Abstract
Purpose: :
Progression of retinal vascular diseases such as hypertensive retinopathy is measured by changes in vascular measurements on imaging. While many studies have reported the effect of disease on retinal vasculature, few have focused on standardizing values. Automated analysis of digital fundus photography offers a way to objectively measure retinal arteriole caliber, retinal venule caliber and retinal arteriole-venule ratio (AVR). The purpose of this study was to determine the effects of age, gender, and eye laterality in the measurement of arteriole and venule caliber.
Methods: :
Clinical data was collected from 1388 patients with nonmydriatic retinal images using a Topcon NW6s digital camera taken during screening examinations at primary care visits. Automated measurements were generated from retinal images using a validated algorithm described previously. All statistical analyses were carried out using JMP software.
Results: :
Of 1388 patients studied, 82% were male, 80% were Caucasian, and there was a mean age of 54.5 years. The majority of patients were free of chronic medical conditions: 32% had a history of smoking, 18% were obese, and 15% had essential hypertension. Significant differences between gender were found with regard to arteriole (OD/OS: p<0.0001/<0.0001) and venule caliber (p=0.0020/0.0018) as well as total venule area (p=0.0032/0.0086), in both eyes. In confirmation with previous studies, increasing AVR correlates with age in right (r=0.09) and left eyes (r=0.15). Additionally, decreasing total arteriole area (OD/OS: r=-0.40/-0.38,), total venule area (r=-0.44/-0.40), arteriole caliber (r=-0.18/-0.16), and venule caliber (r=-0.17/-0.22) correlate with age in left and right eyes. These correlations with age remain statistically significant when variables are stratified by gender. Finally, there were a significant difference between eyes with regard to arteriolar caliber (p=0.0174,0.0386), total arteriolar area (p=0.0316,<0.0001), and AVR (p=0.0220,<0.0001), in females and males respectively.
Conclusions: :
In using metrics such as arteriole caliber, venule caliber and AVR, it is important to recognize the clinically significant effects that age, gender, and laterality have on baseline retinal vascular measurements.
Keywords: retina • imaging/image analysis: clinical • clinical (human) or epidemiologic studies: natural history