Computerized analysis of narrow-field ROP images for the assessment of vessel caliber and tortuosity.

Retinopathy of prematurity (ROP) is a disease involving abnormal development of retinal vasculature in premature infants, which might eventually lead to retinal detachment and visual loss. The quantitative assessment of vessel morphological features, such as width and tortuosity, can improve the clinical diagnosis and evaluation of ROP. We propose here a computerized system for the vascular analysis of narrow-field premature infant images. It is based on the manual drafting of the vessel axis, followed by automatic Canny filter edge extraction and automatic caliber and tortuosity estimation. We implemented this method as a web-based tool, ROPnet, which allows the quantitative assessment of vessel width and tortuosity simply using a web browser. To test the accuracy of the estimated parameters, fifteen narrow-field (30°) retinal images were acquired in infants with a non-contact fundus camera and analyzed with ROPnet. We compared the results with the corresponding ground-truth values derived from manual analysis. Average widths and tortuosities estimated with ROPnet vs. manual ones showed a correlation coefficient of 0.96 and 0.90, respectively.