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S. Knapp, S.T. Awwad, J.P. McCulley; A Comparison of Higher Order Aberration Measurements by the Fourier–Driven WaveScan and the Zernicke–Driven LADARWave Hartmann–Shack Aberrometers . Invest. Ophthalmol. Vis. Sci. 2006;47(13):537.
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© ARVO (1962-2015); The Authors (2016-present)
To compare higher and lower order aberrations measurements by two Hartmann–Shack aberrometers which use different algorithms in wavefront processing.
Ocular aberrations were measured on 33 eyes of 17 patients using the WaveScan and LADARWave aberrometers at an optical zone of 6.0 mm. Pupil size was controlled using a tunable light intensity source and checked using infrared pupillometry before aberration measurement. Individual aberrations were compared between the two devices using the mean of arithmetic and absolute differences, Bland–Altman plots, and vector analysis for directional aberrations.
Average absolute defocus and astigmatism were 2.90+/–2.79 RMS and 0.82+/–0.49 RMS, respectively for WaveScan and 3.11+/–3.32 RMS and 0.87+/–0.57 RMS for LADARWave. The pearson correlation coefficient for defocus and astigmatism as measured by the two devices were 0.806 and 0.870, respectively (P<0.001 for both). The average total higher order aberrations (HOAs) was 0.44+/–0.18 RMS for WaveScan and 0.49+/–0.19 RMS for LADARWave. The mean absolute spherical aberration for the WaveScan was 0.18+/–0.11 RMS, as opposed to 0.24+/–0.17 RMS for the LADARWave. Pearson correlation coefficient between the two devices was 0.673 for total HOAs, and 0.613 for spherical aberration (P<0.001 for both). The mean absolute difference was 0.11+/–0.11 RMS (24.4%) for total HOAs and 0.12+/–0.08 RMS (57.8%) for spherical aberration. Bland–Altman plots showed that the magnitude of the difference of measurements by the two devices for both total HOAs and spherical aberration was independent of the aberration magnitude. Vector analysis revealed that the mean coma vector for WaveScan was 0.06+/–0.02 RMS X 62° vs 0.13+/–0.02 RMS X 59° for LADARWave, and mean trefoil vector was 0.11+/–0.02 RMS X 78° for WaveScan vs 0.14 +/–0.03 RMS X 84° for LADARWave. The mean vector difference between the two devices was 0.07+/–0.03 X 57° for coma, and 0.03 +/– 0.01 X 104° for trefoil. The pearson coefficient for the arithmetic coma values was 0.374 (P=0.032), and 0.727 for trefoil (P<0.001).
The Fourier–driven WaveScan and the Zernicke–driven LADARWave display very similar lower order aberrations measurements, but significantly different higher order aberrations measurements, especially spherical aberration and coma.
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