In this paper, we propose an automatic technique for the assessment of retinal vessel caliber in fundus images using a fully automatic technique exploiting a multi-scale active contour technique. The proposed method is compared with the well-known semi-automated ivan software and the vampire width annotation tool. Experimental results show that our approach is able to provide fast and fully automatic caliber measurements with similar caliber measurement and comparable system error as the ivan software. It will benefit the analysis of quantitative retinal vessel caliber measurements in large-scale screening programs