Optical Coherence Tomography Angiography Analysis of Peripapillary Choroidal Microvascular Density in normal-tension Glaucoma and Primary open-angle Glaucoma

Précis: Glaucoma patients had a reduction in the inner annulus peripapillary choroidal microvascular density (PCMD) that became worse as the glaucoma severity progressed, which might provide new evidence supporting the vascular theory. Purpose: To compare PCMD among normal-tension glaucoma (NTG), primary open-angle glaucoma (POAG), and healthy controls using optical coherence tomography (OCT) angiography (OCTA). Methods: The study included 40 POAG, 25 NTG, and 33 healthy controls. All subjects underwent OCT and OCTA testing. Inner annulus and outer annulus PCMD, as well as peripapillary vessel density (VD), was calculated. One-way analysis of variance was used to compare the vascular parameters of the three groups. Pearson correlation analysis or Spearman correlation test was used to evaluate the correlation between PCMD and glaucomatous severity factors. The spatial positional relationship between PCMD and corresponding peripapillary retinal nerve fiber layer (RNFL) thickness and visual field (VF) mean deviation (MD) was also assessed. Results: The average and four quadrants of the inner annulus PCMD and peripapillary VD in the two glaucomatous groups were significantly lower than in normal eyes ( P <0.05). Strong correlations were found between inner annulus PCMD and VF MD, peripapillary VD, and RNFL in POAG patients. Similarly, the inner annulus PCMD in NTG patients was strongly correlated with peripapillary VD and RNFL (all r>0.5). Strong positional correlations were found between inner superior quadrantal PCMD and RNFL thickness in both POAG and NTG patients (r=0.566, r=0.731, respectively). Likewise, inner inferior quadrantal PCMD exhibited a strong correlation with RNFL thickness in POAG patients (r=0.608). Strong positional correlations were also found between inner superior PCMD and VF MD in both POAG and NTG patients (r=0.589, r=0.622, respectively). Inner inferior PCMD exhibited a moderate correlation with VF MD in both POAG and NTG patients (r=0.487, r=0.440, respectively). Conclusion: The study found that the inner annulus PCMD decreased to varying degrees in NTG and POAG patients. The inner annulus PCMD was closely related to the structural and visual function parameters of glaucoma in both NTG and POAG. Furthermore, inner PCMD demonstrated a spatial correlation with corresponding RNFL thickness and VF MD.