendicular)] 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 lambda( perpendicular) (r = -0.37; P = .001). The retinal nerve fiber layer thickness in the nasal retinal quadrant was also specifically correlated with FA and lambda( perpendicular) in the synaptically connected contralateral OR. In individuals with less severely damaged optic nerves (mean retinal nerve fiber layer thickness >80 mum), letter acuity scores at 2.5% contrast were correlated with OR-specific FA (r = 0.55; P = .004), lambda( perpendicular) (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 lambda( perpendicular) are potentially useful quantitative magnetic resonance imaging biomarkers of OR-specific damage in MS. Such damage is associated with retinal injury and visual disability.