Purpose: With the increasing prevalence of diabetes, fast, noninvasive identification of proliferative diabetic retinopathy (PDR) becomes essential. This study evaluated the utility of optical coherence tomography angiography (OCTA) to characterize intraretinal microvascular abnormalities (IRMA) and retinal neovascularization (NV).
Methods: Patients with severe non-PDR or PDR were imaged with fluorescein angiography and widefield swept-source OCTA (Zeiss Plex Elite 9000; Carl Zeiss Meditec, Dublin, CA). Regions suspicious for IRMA or retinal NV were identified and the OCTA, including flow overlay on the co-registered structural optical coherence tomography, and fluorescein angiography images were graded by two masked readers.
Results: Ninety-six foci of irregular vasculature were analyzed, comprised of 70 IRMA and 26 retinal NV lesions from 14 eyes. Compared with fluorescein angiography, OCTA with flow overlay demonstrated specificity of 99% and sensitivity of 92% in identifying IRMA and NV. Neovascularization differed from IRMA on OCTA by demonstrating supraretinal flow breaching the internal limiting membrane and posterior hyaloid (P < 0.001). Intraretinal microvascular abnormalities were distinguished from NV by outpouching of the internal limiting membrane (P = 0.035). Vascular flow was reduced in the presence of fibrosis.
Conclusion: Optical coherence tomography angiography, through flow overlay, has utility to image and differentiate IRMA and NV, which are key features distinguishing severe non-PDR and PDR, respectively. Noninvasive widefield OCTA may be a useful tool to diagnose high-risk diabetic retinopathy eyes.