PURPOSE: To study the progression of visual acuity and visual function parameters in patients with optic neuritis (ON) treated with high-dose oral corticosteroid therapy. METHODS: This retrospective descriptive monocentric study included nine patients with ON treated with orally administered methylprednisolone at 1000 mg per day for three to five days. The follow-up visits were performed on day 4 (D4), day 15 (D15), day 30 (D30) and day 90 (D90) after treatment was begun. The initial examination (D0) and the follow-up visits included a visual acuity (VA) assessment according to the Early Treatment Diabetic Retinopathy Study scale, a contrast sensitivity test and a 30.2 automated visual field (Visual Field Index [VFI]). The overall subjective tolerance of the treatment was assessed by patients on a scale from 0 to 10. RESULTS: We observed an improvement of all parameters from D4. From D0 to D4, the average VA increased from 40.1 letters to 57.9 letters, the average VFI from 40.9% to 70.3% and the overall average contrast sensitivity from 7.7 dB to 11.3 dB. From D15 to D90, the average VA increased from 77 letters to 80.3 letters, the average VFI from 91.2% to 97.9% and the overall average contrast sensitivity from 15.4 dB to 16.7 dB. Four patients rated tolerance at 10 (excellent), three between 8 and 9, and two at 6. CONCLUSION: We demonstrated rapid improvement of visual function parameters in patients with ON after high-dose oral corticosteroids.