Are Computer-assisted programs for measuring Retinal Vascular Caliber Interchangeable?

Abstract

Purpose: : Changes in retinal vascular caliber reflect early microvascular pathology and may predict ocular and systemic vascular diseases. We compared retinal vascular caliber measurements between two commonly used software: the Singapore I Vessel Assessment (SIVA) and Interactive Vessel Analysis (IVAN).

Methods: : Retinal photographs from the Singapore Chinese Eye Study (SCES), a population-based survey of persons aged 40 to 80 years, were used for this study. A subset of 200 retinal photographs was randomly selected. Retinal arteriolar caliber and venular caliber, summarized as central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE), were measured within a standard zone (from 0.5 to 1.0 disc diameter) by trained graders using both the SIVA (National University of Singapore, version 3.0) and IVAN (University of Wisconsin, Madison) software.Intraclass correlation coefficients (ICC) and Bland Altman plots were used to evaluate the agreement of the measurements between the two software.Associations of CRAE with mean arterial blood pressure (MABP) and CRVE with body mass index (BMI) were evaluated using linear regression. We compared standardized regression coefficients (sβ), with higher sβ value indicating stronger associations with CRAE and CRVE.

Results: : The ICCs were 0.516 (95% CI 0.406 to 0.611) for CRAE and 0.509 (95% CI 0.399 to 0.605) for CRVE between SIVA and IVAN measurements; with mean difference between SIVA and IVAN of -9.1 (95% limit of agreement [LOA] 25.3 to -43.5µm) for CRAE and -8.5 (95% LOA 42.3 to -59.3µm) for CRVE.In the linear regression analysis, after adjusting for age and gender, SIVA CRAE had a stronger association with MABP than IVAN CRAE (sβ: -0.193 vs. -0.159), and SIVA CRVE had stronger association with BMI than IVAN CRVE (sβ: 0.081 vs. 0.009).

Conclusions: : Agreement of retinal vascular caliber measurements between SIVA and IVAN software was only moderate. Retinal vascular calibers measured by SIVA had stronger associations with systemic variables than measurements by IVAN. These findings suggest that the measurements between the computer-assisted software are not interchangeable.

Keywords: imaging/image analysis: clinical • retina • clinical (human) or epidemiologic studies: systems/equipment/techniques