See Petzold (doi:10.1093/aww239) for a scientific commentary on this article.
Assessment of inflammatory disease activity during multiple sclerosis is crucial for selecting appropriate disease-modifying therapies. Previous studies suggested that the retinal inner nuclear layer reflects inflammatory disease severity within the central nervous system. In our study, correlations of longitudinal retinal layer changes as measured by retinal optical coherence tomography with ongoing disease activity were evaluated in 108 multiple sclerosis patients without therapy, on first-line therapy, or on second-line therapy. Healthy subjects served as controls. Inner nuclear layer volume at baseline correlated positively with paraclinical disease activity during the subsequent 12 months. Longitudinal thinning of the inner nuclear layer and thickening of total macular volume were associated with reduced inflammatory disease activity. Reduction in inner nuclear layer volume after 1 year indicated efficient control of inflammatory disease activity including ‘no evidence of disease activity’. In conclusion, the retinal inner nuclear layer could serve as biomarker to monitor sustained control of autoimmune central nervous system inflammation by therapeutic interventions.