Application Of OCTA In Abnormal Optic Disc Microperfusion In The Early Stage Of Diabetic Retinopathy

Objective:Using optical coherence tomography angiography(OCTA)to study the changes of optic disc and peri-disc blood flow supply and peri-papillary retinal nerve fiber layer thickness in the early stage of diabetic retinopathy,and to explore the status of micro-perfusion and structural damage of the optic disc in the early stage of diabetic retinopathy,and their related influencing factors,to further explore the application value of OCTA in the study of abnormal optic disc microperfusion in the early stage of diabetic retinopathy.Methods:A total of 70 eyes of 45 patients with type 2 diabetes diagnosed in the Department of Endocrinology of the First Affiliated Hospital of Kunming Medical University were selected and included in the experimental group(NDR group).Eighty eyes of 40 age-matched healthy people without diabetes were included as the control group.All subjects underwent routine ocular examinations including best corrected visual acuity,anterior segment and fundus.OCTA was used to detect the vessel density(VD)of the optic disc,with 4.5mm×4.5mm scanning of the optic disc,and the microperfusion parameters of the optic disc,the capillary vessel density,such as Inside Disc(ID),Radial Peripapillary Capillary(RPC),Whole Image(WI),and simultaneously,OCTA was used to record structural parameters of the optic disc,such as peri-papillary retinal nerve fiber layer thickness(pRNFL).The different data in the superior,inferior,nasal and temporal quadrants of RPC and RNFL were also recorded.For the NDR group,the peripheral blood cholesterol and fasting blood glucose were detected by enzyme-coupled colorimetry;the glycated hemoglobin was measured by high performance liquid chromatography.The analysis of the micro-perfusion differences and structural damage differences between the NDR group and the control group,the relationship between micro-perfusion changes and structural damages,and those related influencing factors were further completed.Results:A total of 150 eyes were included in this study for the cross-sectional study of OCTA,including 70 eyes in the NDR group with type 2 diabetes without diabetic retinopathy,and 80 normal eyes in the control group.1.A total of 17 diabetic patients with DR in the fundus were excluded from this screening.The proportion of DON with obvious fundus changes in the diabetic patients screened was 3.1%.2.The average age of the NDR group was 51.9 ± 13.3 years,and 50.5±11.2 years of the control group.There was no statistically significant difference(P=0.74).The ratio of male to female in the NDR group was 49/21,and 50/30 in the control group,without statistical difference(P=0.33).In the NDR group,the mean value of glycated hemoglobin was 9.19±2.68%,481.25±130.36 μmol/L of serum fructosamine,4.62±0.95 mmol/L of serum cholesterol,and 7.2 ± 5.2 years(0.1-20 years)of disease course.In the NDR group,there was no statistically significant difference between male and female(49/21)in glycated hemoglobin,serum fructosamine,and serum cholesterol(P>0.05).3.Difference of the optic disc micro-perfusion status between NDR group and the control group.Taking the inside and peri-papillary capillary vessel density representing the optic disc microperfusion as the analysis object,ID was 45.76±6.69%in NDR and 48.50±5.09%in the control(P=0.005);RPC was 51.43±3.23%in NDR and 52.35±2.43%in the control(P=0.048);WI was 48.10 ±3.18%in NDR and 49.68 ±2.11%in the control(P<0.001).ID,RPC,and WI of NDR were significantly lower than those of the control,the difference was statistically significant,especially WI.There is a strong positively linear correlation between RPC(%)and WI(%)(r=0.860,P<0.001).There is a strong correlation between ID(%)and WI(%)(r=0.386,P<0.001),and no statistically significant correlation between RPC(%)and ID(%)(r=0.100,P=0.225).RPC in the four quadrants were analyzed.Superior RPC of NDR was 53.9±4.5%,and 54.0±4.5%of the control(P=0.908);inferior RPC of NDR was 52.9±4.8%,and 53.4±4.2%of the control(P=0.574);nasal RPC in NDR was 46.1±5.1%,and 49.3±4.3%of the control(P=0.001);temporal RPC in NDR was 54.5±3.9%,and 55.0±4.1%of the control(P=0.508).Nasal RPC in NDR was significantly thinner than that in the control,and there was no significant