[An algorithm of corneal reconstruction based on precise location of corneal center]

Placido disk is widely used in corneal topography. In order to solve the problem that the convex of the corneal can not be precisely located in the Placido corneal topography system, an algorithm of corneal reconstruction based on the Placido disk was introduced. The key of this method is the calculation of radius of corneal convex by using the innermost ring data. Based on image analysis result, we precisely calculated the radius of corneal convex iteratively by connecting the convex and the first ring using a circle, and then calculated the location of all the reflect point and its power. At last we created the pseudo color map of the human corneal. The corneal was simulated by using standard steel sphere, and the calculating errors of the result were all below 0.25D. It showed that the algorithm used in this work could get relatively accurate powers and would have fair stability.