Functional and structural analysis in relation to age at onset of Leber hereditary optic neuropathy: a Swedish cohort.

PURPOSE: To evaluate macular ganglion cell complex (GCC) thickness, retinal vessel tortuosity, visual function, and treatment effects in chronic Leber hereditary optic neuropathy (LHON) stratified by age at onset. METHODS: Thirty-one chronic LHON subjects from the Swedish LHON registry were enrolled and grouped by age at onset: <15 years, ≥15 to ≤35 years, and ≥36 years. Visual acuity (VA), visual fields, optical coherence tomography (OCT), and fundus images were assessed. Vessel tortuosity was qualitatively graded. Idebenone treatment history was obtained from the registry. RESULTS: Fifty-nine eyes were analysed. Six eyes exhibited no to mild visual impairment, of which four belonged to individuals with age at onset <15 years. This group demonstrated significantly better VA (0.7 ± 0.8 vs 1.5 ± 0.5 and 1.3 ± 0.5 logMAR), higher visual field score (76.9 ± 25.8 vs 47.1 ± 27.7 and 29.7 ± 21.1%), and thicker average GCC (72.3 ± 30.8 vs 49.9 ± 11.6 and 48.7 ± 4.5 µm) compared with older-onset groups. Moderate to severe tortuosity was more prevalent in the youngest-onset group. Among individuals with onset ≥15 to ≤35 years, GCC thickness correlated with visual function. Overall, 68% received Idebenone and majority of them were treated within six months of onset (68%), but no significant outcome differences were observed between the treated and untreated subjects. CONCLUSIONS: LHON onset before 15 years of age is associated with better preserved retinal structure and visual function in the chronic stage.