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BACKGROUND AND OBJECTIVE: To evaluate the effect of different image compressio n formats of non-analyzed HeidelbergRetina Tomography(HRT;Heidelberg Engineerin g, Heidelberg, Germany) images on the diagnosis of glaucoma by ophthalmologists. MATERIALS AND METHODS: Thirty three topographic and reflectance images taken wi th the HRT representing different levels of disease were transformed using nine different compression formats. Three independent ophthalmologists, masked as to contour line and stereometric parameters, classified the original and compressed HRT images as normal, suspected glaucoma, or glaucoma, and Kappa agreement coef ficients were calculated. RESULTS: The Tagged Image File Format had the largest file size and the Joint Photographic Experts Group (JPEG) 2000 format had the sm allest size. The highest Kappa coefficient value was 1.00 for all ophthalmologis ts using the Tagged Image File Format. Kappa values for JPEG formats were all in the range of good to excellent agreement. Kappa values were lower for Portable Network Graphic and Graphics Interchange Format compression formats. CONCLUSION: Image compression with JPEG 2000 at a ratio of 20:1 provided sufficient quality for glaucoma analysis in conjunction with a relatively small image size format, and may prove to be attractive for HRT telemedicine applications. Further clini cal studies validating the usefulness of interpreting non-analyzed HRT images a re required.
BACKGROUND AND OBJECTIVE: To evaluate the effect of different images compressio n formats of non-analyzed Heidelberg Retina Tomography (HRT; Heidelberg Engineerin g, Heidelberg, Germany) images on the diagnosis of glaucoma by ophthalmologists. MATERIALS AND METHODS: Thirty three topographic and reflectance images Three independent ophthalmologists, masked as to contour line and stereometric parameters, classified the original and compressed HRT images as normal, Suspected glaucoma, or glaucoma, and Kappa agreement coeficients were calculated. RESULTS: The Tagged Image File Format had the largest file size and the Joint Photographic Experts Group (JPEG) 2000 format had the sm allest size. The highest Kappa coefficient value was 1.00 for all ophthalmologis ts using the Tagged Image File Format. Kappa values for JPEG formats were all in the range of good to excellent agree ment. Kappa values were lower for Portable Network Graphic and Graphics Interchange Format compression formats. CONCLUSION: Image compression with JPEG 2000 at a ratio of 20: 1 provided sufficient quality for glaucoma analysis in conjunction with a relatively small image size format, and may prove To be attractive for HRT telemedicine applications. Further clini cal studies validating the usefulness of interpreting non-analyzed HRT images a re required.