Changes Of Choroidal Structure In Diabetic Patients

Purpose:To assess the changes of choroidal structure at different layers in diabetes mellitus(DM)patients using enhanced depth imaging optical coherence tomography(EDI-OCT),and to explore the impact of non-proliferative diabetic retinopathy(NPDR)and duration of DM on choroidal structure.Methods:In this cross-sectional study,100 DM patients(143 eyes)and 42 healthy volunteers(42 eyes)were included.DM patients were divided into non-diabetic retinopathy(non-DR)group(49 patients,76 eyes)and NPDR group(51 patients,67 eyes)according to whether they had NPDR or not.DM patients were also divided into short-term group(disease duration<15 years,43 patients,72 eyes)and long-term group(disease duration≥15 years,57 patients,71 eyes)according to duration of the disease.The subfoveal choroidal thickness(SFCT),total choroidal area(TCA),luminal area(LA)and choroidal vascularity index(CVI)of the whole,inner and outer layers of choroidal were measured,and analyzed.Results:1.Grouped by NPDR or not:(1)Comparison of parameters in the whole layer of choroidal:The whole layer SFCT of NPDR group was significantly lower than that of the control group and the non-DR group(p<0.001,p=0.021).The whole layer LA in the non-DR group and NPDR group was significantly lower than that in the control group(p=0.002,p=0.001).The whole layer CVI of the non-DR group and NPDR group was significantly lower than that of the control group(p<0.001,p<0.001),and the whole layer CVI of the NPDR group was significantly lower than that of the non-DR group(p=0.015).(2)Comparison of parameters in the inner layer of choroidal:The inner layer SFCT of the non-DR group and NPDR group was significantly lower than that of the control group(p=0.021,p=0.001).The inner layer TCA in NPDR group was significantly lower than that in the control group and the non-DR group(p=0.004,p=0.005).The inner layer LA in the NPDR group was significantly lower than that in the control group and the non-DR group(p=0.001,p=0.001).The inner layer CVI in the NPDR group was significantly lower than that in the control group and the non-DR group(p<0.001,p=0.042).There was no significant difference in the inner layer CVI between the non-DR group and the control group(p=0.235).(3)Comparison of parameters in the outer layer of choroidal:The outer layer SFCT of NPDR group was significantly lower than that of the control group and the non-DR group(p=0.001,p=0.020).The outer layer LA in the non-DR group was significantly lower than that in the control group(p=0.005).The outer layer CVI of the non-DR group and NPDR group was significantly lower than that of the control group(p<0.001,p<0.001).There was no significant difference in the outer layer CVI between the NPDR group and the non-DR group(p=1.000).2.Grouped by disease duration:(1)Comparison of parameters in the whole layer of choroidal:The whole layer SFCT of the long-term group was significantly lower than that of the control group(p=0.001).The whole layer LA in the short-term group and the long-term group was significantly lower than that in the control group(p<0.001,p<0.001).The whole layer CVI in the short-term group and the long-term group was significantly lower than that in the control group(p<0.001,p=0.001).The whole layer CVI in the long-term group was significantly lower than that in the short-term group(p=0.001).(2)Comparison of parameters in the inner layer of choroidal:The inner layer SFCT of the short-term group and the long-term group were significantly lower than that of the control group(p=0.007,p=0.005).The inner layer LA of the long-term group was significantly lower than that of the control group(p=0.012).The inner layer CVI of the long-term group was significantly lower than that of the control group and the short-term group(p<0.001,p=0.005).There was no significantly different in the inner layer CVI between the short-term group and the control group(p=0.494).(3)Comparison of parameters in the outer layer of choroidal:The outer layer SFCT of the long-term group was significantly lower than that of the control group and the short-term group(p=0.001,p=0.025).The outer layer LA of the short-term group and the long-term group were significantly lower than that of the control group(p=0.014,p=0.037).The outer layer CVI of the short-term group and the long-term group was significantly lower than that of the control group(p<0.001,p<0.001).There was no significant difference in the outer layer CVI between the long-term group and the short-term group(p=0.864).(4)Partial correlation analysis showed that the whole layer CVI,inner layer CVI and outer layer CVI were negatively correlated with the duration of DM(r=-0.513,p<0.001;r=-0.199,p<0.018;r=-0.215,p=0.010).Conclusion:The whole layer choroidal vessels in DM patients might be damaged before the occurrence of DR,especially in the outer layer choroidal vessels.When DR Occurred,the whole layer choroidal vascular injury was further exacerbated,mainly in the inner layer.The outer layer choroidal vessels were damaged regardless of duration of DM.The inner layer vessels might not be damaged in short-term duration.In long-term group,the inner layer vessels were damaged.CVI of the whole layer,inner layer and outer layer decreased with the prolongation of DM duration.