| Objective Optical coherence tomography angiography（OCTA）was used to measure structural parameters and the blood flow parameters of macular area among the normal subjects,the ocular hypertension（OHT）and the early primary open angle glaucoma（POAG）.To evaluate the differences of parameters among the three groups,analyze the correlation between parameters and visual field and the diagnostic value of parameters for early POAG.Methods This study is a cross-sectional study.Patients diagnosed with OHT（15eyes）and early POAG（14 eyes,）admitted to the Eye Center of Lanzhou University Second Hospital from December 2020 to January 2022 were collected,and healthy adults（26 eyes）were included as the normal group.OCTA was used to measure structural parameters and blood flow parameters in the macular superficial 3×3 mm and 6×6mm region of the three groups.The structural parameters included the rim area,thickness of the retinal nerve fiber layer（RNFL）,thickness of the ganglion cells inner plexiform layer（GCIPL）.Vascular density（VD）,perfusion density（PD）and foveal avascular zone（FAZ）were included to the blood flow parameters in the macular area.Central corneal thickness（CCT）was measured by corneal visualization scheimpflug technology.Visual field Index（VFI）,mean Deviation（MD）and pattern standard deviation（PSD）were obtained by Humphrey field measurement.SPSS 25.0statistical software was used to analyze whether there were statistical differences among parameters of the three groups,and the correlation between OCTA parameters and PSD was analyzed.95%confidence intervals（CI）of the area under receiver operating characteristic（AUROC）was used to evaluate the diagnostic value of each parameter in patients with early glaucoma.Results VFI of normal group,OHT group and early POAG group decreased gradually.Compared with the normal and the OHT group,VFI of the early POAG group was smaller,and the differences were statistically（P were 0.001 and 0.015,respectively）.VFI was no significant difference between OHT and normal group（P=1.000）.PSD increased gradually in the normal group,OHT group and early POAG group,and there was only a statistical difference between the normal group and early POAG group（P<0.001）.The MD of normal group,OHT group and early POAG group were（-1.60±1.91）d B,（-2.50±1.41）d B and（-4.05±1.88）d B,respectively,and the MD showed a decreasing trend among the three groups.Compared with normal group and OHT group,MD of early POAG group was significantly decreased（P were 0.001 and 0.042,respectively）.There was no significant difference in MD between OHT group and normal group（P=0.132）.The CCT of normal group,OHT group and early POAG group were（524.82±31.27）μm,（554.73±25.42）μm and（554.14±14.69）μm,respectively.Compared with OHT group and early POAG group,CCT in normal group was thinner,and the difference was statistically significant（P were 0.001 and 0.002,respectively）.The CCT thickness of OHT group and early POAG group was similar（P=0.951）.The rim area of normal group,OHT group and early POAG group was（1.55±0.22）mm~2,（1.16±0.18）mm~2and（0.95±0.14）mm~2,respectively,and gradually decreased in the three groups.There were statistically significant differences in rim area between normal group and OHT group（P<0.001）,normal group and early POAG group（P<0.001）,OHT group and early POAG group（P=0.004）.The RNFL thickness of normal group,OHT group and early POAG group was（103.08±8.86）μm,（93.13±5.00）μm,（80.64±9.74）μm,and gradually became thinner in the three groups.There were statistically significant differences in RNFL thickness between normal group and OHT group,normal group and early POAG group,OHT group and early POAG group（All P<0.001）.The average thickness of GCIPL among the normal group,OHT group and early POAG group was（85.04±6.62）μm,（80.40±4.93）μm,（78.57±8.29）μm.The minimum thickness of GCIPL in the three groups was（82.12±6.80）μm,（75.80±5.73）μm,（71.64±11.48）μm,respectively.The average and minimum GCIPL thickness gradually thinned in the three groups,and there were statistically significant differences both the early POAG and OHT groups compared to the control group（All P<0.05）,but there were no statistically significant differences between the OHT group and the early POAG group（P>0.05）.In the macular superficial 3×3 mm,the VD of the central region among the three groups were（8.764±3.553）mm-1,（7.620±3.790）mm-1,（7.607±3.089）mm-1,respectively.In the macular superficial 3×3 mm,the VD of inner layer among the three groups were（19.336±2.016）mm-1,（19.973±2.601）mm-1,（17.343±3.077）,respectively.In the macular superficial 3×3 mm,the VD of intact region among the three groups were（18.128±2.001）mm-1 and（18.653±2.741）mm-1 and（16.236±2.846）mm-1,respectively.In the macular superficial 3×3 mm,the PD of central region among the three groups was（0.151±0.063）,（0.132±0.066）,（0.135±0.052）,respectively.In the macular superficial 3×3 mm,the PD of the inner layer was（0.345±0.032）,（0.359±0.042）,（0.321±0.050）,respectively.In the