## Abstract

Recently Sicam *et al.* [J. Opt. Soc. Am. A **21**, 1300 (2004)
] presented a new corneal reconstruction algorithm for estimating corneal sag by Zernike polynomials. An equivalent but simpler derivation of the model equations is presented. The algorithm is tested on a sphere, a conic, and a toric. These tests reveal significant height errors that accrue with distance from the corneal apex. Additional postprocessing steps are introduced to circumvent these errors. A consistent and significant reduction in height errors is observed across the test surfaces. Finally, Sicam *et al.* used the conic *p*-value *p* as a measure of algorithm efficacy. Further investigation shows that the finite Zernike representation affected the reported results. The *p*-value should therefore be used with caution as an efficacy measure.

© 2007 Optical Society of America

Full Article | PDF Article**OSA Recommended Articles**

Victor Arni D. P. Sicam, Joris Coppens, Tom J. T. P. van den Berg, and Rob G. L. van der Heijde

J. Opt. Soc. Am. A **21**(7) 1300-1306 (2004)

Jim Schwiegerling, John E. Greivenkamp, and Joseph M. Miller

J. Opt. Soc. Am. A **12**(10) 2105-2113 (1995)

Antonio Guirao and Pablo Artal

J. Opt. Soc. Am. A **17**(6) 955-965 (2000)