The REFLECT study is a Phase 3, international, multi-center, randomized, double-masked, placebo-controlled, clinical trial. The primary objective is to assess the efficacy of intravitreal (IVT) of GS010 compared to IVT of placebo in second-affected/not-yet-affected eyes at 1.5 years post-treatment, by analyzing the change from baseline of the visual acuity in ND4 LHON subjects with vision loss up to one year.