The Study Of Clinical Significances Of Changes Of Choroidal Thickness And Vascular Index In Macular Area Of Non-Proliferative Diabetic Retinopathy

ObjectiveTo investigate the clinical significance of the changes in choroidal thickness（CT）and choroidal vascular index（CVI）in the macular area of patients with non-proliferative diabetic retinopathy（NPDR）.MethodsThis study is a retrospective study.A total of 60 patients（60 eyes）diagnosed with type 2 diabetes were randomly enrolled in the ophthalmology department of the First Affiliated Hospital of Nanchang University from March 2021 to September2021.After fundus photography and/or fundus fluorescence angiography（FFA）,they were divided into non-diabetic retinopathy group,non-proliferative diabetic retinopathy without diabetic macular oedema group,and non-proliferative diabetic retinopathy with diabetic macular oedema group,with 20 individuals（20 eyes）in each group.In addition,20 people（20 eyes）of the same age who attended the ophthalmology department of the First Affiliated Hospital of Nanchang University in the same period were included as a healthy control group.All study subjects were examined by enhanced depth imaging spectral-domain optical coherence tomography,and the software,Image J,was used to process the obtained images,such as measuring the subfoveal choroidal thickness and the choroidal thickness at the point of nasal,temporal,upper,and lower sides of 750μm away from the fovea,recorded as SFCT,NCT₇₅₀,TCT₇₅₀,SCT₇₅₀and ICT₇₅₀ and calculating the stromal area（SA）,the luminal area（LA）and the total choroidal area（TCA）.CVI,the ratio of LA to TCA,was analyzed and calculated subsequently.At the same time,the basic data of each group of patients,such as age,gender,laterality of the eye,intraocular pressure,axial length,refractive error,the duration of DM and best corrected visual acuity（BCVA）,described with logarithm of mininal angle resolution（Log MAR）were collected,and finally a conclusion was reached after statistical analysis of the obtained data through SPSS 22.0.Results1.There were no statistically significant differences in age,gender,laterality of the eye,intraocular pressure,axial length,refractive error among the four groups（P>0.05）.The duration of DM in NDR group,NPDR/DME-group and NPDR/DME+group increased successively,and the difference was statistically significant（P<0.001）.The central macular thickness（CMT）of the NPDR/DME+group was greater than that of the control group,the NDR group and the NPDR/DME-group,and the difference was statistically significant（P<0.01）,but there were no significant differences in the CMT values among the control group,NDR group and NPDR/DME-group（P>0.05）.The BCVA（Log MAR）of the NPDR/DME+group was significantly greater than the other three groups（P<0.001）,and the BCVA（Log MAR）of the NPDR/DME-group was greater than that of the control and NDR groups（P<0.001）,however,there was no significant difference in the BCVA（Log MAR）between the NDR group and the control group（P>0.05）.2.There were no statistically significant difference in SFCT,NCT₇₅₀,TCT₇₅₀,ICT₇₅₀ and SCT₇₅₀ among the four groups of subjects.3.There were no statistically significant differences in SA,LAand TCA values among the four groups（P>0.05）.The CVI of control group,NDR group,NPDR/DME-group and NPDR/DME+group were 70.56%±2.19%,68.42%±2.95%,66.48%±2.69%and 64.58%±2.55%,respectively,and the differences of CVI values among the four groups were statistically significant（P<0.001）.4.The duration of DM,BCVA（Log MAR）and CMT were negatively correlated with CVI（P<0.001）,while other indicators had no correlation with CVI（P>0.05）.Conclusions1.The choroidal thickness in macular area may not be taken as an observational indicator to predict the occurrence of NPDR and DME.2.The macular choroidal vascular component decreases relatively with the progression of DM,which may be involved in the occurrence and development of NPDR and DME.3.CVI may be used as one of the imaging markers to monitor the development of NPDR and DME.