Determinants of Vessel Defects in Superficial and Deep Vascular Layers in Normal-Tension Glaucoma Using Optical Coherence Tomography Angiography

We investigated the characteristics of localized vessel density defects (VD) either in the deep or superficial vascular layer of normal-tension glaucoma patients using optical coherence tomography angiography (OCTA). In this retrospective, cross-sectional study, 74 eyes with localized retinal nerve fiber layer (RNFL) defect were included. The relationships between the widths of the VD in the superficial and deep layer and ocular factors were evaluated. Eyes with greater deep VD were significantly older ( P = 0.023). Baseline and treated IOPs were significantly related to the width of the deep VD (P=0.009 and 0.014, respectively). By contrast, average ganglion cell inner plexiform layer thickness (GCIPLT) was substantially related to the width of the superficial VD (Both Ps=0.004). In logistic regression analysis, aging was noticeably associated with wider deep VD, whereas worse pattern standard deviation (PSD) had a significant association with wider superficial VD (Both Ps=0.001). In sum, while changes of the superficial layer seemed an overall ramification of glaucomatous damages, the deep layer was more likely to be affected by factors related to ocular microcirculation, such as IOPs and older age. Thus, looking into the deep vascular layer using OCTA could identify risk factors related to the disturbance in ocular microcirculation.