Changes In Retinal Microvascular Structure Before And After Treatment Of Branch Retinal Vein Occlusion-Macular Edema

Objective:By observing the structural changes in the retina and retinal microvessels on the macular fovea and the parafovea of the side of the branch lesions before and after anti-vascular endothelial growth factor(anti-VEGF)treatment of the macular edema secondary to non-ischemic and ischemic branch retinal vein occlusion(BRVO-ME),we can explore and discuss the relevant indexes that affect the prognosis.Methods:A retrospective clinical study was conducted by collect 32 cases of ischemic BRVO-ME(32 eyes,group A)and 22 cases of non-ischemic BRVO-ME(22 eyes,group B),which were diagnosed by ophthalmology clinical examination in our hospital from January 2018 to November 2020.All patients were received intravitreal injections of anti-VEGF treatment for 3times(once a mouth).The study recorded the best-corrected visual acuity(BCVA)at the initial diagnosis and 1 month after each intravitreal injection.And the results of optical coherence tomography angiography(OCTA)detection of patients were compared between pre-treatment and post-treatment(1st and 3rd treatment)in these two groups.The indexes evaluated with OCTA included the central macular thickness(CMT),vessel perfusion density(VPD),vessel length density(VLD),and foveal avascular zone(FAZ)of the superficial capillary plexus(SCP)on the macular fovea,the fan-shaped inner ring and outer ring area on the parafovea of the side of the branch lesions in 6mm×6mm scans centered on fovea that are acquired by OCTA.Single-factor and two-factor repeated measures were used to analyze the variance of each quantitative parameter of the two groups before treatment,after the first treatment,and after the third treatment.Independent sample paired t verification was used for two separate groups of data,single-factor variance analysis was used for multiple groups of data(N≥3).Pearson correlation analysis method was used to analyze the correlation between age,microvascular structure of the macula before treatment and the BCVA difference before and after treatment.The difference or correlation would be statistically significant if P<0.05.Results:1.Univariate analysis and comparison showed that BCVA of the ischemic group A and the non-ischemic group B were apparently increased after treatment(P<0.05);CMT were indicatively reduced(P<0.05);The vessel perfusion density(VPDcentral)and vessel length density(VLDcentral)of SCP on the macular fovea in the two groups were lower than those before treatment(P<0.05);the outer ring VPD on the parafovea of the affected branch side was lower than 1st treatment in group A,but increased compared with the baseline before treatment,and it increased in group B after the treatment(P<0.05);there was no statistically significant difference with the outer ring VLD on the affected branch side in group A before and after treatment(P>0.05),while in group B the outer ring VLD after treatment was higher than before(P<0.05);Foveal avascular area(FAZ)baseline area of group A and B both increased before treatment,and there was no significant change after treatment(P>0.05).2.The average values of the differences were compared in each index between the two groups before and after the treatment.The outer ring VPD and VLD of the affected side of the non-ischemic group B increased with the increase of injection times,and the difference was statistically significant(P<0.05).3.There was no significant difference in the changes of BCVA,CMT,VPD,VLD,FAZ area between group A and group B by two-factor analysis(P>0.05).4.Pearson correlation analysis indicated that BCVA,CMT,VLD,VPD before treatment were correlated with the changes of BCVA before and after treatment(P<0.05),and the changes of BCVA were positively correlated with CMT before treatment(r=0.429,P<0.05),and were positively correlated with VPDcentral and VLDcentral of SCP before treatment(r=0.381,r=0.361,all P<0.05),and it was negatively correlated with the outer ring VPD and VLD of the affected side(r=-0.416,r=-0.419,both P<0.05).However,the correlation between FAZ area and changes of BCVA was not statistically significant(r=-0.075,P>0.05).Conclusion:1.After anti-VEGF treatment of the ischemic and non-ischemic BRVO-ME,CMT decreased,and VPD,VLD on the macular fovea and the affected side of SCP had different changes,but FAZ area did not change significantly.2.Before anti-VEGF treatment of BRVO-ME,BCVA,CMT,VPD,VLD and FAZ area can be used as the evaluation indexes before and after treatment.CMT,VPD,VLD are correlated with the difference of BCVA before and after treatment,which can be used as predictors of visual prognosis.3.OCTA examination can be an effective means to quantitatively evaluate the efficacy of BRVO-ME anti-VEGF treatment and follow-up prognosis.