Changes Of Blood Flow Density In Macular Area In Retinal Vein Occlusion

Background and ObjectiveRetinal vein occlusion(RVO)is the second most common retinal vascular disease after diabetic retinopathy.RVO is most commonly seen in older patients,but it can also occur in younger patients,often with sudden vision loss.The etiology of RVO is various and complex,and all kinds of vascular wall damage,changes in hemorheology and hemodynamics can lead to vein obstruction,among which the common high-risk factors include hypertension,diabetes,hyperlipidemia,and open-angle glaucoma is rare.RVO can be divided into central retinal vein occlusion(CRVO),half-retinal vein occlusion(HRVO)and branch retinal vein occlusion(BRVO).It can also be divided into ischemic and non-ischemic types according to the degree of retinal ischemia.RVO belongs to retinal vascular diseases,and fluorescein fundus angiography(FA)has always been the gold standard for the examination of retinal vascular diseases.The application of FA examination to evaluate the vascular conditions and the detection of retinal capillary non-perfusion areas and new blood vessels are helpful for classification and treatment,as well as the preliminary determination of the prognosis of patients.But FA is an invasive test,with a few people at risk of mild nausea,vomiting and even anaphylaxis.Recently,optical coherence tomography angiography(OCTA)is a new type of fast and non-invasive blood flow imaging technology,which has the advantages of non-invasive,fast and high resolution imaging.First of all,OCTA examination can make up for the fact that traditional OCT can only observe simple cross sections,and the observation of blood vessels and capillaries in each layer is not good enough.It also provides a new alternative method for patients with FA angiography inconvenience.OCTA use the Split-spectrum amplitude-decorrelation angiography(SSADA)algorithm,which greatly reduces the motion artifacts and noise,and improves the signal-to-noise ratio,so as to obtain high-definition fundus vascular images,and can be multi-mode imaging,which has been gradually applied in clinical diagnosis and treatment of various fundus diseases.This article will apply OCTA technology research RVO patients with superficial capillary plexus(SCP),deep capillary plexus(DCP),foveal avascular zone(FAZ)and subfoveal choroidal thickness(SCT),and to explore the differences between normal and significance.MethodsRetrospective study.A total of 59 RVO patients were observed in shandong provincial hospital from January 2018 to October 2018,including 20 CRVO patients and 39 BRVO patients.And 24 eyes of healthy people were collected for control group.Application of logarithmic visual acuity chart to check the best corrected visual acuity(BCVA)of RVO patients.OCTA was used to examine the SCP,DCP,FAZand SCT in the macular area within 6*6mm,and the results were compared with the control group.ResultsA total of 59 RVO patients were included in the study,with an average age of 52.78± 14.49 years(20-79 years).20 patients with CRVO had an average age of 48.3± 15.7 years(20-79 years).39 patients with BRVO had a mean age of 55.1±13.5 years(23-75 years).24 eyes of healthy subjects were used as the control group,and the average age was 50.3 ±8.9(30-65 years old).1.In terms of vessel density compared with the healthy control group(SCP:49.03±2.66%,DCP:48.24±4.89%),the SCP of BRVO patients decreased(44.76±4.47%,P<0.05),DCP also decreased significantly(43.46±4.55%.,P<0.05);Both SCP and DCP were decreased in CRVO patients(SCP:44.98 ±5.15%,P<0.05),DCP:43.24±5.97%,P<0.05);Both SCP and DCP were decreased in RVO patients(SCP:44.84±4.67%,P<0.05).DCP:43.38±5.03%,P<0.05).However,there was no significant difference in blood flow density between BRVO group and CRVO group.2.FAZ:compared with the control group,the area of FAZ in BRVO group was enlarged(0.321±0.09mm2 vs 0.28±0.09mm2).P<0.05));The FAZ of CRVO group was also enlarged(0.40±0.14mm2,P<0.05).FAZ area was also significantly enlarged in RVO group(0.35±0.12mm2,P<0.05).The comparison between BRVO group and CRVO group showed that the expansion of FAZ in CRVO group was more obvious.3.SCT:compared with control group,SCT of BRVO group increased(243.59±45.86um vs 220.79±26.42um,P<0.05);The SCT of CRVO group decreased(205.40±19.03um,P<0.05).There was no significant difference in SCT between RVO group and control group(230.64±42.77um,P>0.05).4.Visual acuity correlation analysis:the results showed that the BCVA of BRVO group,CRVO group and RVO group was negatively correlated with FAZ(BRVO:r=0.45,P<0.01;CRVO:r= 0.664,P<0.01;RVO:r=0.613,P<0.01),while SCP,DCP and BCVA were not significantly correlated(BRVO:SCP:r=-0.165,P=0.314).DCP:r=0.12,P=0.47;CRVO:SCP:r=-0.328,P=0.158;DCP:r=0.004,P=0.986;RVO:SCP:r=-0.211,P=0.11;DCP:r=0.053,P=0.692).5.nonperfused areas(NPA):For the BRVO patients with NPA(with NPA:19 cases;without NPA:20 cases),the comparison showed that SCP was significantly reduced in patients with NPA,and the difference was statistically significant(42.37±3.09%vs.47.23±4.29%,P<0.01);DCP and FAZ were not statistically significant between the two groups.Patients with NPA in CRVO(with NPA:8 cases;without NPA:12 cases),the comparison showed that the SCP of patients with NPA was significantly reduced(41.44±5.86%vs47.34±2.94%,P<0.01).There was no significant difference between DCP and FAZ regardless whether there is NPA or not.ConclusionOCTA examination can examine and quantitatively analyze the blood flow density,FAZ and SCT of RVO patients.OCTA can be used as an important examination method in the diagnosis,treatment,prognosis and follow-up of RVO patients.