CORNEAL GEOMETRY RECONSTRUCTION WITH THE KERATRON VIDEOKERATOGRAPHER

Background. Color-coded corneal maps produced by computer-assisted vid eokeratographers (CAVKs) have become an indispensable tool for clinica l understanding of corneal shape. However, Placido-based CAVKs are cri ticized as theoretically incapable of producing accurate corneal heigh t information. Purpose. This paper describes how the Keratron (Optikon 2000, Rome, Italy) integrated design innovations to achieve accuracy and map use previously thought to be unobtainable. Methods. The Keratr on implemented a spherically unbiased surface reconstruction method th at yields height, axial power, and instantaneous curvature without der ivation of one quantity from another. Processing innovations resulted in sub-micron height accuracy. The Keratron includes axial power, inst antaneous curvature, refractive maps, a height map (spherical offset), pupil edge detection, a ''move axis'' feature, process editing, indic es, a contact lens program, and photorefractive keratectomy (PRK) simu lation. Conclusions. The algorithms for surface reconstruction and the design solutions implemented in the Keratron resulted in accurate hei ght, axial power, and instantaneous curvature measurement and valid, c linically useful maps, as well as additional user options and features .