Optic neuropathy other than that caused by the condition under study including but not limited to: optic neuropathies of infectious, ischemic, infiltrative, traumatic, compressive, infiltrative, toxic (including prescription drugs), nutritional deficiencies, hereditary or other etiologies in the study eye.
Already known positive anti-aquaporin-4 antibody (AQP4-Abs) or anti-myelin oligodendrocyte glycoprotein antibodies (MOG-Abs) at Screening.
An alternative cause of visual loss (eg, amblyopia, macula lesion or disorders of any etiology, compressive or infiltrative active lesion of the optic nerve, retinal diseases, infection, genetic forms of visual loss), per Investigator’s judgement.
Ophthalmic conditions that can affect the measurement of LCVA, per protocol.
Participant unwillingness/inability to complete the study treatments and assessments.
Refractive error ≥6.00 diopters (myopia or hyperopia) spherical equivalent (SE)
History of, or current clinically significant cardiovascular disease, arrhythmia, heart block, QRS, prolonged QT or other clinically significant ECG abnormalities.
Any clinically significant abnormal findings on the Screening ECG.
Participants with white matter alterations in the MRI suggestive of noninflammatory optic neuropathies (eg, metabolic disorders, mitochondrial disorders).
History of, or current neurodegenerative disease that can affect the measurement of LCVA in the study eye (eg. amyotrophic lateral sclerosis, Parkinson’s disease, Alzheimer’s disease).
Current seizures or a medical history of seizures that required intervention for a minimum of 1 year. Note: Participants with petit mal or febrile seizures are not excluded
Current severe or poorly controlled systemic disease, including, but not limited to hepatic, gastrointestinal, cardiovascular, respiratory, hematological, renal (glomerular filtration rate [GFR] <30 mL/min/1.73 m2 ), pulmonary, endocrinologic, or dermatological disorders.
Any medically unstable conditions at the time of enrollment, including uncontrolled diabetes (types 1 and 2) and hypertension.
Systemic conditions that can affect safety assessments of the study and/or participant ability/willingness to comply with the study assessments.
Active systemic bacterial, viral, or fungal infection.
Active or chronic infection requiring ongoing therapy, including tuberculosis, mycobacterium avium–intracellulare (MAI), HIV, hepatitis B, hepatitis C, or recurrent/severe infections.
Active or chronic disease of the immune system requiring ongoing therapy, including but not limited to Sjögren’s disease, systemic lupus erythematosus, or other autoimmune disorders. Note: Diagnosis of MS, myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD) or neuromyelitis optica spectrum disorder (NMOSD) is not exclusionary.
Known immunodeficiency syndrome (Acquired Immune Deficiency Syndrome, hereditary immune deficiency, drug-induced immune deficiency). Note, asymptomatic HIV is not exclusionary; it is based on the judgment of the Investigator History of cancer within past 5 years, except adequately treated basal/squamous cell carcinoma of the skin or in situ cervical cancer.
History of, or current, invasive malignancy of the upper face (forehead, eyes, temporal region).
History of, or current, major psychiatric illness within 2 years prior to Screening.
History of, or current alcohol or drug abuse within 2 years prior to Screening.
Treatment with corticosteroids for current episode of ON prior to enrollment.
Use of prohibited concomitant medications at Screening or planned use during the study.
Hypersensitivity or allergy to study treatment or similar chemical classes or methylprednisolone.
Treatment with IVIg within 3 months before V2 (Day 0, Baseline), or anticipated need within 3 months after randomization.
Treatment with therapeutic apheresis (PLEX or immunoadsorption) within 3 months before V2 (Day 0, Baseline), or planned need within 3 months after randomization.
Previous treatment with inhibitors of IGF-1R (eg. teprotumumab) within 6 months.
Treated with the following medications within 3 months before V2 (Day 0, Baseline), or anticipated need during the treatment period (V3; t1-t5):
Class Ia anti-arrhythmic drugs (eg, quinidine, disopyramide)
Class III anti-arrhythmic drugs (eg, amiodarone, sotalol)
Contraindication or inability to undergo to MRI with gadolinium.
Use of any investigational drug within 3 months before enrollment or 5 half-lives, (whichever is longer).
Pregnant women or breastfeeding women who are unwilling/ unable to stop breastfeeding.
Women of childbearing potential not willing to use effective contraception for at least 6 months after the final dose of study treatment.
Men unwilling to use effective contraception until 2 days after the final dose of study treatment.
Any condition that, in the Investigator’s opinion, would interfere with participation or pose an unacceptable risk.
Participants with physical or logistical constraints, or unwillingness that impacts their ability to comply with study assessments for the duration of the study (12 months).
Planned move to region with no study investigation site.
Participant is the Investigator, sub-investigator, research assistant, pharmacist, study coordinator, staff member, or relative directly involved in study conduct.