Development of a scale for grading pre-plus and plus disease using retinal images: A pilot study.

When screening infants for retinopathy of prematurity, evaluating posterior pole vascular characteristics (ie, the presence or absence of pre-plus or plus disease) is subjective and prone to error. ROPtool, a semiautomated computer program, measures retinal vessel tortuosity and dilation. In this pilot study, we created an abbreviated pictorial scale of varying vascular tortuosity and dilation based on expert perception of vascular characteristics. We used ROPtool to evaluate the experts' ability to arrange these images in order of increasing vascular tortuosity and dilation. ROPtool values confirmed successful arrangement of images in order of increasing vascular tortuosity and dilation. This pictorial scale could serve as a reference to decrease subjectivity when diagnosing pre-plus or plus disease.