Individuals with the RIS are at increased risk of converting to MS. Early identification of later converters is crucial for optimal treatment decisions. The objective of this study was to assess the predictive potential of OCT measures in individuals with RIS regarding conversion to MS.

This was a prospective observational cohort study that included 36 individuals with RIS and 36 healthy controls recruited from two German MS centers. During clinical follow‐up of 46 months, eight individuals with RIS converted to MS. Individuals converting to MS showed a thinning of the pRNFL and the common GCIP at baseline and during follow‐up. Individuals with a pRNFL of 99 µm or lower or a GCIP of 1.99 mm3 or lower were at a 7.5‐ and 8.0‐fold risk for MS conversion, respectively, compared to individuals with higher measures. After correction for other known risk factors, Cox proportional hazards regression revealed a hazard ratio of 1.08 for conversion to MS for each 1 µm decline in pRNFL.

The reduction of the pRNFL might be a novel and independent risk factor for conversion to MS in individuals with RIS. OCT might be useful for risk stratification and therapeutic decision‐making in individuals with RIS.