A novel method of quantifying retinal vascular tortuosity in retinopathy of prematurity

This study evaluated the diagnostic performance of a novel vessel tracing software that quantifies retinal vessel tortuosity in premature infants for assessing retinopathy of prematurity (ROP). Seventy-three retinal images of premature infants were subjectively classified as having "Normal" or "Abnormal" tortuosity based on arterial tortuosity of the posterior retina by seven clinicians. The software then semi-automatically traced the same arteries within circular regions of interest centered at the optic disc, with radii ranging from 2 to 20x the disc diameters. Vessel tortuosity was defined as the sum of external angles at vessel bend points. Tortuosity was significantly greater in Abnormal images within regions exceeding 4-disc diameters (p < 0.05). Diagnostic accuracy improved with larger regions: the area under the curve increased from 0.56 at 2 times to 0.90 at 8 times and 1.00 at 14 times the diameter. At 14 times, corresponding approximately to Zone I, the software achieved 100% sensitivity and specificity for detecting abnormal tortuosity. The software accurately quantified vessel tortuosity especially within Zone I of the retina, which may reduce inter-observer variability and aid clinicians, including non-specialists, in the evaluation of ROP eyes.