Associations Between Retinal Microvascular Changes And Renal Function In T2DM Patients By Using Optical Coherence Tomography Angiography(OCTA)

Purpose Diabetic retinopathy(DR)and diabetic kidney disease(DKD)are main microvascular complications of type 2 diabetes mellitus(T2DM).Our study aims to evaluate associations between retinal microvascular changes and renal function in T2 DM patients by using optical coherence tomography angiography(OCTA).Methods Ocular treatment-na?ve patients with T2 DM registered in Ruijin Hospital,Shanghai Jiaotong University School of Medicine,were recruited in this prospective cross-sectional study during March to November in 2021.All participants undergone complete ophthalmic examination including OCTA and fundus microvascular parameters including vessel density of superficial vascular complex(SVC),deep vascular complex(DVC)layer in macular area and radial peripapillary capillary(RPC)layer in optic disc area were measured.We also obtained clinical characteristics of study participants including age,sex,durations of DM,systolic blood pressure(SBP),diastolic blood pressure(DBP),glycosylated hemoglobin Hb A1c(Hb A1c),low-density lipoprotein(LDL),high-density lipoprotein(HDL),triglyceride(TG),total cholesterol(TC),hemoglobin,estimated glomerular filtration rate(e GFR)and urine albumin to creatinine ratio(UACR).Participants were divided into normoalbuminuria group,microalbuminuria group and macroalbuminuria group according to UACR level by guidelines.The discrepancy of microvascular parameters among three groups was analyzed.Correlations between OCTA parameters and renal function were assessed by univariate and multiple regression analyses.Logistic regression analyses were used to find out potential risk factors related to renal impairment.Finally we built models to find out whether OCTA parameters could be used in identification renal impairment of T2 DM patients.Results Our study included 197 patients and 197 eyes.There were 145 subjects in normoalbuminuria group,42 subjects in microalbuminuria group and 10 subjects in macroalbuminuria group.111 males and 86 females were included.Mean age was 56.56±12.18 in all participants.Mean BMI was 25.0(23.2-27.0)kg2/m2.Mean SBP was 125.57±18.16 mm Hg.Mean durations of DM were 123(55-181)months.Mean Hb A1 c was 7.3(6.7-8.5)%.Group with higher UACR level had lower vessel density in SVC(49.27±3.97% vs 47.63±3.70% vs 47.03±3.83%,p=0.004)and DVC(52.36±5.88% vs50.26±5.34% vs 48.95±6.39%,p=0.037)layer in macular area and lower vessel density in RPC layer(51.67±2.80% vs 50.90±2.95% vs 49.20±4.43%,p=0.019)in optic disc area.Group with higher UACR level had thinner peripapillary retinal nerve fiber layer(p RNFL)thickness(102.21(97.68-108.40)μm vs 101.24(94.57-107.98)μm vs 95.55(91.24-101.72)μm,p=0.035),while there was no significant difference in retinal thickness and ganglion cell complex parameters in macular area.Macular vessel density decreased in almost all region with higher UACR level while peripapillary RPC vessel density mainly decreased in nasal and inferior region(pNI=0.007,pIN=0.004;pIN=0.004).There were positive correlations between vessel density in each region of macular and optic disc area and retinal thickness/RNFL thickness in corresponding region(all p<0.05).After adjusting for age,sex,duration of T2 DM,SBP,axial length and other confounding factors,decreased e GFR(e GFR<90m L/min/1.73m2)was still significantly negatively correlated with macular SVC vessel density in ETDRS region,parafovea region,perifovea region,FD-300 area density and FD-300 length density(β=-1.763,p=0.006;β=-1.830,p=0.025;β=-1.768,p=0.005;β=-1.794,p=0.024;β=-0.674,p=0.012).But the correlation between UACR and retinal microvascular changes was no longer significant.Correlation between peripapillary RPC vessel density and renal function was no longer significant either.Logistic regression revealed that macular SVC vessel density in ETDRS region,parafovea region,perifovea region was independent protective factor of abnormal albuminuria and decreased e GFR when only ocular parameters were included(all p<0.05).Hybrid Model including basic clinical characteristics and vessel density performed well in renal impairment identification and it performed better in predicting e GFR decreasing.Conclusion Group with higher UACR level had lower vessel density in SVC and DVC layer in macular area and lower vessel density in RPC layer in optic disc area in T2 DM patients.After adjusting for age,sex,duration of T2 DM,SBP,axial length and other confounding factors,decreased e GFR(e GFR<90m L/min/1.73m2)was significantly negatively correlated with macular SVC vessel density in ETDRS region,parafovea region,perifovea region,FD-300 area density and FD-300 length density.But the correlation between UACR and microvascular changes is no longer significant.It may suggest that compared with UACR,e GFR is more closely related to retinal microvascular changes in T2 DM patients.OCTA may be a good tool for identification renal impairment of T2 DM patients.