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

1. Age 15 years or older on the date of signed informed consent.
2. Clinically manifested vision loss due to ND4 LHON, to any extent, in at least one eye.
3. Vision loss duration of ≤ 365 days (i.e. ≤ 1 year) in each affected eye at Inclusion Visit (Visit 2).

Main Non-Selection Criteria:

1. Contraindication to intravitreal injection in any eye.
2. Subjects refusing to discontinue idebenone.
3. Previous vitrectomy in either eye.
4. Narrow angle in any eye contra-indicating pupillary dilation.
5. 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.
6. History of recurrent uveitis (idiopathic or immune-related) or active ocular inflammation.

Main Inclusion Criteria:

1. Vision loss duration of ≤ 365 days (i.e. ≤ 1 year) in each affected eye at Inclusion Visit (Visit 2).
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.
3. 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:

1. 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.
2. Presence of active infectious conjunctivitis, keratitis, scleritis or endophthalmitis in either eye.
3. Presence of alcoholism, alcohol dependence, or alcohol or drug abuse (excluding nicotine).