Quantitative Analysis Of The Measurements In Retinal Capillary Nonperfusion Areas In PDR Patients With FFA And Wide-field SS-OCTA

Backgrounds and AimsDiabetic retinopathy(DR)is one of the leading blinding ophthalmopathy worldwide,the number of patients has shown an upward trend in recent years.Macular edema and proliferative diabetic retinopathy(PDR)are the main causes of visual impairment in DR patients.During the progression of DR,the accurate identification of retinal capillary nonperfusion areas(NPAs)makes great significance.The fluorescein fundus angiography(FFA)is an authoritative method for detecting retinal blood vessels by intravenous fluorescent dye.As an invasive examination,FFA is not suitable for all patient.swept source optical coherence tomography angiography(SSOCTA)generate images by scanning red blood cells moving within the blood vessels,which is a relatively fast,non-invasive emerging technology.The purpose of this study was to compare the difference between the two examinations in the identification of retinal NPAs of PDR patients,to analyze whether different examiners will produce individual differences in the process of measurement,and to analyze the distribution characteristics of retinal NPAs in wide-field SS-OCTA.Material and Methods1.Thirty-one eyes of twenty-four PDR patients visited Henan Provincial People’s Hospital from July 2019 to January 2020 were included.Thirty-one eyes stages PDR,all of eyes were examined by wide-field SS-OCTA and eighteen eyes were examined by FFA.2.The outcome of wide-field SS-OCTA measurements were divided into three groups,i.e.retina,superficial capillary plexus(SCP)and deep capillary plexus(DCP).Same observation area was 80° × 60° for SS-OCTA and 55° for FFA with both setting centered on the fovea.We observed forty-nine retinal capillary nonperfusion areas in eighteen eyes.Three examiners used Image J to measure all the retinal capillary nonperfusion areas in each group.Measurements of FFA,retina,SCP and DCP of Wide-field SS-OCTA were defined as Fa,Oa1,Oa2 and Oa3,respectively.The intrapersonal variability of the three examiners was analyzed.3.The distribution of retinal NPAs was analyzed in 31 eyes with Wide-field SSOCTA examination,the image was divided into superior nasal,inferior nasal,superior temporal and inferior temporal groups with the horizontal and vertical lines through center of the fovea.Results1.No significant intrapersonal variance was found in Fa,Oa1,Oa2 and Oa3measurements(P>0.05),and the results showed good consistent(CCC>0.9).2.No difference was found between the result of FFA and retina of wide-field SS-OCTA(P=0.054).No difference was found between the result of FFA and SCP of wide-field SS-OCTA(P=0.198).The result of DCP of wide-field SS-OCTA was significantly larger than FFA(P<0.001).Bland-Altman analysis showed that in 93.88%of the cases,retinal NPAs in the DCP of Wide-field SS-OCTA were larger than those of FFA.3.There were no significant differences in the number of retinal NPAs in PDR patients among groups superior nasal field,inferior nasal field,superior temporal field and inferior temporal field in wide-field SS-OCTA(P=0.265).Conclusions1.The quantitative analysis of retinal NPAs by FFA and wide-field SS-OCTA showed good consistency among the examiners.2.The retinal NPAs areas in DCP of wide-field SS-OCTA were larger than those in FFA.The advantages of wide-field SS-OCTA,such as noninvasive,delamination and more sensitive in DCP,make it more promising in application.3.In the wide-field SS-OCTA,there was no difference in the distribution of retinal NPAs in superior nasal field,inferior nasal field,superior temporal field and inferior temporal field.