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    In this retrospective analysis, investigators identified retinal nonperfusion characteristics that led to the development of proliferative diabetic retinopathy (PDR).

    Study design

    This retrospective, cross-sectional image analysis study used widefield fundus photography obtained from 2 completed randomized controlled trials from the United Kingdom: patients with severe nonproliferative PDR (NPDR) in the RDP study and patients with PDR in the CLARITY study. Total area of retinal nonperfusion on fluorescein angiography was measured.


    A total of 92 patients were included in the study: 59 in the PDR group and 33 in the NPDR group. In eyes with NPDR, a retinal nonperfusion threshold of 118.3 disc areas (DA) had a 84.9% specificity for PDR.

    The median total area of retinal nonperfusion was 67.8 DA for eyes with NPDR and 147.9 DA for eyes with PDR. There was a median difference of 69.0 DA between groups, driven primarily by nonperfusion in the periphery rather than the posterior pole. Eyes with neovascularization of the optic disc had the largest total area of retinal nonperfusion.


    The major limitation is the cross-sectional design of this retrospective study. There was no data on other factors such as glycemic control, systemic hypertension and other ischemic risk factors (e.g., anemia) that can contribute to the development of neovascularization.

    Clinical significance

    This study suggests that total area of retinal nonperfusion, specifically in the periphery, is greater in eyes with PDR than in eyes with NPDR. This data supports the hypothesis that increased peripheral nonperfusion may be an early predictor of transition to PDR.