Comparison of Ultra-Widefield Imaging and Standard Imaging in Assessment of Early Treatment Diabetic Retinopathy Severity Scale

Purpose: To compare Early Treatment Diabetic Retinopathy Study (ETDRS) severity levels between standard 7-field imaging and ultra-widefield (UWF) imaging and to incorporate peripheral diabetic retinopathy (DR) lesions into the ETDRS grading system. Design: Cross-sectional Study. Participants: Paired images from 192 eyes (189 participants) with diabetic retinopathy were included. Methods: The ETDRS levels were determined by masked graders in 3 ways: standard 7-field imaging, UWF within the 7-field region (7-field UWF imaging), and the entire UWF image (global ETDRS imaging). Main Outcome Measures: Percentage agreement between 7-field and UWF imaging for ETDRS levels. Results: Of the 166 paired images evaluated, exact agreement was found in 48.8% of eyes between standard 7-field and 7-field UWF ETDRS levels with a weighted K value of 0.59 (95% confidence interval [CI], 0.5-0.68). Agreement rates varied with DR severity and were least in early DR (30.8%) and moderate non -proliferative DR (26.5%) groups. In 156 eyes with 7-field UWF ETDRS and global UWF ETDRS levels, exact agreement was found in 143 eyes (92%), with a weighted K value of 0.9 (95% CI, 0.9-0.98). The peripheral lesions contributed to a higher DR severity in 8% and changed the eye to a proliferative DR level in 2%. Reproducibility of the 3 ETDRS evaluations was comparable with a weighted K value of 0.57 with standard 7-field imaging, 0.65 with 7-field UWF imaging, and 0.60 with global ETDRS scale imaging. Conclusions: Moderate agreement was found in the ETDRS DR severity scale between standard 7-field and UWF imaging, indicating caution in interchanging data from the 2 methods. Both methods showed good reproducibility for clinical trial outcome of 2-step change. The global ETDRS scale provides a comprehensive score to incorporate peripheral changes into the ETDRS scale. The implications of the global scale on progression rate are yet to be determined. (C) 2021 by the American Academy of Ophthalmology.