| Objective:Optical coherence tomography angiography?OCTA?was used to quantitatively evaluate the area,perimeter and circularity of foveal avascular zone?FAZ?,perfusion density?PD?and vessel density?VD?in patients with type 2diabetes mellitus,and to explore its characteristics,so as to provide objective basis for early prevention and treatment of diabetic retinopathy?DR?.Methods:A total of 333 patients?559 eyes?were collected from the wards of the people's Hospital of Ningxia Hui Autonomous region from January 2019 to September 2019.There were 179 eyes of 103 healthy subjects?normal control group?with an average age of?55.46±9.97?years.230 patients with type 2 diabetes?380eyes?were enrolled in the diabetes group,with an average age of?55.94±8.94?years.According to the new international clinical classification of diabetic retinopathy in2002,the diabetic group was divided into non-diabetic retinopathy group??NDR??,mild non-proliferative diabetic retinopathy?mild NPDR?group and moderate-severe non-proliferative diabetic retinopathy?moderate-severe NPDR?group.The average age was?55.67±9.24,58.48±7.50,55.77±8.54?years old.All the subjects used Cirrus HD-OCT 5000 OCTA to scan the macular area with 3mm×3mm.The area,perimeter and circularity of FAZ in the superficial retina,The perfusion density of macular fovea?PD central?,the perfusion density of para-macular fovea?PD inner?and the perfusion density of macular area within 3 mm?PD full?.The vessel density(?VD central?in the macular fovea,the vessel density?VDinner?in the para-fovea and the vessel density?VD full?in the macular region within 3 mm were quantitatively measured.The differences of the parameters of FAZ and superficial macular area of retina in each group were analyzed by analysis of variance,and the differences between groups were compared by LSD method.Linear correlation analysis was used to analyze the correlation between systemic factors,best corrected visual acuity?BCVA?and FAZ and macular average vascular density in diabetic group,and multiple linear regression analysis was used to analyze the correlation between systemic factors and above-mentioned indexes.Results1.General information:There was no significant difference in age,sex ratio and intraocular pressure?IOP?between the normal control group and the diabetic group?P>0.05?.There were significant differences in the course of diabetes mellitus?DM?,BCVA?logMAR?,glycosylated hemoglobin?HbA1c?,serum total cholesterol?TC?and serum triglyceride?TG??P<0.05?.There was no significant difference in age,sex ratio,TC and IOP among normal control group,NDR group,mild NPDR group and moderate-severe NPDR group?P>0.05?,but there was significant difference in DM course,BCVA?logMAR?,HbA1c and TG?P<0.05?.2.Parameters of FAZ:The area and perimeter of FAZ in the normal control group were smaller than those in the diabetic group?t=-5.589,-7.101,P<0.05?,while the circularity of FAZ in the normal control group was higher than that in the diabetic group?t=5.895,P<0.05?.The area and perimeter of FAZ were gradually enlarged from normal control group,NDR group,mild NPDR group and moderate-severe NPDR group,and there were significant differences among the four groups.There was no significant difference in circularity between mild NPDR group and moderate-severe NPDR group.3.Average perfusion density in the superficial macular area of the retina:The levels of PD central,PD inner and PD full in the normal control group were higher than those in the diabetic group?t=6.144,5.956 and 6.510,all P<0.05?.There was no significant difference in PD central,PD inner and PD full between mild NPDR group and moderate-severe NPDR group?P>0.05?.There was no significant difference in PDcentral between NDR group and mild NPDR group?P>0.05?,but there were significant differences in other groups?all P<0.05?.4.Mean Vessel density in the superficial macular area of retina:The parameters of mean Vessel density?VD central,VD inner,VD full?in the diabetic group were lower than those in the normal control group?all P<0.05?.VD inner decreased gradually from normal group,NDR group,mild NPDR group and moderate to severe NPDR group,and there was significant difference among the four groups[?22.3±1.4?mm-11 to?21.5±1.4?mm-11 to?20.1±2.2?mm-11 to?19.9±2.1?mm-1,F=45.594,P<0.001].In the comparison of VD central and VD full,there was no significant difference between mild NPDR group and moderate-severe NPDR group?P>0.05?,There were significant differences among the other groups?all P<0.05?.5.Linear correlation analysis results:In the DM group,the area and perimeter of FAZ were positively correlated with BCVA?P<0.05?,and negatively correlated with other parameters?P<0.05?.The course of DM and TC were positively correlated with the area and perimeter of FAZ?P<0.05?.The course of DM,HbA1c and the Circularity of FAZ were negatively correlated?P<0.05?.There was a negative correlation between TC and PD central?P<0.05?.Age,course of DM and HbA1c were negatively correlated with the parameters of PD central,PD inner,PD full,VD central,VD inner and VD full in the superficial macular area of the retina?P<0.05?;other indicators showed zero correlation?P>0.05?.6.The results of multiple linear regression showed that the course of DM was the independent factor affecting the area,perimeter and circularity of FAZ,the course of DM and TC were the main factors affecting the area and perimeter of FAZ.Age and the course of DM are the independent influencing factors of the average VD,PD inner and PD full in the superficial macular area of the retina,while TC and the course of DM are the main factors affecting PD central.There was no correlation between HbA1c and the parameters of average vascular density in the superficial macular area of the retina.The perimeter of FAZ,PD inner,VD central and VD inner are the main factors affecting BCVA.Conclusion1.The area and perimeter of FAZ in diabetic patients were significantly larger than those in healthy subjects,and the circularity of FAZ in healthy people was significantly higher than that in diabetic patients;However,the levels of PD central,PD inner,PD full and VD central,VD inner and VD full were lower than those of healthy people.It is suggested that no matter whether or not the morphology of DR,FAZ may have changed,ischemic pathological changes may have appeared in the macular area,and retinal microvascular damage may occur earlier than we expected.2.With the increase of the severity of DR,the area and perimeter of FAZ gradually expanded,and the average VD of the para-macular fovea decreased gradually,suggesting that vascular loss and ischemic changes gradually appeared in the macular area.VD may be an objective and reliable indicator for monitoring the progress of DR.3.These quantitative indicators of OCTA have a certain correlation with BCVA,which may be potential indicators of vision loss,may also play a certain role in predicting visual function,and provide an objective basis for early detection,early prevention and treatment of DR.4.The course of DM and TC are the main factors affecting the superficial PDcentral of the retina,so regular detection,reasonable management of TC and regular fundus screening in patients with diabetes may greatly reduce the occurrence and development of complications. |
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