Assessing the effect of idebenone in LHON by silent-MT 7T-MRI of the optic nerve requires appropriate study designs

With interest we read the article by Grochowski et al.about an investigation of the optic nerves in 6 patientswith Leber’s hereditary optic neuropathy (LHON) receivingidebenone and 9 LHON patients not receiving idebenone bymeans of a Zero Echo Time (ZET) 7T MRI sequence withan Adiabatic Spectral Inversion Recovery (ASPIR) fat suppressionpulse (silent-MT 7T-MRI) [1]. It was concludedthat the technique confirms known pathology of the opticnerve in LHON [1]. We have the following comments andconcerns.We disagree with the notion that ‘LHON is a disorder ofthe optic nerve. LHON is pirmarely a disorder of the retinalganglion cells (RGCs), which is why it can be diagnosed bythe ophthalmologist. Secondarily, LHON affects dendritesand axons of RGCs resulting in asymmetric optic atrophy.There are no striking conclusions from this study. Theonly results were that the silent-MT at 7T depicts the opticnerve with high quality and artefact-free, that quantitativemeasures of the optic nerve can be obtained, and thatLHON optic nerves showed focal hyperintensities.The authors do not differentiate b etween L HON andLHON plus [2]. LHON exclusively affects t he retina,whereas LHON plus is characterised by multiorgan involvement,affecting i n p articular t he e yes b ut a lso t he brain,endocrine organs, bone marrow, arteries, kidneys, peripheralnerves, and the heart [2]. We should know how manyof the included patients had LHON and how many LHONplus. This is crucial as it may determine the outcome ofthese patients [3].