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Objective refraction from monochromatic wavefront aberrations via Zernike power polynomials.

Robert Iskander D, Davis BA, Collins MJ, Franklin R

Contact Lens and Visual Optics Laboratory, School of Optometry, Queensland University of Technology, Brisbane, Queensland, Australia. d.iskander@qut.edu.au

With the increased popularity of wavefront sensor devices there has been significant interest in relating the subjectively measured sphero-cylindrical refractive error to the objectively measured wavefront aberrations. We investigate the applicability of four different measures for objective refraction assessment that are derived from a set of estimated Zernike wavefront coefficients. Two of the measures are based on the second- and higher-order Zernike polynomials while the other two measures are based on the estimated dioptric power representations. For the latter, closed-form expressions for dioptric powers based on the estimated focal length and the wavefront curvature are derived. We call these two new representations the 'refractive Zernike power polynomials' and 'curvature Zernike power polynomials'. Data from 120 eyes from 60 normal subjects were used to assess the correlation between the subjective and objective refractions. The results indicate that the objective sphero-cylindrical refraction calculated from the estimated refractive power map via the Zernike power polynomials is superior to the other considered representations and achieves best correlation with subjective sphero-cylindrical refraction.

Published 1 May 2007 in Ophthalmic Physiol Opt, 27(3): 245-55.
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