Keratotomy Procedures for the Correction of Astigmatism

Seven patterned keratotomy procedures in an enucleated canine model were evaluated. Forty-four of 65 eyes achieved significant keratometry changes; some procedures produced steepening whereas others produced flattening of the meridian 90° away. Greater astigmatic shifts were produced with smaller optical zones. Three of the procedures produced equivalent flattening of the operated meridian without producing significant corneal distortion. We found no consistent relationship between the change in the vertical and horizontal meridian with a given procedure compared with other procedures.