Absence of keratectasia after LASIK in eyes with preoperative central corneal thickness of 450 to 500 microns

PURPOSE: To determine whether preoperative central corneal thickness less than or equal to 500 mu m is an independent risk factor for development of keratectasia following LASIK. METHODS: Chart review was performed for 109 eyes with preoperative central corneal thickness of 452 to 500 mu m in 69 patients who underwent LASIK between September 2000 and July 2005 and had no known risk factors for keratectasia. All eyes included in this analysis had postoperative manifest refractions at follow-up at 1-month and 12-months or greater (median: 452 days; range: 365 to 1980 days). RESULTS: Attempted "correction" (spherical equivalent refraction) ranged from +3.13 to -7.75 diopters. There were no clinical signs of keratectasia at any postoperative visits in the 109 eyes in this Study. There was no statistically significant change in mean spherical equivalent or manifest cylinder from the 1-month follow-up examination to the last documented visit (12 months or greater). No correlation was found for preoperative pachymetry and refractive change between postoperative examinations at 1 month and 12 months or greater. Double-angle vector analysis determined the directional shift in postoperative refractive cylinder was not statistically significant from zero (P>.05). CONCLUSIONS: In this group of 109 LASIK-treated eyes with preoperative central corneal thickness less than or equal to 500 mu m that were screened for known keratectasia risk factors, there was no evidence of postoperative keratectasia.