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).