A prospective comparison of ultrawide-field and two-field fundus imaging for diabetic retinopathy assessment

BACKGROUND: To evaluate the efficacy of nonmydriatic ultrawide-field (UWF) imaging in diagnosing diabetic retinopathy (DR) compared to nonmydriatic 2-field 45° fundus photography (FP). METHODS: A total of 769 eyes with diabetes were included in this prospective, observational, comparative, real-world study. We captured both nonmydriatic 2-field 45° FP and UWF images for each patient. Both imaging modalities were analyzed according to the International Classification of Diabetic Retinopathy Disease Severity Scale to assess agreement in DR grading and image gradability. We also investigated DR lesions visible in UWF images beyond and within the scope of the 2-field 45° fundus images. RESULTS: UWF imaging and 2-field 45° FP showed substantial agreement in DR grading (weighted κ = 0.798), which decreased to moderate agreement (weighted κ = 0.495) after excluding the eyes graded as ‘no DR’ in both modalities. UWF imaging yielded higher severity grades in 14.33% of cases (87 eyes). A statistically significant difference was observed between UWF imaging and 2-field 45° FP in detecting DR (56.96% vs. 44.47%, p < 0.0001) and referable DR (46.81% vs. 36.02%, p < 0.0001). Among the 369 DR-affected eyes, 24.39% exhibited lesions mainly within the central field, 45.25% showed primarily peripheral lesions, and 30.35% presented lesions uniformly distributed. UWF imaging demonstrated a significantly lower ungradable rate for DR assessment compared to 2-field 45° FP (3.77% vs. 19.90%, p < 0.0001). CONCLUSIONS: UWF imaging offers significant advantages over 2-field 45° FP in DR detection, severity grading, and image gradability, demonstrating strong potential to enhance clinical DR management. TRIAL REGISTRATION: This study was registered with ClinicalTrials.gov (NCT05836194) on May 1, 2023.