Correlation between radius and asphericity in surfaces fitted by conics

摘要

The optical surfaces of the eye are often described in terms of their radius and asphericity. The variationsncaused by experimental noise in repeated measurements of radius and asphericity of the same surface arenstrongly correlated. We show this correlation in experimental corneal elevation data from videokeratoscopynand Scheimpflug topography, in non-contact profilometry data of artificial lenses, and in simulations. The effectnis a characteristic of the fits to conic curves, and not restricted to any experimental device or fitting procedure.nA separate analysis of radius and asphericity may estimate incorrectly the statistical significance of thenchanges in the ocular surfaces. We propose a MANOVA-based statistical analysis that increases sensitivity byna factor of 4. © 2010 Optical Society of America