The skew ray issue in ocular aberration measurement [technical report]

Abstract

I investigated the "skew ray" issue with respect to ocular aberration measurement. This arises for aberrometers that can distinguish only radial components of aberrations. Using simulations and Zernike aberrations, I found that rotationally symmetric coefficients are correctly determined but that asymmetric coefficients are underestimated. This underestimation is more pronounced as radial order of the aberrations becomes smaller and as angular dependence of aberrations becomes greater. There is also "leakage" to other orders, and errors are slightly affected by the sampling pattern. Aberrometers that can distinguish only radial components of aberrations do not provide good estimates of asymmetric aberrations.