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Oliver K. Klaproth, Jens Buehren, Kristina Otto, Thomas Kohnen; Repeatability Of The Corneal Wavefront Measurements With Pentacam Hr. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4174.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the repeatability of corneal first-surface Zernike decomposition in normal eyes and eyes with mild keratoconus using the Pentacam HR Scheimpflug topographer (Oculus, Germany).
From 97 normal eyes of 58 patients and 29 eyes of 21 patients with early to moderate keratoconus corneal topography scans were taken with a commercial Scheimpflug system (PentacamTM, Oculus, Germany). Wavefront aberrations from the anterior surface were calculated using a Zernike decomposition up to the 8th order (6 mm pupil diameter, Pentacam Software). From each eye two triplets of measurements were taken. The values were averaged resulting in two measurements. The repeatability of individual Zernike coefficients and corresponding RMS metrics was evaluated with Bland-Altman-Analysis.
The coefficient of repeatability (COR) in the normal eyes group for lower order aberration RMS (LOA RMS) was 0.459 µm, for coma RMS 0.194 µm, the value of spherical aberration (SA RMS) was 0.108 µm, 0.508 µm was the value for all high order aberrations excluding coma and SA (residual HOA RMS). The COR values for the individual coefficients were significantly higher (minimum: 0.04 µm [C62], maximum 0.549 µm [C20]). There were significant higher values in the keratoconus group (LOA RMS: 1.179 µm; HOA RMS: 0.913 µm; coma RMS 0.720 µm; SA RMS: 0.352 µm; residual HOA RMS: 0.202 µm).
The repeatability of Zernike coefficients from corneal wavefront reconstruction with the Pentacam HR was satisfying in normal eyes but questionable in eyes with keratoconus.
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