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D. K. Wallace, S. Ahmad, S. F. Freedman, Z. Zhao; A Pilot Study Using "ROPtool" to Analyze Video Indirect Ophthalmoscopy Images. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1398.
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We have developed a computer program ("ROPtool") that measures dilation and tortuosity of retinal blood vessels in infants with retinopathy of prematurity (ROP). ROPtool has shown promise in reducing subjectivity of diagnosing pre-plus and plus disease when using images obtained by RetCam fundus photography. Since indirect ophthalmoscopy is the standard for diagnosing ROP, the aim of this pilot study was to determine the feasibility and accuracy of analyzing images with ROPtool which were obtained using video indirect ophthalmoscopy.
Twenty-five posterior pole still images captured from indirect ophthalmoscopy video clips were randomly selected without regard to image quality. One of the authors (SA) used ROPtool to measure tortuosity for each quadrant of each image. Two of the authors (DKW and SFF) independently judged tortuosity on a 10 point scale for each quadrant of each image, and their averaged grades were used as the reference standard to which ROPtool’s results were compared.
ROPtool was able to trace at least two major vessels in 43 of 100 quadrants (43%), and it was able to trace two major vessels in all four quadrants in 6 of 25 images (24%). Lighter fundus pigment color was associated with ROPtool’s ability to analyze images (p = 0.004). When considering only those images for which at least one vessel could be traced in each quadrant, ROPtool’s sensitivity in detecting tortuosity sufficient for plus disease was 100% (3/3) and specificity was 89% (8/9). ROPtool’s sensitivity for pre-plus tortuosity was 100% (4/4) and the specificity was 63% (6/9).
ROPtool is useful for analyzing video indirect ophthalmoscopy images only when applied to the highest quality images. ROPtool has particular difficulty tracing and analyzing images of darkly pigmented fundi. When analyzing high-quality images, it has very good accuracy compared to consensus of experienced examiners.
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