Clinical comparison of 6 aberrometers. Part 2: statistical comparison in a test group.

PURPOSE: To compare and mutually validate the measurements of 6 aberrometers: the Visual Function Analyzer (Tracey), the OPD-Scan (ARK-10000, Nidek), the Zywave (Bausch & Lomb), the WASCA (Carl Zeiss Meditec), the MultiSpot Hartmann-Shack device, and the Allegretto Wave Analyzer. SETTING: University Hospital Antwerp, Antwerp, Belgium. METHODS: This prospective study was conducted on a group of 44 healthy eyes with refractions ranging from -5.25 diopters (D) to +5.25 D (cylinder 0 to -2 D). For each aberrometer and each eye, the averaged Zernike data were used to calculate various kinds of root-mean-square (RMS). These parameters, together with the refractive parameters, were then analyzed with a repeated-measures analysis of variance (ANOVA) test, complemented by paired t tests. A similar analysis was done for the comparison of the variances of these parameters. RESULTS: The aberrometers gave comparable values for all studied parameters with the following exceptions: The OPD-Scan underestimated the polynomials describing 4- and 5-fold symmetries, and the Visual Function Analyzer slightly overestimated the astigmatism terms. The 3rd-order radial RMS value was different for each device, as well as the RMS in the central 2.0 mm zone. The WASCA presented the lowest variance. CONCLUSION: These results suggest that in healthy eyes, all aberrometers produced globally similar results but they may vary in some details.

Clinical comparison of 6 aberrometers. Part 1: Technical specifications.

PURPOSE: To provide a detailed assessment of the techniques, technical features, and practical use of 6 aberrometers made available to our institution from September 2002 to January 2004. SETTING: Department of Ophthalmology, University Hospital Antwerp, Antwerp, Belgium. METHODS: A number of technical and practical parameters are listed for the Visual Function Analyzer (Tracey), the OPD-scan (ARK 10000; Nidek), the Zywave (Bausch & Lomb), the WASCA (Carl Zeiss Meditec), the MultiSpot Hartmann-Shack device, and the Allegretto Wave Analyzer including working principles, data acquisition, aberrometer alignment, wavefront calculation, and data analysis. Operator and patient comfort as well as practical advantages and disadvantages are discussed. CONCLUSION: All devices met at least half the following parameters: alignment, correction for source wavelength, data averaging, measurement quality check, and inhibition of accommodation.