| Summary: | Hong Jiang,1,2 Ava-Gaye Simms,1 Shokufeh Sadaghiani,3 Yu You Jiang,4 Jessica IW Morgan,4 Geoffrey K Aguirre,3 Pradip M Pattany,5 John A Detre,2 Jianhua Wang1 1Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; 2Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA; 3Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; 4Scheie Eye Institute and Center for Advanced Retinal and Ocular Therapeutics, Department of Ophthalmology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; 5Department of Radiology, University of Miami Miller School of Medicine, Miami, FL, USACorrespondence: Jianhua Wang, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, 1638 NW 10th Avenue, McKnight Building - Room 202A, Miami, FL, 33136, USA, Tel +1 305 482-5010, Fax +1 305 482-5012, Email jwang3@med.miami.eduBackground/Aims: This study was to determine the test–retest repeatability in quantifying macular capillary perfusion density (CPD, expressed as fractal dimension) using optical coherence tomography angiography (OCTA) in a multi-center setting.Methods: OCTA data were obtained in self-reported healthy subjects from Bascom Palmer Eye Institute at the University of Miami (UM, N = 18) and the University of Pennsylvania (UPenn, N = 22). The right eye of each subject was imaged twice at the first visit and then again at an interval of one week to assess intra-visit and inter-visit repeatability. The macular area of the OCTA-derived capillary perfusion density (OCTA-CPD) was analyzed by custom-made image processing and fractal analysis software. Fractal analysis was performed on the skeletonized microvascular network to yield OCTA-CPD by box-counting to the fractal dimension (Dbox) in the superficial vascular plexus (SVP). Repeatability was assessed by three measures: within-subject standard deviation (Sw), coefficient of variation (CoV) of repeated measures, and intraclass correlation coefficient (ICC).Results: OCTA-CPD from both sites (UM and UPENN) showed good to excellent intra-visit repeatability, as demonstrated by the Sw ≤ 0.004, CoVs ≤ 0.23%, and ICCs ≥ 0.61. Similarly, both sites had good to excellent inter-visit repeatability, as shown by the Sw ≤ 0.005, CoVs ≤ 0.28%, and ICCs ≥ 0.61. The Bland-Altman plots of the intra-visit and inter-visit measurements showed excellent agreements between the paired measurements with minimal biases.Conclusion: Our data showed that comparable high repeatability of OCTA-CPD can be achieved in both research sites using the same device, scan protocol, and image analysis.Keywords: retinal capillary perfusion density, optical coherence tomography angiography, repeatability, multi-center study
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