Dynamic Range of the Peripapillary Retinal Vessel Density for Detecting Glaucomatous Visual Field Damage

Purpose To evaluate the dynamic range of peripapillary retinal vessel density (ppVD) for predicting the severity of visual field (VF) damage in comparison with that of circumpapillary retinal nerve fiber layer thickness (cpRNFLT) in primary open-angle glaucoma (POAG) patients and to determine the severity of VF damage below which progressive VF loss becomes undetectable based on either ppVD or cpRNFLT. Design Cross-sectional study. Participants One hundred thirty-three POAG patients having ppVD, cpRNFLT, and VF sensitivity (VFS) measurements evaluated using OCT angiography, spectral-domain OCT, and standard automated perimetry, respectively. Methods Correlations between ppVD and VFS (vessel–function) and between cpRNFLT and VFS (structure–function) were assessed using both linear and fractional polynomial (FP) models. Davies' test was used to determine the breakpoints for VFS below which progressive VF loss became undetectable based on ppVD or cpRNFLT. Main Outcome Measures Comparison of the vessel–function and structure–function correlations, and the VFS breakpoints in each correlation. Results Both ppVD and cpRNFLT exhibited significant linear correlations with VFS globally. In the temporal–superior, temporal, and temporal–inferior sectors, the correlations were explained better by the FP model than by the linear model for both ppVD (P ≤ 0.009) and cpRNFLT (P ≤ 0.008). The breakpoints for VFS in the vessel–function and structure–function correlations were –8.28 dB and –6.41 dB, respectively, in the temporal–superior sector, –11.83 dB and –8.42 dB, respectively, in the temporal sector, and –7.92 dB and –6.28 dB, respectively, in the temporal–inferior sector. Conclusions The sectoral ppVD exhibits curvilinear correlations with VFS and has significant breakpoints below which the VFS decline becomes undetectable. The VFS breakpoints were lower for ppVD than for cpRNFLT, indicating that the dynamic range of ppVD is potentially larger for detecting more advanced VF damage.