The purpose of this study is to determine if oral lipoic acid can safely help relieve permanent optic nerve injury in patients diagnosed with acute optic neuritis. It will also explore how the body absorbs and breaks down the study drug, and what effects it has on the immune system.

Oral lipoic acid is an antioxidant that helps proteins work in the body. It is available in oral and intravenous formulations and has been used in the past to treat nerve damage like that seen in diabetes and some other metabolic disorders. It is available as a dietary supplement in the United States.

Patients with a diagnosis of acute optic neuritis who are enrolled in the study will undergo medical and nervous system examinations, and blood draws. The study doctor will take a medical history and perform physical examinations. Research assistants at the MS Center, who are trained in blood draws, will perform the blood draws. Patients will also undergo Optical coherence tomography (OCT) examination at Casey Eye Institute, and receive two MRIs at Oregon Health and Science University (OHSU). Because it is a placebo-controlled trial, subjects will have a 50:50 chance of receiving either placebo (inactive) or study drug. If enrolled in the study, patients will take two gel capsules of the study drug or placebo at the same time every day for six weeks.

Inclusion Criteria:

• Diagnosis of acute, unilateral AON with visual symptoms (vision loss) of 14 days or less
• 18 - 65 years of age, inclusive
• AON as a first event (possibly idiopathic) or in relationship to clinically isolated syndrome or to MS according to McDonald criteria
• No previous history of optic neuritis or ophthalmoscopic signs of optic atrophy in the affected eye
• Subject is available for treatment initiation within 14 days of onset of AON symptoms

Exclusion Criteria:

• Other causes of visual loss in the affected eye (e.g. amblyopia or glaucoma
• OCT is non-evaluable at screening visit due to edema.
• AON symptoms improve before administration of study medication.
• Subject has fever or active infection at time of enrollment.
• Subject is pregnant or breast-feeding.
• Subject has diabetes mellitus.
• Subject has another significant health problem (e.g. active coronary heart disease, liver disease, significant pulmonary disease).