Repeatability and reproducibility of IVAN software measuring retinal vascular caliber

Abstract

Background Retinal vascular caliber changes can reflect the development status of cardiovascular disease and diabetes-associated vascular diseases, so it is very important to quantitatively measure retinal vascular caliber in the study of systemic diseases and retinal vascular disease.However, the methodology study is rately seen in China within our knowledge. Objective The present study was to investigate the repeatability and reproducibility of IVAN software in measuring retinal vascular caliber. Methods This study was approved by Ethic Committee of Affiliated Hospital of Inner Mongolia Medical University, and written informed consent was obtained from each subject prior to medical examination.A prospectively diagnostic trail was performed.The digitized fundus color photograph centered on the disc from 192 eyes of 96 healthy volunteers were collected in Affiliated Hospital of Inner Mongolia Medical University from January, 2013 to December, 2014, and central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE) and arteriovenous ratio (AVR) were analyzed by IVAN measurement software.The repeatability and reproducibility of IVAN software for random repeat measurement of retinal vessel caliber from consecutive 85 right eyes of 85 volunteers were evaluation by interobserver and intraobserver measurement with interclass correlation coefficient (ICC). The correlations of measuring results between two observers or two-time measuring were analyzed with Pearson linear correlation analysis.Bland-Altman agreeement analysis was employed to assess the agreeement of the outcomes. Results No significant differences were found in CRAE, CRVE and AVR between the right eyes and the left eyes (t=-1.009, 1.090, -1.259, all at P>0.05). The CRAE, CRVE and AVR values from observer 1 were (145.02±12.94)μm, (400.72±9.12)μm and 0.36±0.03, and those from observer 2 were (145.10±11.86)μm, (401.17±9.85)μm and 0.36±0.03, with no significant differences between observer 1 and observer 2 (t=-0.074, -0.913, 0.116, all at P>0.05). The repeat CRAE, CRVE and AVR values from observer 1 were (145.02±12.94)μm, (400.72±9.12)μm and 0.36±0.03, which were significantly different from the initial values (t=-0.777, -0.048, -0.745, all at P>0.05). In two-time measurements of intra-observer, all ICC were ≥0.738 and showed good correlations (all at r≥0.739). The two measurements of inter-observer, showed good correlations (r≥0.662), with all ICC ≥0.657.Bland-Altman plots showed good agreements in CRAE and CRVE measurement with 95% limits of agreement(LoA) ranged from -18.5 μm to 17.3 μm and -9.8 μm to 9.6 μm in intraobserver, and from -19.3 μm to 20.0 μm and -10.2 μm to 9.0 μm in interobserver, respectively. Conclusions IVAN measurement software yields good repeatability and reproducibility in the quantitative measurement of retinal vascular caliber. Key words: Vascular caliber, retinal; Biometry; Repeatability; Reproducibility; IVAN software