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A Methodological Approach to Non-invasive Assessments of Vascular Function and Morphology
Published on: February 7, 2015
Comparison between methods of vascular calibre characterization and measurement protocols: Influence of vessels
Asmae Igalla-El Youssfi1, José Manuel López-Alonso2
1Formerly Optics Department, Faculty of Optics and Optometry, University Complutense of Madrid, C/ Arcos de Jalón, 118, 28037, Madrid, Spain.
Insights
Optimizing retinal vascular calibre measurements is key for assessing microvascular health. This study recommends using five or six vessels for accurate central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) calculations, ensuring reliable diagnostic decisions.
Area of Science:
- Ophthalmology and Cardiovascular Research
- Biomarkers and Diagnostic Methods
Background:
- Retinal vascular calibre is a crucial non-invasive biomarker for microvascular health in ophthalmology and systemic disease research.
- Methodological questions persist regarding the optimal number of vessels for calculation and agreement between Parr-Hubbard and Knudtson formulas.
Purpose of the Study:
- To analyze agreement between Parr-Hubbard and Knudtson formulas for retinal vascular calibre estimation.
- To evaluate the influence of vessel count on central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and arteriovenous ratio (AVR) calculations.
Main Methods:
- Bland-Altman analysis, interclass correlation coefficient (ICC), and Pearson coefficient were employed.
- Accuracy and reliability were assessed for varying numbers of analyzed retinal vessels.
Main Results:
- Formula agreement improves with fewer analyzed vessels.
- Reducing vessel count impacts CRAE and CRVE accuracy.
- Arteriovenous ratio (AVR) using the Parr-Hubbard formula shows stability despite increased variability with fewer vessels.
Conclusions:
- Using five or six retinal vessels is recommended for reliable CRAE and CRVE measurements.
- Fewer than five vessels may necessitate additional diagnostic indicators for accurate clinical decisions.
Abstract:
In recent years, retinal vascular calibre has emerged as an important non-invasive biomarker of microvascular health, widely used in ophthalmology for the detection and monitoring of various ocular diseases and has attracted growing interest in the study of various systemic diseases. However, significant methodological questions remain regarding the precise number of vessels to include in the calculation, as well as the agreement between the two most widely used formulas for estimating the retinal vascular calibre: the Parr-Hubbard formula and the Knudtson formula. The aim of this study is to provide evidence regarding these issues by analysing the agreement between both formulas and evaluating the influence of the number of vessels included in the calculation of retinal vascular calibre: central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and the arteriovenous ratio (AVR). Bland-Altman analysis, the interclass correlation coefficient (ICC), and the Pearson coefficient were used to analyse the accuracy and reliability of the measurements for different number of vessels. The results indicate that the agreement between both formulas improves as the number of analysed vessels decreases. Reducing the number of vessels analysed affects the accuracy of the CRAE and CRVE parameters calculated with both formulas. In contrast, the AVR calculated using the Parr-Hubbard formula remains more stable, even though the reproduction coefficient (RPC) and limits of agreement (LOA) values increase as the number of analysed vessels decreases. Therefore, using six or five vessels is recommended; if fewer are analysed, diagnostic decisions should be supported by additional tests and indicators.
