Background: Plus disease is abnormal retinal vascular dilation and tortuosity, and it is now the primary indication for laser treatment in retinopathy of prematurity (ROP). ROPtool is a computer program that measures retinal arteriolar tortuosity. Our aim was to assess the accuracy of ROPtool's newly developed measurement of retinal vascular width (dilation).
Methods: ROPtool was used to measure the width of 154 blood vessels in 20 high-quality RetCam images from 20 premature infants. ROPtool's accuracy was determined by comparing results with the mean grades of 2 authors who scored retinal vascular dilation using a 10-point scale.
Results: There was very good correlation (r = 0.80) between ROPtool's measurement of retinal vascular dilation and author judgment. Areas under receiver operating characteristics curves for identification of dilation sufficient for plus disease and for pre-plus disease were 0.93 and 0.90, respectively. At an optimal point on the receiver operating characteristics curve, ROPtool's sensitivity for diagnosing dilation sufficient for plus disease was 89% (24/27), and its specificity was 83% (106/127).
Conclusion: In addition to measuring retinal vascular tortuosity, ROPtool now accurately measures retinal vascular width in high-quality RetCam images. Application of this technology has the potential to remove subjectivity from the assessment of plus disease.