A comparison of peripapillary vessel density between subjects with normal-tension glaucoma and primary open-angle glaucoma with similar extents of glaucomatous damage.

The purpose of this study was to identify differences in retinal microvasculature impairments between patients with normal-tension glaucoma (NTG) and those with primary open-angle glaucoma (POAG) with similar extents of structural and visual field damage. Participants with glaucoma-suspect (GS), NTG, POAG, and normal controls were consecutively enrolled. Peripapillary vessel density (VD) and perfusion density (PD) were compared among the groups. Linear regression analyses were performed to identify the relationship between VD, PD and visual field parameters. The VDs of the full areas were 18.3 ± 0.7, 17.3 ± 1.7, 16.5 ± 1.7, and 15.8 ± 2.3 mm-1 in the control, GS, NTG, and POAG groups, respectively (P < 0.001). The VDs of the outer and inner areas and the PDs of all areas also differed significantly among the groups (all P < 0.001). In the NTG group, the VDs of the full, outer, and inner areas were significantly associated with all visual field parameters including the mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI). In the POAG group, the VDs of the full and inner areas were significantly associated with PSD and VFI but not with MD. In conclusion, with similar degrees of retinal nerve fiber layer thinning and visual field damage in both groups, the POAG group showed a lower peripapillary VD and PD than the NTG group. VD and PD were significantly associated with visual field loss.