AB031.Switching to aflibercept in diabetic macular edema not responding to bevacizumab in a Canadian real-life setting

Background:Diabetic macular edema(DME)is a leading cause of severe visual impairments in older and the working-age population.An important target of current therapy is vascular endothelial growth factor(VEGF),which plays a role in the pathogenesis of DME by inducing angiogenesis and increasing vascular permeability.Currently available anti-VEGF agents include off-label use of Bevacizumab,which has been shown to be effective in the treatment of DME.However,many patients with DME do not respond or demonstrate only a partial response to this agent.As of November 2016,the Canadian Health authorities approved Aflibercept as an anti-VEGF agent for treatment of DME,and the patients who are non-responders to Bevacizumab are switched to this non-off label medication.We aimed to investigate the anatomical and functional visual changes associated with response to Aflibercept in a real-life Canadian population of Bevacizumab non-responders.Methods:A retrospective review of chronic DME patients refractory to bevacizumab treatment who were switched to Aflibercept was done.Best-corrected visual acuity(BCVA),Intraocular pressure(IOP),central subfield thickness(CST),average macular thickness,and total macular volume were extracted at the visit prior to switching to Aflibercept(baseline)as well as the first,second and third follow-up visits after switching.Anatomical and functional visual changes were compared using Generalized Estimating Equations and the association between variables was tested using Pearson correlation test with significance set at P<0.05.Results:Twenty-six eyes with mean age of 63 were included.Average CST at baseline was 421.5±116.1μm and the number of Bevacizumab injections received prior to switching was 15.3±8.0.No significant changes were observed in terms of BCVA and IOP,from baseline to any of the follow-ups.Switching to Aflibercept significantly improved CST,average macular thickness,and total macular volume.From baseline to the first follow-up visit,CST decreased from 421.5±116.1 to 333.0±91.2μm(P=0.001)and average macular thickness reduced from 344.6±74.9 to 322.2±60.5μm(P=0.008).Similarly,total macular volume decreased from 12.4±2.7 to 11.6±2.2μm3,measured at baseline and the first follow-up(P=0.007).No further improvements were observed from the first follow-up to the subsequent ones.The median CST value at baseline(378μm)was used to classify the patients into low and high CST groups.We observed that those with higher CST at baseline(>378μm)showed a trend for improvements in visual acuity(P=0.058).Pearson correlation test confirmed the association between higher CST at baseline and better visual outcomes in response to switching to Aflibercept(P=0.018).Conclusions:Our data evidenced significant anatomical improvements in macula,which did not translate to immediate functional vision improvements.Bevacizumab non-responders with higher CST might also gain visual acuity and benefit functionally from switching to Aflibercept.