Evaluation of the percentage tissue altered as a risk factor for developing post-laser in situ keratomileusis ectasia

Purpose To assess the currently recommended percentage tissue altered (PTA) metric for its ability to screen for ectasia after laser in situ keratomileusis (LASIK). Setting Gavin Herbert Eye Institute, University of California, Irvine, California, USA, and Rothschild Foundation, Paris, France. Design Retrospective case series. Methods The study used a LASIK database created by 1 surgeon for LASIK cases with normal preoperative topography that...