Modeling the cornea with the topographic modeling system videokeratoscope

The algorithms and models used by the Topographic Modeling System (TMS) corneal topography systems are described. The systems are calibrated to report the power at a number of points along each of 256 meridians. The power reported is the power of an equivalent sphere. From the radius of the equivalent sphere and the optical properties of the videokeratoscope, shape and a more accurate estimate of power are calculated. The TMS differs from most other videokeratoscopic systems in that it estimates the power and does not use axial distance.