IFNB1 and optic neuritis: At baseline, mean VEP latencies were longer in patients which were assigned to the IFN-β treatment group (161.1±4.072) compared to untreated patients (144.1±6.414; ±SD; p = 0.033; 95% CI 1.592 to 32.57) indicating potentially more severe optic neuritis in this group.