The Characteristics Analysis Of Retina And Choroid In Patients With Early Diabetic Retinopathy By Ultra-Wide Field Swept-Source OCTA

Objective:To investigate the changes in the thickness and vessel density(VD)of choroid and each layer of retina in early and preclinical diabetic retinopathy(DR),explore the microcirculatory alterations in the mid-peripheral extent of each layer and to characterize the changes in choroidal and retinal structures and blood flow in early DR.Methods:In this cross-sectional study,clinical data of 175 eyes from 113 individuals were analyzed,and those who met the inclusion criteria were divided into 20 individuals with 28 eyes in control group(Cont),53 individuals with 89 eyes in diabetes without DR(NDR)group,and 40 individuals with 58 eyes in the non-proliferative diabetic retinopathy(NPDR)group.The fundus images of 12 × 12mm were scanned by wildfield swept source optical coherence tomography angiography(WSS-OCTA)and were automatically divided into nine 4 × 4mm quadrants with macular area as the center.The VD in superficial capillary plexus(SCP),deep capillary plexus(DCP),choroidal capillary(CC)and middle-to-large choroidal vessel(MLCV)were measured.Evaluate the superficial retina thickness(SRT),deep retina thickness(DRT)and choroid thickness(CT).The differences in the thickness/VD in each quadrant of each layer between groups were analyzed using mathematical and statistical methods,the distribution of changes in retinal and choroidal thickness/VD and the period of changes were studied.Since this study used mostly binocular data,which did not meet the assumption of independence,the generalized linear mixed-effects model in R language was used for the variability analysis.Results:Retinal blood flow density analysis showed that in NPDR group,VD of SCP in macular,inferior,and subtemporal quadrants,VD of DCP in inferior and subtemporal quadrants were lower than those in Cont group(all P<0.05),while retinal thickness analysis found SRT in supratemporal and subtemporal quadrants,DRT in supratemporal and optic disc quadrants in NPDR group were higher than those in Cont groups(all P<0.05).Choroidal blood flow density analysis showed that VD of MLCV in NDR group was lower than that in Cont group in subnasal,inferior and optic disc quadrants(all P<0.05),but there was no difference in VD of CC in NDR and NPDR groups.Choroidal thickness analysis showed that CT in NDR group was lower than that in Cont group in supratemporal,temporal,inferior,superior nasal and inferior nasal quadrants(all P<0.05).Conclusion:Structural and blood flow changes in the macrovascular layer of choroid appear before the onset of DR and precede changes in the retinal microcirculation;MLCV thickness/VD is a more sensitive imaging indicator for clinical detection of DR;choroidal capillary blood flow may be unaffected in early DR;WSS-OCTA,as a noninvasive clinical adjunct,offers a new approach to prevent and monitor the onset of DR in patients with type 2 diabetes strategy.