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H. Ishikawa, H. Ishikawa, G. Wollstein, M.L. Gabriele, A.A. Bonfioli, W.D. Dilworth, Z. Burgansky, R.J. Noecker, J.S. Schuman; Red Free Images Converted From Regular Color Disk Photos Helps to Detect Nerve Fiber Bundle Defect . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2492.
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To test a newly developed method of converting color disk photo images into pseudo red free (RF) images (forced RF) in terms of helping ophthalmologists find nerve fiber bundle defect (NFBD) in comparison with conventional RF photos.
A software program was developed to convert color disk photo images into forced RF images by removing the red channel information and halving the intensity of the blue channel. Contrast and brightness were automatically adjusted based on image histogram. Color disk photo images and conventional RF photo images taken from the same normal or glaucomatous eyes on the same day were exported to an IBM compatible PC from our ocular imaging database. Color images, including scanned color slides and digital photos, were converted to forced RF images using the software described above. Two glaucoma specialists and two ophthalmology residents were asked to find any visible NFBD in a randomized masked fashion. To eliminate the possibility of reading NFBD by observing the shape of optic disk, optic disk area was masked by monochromatic circle. Color images were shown first, followed by forced RF and then conventional RF images.
Thirteen images of ten subjects (3 normal, 8 glaucoma with focal defects, and 2 glaucoma with diffuse damage) were enrolled in this study. Subjects were selected in a consecutive and retrospective fashion from our ocular imaging database. Forced RF helped glaucoma specialists find NFBD on an average of 1 eye (7.7%), while it helped residents on an average of 2 eyes (15.4%). All participants agreed that subjectively there was significant improvement in finding NFBD on forced RF images in comparison with color images. Additionally, all agreed that conventional RF images were superior to forced RF images.
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