Comparison of Diabetic Retinopathy Lesions Identified Using Ultrawide Field Imaging and Optical Coherence Tomography Angiography

Introduction: Optical coherence tomography (OCT) angiography (OCTA) has the potential to influence the diagnosis and management of diabetic eye disease. This study aims to determine the correlation between diabetic retinopathy (DR) findings on ultrawidefield (UWF) colour photography (UWF-CP), UWF fluorescein angiography (UWF-FA) and OCTA. Methods: Cross-sectional, prospective study. One-hundred-fourteen eyes from 57 diabetic patients underwent mydriatic UWF-CP, UWF-FA and OCTA. DR severity was assessed. Ischemic areas were identified on UWF-FA using Image J and the nonperfusion-index (NPI) was calculated. Diabetic macular edema (DME) was assessed using OCT. Superficial capillary plexus vessel density (VD), vessel perfusion (VP) and foveal avascular zone (FAZ) area were automatically measured on OCTA. Pearson correlation coefficient between the imaging modalities was determined. Results: Forty-five eyes were excluded due to non-DR findings or prior laser photocoagulation; 69 eyes were analysed. DR severity was associated with larger NPI (r=0.55944,p<0.0001) even after distinguishing between cones (Cone Nonperfusion Index [CPI]: r=0.55617,p<0.0001) and rods (Rod Nonperfusion Index [RPI]: r=0.55285,p<0.0001). In eyes with NPDR, NPI is correlated with DME (r=0.51156,p=0.0017) and central subfield thickness (CST) (r=0.67496,p<0.0001). UWF-FA macular nonperfusion correlated with NPI (r=0.42899,p=0.0101), CPI (r=0.50028,p=0.0022) and RPI (r=0.49027,p=0.0028). Central VD and VP correlated with the DME presence (r=0.52456,p<0.0001; r=0.51952,p<0.0001) and CST (r=0.50133,p<0.0001; r=0.48731,p<0.0001). Central VD and VP were correlated with macular nonperfusion (r=0.44503,p=0.0065; r=0.44239,p=0.0069) in eyes with NPDR. Larger FAZ was correlated with decreased central VD (r=-0.60089,p=0.0001) and decreased central VP (r=-0.59224,p=0.0001). Conclusion: UWF-CP, UWF-FA and OCTA findings provide relevant clinical information on diabetic eyes. Nonperfusion on UWF-FA is correlated with DR severity and DME. OCTA metrics of the SCP correlate with the incidence of DME and macular ischemia.