Comparison between post treatment vascular density, fractal dimension and choriocapillaris flow in ischemic and non-ischemic retinal vein occlusion using optical coherence tomography angiography

Abstract

The aim of the study was to compare vascular density (VD), fractal dimension (FD), foveal avascular zone (FAZ) and choriocapillaris flow and using optical coherence tomography angiography (OCTA) before and after Bevacizumab therapy in patients with macular edema associated with ischemic and non-ischemic retinal vein occlusion (RVO). 15 eyes with ischemic RVO and 20 with non-ischemic RVO were included. Each patient had 3 consecutive intravitreal injections of Bevacizumab every month. Best-corrected visual acuity (BCVA), central macular thickness (CMT) and retinal microvasculature were measured using OCTA before and one month after the third injection. The BCVA and FAZ area improved significantly after treatment in both ischemic and non-ischemic cases. Although, in ischemic group, FD, superficial and deep capillary VD decreased with no statistically significant change in the choriocapillaris flow. In the non-ischemic group, there was an increase in the FD, superficial parafoveal, perifoveal VD and choriocapillaris flow with insignificant increase in the DCP VD while the foveal VD showed a statistically significant decrease. In conclusion, anti-VEGF therapy improved the BCVA, retinal FD, VD in non-ischemic case but despite improvement in BCVA it reduced the VD in the ischemic cases.