macular superficial 3×3 mm,the PD of intact region were（0.324±0.032）,（0.333±0.044）and（0.294±0.046）,respectively.FAZ area of in the macular 3×3 mm in the three groups were（0.267±0.101）mm~2,（0.330±0.109）mm~2 and（0.219±0.14）mm~2,respectively.In the macular superficial 6×6 mm,the VD of the central area among the three groups were（6.246±3.452）mm-1,（5.907±3.459）mm-1,（5.686±3.909）mm-1,respectively.In the macular superficial 6×6 mm,the VD of the inner layer among the three groups were（14.971±2.617）mm-1,（15.280±4.152）mm-1,（13.893±3.631）mm-1,respectively.In the macular superficial 6×6 mm,the VD of outer region among the three groups were（15.796±1.973）mm-1,（16.067±2.913）mm-1,（13.786±3.225）mm-1,respectively.The VD of the intact region in the macular superficial 6×6 mm among the three groups were（15.329±2.007）mm-1,（15.607±3.173）mm-1 and（13.586±3.223）mm-1,respectively.The PD of central area in the macular superficial 6×6 mm among the three groups were（0.144±0.090）,（0.128±0.079）,（0.121±0.089）,respectively.The PD of the inner layer in the macular superficial 6×6 mm among the three groups were（0.337±0.077）,（0.356±0.103）,（0.320±0.091）,respectively.The PD of outer region in the macular superficial 6×6 mm among the three groups were（0.380±0.050）,（0.388±0.077）,（0.327±0.080）,and the PD of intact region were（0.369±0.055）,（0.374±0.082）,（0.320±0.080）,respectively.FAZ area of macular 6×6 mm in the three groups were（0.242±0.100）mm~2,（0.250±0.090）mm~2 and（0.173±0.084）mm~2,respectively.The VD and PD of central region in the macular superficial 3×3 mm and6×6 mm were decreased in the normal group,OHT group and early POAG group,but the differences were not statistically significant（P>0.05）.The VD and PD of inner and intact regions in macular superficial 3×3 mm,and the VD and PD of the inner,outer and intact regions in macular superficial 6×6 mm increased first and then decreased in normal group,OHT group and early POAG group.The VD of inner region and VD and PD of intact region in the macular superficial 3×3 mm,and VD and PD of outer region in the macular superficial 6×6 mm were significantly different between normal group and early POAG group,OHT group and early POAG group（P<0.05）.There was no significant difference in PD of inner region in the macular superficial 3×3 mm between the normal group and the early POAG group（P=0.083）.FAZ area of macula 3×3 mm and 6×6 mm increased first and then decreased in normal group,OHT group and early POAG group,but only FAZ area of 3×3 mm between OHT group and early POAG group had statistical significance（P=0.011）.There were no statistically significant differences in VD and PD of each zone and FAZ between the normal group and the OHT group through the two Angiography scan modes（P>0.05）.The correlation analysis between OCTA parameters and PSD shows that:PSD was negatively correlated with rim area,RNFL thickness,minimum GCIPL thickness,VD of inner zone in macula 3×3 mm and VD and PD of intact zone in macula 3×3 mm（P<0.05）.Among all OCTA parameters,the correlation between structural parameters and PSD was stronger than that of blood flow parameters（r=-0.493）.Among all the blood flow parameters,VD of inner layer in the macula 3×3mm had the strongest correlation with PSD（r=-0.335）.By plotting AUROC of OCTA parameters,it was found that OCTA had a good diagnostic value for early glaucoma,and the diagnostic value of structural indicators was higher than that of blood flow parameters.The rim area was the most valuable to distinguish the normal group from the early POAG group（AUROC=0.996,P<0.001）,and the thickness of RNFL was the most valuable to distinguish the OHT group from the early POAG group（AUROC=0.996,P<0.001）.Conclusions 1.Compared with the normal group,the structural parameters of OHT group decreased,while the blood flow parameters did not change significantly,suggesting that OHT patients may have structural damage,and the structural damage occurs earlier than the damage to the macular blood flow in the progression of glaucoma.2.Compared with the normal group and OHT group,VD and PD in the macular superficial 3×3 mm inner and intact region and in the macular superficial 6×6mm outer region of the early POAG group were decreased,suggesting that the damage to blood flow in the macula of early POAG occurs first in the inner and outer macular regions,but early POAG has no significant effect on the blood flow in the central region.3.The combination of 3×3 mm and 6×6 mm scanning patterns in macular superficial area can provide a more comprehensive assessment of the changes in macular blood flow density in patients with early POAG.4.The structural parameters and blood flow parameters were negatively correlated with PSD,suggesting that the functional changes of early POAG patients were closely related to the structural damage.5.Both structural parameters and macular blood flow parameters have good diagnostic value for early POAG. |
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