Assessment of papillary and macular blood flow by OCT Angiography: a comparative study in healthy subjects and patients with different optic neuropathies

PURPOSE This project investigates ocular perfusion using optical coherence tomography angiography (OCT-A), which provides a rapid, quantitative, and non-invasive assessment of blood flow in the papillary, peripapillary, and macular regions. The study hypothesizes that vascular dysregulation is a key factor in optic neuropathies and aims to identify microcirculatory defects that could serve as early diagnostic markers. Such markers may predict the risk of ocular pathology, facilitate prognostic evaluation, and improve clinical monitoring to prevent severe visual impairment. METHODS: The multi-phase study began with a reproducibility assessment to identify reliable vessel layers for OCT-A analysis. OCT-A images of 20 normal eyes were then compared with 20 eyes of patients with glaucoma, 17 with anterior ischemic optic neuropathy (AION) and 25 with multiple sclerosis (MS). All eyes underwent a comprehensive ophthalmic examination and OCT-A imaging using a swept-source system (Topcon, DRI OCT Triton). An AI-based system was used to extract volumetric data and quantify blood flow to detect microvascular abnormalities. RESULTS: Reproducibility Study: Coefficients of variation for vessel layer measurements were higher in glaucomatous eyes (4.49%-8.54%) compared to controls (3.58%-8.32%), particularly at the optic disc. Reproducibility was similar for papillary and macular microvasculature across groups. Glaucoma Study: Significant differences in blood flow were found in the superficial and deep macular plexus (p < 0.001) and in 94% of bins at the ONH for both the vitreous and radial peripapillary capillary layers (p < 0.001). Differences in the choroidal layer at the ONH were significant, but not in the macular choriocapillaris layer (57%). AION Study: Blood flow differences were significant in superficial retinal layers supplied by the Central Retinal Artery (p < 0.001), but less so in layers provided by the Posterior Ciliary Arteries (p < 0.05). Demyelinating Optic Neuritis Study: No significant blood flow differences were observed between healthy eyes and MS patients without optic neuritis. However, MS patients with optic neuritis had reduced blood flow in the choroidal layer at the ONH, with significant differences at 65% of bins (p < 0.05). CONCLUSION: This study highlights the potential of OCT-A to detect and analyze microvascular defects associated with optic neuropathies, which could lead to earlier diagnosis and improved management of these conditions.