Total aberrations vs. high order aberrations in operated eyes

Human eyes present natural amounts of optical aberrations that can be studied by measuring the eye's wavefront. This measurement can be performed using commercial devices called aberrometers. We developed a simulation tool using MATLAB that reconstructs the eye's wavefront from Zernike's polynomials and calculates different optical functions such as the Point Spread Function (PSF) and the Modulation Transfer Function (MTF). Using Fourier techniques we convoluted the PSF with test images in order to observe the image's degradation induced by the measured aberration. We compared test images of both non operated eyes and operated ones and we evaluated the contribution of high order and total aberrations to visual acuity. We verified that in contrast to the predicted, the simulated images computed from all Zernike's coefficients terms (total aberrations) presented better visual acuity than the ones computed from high order terms (high order aberrations). This was more noticeable for the operated eyes, which presented bigger amounts of spherical aberration. Regarding the modus operandi of the commercial aberrometers, we should not dissociate lower order and high order terms when evaluating the eye's visual acuity since both can balance each other.