An adaptive algorithm for the cornea modeling from keratometric data
For ophthalmologists and biomedical engineers, this provides a more accurate and adaptive method for corneal modeling from keratoscopic data, potentially improving early diagnosis of keratoconus.
The paper presents an adaptive multi-scale algorithm for fitting corneal surface data that adjusts the number of basis functions to each cornea's conditions, achieving exponential error decay independent of aberration level. It outperforms standard Zernike polynomial expansions in real-time reconstruction for early keratoconus detection.
In this paper we describe an adaptive and multi-scale algorithm for the parsimonious fit of the corneal surface data that allows to adapt the number of functions used in the reconstruction to the conditions of each cornea. The method implements also a dynamical selection of the parameters and the management of noise. It can be used for the real-time reconstruction of both altimetric data and corneal power maps from the data collected by keratoscopes, such as the Placido rings based topographers, decisive for an early detection of corneal diseases such as keratoconus. Numerical experiments show that the algorithm exhibits a steady exponential error decay, independently of the level of aberration of the cornea. The complexity of each anisotropic gaussian basis functions in the functional representation is the same, but their parameters vary to fit the current scale. This scale is determined only by the residual errors and not by the number of the iteration. Finally, the position and clustering of their centers, as well as the size of the shape parameters, provides an additional spatial information about the regions of higher irregularity. These results are compared with the standard approximation procedures based on the Zernike polynomials expansions.