Extended field imaging using swept-source optical coherence tomography angiography in retinal vein occlusion
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To evaluate the degree of ischemia in eyes with retinal vein occlusion (RVO) using swept-source optical coherence tomography angiography (SS-OCTA) with the extended field imaging (EFI) technique, which extends the area encompassed by SS-OCTA by scanning through trial frames fitted with a +20-diopter lens.
Retrospective observational study.
Twenty-three consecutive eyes of 22 patients with RVO underwent 12 × 12 mm SS-OCTA imaging both with and without EFI for determination of extension rate. Two graders blinded to the clinical data evaluated the degree of retinal ischemia in paired EFI-SS-OCTA and fluorescein angiography (FA) images, and the concordance rates between the grades were statistically examined.
One EFI-SS-OCTA image was not successfully obtained due to motion artifacts caused by the patient’s poor central vision, while SS-OCTA images without EFI were captured in all 23 eyes. The average extension rate of EFI-SS-OCTA over SS-OCTA was 1.39 ± 0.06 and the average scanning area was enlarged by 76.4%. Two graders evaluated the degree of retinal ischemia by measuring nonperfusion areas as the sum of disc areas/diameters. Although their assessments of the EFI-SS-OCTA images were in complete agreement (Cohen’s Unweighted Kappa coefficient = 1.00), concordance using FA images was only moderate (Cohen’s Unweighted Kappa coefficient = 0.60).
EFI-SS-OCTA noninvasively produces wider field images of retinal vasculature with one capture and provides resolution sufficient to accurately evaluate retinal capillary nonperfusion in RVO.
KeywordsRetinal vein occlusion Optical coherence tomography Optical coherence tomography angiography Capillary nonperfusion Fluorescein angiography
The authors thank Yoshitaka Takano, a certified orthoptist at Shinshu University hospital, for collecting data and other paramedical staff in our team for helping to make this study possible.
Conflicts of interest
S. Kakihara, None; T. Hirano, Lecture fees (Bayer, Novartis, Santen, Zeiss); Y. Iesato, Lecture fees (Bayer, Novartis, Santen); A. Imai, None; Y. Toriyama, Lecture fees (Bayer, Nidek, Novartis); T. Murata, Lecture fees (Bayer, Novartis, Santen, Zeiss).
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