Abstract
Purpose: :
a standard way of recovery of the corneal surface and aberrometry, based on a fitting by Zernike polynomials, lacks precision in the case of complex corneas. The goal is to devise a reliable and robust alternative for reconstruction and modeling of the front surface of the cornea from the data offered by videokeratometers, both based on Placido discs and on Scheimpflug cameras.
Methods: :
A combined method is used based on an initial reconstruction of low precision, and a further adaptive and multiscale fit by means of the Gaussian radial basis functions. The shape parameters of the Gaussians, chosen dynamically in dependence of the data, constitute an important additional source of information about the corneal irregularity.
Results: :
several synthetic corneas have been reconstructed from the data, both on the whole disc and on its subset (incomplete data, simulating common situations in the clinical practice). The method was applied also to the recovery of real complicated corneas (as those from patients treated with presbilasik), comparing the results, both in terms of precision and computational cost, with the fit given by the Zernike expansion of high order.
Conclusions: :
although simple corneas are easily reconstructed with any reasonable technique currently used, in more complicated cases we could appreciate the robustness and effectiveness of the proposed method, as well as its capability to recover small irregularities on the anterior surface of the cornea, which eventually could be relevant both for a diagnosis of pathologies in an early stage and for a customized treatment of the cornea.
Keywords: topography • refractive surgery: corneal topography • cornea: basic science