Aims To quantify retinal vascular bed area (RVBA) in square millimetres on stereographically projected ultra-wide field (UWF) fluorescein angiography (FA) in eyes with diabetic retinopathy (DR).
Methods A prospective, observational study. Baseline Optos 200Tx UWF FA images of 80 eyes with DR from the DAVE (NCT01552408) and RECOVERY (NCT02863354) studies were stereographically projected at the Doheny Image Reading Center to adjust for peripheral distortion. The early-phase FA frame was used to extract the retinal vasculature as a mask for calculating RVBA. The pixels of the retinal vasculature were automatically computed in square millimetres using manufacturer-provided software.
Results Eighteen of 80 diabetic eyes were excluded because image quality and contrast were insufficient for automatic extraction of the retinal vasculature from the background fluorescence. The remaining 62 eyes were included in the final analysis. In comparison with age-matched and sex-matched normal controls, eyes with DR had a higher global RVBA for the entire retina (p<0.001), and RVBA correlated with DR severity (p<0.001), with a higher RVBA in eyes with proliferative DR (66.1±16.2 mm2) than in those with non-proliferative DR (56.2±16.6 mm2) or in normal controls (37.2±9.9 mm2). This tendency was also present in the posterior retina and mid-periphery but absent in the far-periphery. RVBA did not correlate with retinal ischaemia (p>0.05).
Conclusions Eyes with DR harboured a larger global RVBA for the entire retina than normal controls, and RVBA appeared to indicate DR severity. However, this biomarker was not observed to be a good indicator of retinal ischaemia.
Data availability statement
All data relevant to the study are included in the article or uploaded as online supplemental information. The data are available from WF (email@example.com).
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Contributors Designed the experiment, conducted the experiment and proofed/revised article: WF and MSI. Analysed/interpreted data: WF. Provided materials: CCW. Wrote the article: WF and MSI.
Funding The research presented herein by WF received support from the National Natural Science Foundation of China (Grant No. 81900863).
Competing interests SS reported receiving grants, personal fees or non-financial support from Carl Zeiss Meditec, Optos, Allergan, Genentech, Alcon, Novartis, Roche, Regeneron, Bayer, Thrombogenics, StemCells Inc and Avalanche. MSI reported receiving grants, personal fees or non-financial support from Thrombogenics, Omeros, Boehringer Ingelheim and Genentech.
Provenance and peer review Not commissioned; externally peer reviewed.