Impact of intravitreal anti-VEGF therapy on intraretinal microvascular abnormalities in proliferative diabetic retinopathy

Introduction: To assess the characteristics of intraretinal microvascular abnormalities (IRMA) before and after anti-VEGF treatment in proliferative diabetic retinopathy (PDR) eyes using swept source-widefield optical coherence tomography angiography (SS-WF OCTA). Methods: Single-center observational case series. 10 PDR eyes naïve to treatment that received 3 monthly intravitreal injections of aflibercept were included. All eyes were imaged with SS-WF OCTA PLEX Elite 9000 (Carl Zeiss Meditec, Inc., Dublin, California, USA) at baseline (T0) and 1 month after the third injection (T1). Based on the morphological changes on the enface OCTA images, the IRMAs were divided into five subtypes: tuft regression; reperfusion; mixed (combined tuft regression/reperfusion); worsening (new appearance of tuft), and unchanged. A concomitant flow overlaid analysis was performed focusing on the presence of the outpouching of the ILM at T0 and T1 for each subtype. Results: Forty-three IRMAs were identified at the baseline. Most of them (58.1%) showed tuft regression after treatment. The reperfusion phenomenon was observed in 11.6%, and 18.6% appeared unchanged after treatment. The worsening type was observed in 9.3% of them. The least represented was the mixed type (2.3%). Most of the tuft regression type IRMAs (98.1%) showed an association with the ILM outpouching at T0 (p<0.001) and not at T1 (p=0.111). Conclusions: OCTA allows classifying the IRMA into different types and to monitors the IRMA changes after anti-VEGF treatment. Anti-VEGF agents may promote retinal vascular remodeling, with regression of tufts being observed in most cases. The tuft regression is associated with a reduction of the outpouching of the ILM, resulting in a decreased risk of progression to PDR.