Ultra-widefield, 7-field imaging show concordance for diabetic retinopathy grading
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Key takeaways:
- Ultra-widefield and 7-field imaging were correlated for all diabetic retinopathy outcomes.
- Concordance was especially high for severe outcomes.
Evaluations of diabetic retinopathy severity appeared comparable with ultra-widefield and 7-field imaging, suggesting ultra-widefield imaging can be used in future longitudinal studies without bias, according to a cross-sectional study.
“Over the combined 38-year duration of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications study (DCCT/EDIC), there have been major advances in the technology used to acquire retinal images,” Lloyd Paul Aiello, MD, PhD, professor of ophthalmology at Harvard Medical School and director of the Beetham Eye Institute at Joslin Diabetes Center, and colleagues wrote in JAMA Ophthalmology.
“Although several studies have reported that ultra-widefield (UWF) systems provide equivalent or more data than 7-field (7F) imaging alone, most represent single-center experiences, some include a limited range of retinopathy severity, only one includes data from a multicenter, longitudinal prospective study, and none reflect a cohort like that of the DCCT/EDIC studies, wherein the associations among risk factors evaluated over decades with the DCCT/EDIC primary study outcomes can be assessed for consistency across the different imaging modalities,” they added.
To assess the concordance of 7F and UWF imaging for diabetic retinopathy severity grading and its associations with previously identified nonocular risk factors, Aiello and colleagues evaluated data of 785 participants (mean age, 61 years; 53% men) with type 1 diabetes in the active DCCT/EDIC cohort with both UWF and standardized stereoscopic 7F fundus images obtained once at the same visit between March 2019 and December 2021.
The nonocular risk factors included HbA1c, which was assessed quarterly during DCCT and annually during EDIC using high-performance liquid chromatography, as well as age, sex and duration of type 1 diabetes.
Central graders from the Central Ophthalmic Reading Center at the University of Wisconsin, Madison, used the stereoscopic 7F fundus images to assess the ETDRS severity score, then used UWF with a 7F template masking the retinal periphery (UWF-7F) to perform initial diabetic retinopathy severity assessment.
After completing the UWF-7F grading, they removed the mask and evaluated the full image by extending the standard ETDRS grading scale into the periphery (UWF-global).
For each of the three imaging modalities (7F, UWF-7F and UWF-global), the researchers determined retinopathy independently as mild, moderate or severe nonproliferative diabetic retinopathy.
Overall, UWF and 7F imaging were correlated for all outcomes, with high concordance for severe outcomes including severe nonproliferative diabetic retinopathy (Cohen’s kappa coefficient = 0.73; concordance, 96%), proliferative diabetic retinopathy (kappa = 0.74; concordance, 97%), scatter photocoagulation (kappa = 0.97; concordance, 99%) and focal photocoagulation (kappa = 0.71; concordance, 98%), according to the researchers.
“These data support the transition between these techniques as not compromising data quality in the DCCT/EDIC studies, similar to the successful transition from film to digital images in 2009,” the researchers wrote. “They also support the use of UWF imaging as a way to both maintain comparison to prior DCCT/EDIC data and to allow study of the novel information provided by the new modality.”
Of 1,529 ETDRS eye-level severity scores between 7F and UWF-7F, 92% were within 1 step, and 3% were more than 2 steps apart (kappa = 0.45, weighted kappa = 0.63).
The researchers also found that diabetic retinopathy severity scores within the UWF-global area tended to be higher compared with 7F (median UWF-global score, 3; interquartile range [IQR], 2-3 vs. median 7F eye-level score, 2; IQR, 1-3; P < .001); however, they noted that the two imaging modalities were still correlated (81% agreement within 1 step; weighted kappa = 0.41).
Aiello and colleagues acknowledged that it is unknown how the study outcomes would be affected by imaging obtained under different or less ideal circumstances.
“Nevertheless, this study demonstrates what can be achieved with such rigor and supports the imaging transition in the DCCT/EDIC studies where such protocols are mandated,” they wrote, adding that their data suggest use of UWF imaging in future longitudinal studies is unlikely to introduce measurement bias.
Perspective
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This study compared UWF imaging with traditional ETDRS 7-field imaging for grading diabetic retinopathy and found high concordance across both methods.
For clinicians, this suggests that UWF imaging could reliably replace 7-field imaging in monitoring DR, without compromising diagnostic accuracy. UWF’s ability to capture a larger retinal area allows for detection of peripheral lesions, potentially offering a fuller understanding of disease severity and progression risk, which can improve clinical assessments and management plans.
The 97% concordance in proliferative diabetic retinopathy grading suggests that UWF can confidently be integrated into standard care, particularly for patients requiring comprehensive staging. However, a noted shortcoming is that UWF imaging occasionally resulted in discordant grading due to variability in peripheral lesion visibility and image quality. This highlights the importance of training and quality control when using UWF in clinical settings.
Overall, the study supports UWF as a valuable tool, with practical implications for enhancing diabetic retinopathy management by encompassing a more extensive retinal view.
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