Radial keratotomy: an overview of the Kansas City study

The first 290 consecutive eyes (192 patients) to undergo radial keratotomy by one surgeon were evaluated prospectively. All had had complete preoperative evaluation and 269 (93%) were examined one or more years after surgery. Preoperatively, all patients except one had worse than 20/100 uncorrected visual acuity, 65% had less than 20/400, and mean spherical equivalent (SE) was -4.8 diopters. One year postoperatively, 40% of the patients had uncorrected visual acuity of 20/20 or better and 83% had 20/40 or better. The mean change in SE after 1 year was 5.0 diopters, and 60% of eyes were within 1 diopter of emmetropia. Keratometric changes paralleled refractive changes, and both appeared stable within 1 to 3 months. Complications were few and most were transient or well-tolerated. One case of presumably viral disciform keratitis occurring 8 months postoperatively had a three Snellen line decrease in best-corrected acuity 1 year postoperatively. Factors affecting refractive outcome were studied using stepwise multiple regression analysis. Size of the optical zone, depth of incision, patient age, patient sex, intraocular pressure, number of incisions, preoperative average keratometry, and corneal diameter were each found to affect clinical outcome significantly.