Resolution of optic neuritis and probable multiple sclerosis after long-term ingestion of very high doses of vitamin D3: A case report

A 36-year-old male presented with 2 months of left-eye visual disturbance and was diagnosed with optic neuritis due to probable multiple sclerosis (MS). He was advised to undergo periodic ophthalmology follow-up without immunosuppressive treatment. Due to persistent symptoms, he expressed interest in very high-dose vitamin D₃ therapy of 54,000 IUs/day (1,000 IUs/kg/day) along with a zero-calcium diet. After starting the therapy, he experienced sustained symptomatic improvement of visual symptoms over 4 years, along with radiological stability of the optic neuritis lesion without developing hypercalcemia. This case supports the potential therapeutic efficacy of very high-dose vitamin D for MS.