AIM: To study the relationship between the changes of blood vessel density in optic disc area of normal tension glaucoma(NTG)and visual field index(VFI)of glaucoma and morphological staging of visual field defect. METHODS: Totally 106 patients(106 eyes)with NTG and 79 patients(79 eyes)with primary open angle glaucoma(POAG)in the hospital between December 2018 and December 2020 were selected for cross-sectional study. Among them, 1 eye of binocular disease was selected as the sample by the random number table method, and another 92 healthy subjects with physical examination in the hospital were selected as control group. All three groups completed the optic disc blood vessel density, VFI detection and visual field defect morphological staging, and the relationship between optic disc blood vessel density and VFI and visual field defect morphological staging were analyzed.RESULTS: The intraocular pressure in POAG group was significantly higher than that in NTG group and control group(P<0.05). The whole optic disc area blood vessel density, large vessel density and capillary density of NTG group and POAG group were significantly lower than those of control group(P<0.05)while the density of avascular area was significantly higher than that of control group(P<0.05), and there were differences in various indicators between NTG group and POAG group(P<0.05). The VFI of NTG group and POAG group was significantly lower than that of control group(P<0.05)while the mean visual field defect(MD)was significantly higher than that of control group(P<0.05), and there were no statistical differences in VFI and MD between NTG group and POAG group(P>0.05). With the increase in visual field defect morphology staging, the whole optic disc area blood vessel density and capillary density of patients with NTG showed a significant decrease(P<0.05). The whole optic disc area blood vessel density and capillary density of patients with NTG were positively correlated with VFI and negatively correlated with visual field defect staging, and avascular area density was negatively correlated with VFI and positively correlated with visual field defect staging(all P<0.05). CONCLUSION:Optic disc blood vessel density of patients with NTG is significantly lower than that of patients with POAG and normal people, and it is significantly correlated with VFI and visual field defect morphological staging. Among them, capillary density has the highest correlation. It can be seen that OCTA has important clinical significance for NTG diagnosis, treatment and follow-up.