Dynamic shifts in corneal topography during the modified Ruiz procedure for astigmatism

We utilized ten eye bank eyes to evaluate and quantitate the immediate corneal topographic shifts that occur after each stage of a modified Ruiz procedure for astigmatism. Computer digitization of photokeratoscope (Corneascope) photographs revealed that the initial two central paired tangential incisions induced an average of 5.10 diopters (D) of central astigmatism by flattening the meridian perpendicular to the incisions and by steepening the meridian 90 degrees away. Additional tangential incisions did not significantly alter the topography after placement of the first two central incisions. Addition of corridor incisions produced an additional 5.25 D of induced astigmatism by further extensive flattening of the incised meridian. The completed procedure produced an average of 11.03 D of astigmatic shift, but with a wide range of effect (7.15 to 12.96 D). With modification, the Ruiz procedure is a powerful keratorefractive surgical technique.