Screening for Corneal Topographic Abnormalities before Refractive Surgery Steven E. Wilson, MD, 1 Stephen D. Klyce, PhiY Purpose: The purpose of this prospective study is to evaluate the corneal topog- raphy of patients who sought an opinion regarding refractive surgery for the correction of myopia. Methods: Both eyes of 53 patients were evaluated with a topographic modeling system. Forty-two patients wore contact lenses (84 eyes: 36 rigid contact lenses and 48 soft contact lenses). Ten patients (20 eyes) wore glasses alone and one patient (2 eyes) wore neither glasses nor contact lenses for correction of myopia. Results: Thirty-five (33%) of 106 eyes were found to have abnormal corneal to- pography. Of the 42 patients (84 eyes) who wore contact lenses, 32 eyes (38%) had irregular astigmatism, loss of radial symmetry, or absence of the normal progressive flattening from the center to the periphery of the cornea, consistent with contact lens- induced corneal warpage. Alterations were more frequent and severe in rigid contact lens wearers. Three patients (5. 7%) received a diagnosis of definite keratoconus, a higher incidence than has been reported in the general population. Topographic abnor- malities in most, if not all, of the eyes would not have been detected by visual inspection of the photokeratoscopic images alone. Conclusions: Appropriate preoperative detection and management of corneal to- pographic abnormalities are essential steps in every refractive surgical procedure. The overall efficacy and safety of procedures such as radial keratotomy and photorefractive keratectomy likely will be improved once the unpredictable variables of contact lens- induced warpage and occult ectatic disease are eliminated by topographic screening before surgery. Patients with keratoconus may be over-represented in the refractive surgery population due to self-selection. Ophthalmology 1994;101:147-152 Increasing interest in refractive surgical procedures such Originally received: March 8, 1993. as radial keratotomy and excimer laser photorefractive Revision accepted: June 9, 1993. keratectomy has stimulated greater awareness of the im- 1 Department of Ophthalmology, University of Texas Southwestern portance of monitoring alterations of corneal contour after Medical Center at Dallas, Dallas. surgery. Computed topographic analysis provides infor- 2 LSU Eye Center, Louisiana State University Medical Center School of mation about centration, regular and irregular astigma- Medicine, New Orleans. tism, multifocality, fluctuating vision, and regression. 1 - 3 Supported in part by U.S. Public Health Service grants EY09379 and EY03311 from the National Eye Institute, National Institutes of Health, Detection of subtle, but clinically significant, topographic Bethesda, Maryland, and an unrestricted grant from Research to Prevent details that are provided by keratography are essential for Blindness, Inc, New York, New York. Dr. Wilson is a Research to Prevent evaluating and improving the results of surgery. These Blindness William and Mary Greve International Research Scholar. details frequently are unobtainable with any other mo- Dr. Klyce is a paid consultant to Computed Anatomy, Inc, New York, dality.4 New York. Neither Dr. Wilson nor any of his family members have a Recently, Nesbum and co-workers (unpublished data; proprietary or commercial interest in the instruments used in this study. presented at the 1992 ARVO Annual Meeting) and other Reprint requests to Steven E. Wilson, MD, Department of Ophthal- mology, University of Texas Southwestern Medical Center at Dallas, investigators 5 have increased our awareness of the need 5323 Harry Hines Blvd, Dallas, TX 75235-9057. for preoperative screening of candidates for refractive sur- 147