Peripapillary vessel density changes in Leber's Hereditary Optic Neuropathy: a new biomarker.

Importance The contribution of the microvascular supply to the pathogenesis of Leber's hereditary optic neuropathy (LHON) is poorly understood. Background We aimed at measuring the peripapillary capillary vessel density (VD) using optical coherence tomography angiography (OCT-A) at different stages of LHON. Design Prospective, cross-sectional, multicenter, observational study. Participants Twenty-two LHON patients divided in four groups: unaffected mutation carriers (LHON-u); early sub-acute stage (LHON-e); late sub-acute stage (LHON-l); chronic stage (LHON-ch). Methods OCT-A scans centred on the optic disc were obtained by spectral domain OCT system. Main Outcome Measures VD, retinal nerve fibre layer (RNFL) and ganglion cell-inner plexiform layer (GC-IPL) thickness were compared between groups. Results Significant VD changes were detected in every sector (P < 0.0001). In LHON-e, the VD was reduced in the temporal sector compared with LHON-u and in the temporal and inferotemporal sectors compared with controls. In LHON-l, VD was reduced in whole, temporal, superotemporal and inferotemporal sectors compared with LHON-u and controls. In LHON-ch, the VD was reduced in all sectors compared to the other groups. An asynchronous pattern emerged in the temporal sector with VD changes occurring earlier than RNFL thickness changes and together with GC-IPL thinning. Conclusions and Relevance Significant peripapillary miscrovascular changes were detected over the different stages of LHON. Studying the vascular network separately from fibres revealed that microvascular changes in the temporal sector preceded the changes of RNFL and mirrored the GC-IPL changes. Measurements of the peripapillary vascular network may become a useful biomarker to monitor the disease process, evaluate therapeutic efficacy and elucidate pathophysiology.