A corneal topography algorithm that produces continuous curvature.

A new method is developed for calculating corneal curvature based on the reflected image of a series of concentric rings (keratoscopy). Previous methods had the drawback that the calculated corneal power was discontinuous in that it changed abruptly at each ring. The present method fits the corneal curvature with a cubic polynomial and produces a continuous estimate of the local power of the cornea. The cubic function also provides a better fit to the corneal curvature than previous methods that used a circle to provide the local fit. The full computer program for the algorithm is presented. Four different definitions of the local dioptric power are discussed.