Measurement of corneal topography in keratoconus.

A new method is described for calculating the topography and curvature of an irregularly shaped cornea. Vertical planes of light are projected onto the cornea and points in x, y, z space are calculated from the light images on the corneal surface. A matrix of points is produced on the cornea and a mathematical surface is fitted to them. Using differential geometry theory, curvature values are calculated to find the corneal apex position, apex curvature and curvature change away from the apex. Typical results, in the form of a contour map, are shown for normal corneas and corneas with mild to severe keratoconus. The method gives an accurate quantitative measurement of keratoconic and other irregular corneas.