Efficacy & Safety Study of Bilateral IVT Injection of GS010 in LHON Subjects Due to the ND4 Mutation for up to 1 Year

Main Selection Criteria: * Age 15 years or older on the date of signed informed consent. * Clinically manifested vision loss due to ND4 LHON, to any extent, in at least one eye. * Vision loss duration of ≤ 365 days (i.e. ≤ 1 year) in each affected eye at Inclusion Visit (Visit 2). Main Non-Selection Criteria: * Contraindication to intravitreal injection in any eye. * Subjects refusing to discontinue idebenone. * Previous vitrectomy in either eye. * Narrow angle in any eye contra-indicating pupillary dilation. * Presence of known/documented mutations, other than the G11778A ND4 LHON-causing mutation, which are known to cause pathology of the optic nerve, retina or afferent visual system. * History of recurrent uveitis (idiopathic or immune-related) or active ocular inflammation. Main Inclusion Criteria: * Vision loss duration of ≤ 365 days (i.e. ≤ 1 year) in each affected eye at Inclusion Visit (Visit 2). * Each eye of the subject must maintain at least Hand Motion (HM) visual acuity, as defined by the study's SOP for visual acuity testing. * Documented results of genotyping showing the presence of the G11778A mutation in the ND4 gene and the absence of the other primary LHON-associated mutations (ND1 or ND6) in the subject's mitochondrial DNA. Main Exclusion Criteria: * Light Perception (LP) or No Light Perception (NLP) visual acuity in any eye, as defined by the study's standard operating procedure (SOP) for visual acuity testing. * Presence of active infectious conjunctivitis, keratitis, scleritis or endophthalmitis in either eye. * Presence of alcoholism, alcohol dependence, or alcohol or drug abuse (excluding nicotine).