LEROS is an open-label interventional Phase IV study, designed to further assess the efficacy and safety of Raxone® in the long-term treatment of LHON patients.

Inclusion Criteria:

1. Impaired visual acuity in affected eyes due to LHON
2. No explanation for visual loss besides LHON
3. Age more or equal 12 years
4. Onset of symptoms ≤5 years of Baseline
5. Confirmation of either G11778A, G3460A or T14484C LHON mtDNA (for the Intent-to Treat (ITT) population, not required for enrolment)
6. Written informed consent obtained from the patient
7. Ability and willingness to comply with study procedures and visits
8. Women of Childbearing Potential (WCBP) who have a negative urine or serum pregnancy test at Baseline visit and who are willing to use a highly effective contraceptive measure and maintain it until treatment discontinuation.

Exclusion Criteria:

1. Patient has provided natural history data to the Case Record Survey (SNT-CRS-002)
2. Any previous use of idebenone
3. Any other cause of visual impairment (e.g. glaucoma, diabetic retinopathy, AIDS related visual impairment, cataract, macular degeneration, etc.) or any active ocular disorder (uveitis, infections, inflammatory retinal disease, thyroid eye disease, etc.)
4. Known history of clinically significant elevations (greater than 3 times the upper limit of normal) of aspartate aminotransferase (AST), alanine transaminase (ALT) or creatinine
5. Patient has a condition or is in a situation which, in an investigator's opinion may put the patient at significant risk, may confound study results or may interfere significantly with the patient's participation in the study
6. Participation in another clinical trial of any investigational drug within 3 months prior to Baseline
7. Hypersensitivity to the active substance or to any of the following excipients (as listed in section 6.1 of Raxone SmPC): Lactose monohydrate, Microcrystalline cellulose, Croscarmellose sodium, Povidone K25, Magnesium stearate, Colloidal silica, Macrogol 3350, Poly(vinyl alcohol), Talc, Titanium dioxide, Sunset yellow FCF (E110).
8. Women who are pregnant or have a positive pregnancy test at Baseline visit
9. Women who are breastfeeding