Quantifying Spatial and Temporal Vascular Perfusion Changes Before and After Intravitreal Anti-VEGF Injections in Proliferative Diabetic Retinopathy(PDR)

Abstract

Purpose : To assess non-perfusion, re-perfusion, and intermittent flow before and after intravitreal anti-VEGF injections in PDR patients using OCT-A.

Methods : 4 patients with PDR were imaged using a commercial SDOCT system (Avanti RTVue-XR; Optovue). Only 1 patient showed substantial posterior neovascularization (Fig. A). Ten 3x3 mm macular OCT-A images were obtained and averaged (Mo et al., 2017). Full retina slab located between the ILM and OPL +10µm was used for image analysis. OCT-A imaging was performed pre-injection, biweekly folowing injections for one month (2,total) of 1.25Mg Bevacizumab. OCT-A image processing and custom perfusion density computation were performed using MATLAB(Andrade Romo et al 2018) (Fig. A-F). Non-perfusion and re-perfusion were defined as perfusion density differences between visits lower than 0.1% or higher than 99.9% of the normal variation, respectively (Fig. E). Number of capillary segments with intermittent flow identified on the 10 registered OCT-A images and number of microaneurysms identified on the averaged OCT-A image were also recorded at each visit.

Results : Between pre-injection and 2 weeks after injection, non-perfusion and re-perfusion area changes (mean±SDs) were 6.00±9.59% and 2.10±3.16%, respectively. Between pre-injection and 4 weeks after injection, non-perfusion and re-perfusion area changes (mean±SD)were 13.34±17.38% and 2.78±2.35%, respectively. The majority of the non-perfusion over time was attributed to regression of neovascularization in 1 patient. Two capillary segments with intermittent flow were identified at pre-injection and were noted to be constantly perfused after injections. 26 microaneurysms were identified pre-injection with noticeable regression in sizes 2 weeks after injection.

Conclusions : Our findings demonstrate that non-perfusion, re-perfusion, and intermittent flow in proliferative diabetic retinopathy treated with anti-VEGF injections can be identified qualitatively and quantitatively using OCT-A. The clinical application of this approach will require expanded studies

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

OCT-A perfusion density changes in PDR. A-F) before and after anti VEGF injections (2, 4 weeks). G) Perfusion density changes, G) before and 2 weeks after injection, and H) before and 4 weeks after injection. Areas of non-perfusion and re-perfusion (<0.1% or >99.9% of normal) were highlighted in red and cyan.