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Ahmad Al-Heeti, Kevin Yum, Dorothy Pham, Samir I Sayegh; Clinical comparison of keratometry measurements between IOL Master vs automated keratometer and IOL Master vs Placido-based topographer. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1628.
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© ARVO (1962-2015); The Authors (2016-present)
To compare keratometry measurements and orientation of pre-operative cataract patients using the IOL Master to to automated keratometry and placido-based topography devices.
K-values of 47 eyes from pre-operative cataract patients, ages ranging from 46 to 90 mean age of 69, were obtained using the IOL Master (IOL Master 500), automated keratometer (HumphreyZeiss 599) and the placido-based topographer (Topcon CA-200F). All patients were sequentially tested with the keratometer followed by the topographer and IOL Master on the same day in order to minimize variability. Mean and standard deviation were calculated, and various keratometry correlation graphs were plotted and analyzed. Each graph consists of equivalent K-values obtained from the IOL master vs keratometer and IOL master vs topographer devices on two separate axes. All correlation coefficients were calculated based on mean and standard deviation obtained from various K-values.
Our preliminary data demonstrate that there were good concordance correlation coefficient in flat K (CCCOD= 0.9528, CCCOS= 0.9631) and (CCCOD= 0.9097, CCCOS= 0.9344), steep K (CCCOD= 0.9515, CCCOS= 0.9277) and (CCCOD= 0.9128, CCCOS= 0.9517), and mean K (CCCOD= 0.9665, CCCOS= 0.9586) and (CCCOD= 0.9197, CCCOS= 0.9565) for IOL master vs keratometer and IOL master vs topographer devices respectively, and also flat K-orientation (CCCOD= 0.9177, CCCOS= 0.871) for IOL master vs keratometer. CCC for variables relevant to toric lenses computations had slightly lesser values. For example ftat K-orientation for IOL master vs topographer was (CCCOD= 0.8923, CCCOS= 0.8026).
As optical biometry becomes a gold standard relied upon for IOL power calculation, it is important to characterize its concordance with instruments that have been relied on for decades. This study takes a step in this direction, illustrating the methods and some preliminary conclusions.
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