A Randomized, Double-blind, Placebo-controlled, Multicenter Study of the Effects of Glatiramer Acetate (GA) on the Retinal Nerve Fiber Layer (RNFL) and Visual Function in Patients With a First Episode of Acute Optic Neuritis (AON). (Octagon)

Inclusion Criteria: * Age: 18 - 45 years * Isolated, unilateral, first acute optic neuritis (AON) event consistent with inflammatory demyelinization, not explained by other etiologies. Onset of AON is defined by the presentation of visual disturbances. * Able to provide written informed consent prior to enrollment * Willing and able to comply with the protocol requirements for the duration of the study * For women of child bearing potential: * A negative urine pregnancy test o * Willing to practice an acceptable method of birth control • * Willing to receive a steroidal regimen Exclusion Criteria: * A diagnosis of clinically definite multiple sclerosis (MS) (Clinically Definite Multiple Sclerosis) * Current use of any approved disease modifying agents for treatment of MS * Prior clinical episode of optic neuritis in either eye * Bilateral AON * Inability to undergo study evaluations in both eyes * Known ocular or neurological conditions or abnormalities other than refractive error that impair visual function * Retrogeniculate visual loss * Refractive error of greater than +6 or -6 diopters * Neuromyelitis Optica (Devic's disease) * Systemic diseases that cause inflammatory optic neuropathy, including but not limited to Sarcoidosis, Systemic lupus erythematosus (SLE), Wegener's Granulomatosis, Syphilis, human immunodeficiency virus (HIV) * Known ocular conditions that preclude dilation * Any condition that may interfere with performance of Optical Coherence Tomography (OCT): corneal, lens or fundoscopic abnormality, a co-morbid ocular condition not related to optic neuritis as detected on the OCT reading * Any condition that precludes administration of Glatiramer Acetate, such as a known history of sensitivity to mannitol * Diabetes Mellitus Types I or II * Gastric bypass surgery * Current use of chemotherapy or radiotherapy * Treatments that may cause visual loss such as plaquenil, anti-tubercular agents, interferon (IFN)-alpha therapy, monoclonal antibodies Cardiac medications that may affect visual evaluations such as digitalis, amiodarone, quinine * Ongoing treatment with steroids (for longer than 10 days) within the last 3 months * Significant or unstable medical, systemic, psychiatric or logistical condition that affects the patient's ability to give informed consent or to complete the study procedures * Use of an investigational drug within 30 days prior to randomization