Severe Bilateral Optic Neuritis: A Rare Presentation of Clinically Isolated Syndrome.

Multiple sclerosis (MS) is a disabling disease involving the myelin sheath of neurons in the brain and spinal cord. Optic neuritis (ON) is one of the common presentations of MS, and it typically presents as acute unilateral ON. In the absence of a prior history of MS, the first episode of clinically determined acute ON is considered as a clinically isolated syndrome (CIS). CIS presenting with bilateral acute ON resulting in complete vision loss is very rare. We present a case of a young female patient who presented with bilateral progressive vision loss and was ultimately found to have ON in the absence of a prior history of MS. Important differentials were ruled out. Significant improvement was observed in the patient with high doses of intravenous methylprednisolone. As compared to oral prednisone, intravenous steroids have been shown to be more effective in the treatment of ON in the Optic Neuritis Treatment Trial.