statistical difference in the other quadrants.4.Difference of the optic disc structure status between NDR group and the control group.Taking the thickness of pRNFL representing the optic nerve structure as the analysis object,the one of NDR was 114.0±11.5 μm,and 127.1±14.0 μm of the control(P<0.001).The thickness of pRNFL in the four quadrants was analyzed.Superior RNFL of NDR was 148.4±20.7 μm,and 160.8±17.2 μm of the control(P<0.001);inferior RNFL of NDR was 141.1±19.3μm,and 154.4±14.2 μm of the control(P<0.001);nasal RNFL of NDR was 96.1±13.4 μm,and 109.4±24.4 μm of the control(P<0.001);temporal RNFL of NDR was 77.6±9.5 μm,and 89.1±10.5 μm of the control(P<0.001).The thicknesses of pRNFL and RNFL in four quadrants of NDR were significantly lower than those of the control.5.Pearson correlation analysis of optic disc vessel density and pRNFL.RPC was significantly positively correlated with pRNFL(r=0.346,P<0.001),WI was significantly positively correlated with pRNFL(r=0.449,P<0.001),and ID was significantly positively correlated with pRNFL(r=0.207,P=0.011).The pRNFL in the four quadrants was significantly positively correlated with RPC in the corresponding quadrants,superiorly r=0.517 and P<0.001,inferiorly r=0.517 and P<0.001,nasally r=0.600 and P<0.001,and temporally r=0.334,P=0.005.6.Analysis of related factors of abnormal optic disc microperfusion in NDR group6.1 Pearson correlation analysis of optic disc vessel density and disease-related factors.RPC,ID and WI had no significant correlation with glycated hemoglobin,serum fructosamine,total cholesterol or other factors(P>0.05).6.2 Influencing analysis of age in the abnormality of optic disc microperfusion.According to the fact that anterior ischemic optic neuropathy often occurs in people over the age of 45,NDR group was divided into>45 years old subgroup and<45 years old subgroup.The statistically significant difference between those two subgroups was only in the temporal RNFL thickness,with temporal RNFL of 75.7±8.9 μm in≥45 years old subgroup and 80.4±9.7μm in<45 years old one(P=0.044).The control group is also divided into those two subgroups.Superior RNFL of≥45 years old was 141.0±23.6 μm,and 154.0±6.5 μm of<45 years old(P=0.038);inferior RNFL of ≥45 years old was 150.7 ±30.7 μm,and 161.0±13.2 μm of<45 years old(P=0.039);nasal RNFL of ≥45 years old was 102.8±24.6 μm,and 118.9±12.0 μm of<45 years old(P=0.002).There were statistical significant differences in the superior,inferior and nasal quadrants.6.3 Influencing analysis of the course of diabetes in the abnormality of optic disc microperfusion.According to the average course of diabetes 7.2 years,NDR group was divided into ≤7 year subgroup and>7 year subgroup.There was no statistical difference between the two subgroups in ID,RPC,WI and pRNFL in each quadrant around the disc(P>0.05).Only glycated hemoglobin had statistical difference,with 9.90±3.17%of ≤7 years and 8.53±1.96%of>7 years(P=0.047),which one in the shorter course subgroup was significantly larger than the longer course subgroup.6.4 Influencing analysis of the glycated hemoglobin in the abnormality of optic disc microperfusion.There was no statistically significant difference in the optic disc vessel density or pRNFL between the normal glycated hemoglobin subgroup and the higher subgroup(P>0.05).7.The multiple linear regression analysis of factors affecting pRNFL was completed,such as ID,RPC,glycated hemoglobin,serum fructosamine,total cholesterol,age,diabetes course,etc.The results suggest that RPC,total cholesterol and age have a significant impact on pRNFL(R=0.729,R2=0.531),RPC(P=0.000)and total cholesterol(P=0.030)had a positive correlation with pRNFL,and age(P=0.039)had a negative correlation with pRNFL.Conclusion:In the early stage of diabetic retinopathy,the diabetic patients without obvious diabetic retinopathy at the fundus,although there is no obvious abnormality in the appearance of the optic disc,had the decrease of the inside and peripapillary microvascular perfusion of the optic disc,and the thinning of the peripapillary retinal nerve fiber layer thickness.Peripheral vessel density and age are important factors influencing the peripapillary retinal nerve fiber layer thickness.OCTA has important practical value in the study of abnormal optic disc microperfusion in preclinical DR.