| ObjectiveTo observe the foveal microvasculature features in superficial and deep vascular netwook of eyes with branch retinal vein occlusion(BRVO)using optical coherence tomography angiography(OCTA).Quantify and compare the foveal avascular zone(FAZ)area and macular vessel density in two layers in BRVO eyes and fellow eyes,and analyse FAZ and its correlation in BRVO eyes,and the effect of retinal thickness in macular center on the quantitative results and correlation was also discussed.MethodsThe eyes diagnosed with BRVO were included in the study.The eyes were evaluated by OCTA(XR-Avanti;Optovue).The macular angiography scan protocol covered a 3mm×3mm area.The focus of angiography analysis was two retinal layers:superficial vascular network and deep vascular network.The following vascular morphological parameters were assessed in these two networks:FAZ enlargement,capillary non-perfusion occurrence(CNP),microvascular abnormalities(MA)appearance,and vascular congestion(VC)signs.Compare the macular microvascular morphology changes in superficial vascular network and deep vascular network through McNemar test.The parameters of macular were measured by the built-in measurement software of the system(OCTA blood flow measurement standard version2.0):(1)Area of FAZ,perimeter of FAZ(PERIM),avascular index of FAZ(AI),vascular density within a width of 300 microns around the FAZ region(FD-300).(2)Central retinal thickness(CRT).(3)Vascular density(VD):the superficial central fovea vascular density(SFVD),the deep central fovea vascular density(DFVD),the superficial hemi-macular vascular density(SHVD),the deep hemi-macular vascular density(DHVD).BRVO patients were divided into two groups according to the degree of macular edema:group M300 that is CRT≥300 microns and L300 that is CRT<300microns.Each group was divided into two groups:BRVO group that is BRVO eyes and control group that is the fellow eyes.The quantitative parameters of the BRVO group and the control group in the M300 group and L300 group were respectively analyzed.Paired sample t test was used to compare the parameters.The comparison of age,FAZ parameters and VD between M300 group and L300 group was performed by non-parametric test.Spearman test was used to test the correlation between FAZ area and other parameters in M300 group and L300 group respectively,P<0.05 was considered statistically significant.ResultsA total of 63 BRVO eyes were included in the part I,age 39-74years old,(mean age 59.76±8.48 years).The superficial network and deep network showed FAZ enlargement 43 eyes(68.3%)and 50 eyes(79.4%),CNP 51 eyes(81%)and 50 eyes(79.4%),MA 62 eyes(98.4%)and 62 eyes(98.4%),VC 23 eyes(36.5%)and 52eyes(82.5%).FAZ area is(0.55±0.37)mm~2.CNP and MA have no significant difference between superficial and deep networks(P=1.000,P=1.000),FAZ enlargement and VC signs have significant difference between superficial and deep networks(P=0.039,P<0.001).A total of 49 BRVO eyes were included in the part II,10(20.41%)of the FAZ area’s automatic identification zone was inconsistent with the real presentation area of FAZ,which was manually adjusted and the modified results were recorded.In the group M300,23 patients,17 males and 6 females,aged56.3±10.61 years(36-71 years);group L300,26 cases,10 cases of males and 16 cases of females,aged 51.9±7.07 years(27-69 years).In group M300:BRVO eyes,FAZ area=(0.477±0.229)mm~2,PERIM=(3.976±1.986)mm,AI=1.60±0.48,FD-300=(46.00±34.13)%,CRT=(511.61±163.78)micron,SFVD=(25.06±9.17)%,DFVD=(29.45±10.21)%,SHVD=(38.75±5.11)%,DHVD=(39.70±5.47)%.The fellow eyes:FAZ area=(0.376±0.132)mm~2,PERIM=(2.454±0.459)mm,AI=1.14±0.04,FD-300=(48.44±4.11)%,CRT=(239.43±20.52)micron,SFVD=(17.37±6.53)%,DFVD=(25.87±6.26)%,SHVD=(46.79±4.17)%,DHVD=(44.93±4.53)%.The differences of FAZ area,PERIM,AI,FD-300,CRT,SFVD,SHVD and DHVD between BRVO group and control group were statistically significant(P=0.040,P=0.001,P=0.000,P=0.019,P=0.000,P=0.001,P=0.000),while the differences of DFVD between the two groups were not statistically significant(P=0.057).In group L300:BRVO eyes,FAZ area=(0.520±0.515)mm~2,PERIM=(3.371±2.157)mm,AI=1.322±0.33,FD-300=(43.70±7.36)%,CRT=(249.50±32.28)micron,SFVD=(15.6±5.13)%,DFVD=(26.37±6.73)%,SHVD=(36.81±5.43)%,DHVD=(37.50±5.74)%.The fellow eyes:FAZ area=(0.356±0.122)mm~2,PERIM=(2.354±0.409)mm,AI=1.13±0.03,FD-300=(49.03±4.52)%,CRT=(239.77±16.18)micron,SFVD=(17.24±5.42)%,DFVD=(28.31±7.27)%,SHVD=(46.10±3.89)%,DHVD=(47.20±4.33)%.The differences of PERIM,AI,FD-300,SHVD and DHVD between BRVO group and control group were statistically significant(P=0.021,P=0.008,P=0.006,P=0.000,P=0.000),while the differences of FAZ area,CRT,SFVD and DFVD between the two groups were not statistically significant(P=0.118,P=0.140,P=0.137,P=0.198).A total of 75 BRVO eyes were included in the part III.39 eyes in group M300,Male 27 eyes,female 12 eyes,age 59.3±9.08 years(40-77 years),36 eyes in group L300,Male 14 eyes,female 22 eyes,age 52.43±9.75 years(27-69 years).The differences of FAZ area,PERIM,AI,fd-300,SHVD and DHVD between M300 group and L300 group were not statistically significant(P=0.068,P=0.140,P=0.774,P=0.645,P=0.080,P=0.073).The differences in age,SFVD and DFVD between the two groups were statistically significant(P=0.002,P=0.000,P=0.006).In group M300,FAZ area is0.388±0.166mm2,which is negatively correlated with CRT,but there was no statistical significance(r=-0.053,P=0.749).FAZ area was positively correlated with PERIM and AI,which had statistical significance(r=0.932,P=0.000;r=0.591,P=0.000).FAZ area was negatively correlated with SFVD,DFVD and SHVD,which had statistical significance(r=-0.490,P=0.002;r=-0.429,P=0.006;r=-0.339,P=0.035).In group L300,FAZ area is 0.596±0.512mm~2,which is negatively correlated with CRT,and there was statistical significance(r=-0.413,P=0.012),FAZ area was positively correlated with PERIM and AI,which had statistical significance(r=0.887,P=0.000;r=0.633,P=0.000),FAZ area was negatively correlated with SFVD,DFVD,SHVD and DHVD,which had statistical significance(r=-0.643,P=0.000;r=-0.630,P=0.000;r=-0.370,P=0.026;r=-0.411,P=0.013).ConclusionOCTA can display the morphological changes of macular microvessels in BRVO,measure the area,roundness,perimeter of FAZ and vessel density.The definition of area of FAZ cannot depend entirely on automatic recognition of software.Deep vascular network will show more FAZ enlargement and VC sign than superficial vascular network.Different thickness of macular center will affect the results of partial quantitative comparison between BRVO eyes and fellow eyes,as well as the correlation between FAZ area and CRT and DHVD. |
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